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-rw-r--r--synapse/__init__.py2
-rw-r--r--synapse/api/errors.py11
-rw-r--r--synapse/app/appservice.py50
-rw-r--r--synapse/app/client_reader.py22
-rw-r--r--synapse/app/federation_reader.py22
-rw-r--r--synapse/app/federation_sender.py193
-rwxr-xr-xsynapse/app/homeserver.py19
-rw-r--r--synapse/app/media_repository.py22
-rw-r--r--synapse/app/pusher.py122
-rw-r--r--synapse/app/synchrotron.py367
-rwxr-xr-xsynapse/app/synctl.py8
-rw-r--r--synapse/appservice/__init__.py38
-rw-r--r--synapse/config/emailconfig.py16
-rw-r--r--synapse/config/registration.py1
-rw-r--r--synapse/config/server.py12
-rw-r--r--synapse/config/voip.py8
-rw-r--r--synapse/config/workers.py4
-rw-r--r--synapse/events/snapshot.py3
-rw-r--r--synapse/events/utils.py23
-rw-r--r--synapse/federation/federation_client.py50
-rw-r--r--synapse/federation/federation_server.py10
-rw-r--r--synapse/federation/send_queue.py375
-rw-r--r--synapse/federation/transaction_queue.py95
-rw-r--r--synapse/federation/transport/client.py40
-rw-r--r--synapse/federation/transport/server.py9
-rw-r--r--synapse/handlers/_base.py34
-rw-r--r--synapse/handlers/device.py29
-rw-r--r--synapse/handlers/e2e_keys.py86
-rw-r--r--synapse/handlers/federation.py125
-rw-r--r--synapse/handlers/identity.py11
-rw-r--r--synapse/handlers/message.py37
-rw-r--r--synapse/handlers/presence.py218
-rw-r--r--synapse/handlers/profile.py2
-rw-r--r--synapse/handlers/read_marker.py64
-rw-r--r--synapse/handlers/register.py7
-rw-r--r--synapse/handlers/room.py2
-rw-r--r--synapse/handlers/room_member.py27
-rw-r--r--synapse/handlers/typing.py7
-rw-r--r--synapse/http/client.py58
-rw-r--r--synapse/http/matrixfederationclient.py21
-rw-r--r--synapse/notifier.py34
-rw-r--r--synapse/push/bulk_push_rule_evaluator.py6
-rw-r--r--synapse/push/mailer.py6
-rw-r--r--synapse/push/push_tools.py7
-rw-r--r--synapse/replication/expire_cache.py60
-rw-r--r--synapse/replication/presence_resource.py59
-rw-r--r--synapse/replication/pusher_resource.py54
-rw-r--r--synapse/replication/resource.py576
-rw-r--r--synapse/replication/slave/storage/_base.py31
-rw-r--r--synapse/replication/slave/storage/account_data.py49
-rw-r--r--synapse/replication/slave/storage/deviceinbox.py23
-rw-r--r--synapse/replication/slave/storage/devices.py24
-rw-r--r--synapse/replication/slave/storage/events.py64
-rw-r--r--synapse/replication/slave/storage/presence.py29
-rw-r--r--synapse/replication/slave/storage/push_rule.py23
-rw-r--r--synapse/replication/slave/storage/pushers.py16
-rw-r--r--synapse/replication/slave/storage/receipts.py24
-rw-r--r--synapse/replication/slave/storage/room.py11
-rw-r--r--synapse/replication/tcp/__init__.py30
-rw-r--r--synapse/replication/tcp/client.py196
-rw-r--r--synapse/replication/tcp/commands.py346
-rw-r--r--synapse/replication/tcp/protocol.py640
-rw-r--r--synapse/replication/tcp/resource.py290
-rw-r--r--synapse/replication/tcp/streams.py464
-rw-r--r--synapse/rest/__init__.py2
-rw-r--r--synapse/rest/client/v1/directory.py6
-rw-r--r--synapse/rest/client/v1/room.py9
-rw-r--r--synapse/rest/client/v1/voip.py5
-rw-r--r--synapse/rest/client/v2_alpha/_base.py10
-rw-r--r--synapse/rest/client/v2_alpha/account_data.py9
-rw-r--r--synapse/rest/client/v2_alpha/filter.py6
-rw-r--r--synapse/rest/client/v2_alpha/read_marker.py66
-rw-r--r--synapse/rest/client/v2_alpha/register.py42
-rw-r--r--synapse/rest/client/v2_alpha/sync.py5
-rw-r--r--synapse/rest/client/v2_alpha/thirdparty.py8
-rw-r--r--synapse/rest/key/v2/local_key_resource.py5
-rw-r--r--synapse/rest/media/v1/media_repository.py4
-rw-r--r--synapse/server.py9
-rw-r--r--synapse/state.py11
-rw-r--r--synapse/storage/_base.py8
-rw-r--r--synapse/storage/background_updates.py98
-rw-r--r--synapse/storage/client_ips.py4
-rw-r--r--synapse/storage/deviceinbox.py11
-rw-r--r--synapse/storage/devices.py31
-rw-r--r--synapse/storage/end_to_end_keys.py56
-rw-r--r--synapse/storage/events.py249
-rw-r--r--synapse/storage/push_rule.py13
-rw-r--r--synapse/storage/pusher.py42
-rw-r--r--synapse/storage/receipts.py11
-rw-r--r--synapse/storage/room.py36
-rw-r--r--synapse/storage/roommember.py149
-rw-r--r--synapse/storage/schema/delta/37/remove_auth_idx.py4
-rw-r--r--synapse/storage/schema/delta/41/event_search_event_id_idx.sql17
-rw-r--r--synapse/storage/schema/delta/41/ratelimit.sql22
-rw-r--r--synapse/storage/state.py60
-rw-r--r--synapse/types.py10
-rw-r--r--synapse/util/__init__.py2
-rw-r--r--synapse/util/async.py7
-rw-r--r--synapse/util/caches/__init__.py31
-rw-r--r--synapse/util/caches/descriptors.py128
-rw-r--r--synapse/util/logcontext.py6
-rw-r--r--synapse/util/stringutils.py14
-rw-r--r--synapse/visibility.py3
103 files changed, 4530 insertions, 1991 deletions
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 2e5f4e0ead..2a40bab3f0 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -16,4 +16,4 @@
 """ This is a reference implementation of a Matrix home server.
 """
 
-__version__ = "0.20.0"
+__version__ = "0.21.0"
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 6fbd5d6876..d0dfa959dc 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -66,6 +66,17 @@ class CodeMessageException(RuntimeError):
         return cs_error(self.msg)
 
 
+class MatrixCodeMessageException(CodeMessageException):
+    """An error from a general matrix endpoint, eg. from a proxied Matrix API call.
+
+    Attributes:
+        errcode (str): Matrix error code e.g 'M_FORBIDDEN'
+    """
+    def __init__(self, code, msg, errcode=Codes.UNKNOWN):
+        super(MatrixCodeMessageException, self).__init__(code, msg)
+        self.errcode = errcode
+
+
 class SynapseError(CodeMessageException):
     """A base exception type for matrix errors which have an errcode and error
     message (as well as an HTTP status code).
diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index a6f1e7594e..9a476efa63 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -26,17 +26,17 @@ from synapse.replication.slave.storage.directory import DirectoryStore
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.appservice import SlavedApplicationServiceStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.storage.engines import create_engine
-from synapse.util.async import sleep
 from synapse.util.httpresourcetree import create_resource_tree
-from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext, preserve_fn
 from synapse.util.manhole import manhole
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
 
 from synapse import events
 
-from twisted.internet import reactor, defer
+from twisted.internet import reactor
 from twisted.web.resource import Resource
 
 from daemonize import Daemonize
@@ -120,30 +120,25 @@ class AppserviceServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
-    @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
-        appservice_handler = self.get_application_service_handler()
-
-        @defer.inlineCallbacks
-        def replicate(results):
-            stream = results.get("events")
-            if stream:
-                max_stream_id = stream["position"]
-                yield appservice_handler.notify_interested_services(max_stream_id)
-
-        while True:
-            try:
-                args = store.stream_positions()
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-                replicate(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(30)
+        self.get_tcp_replication().start_replication(self)
+
+    def build_tcp_replication(self):
+        return ASReplicationHandler(self)
+
+
+class ASReplicationHandler(ReplicationClientHandler):
+    def __init__(self, hs):
+        super(ASReplicationHandler, self).__init__(hs.get_datastore())
+        self.appservice_handler = hs.get_application_service_handler()
+
+    def on_rdata(self, stream_name, token, rows):
+        super(ASReplicationHandler, self).on_rdata(stream_name, token, rows)
+
+        if stream_name == "events":
+            max_stream_id = self.store.get_room_max_stream_ordering()
+            preserve_fn(
+                self.appservice_handler.notify_interested_services
+            )(max_stream_id)
 
 
 def start(config_options):
@@ -199,7 +194,6 @@ def start(config_options):
             reactor.run()
 
     def start():
-        ps.replicate()
         ps.get_datastore().start_profiling()
         ps.get_state_handler().start_caching()
 
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index e4ea3ab933..9b72c649ac 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -30,11 +30,11 @@ from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.slave.storage.directory import DirectoryStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.slave.storage.transactions import TransactionStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.client.v1.room import PublicRoomListRestServlet
 from synapse.server import HomeServer
 from synapse.storage.client_ips import ClientIpStore
 from synapse.storage.engines import create_engine
-from synapse.util.async import sleep
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 from synapse.util.manhole import manhole
@@ -45,7 +45,7 @@ from synapse.crypto import context_factory
 from synapse import events
 
 
-from twisted.internet import reactor, defer
+from twisted.internet import reactor
 from twisted.web.resource import Resource
 
 from daemonize import Daemonize
@@ -145,21 +145,10 @@ class ClientReaderServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
-    @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
+        self.get_tcp_replication().start_replication(self)
 
-        while True:
-            try:
-                args = store.stream_positions()
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(5)
+    def build_tcp_replication(self):
+        return ReplicationClientHandler(self.get_datastore())
 
 
 def start(config_options):
@@ -209,7 +198,6 @@ def start(config_options):
     def start():
         ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
-        ss.replicate()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index e52b0f240d..eb392e1c9d 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -27,9 +27,9 @@ from synapse.replication.slave.storage.keys import SlavedKeyStore
 from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.slave.storage.transactions import TransactionStore
 from synapse.replication.slave.storage.directory import DirectoryStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
 from synapse.storage.engines import create_engine
-from synapse.util.async import sleep
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 from synapse.util.manhole import manhole
@@ -42,7 +42,7 @@ from synapse.crypto import context_factory
 from synapse import events
 
 
-from twisted.internet import reactor, defer
+from twisted.internet import reactor
 from twisted.web.resource import Resource
 
 from daemonize import Daemonize
@@ -134,21 +134,10 @@ class FederationReaderServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
-    @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
+        self.get_tcp_replication().start_replication(self)
 
-        while True:
-            try:
-                args = store.stream_positions()
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(5)
+    def build_tcp_replication(self):
+        return ReplicationClientHandler(self.get_datastore())
 
 
 def start(config_options):
@@ -198,7 +187,6 @@ def start(config_options):
     def start():
         ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
-        ss.replicate()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 76c4cc54d1..e51a69074d 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -23,19 +23,19 @@ from synapse.config.homeserver import HomeServerConfig
 from synapse.crypto import context_factory
 from synapse.http.site import SynapseSite
 from synapse.federation import send_queue
-from synapse.federation.units import Edu
 from synapse.metrics.resource import MetricsResource, METRICS_PREFIX
 from synapse.replication.slave.storage.deviceinbox import SlavedDeviceInboxStore
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
+from synapse.replication.slave.storage.presence import SlavedPresenceStore
 from synapse.replication.slave.storage.transactions import TransactionStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.storage.engines import create_engine
-from synapse.storage.presence import UserPresenceState
-from synapse.util.async import sleep
+from synapse.util.async import Linearizer
 from synapse.util.httpresourcetree import create_resource_tree
-from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext, preserve_fn
 from synapse.util.manhole import manhole
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
@@ -50,16 +50,36 @@ from daemonize import Daemonize
 import sys
 import logging
 import gc
-import ujson as json
 
 logger = logging.getLogger("synapse.app.appservice")
 
 
 class FederationSenderSlaveStore(
     SlavedDeviceInboxStore, TransactionStore, SlavedReceiptsStore, SlavedEventStore,
-    SlavedRegistrationStore, SlavedDeviceStore,
+    SlavedRegistrationStore, SlavedDeviceStore, SlavedPresenceStore,
 ):
-    pass
+    def __init__(self, db_conn, hs):
+        super(FederationSenderSlaveStore, self).__init__(db_conn, hs)
+
+        # We pull out the current federation stream position now so that we
+        # always have a known value for the federation position in memory so
+        # that we don't have to bounce via a deferred once when we start the
+        # replication streams.
+        self.federation_out_pos_startup = self._get_federation_out_pos(db_conn)
+
+    def _get_federation_out_pos(self, db_conn):
+        sql = (
+            "SELECT stream_id FROM federation_stream_position"
+            " WHERE type = ?"
+        )
+        sql = self.database_engine.convert_param_style(sql)
+
+        txn = db_conn.cursor()
+        txn.execute(sql, ("federation",))
+        rows = txn.fetchall()
+        txn.close()
+
+        return rows[0][0] if rows else -1
 
 
 class FederationSenderServer(HomeServer):
@@ -127,26 +147,27 @@ class FederationSenderServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
-    @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
-        send_handler = FederationSenderHandler(self)
-
-        send_handler.on_start()
-
-        while True:
-            try:
-                args = store.stream_positions()
-                args.update((yield send_handler.stream_positions()))
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-                yield send_handler.process_replication(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(30)
+        self.get_tcp_replication().start_replication(self)
+
+    def build_tcp_replication(self):
+        return FederationSenderReplicationHandler(self)
+
+
+class FederationSenderReplicationHandler(ReplicationClientHandler):
+    def __init__(self, hs):
+        super(FederationSenderReplicationHandler, self).__init__(hs.get_datastore())
+        self.send_handler = FederationSenderHandler(hs, self)
+
+    def on_rdata(self, stream_name, token, rows):
+        super(FederationSenderReplicationHandler, self).on_rdata(
+            stream_name, token, rows
+        )
+        self.send_handler.process_replication_rows(stream_name, token, rows)
+
+    def get_streams_to_replicate(self):
+        args = super(FederationSenderReplicationHandler, self).get_streams_to_replicate()
+        args.update(self.send_handler.stream_positions())
+        return args
 
 
 def start(config_options):
@@ -205,7 +226,6 @@ def start(config_options):
             reactor.run()
 
     def start():
-        ps.replicate()
         ps.get_datastore().start_profiling()
         ps.get_state_handler().start_caching()
 
@@ -229,9 +249,15 @@ class FederationSenderHandler(object):
     """Processes the replication stream and forwards the appropriate entries
     to the federation sender.
     """
-    def __init__(self, hs):
+    def __init__(self, hs, replication_client):
         self.store = hs.get_datastore()
         self.federation_sender = hs.get_federation_sender()
+        self.replication_client = replication_client
+
+        self.federation_position = self.store.federation_out_pos_startup
+        self._fed_position_linearizer = Linearizer(name="_fed_position_linearizer")
+
+        self._last_ack = self.federation_position
 
         self._room_serials = {}
         self._room_typing = {}
@@ -243,98 +269,35 @@ class FederationSenderHandler(object):
             self.store.get_room_max_stream_ordering()
         )
 
-    @defer.inlineCallbacks
     def stream_positions(self):
-        stream_id = yield self.store.get_federation_out_pos("federation")
-        defer.returnValue({
-            "federation": stream_id,
+        return {"federation": self.federation_position}
 
-            # Ack stuff we've "processed", this should only be called from
-            # one process.
-            "federation_ack": stream_id,
-        })
-
-    @defer.inlineCallbacks
-    def process_replication(self, result):
+    def process_replication_rows(self, stream_name, token, rows):
         # The federation stream contains things that we want to send out, e.g.
         # presence, typing, etc.
-        fed_stream = result.get("federation")
-        if fed_stream:
-            latest_id = int(fed_stream["position"])
-
-            # The federation stream containis a bunch of different types of
-            # rows that need to be handled differently. We parse the rows, put
-            # them into the appropriate collection and then send them off.
-            presence_to_send = {}
-            keyed_edus = {}
-            edus = {}
-            failures = {}
-            device_destinations = set()
-
-            # Parse the rows in the stream
-            for row in fed_stream["rows"]:
-                position, typ, content_js = row
-                content = json.loads(content_js)
-
-                if typ == send_queue.PRESENCE_TYPE:
-                    destination = content["destination"]
-                    state = UserPresenceState.from_dict(content["state"])
-
-                    presence_to_send.setdefault(destination, []).append(state)
-                elif typ == send_queue.KEYED_EDU_TYPE:
-                    key = content["key"]
-                    edu = Edu(**content["edu"])
-
-                    keyed_edus.setdefault(
-                        edu.destination, {}
-                    )[(edu.destination, tuple(key))] = edu
-                elif typ == send_queue.EDU_TYPE:
-                    edu = Edu(**content)
-
-                    edus.setdefault(edu.destination, []).append(edu)
-                elif typ == send_queue.FAILURE_TYPE:
-                    destination = content["destination"]
-                    failure = content["failure"]
-
-                    failures.setdefault(destination, []).append(failure)
-                elif typ == send_queue.DEVICE_MESSAGE_TYPE:
-                    device_destinations.add(content["destination"])
-                else:
-                    raise Exception("Unrecognised federation type: %r", typ)
-
-            # We've finished collecting, send everything off
-            for destination, states in presence_to_send.items():
-                self.federation_sender.send_presence(destination, states)
-
-            for destination, edu_map in keyed_edus.items():
-                for key, edu in edu_map.items():
-                    self.federation_sender.send_edu(
-                        edu.destination, edu.edu_type, edu.content, key=key,
-                    )
-
-            for destination, edu_list in edus.items():
-                for edu in edu_list:
-                    self.federation_sender.send_edu(
-                        edu.destination, edu.edu_type, edu.content, key=None,
-                    )
-
-            for destination, failure_list in failures.items():
-                for failure in failure_list:
-                    self.federation_sender.send_failure(destination, failure)
-
-            for destination in device_destinations:
-                self.federation_sender.send_device_messages(destination)
-
-            # Record where we are in the stream.
-            yield self.store.update_federation_out_pos(
-                "federation", latest_id
-            )
+        if stream_name == "federation":
+            send_queue.process_rows_for_federation(self.federation_sender, rows)
+            preserve_fn(self.update_token)(token)
 
         # We also need to poke the federation sender when new events happen
-        event_stream = result.get("events")
-        if event_stream:
-            latest_pos = event_stream["position"]
-            self.federation_sender.notify_new_events(latest_pos)
+        elif stream_name == "events":
+            self.federation_sender.notify_new_events(token)
+
+    @defer.inlineCallbacks
+    def update_token(self, token):
+        self.federation_position = token
+
+        # We linearize here to ensure we don't have races updating the token
+        with (yield self._fed_position_linearizer.queue(None)):
+            if self._last_ack < self.federation_position:
+                yield self.store.update_federation_out_pos(
+                    "federation", self.federation_position
+                )
+
+                # We ACK this token over replication so that the master can drop
+                # its in memory queues
+                self.replication_client.send_federation_ack(self.federation_position)
+                self._last_ack = self.federation_position
 
 
 if __name__ == '__main__':
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 2cdd2d39ff..3457402596 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -25,7 +25,7 @@ import synapse.config.logger
 from synapse.config._base import ConfigError
 
 from synapse.python_dependencies import (
-    check_requirements, DEPENDENCY_LINKS
+    check_requirements, CONDITIONAL_REQUIREMENTS
 )
 
 from synapse.rest import ClientRestResource
@@ -55,7 +55,7 @@ from synapse.crypto import context_factory
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 from synapse.metrics import register_memory_metrics, get_metrics_for
 from synapse.metrics.resource import MetricsResource, METRICS_PREFIX
-from synapse.replication.resource import ReplicationResource, REPLICATION_PREFIX
+from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
 from synapse.federation.transport.server import TransportLayerServer
 
 from synapse.util.rlimit import change_resource_limit
@@ -92,7 +92,7 @@ def build_resource_for_web_client(hs):
                 "\n"
                 "You can also disable hosting of the webclient via the\n"
                 "configuration option `web_client`\n"
-                % {"dep": DEPENDENCY_LINKS["matrix-angular-sdk"]}
+                % {"dep": CONDITIONAL_REQUIREMENTS["web_client"].keys()[0]}
             )
         syweb_path = os.path.dirname(syweb.__file__)
         webclient_path = os.path.join(syweb_path, "webclient")
@@ -166,9 +166,6 @@ class SynapseHomeServer(HomeServer):
                 if name == "metrics" and self.get_config().enable_metrics:
                     resources[METRICS_PREFIX] = MetricsResource(self)
 
-                if name == "replication":
-                    resources[REPLICATION_PREFIX] = ReplicationResource(self)
-
         if WEB_CLIENT_PREFIX in resources:
             root_resource = RootRedirect(WEB_CLIENT_PREFIX)
         else:
@@ -222,6 +219,16 @@ class SynapseHomeServer(HomeServer):
                         ),
                         interface=address
                     )
+            elif listener["type"] == "replication":
+                bind_addresses = listener["bind_addresses"]
+                for address in bind_addresses:
+                    factory = ReplicationStreamProtocolFactory(self)
+                    server_listener = reactor.listenTCP(
+                        listener["port"], factory, interface=address
+                    )
+                    reactor.addSystemEventTrigger(
+                        "before", "shutdown", server_listener.stopListening,
+                    )
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index 1444e69a42..26c4416956 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -25,13 +25,13 @@ from synapse.replication.slave.storage._base import BaseSlavedStore
 from synapse.replication.slave.storage.appservice import SlavedApplicationServiceStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.slave.storage.transactions import TransactionStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.media.v0.content_repository import ContentRepoResource
 from synapse.rest.media.v1.media_repository import MediaRepositoryResource
 from synapse.server import HomeServer
 from synapse.storage.client_ips import ClientIpStore
 from synapse.storage.engines import create_engine
 from synapse.storage.media_repository import MediaRepositoryStore
-from synapse.util.async import sleep
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 from synapse.util.manhole import manhole
@@ -45,7 +45,7 @@ from synapse.crypto import context_factory
 from synapse import events
 
 
-from twisted.internet import reactor, defer
+from twisted.internet import reactor
 from twisted.web.resource import Resource
 
 from daemonize import Daemonize
@@ -142,21 +142,10 @@ class MediaRepositoryServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
-    @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
+        self.get_tcp_replication().start_replication(self)
 
-        while True:
-            try:
-                args = store.stream_positions()
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(5)
+    def build_tcp_replication(self):
+        return ReplicationClientHandler(self.get_datastore())
 
 
 def start(config_options):
@@ -206,7 +195,6 @@ def start(config_options):
     def start():
         ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
-        ss.replicate()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index ab682e52ec..f9114acfcb 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -27,9 +27,9 @@ from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.pushers import SlavedPusherStore
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 from synapse.replication.slave.storage.account_data import SlavedAccountDataStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.storage.engines import create_engine
 from synapse.storage import DataStore
-from synapse.util.async import sleep
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, preserve_fn, \
     PreserveLoggingContext
@@ -89,7 +89,6 @@ class PusherSlaveStore(
 
 
 class PusherServer(HomeServer):
-
     def get_db_conn(self, run_new_connection=True):
         # Any param beginning with cp_ is a parameter for adbapi, and should
         # not be passed to the database engine.
@@ -109,16 +108,7 @@ class PusherServer(HomeServer):
         logger.info("Finished setting up.")
 
     def remove_pusher(self, app_id, push_key, user_id):
-        http_client = self.get_simple_http_client()
-        replication_url = self.config.worker_replication_url
-        url = replication_url + "/remove_pushers"
-        return http_client.post_json_get_json(url, {
-            "remove": [{
-                "app_id": app_id,
-                "push_key": push_key,
-                "user_id": user_id,
-            }]
-        })
+        self.get_tcp_replication().send_remove_pusher(app_id, push_key, user_id)
 
     def _listen_http(self, listener_config):
         port = listener_config["port"]
@@ -166,73 +156,52 @@ class PusherServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
+        self.get_tcp_replication().start_replication(self)
+
+    def build_tcp_replication(self):
+        return PusherReplicationHandler(self)
+
+
+class PusherReplicationHandler(ReplicationClientHandler):
+    def __init__(self, hs):
+        super(PusherReplicationHandler, self).__init__(hs.get_datastore())
+
+        self.pusher_pool = hs.get_pusherpool()
+
+    def on_rdata(self, stream_name, token, rows):
+        super(PusherReplicationHandler, self).on_rdata(stream_name, token, rows)
+        preserve_fn(self.poke_pushers)(stream_name, token, rows)
+
     @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
-        pusher_pool = self.get_pusherpool()
-
-        def stop_pusher(user_id, app_id, pushkey):
-            key = "%s:%s" % (app_id, pushkey)
-            pushers_for_user = pusher_pool.pushers.get(user_id, {})
-            pusher = pushers_for_user.pop(key, None)
-            if pusher is None:
-                return
-            logger.info("Stopping pusher %r / %r", user_id, key)
-            pusher.on_stop()
-
-        def start_pusher(user_id, app_id, pushkey):
-            key = "%s:%s" % (app_id, pushkey)
-            logger.info("Starting pusher %r / %r", user_id, key)
-            return pusher_pool._refresh_pusher(app_id, pushkey, user_id)
-
-        @defer.inlineCallbacks
-        def poke_pushers(results):
-            pushers_rows = set(
-                map(tuple, results.get("pushers", {}).get("rows", []))
+    def poke_pushers(self, stream_name, token, rows):
+        if stream_name == "pushers":
+            for row in rows:
+                if row.deleted:
+                    yield self.stop_pusher(row.user_id, row.app_id, row.pushkey)
+                else:
+                    yield self.start_pusher(row.user_id, row.app_id, row.pushkey)
+        elif stream_name == "events":
+            yield self.pusher_pool.on_new_notifications(
+                token, token,
             )
-            deleted_pushers_rows = set(
-                map(tuple, results.get("deleted_pushers", {}).get("rows", []))
+        elif stream_name == "receipts":
+            yield self.pusher_pool.on_new_receipts(
+                token, token, set(row.room_id for row in rows)
             )
-            for row in sorted(pushers_rows | deleted_pushers_rows):
-                if row in deleted_pushers_rows:
-                    user_id, app_id, pushkey = row[1:4]
-                    stop_pusher(user_id, app_id, pushkey)
-                elif row in pushers_rows:
-                    user_id = row[1]
-                    app_id = row[5]
-                    pushkey = row[8]
-                    yield start_pusher(user_id, app_id, pushkey)
-
-            stream = results.get("events")
-            if stream and stream["rows"]:
-                min_stream_id = stream["rows"][0][0]
-                max_stream_id = stream["position"]
-                preserve_fn(pusher_pool.on_new_notifications)(
-                    min_stream_id, max_stream_id
-                )
-
-            stream = results.get("receipts")
-            if stream and stream["rows"]:
-                rows = stream["rows"]
-                affected_room_ids = set(row[1] for row in rows)
-                min_stream_id = rows[0][0]
-                max_stream_id = stream["position"]
-                preserve_fn(pusher_pool.on_new_receipts)(
-                    min_stream_id, max_stream_id, affected_room_ids
-                )
-
-        while True:
-            try:
-                args = store.stream_positions()
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-                poke_pushers(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(30)
+
+    def stop_pusher(self, user_id, app_id, pushkey):
+        key = "%s:%s" % (app_id, pushkey)
+        pushers_for_user = self.pusher_pool.pushers.get(user_id, {})
+        pusher = pushers_for_user.pop(key, None)
+        if pusher is None:
+            return
+        logger.info("Stopping pusher %r / %r", user_id, key)
+        pusher.on_stop()
+
+    def start_pusher(self, user_id, app_id, pushkey):
+        key = "%s:%s" % (app_id, pushkey)
+        logger.info("Starting pusher %r / %r", user_id, key)
+        return self.pusher_pool._refresh_pusher(app_id, pushkey, user_id)
 
 
 def start(config_options):
@@ -288,7 +257,6 @@ def start(config_options):
             reactor.run()
 
     def start():
-        ps.replicate()
         ps.get_pusherpool().start()
         ps.get_datastore().start_profiling()
         ps.get_state_handler().start_caching()
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 34e34e5580..13c00ef2ba 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -16,11 +16,11 @@
 
 import synapse
 
-from synapse.api.constants import EventTypes, PresenceState
+from synapse.api.constants import EventTypes
 from synapse.config._base import ConfigError
 from synapse.config.homeserver import HomeServerConfig
 from synapse.config.logger import setup_logging
-from synapse.handlers.presence import PresenceHandler
+from synapse.handlers.presence import PresenceHandler, get_interested_parties
 from synapse.http.site import SynapseSite
 from synapse.http.server import JsonResource
 from synapse.metrics.resource import MetricsResource, METRICS_PREFIX
@@ -40,15 +40,14 @@ from synapse.replication.slave.storage.presence import SlavedPresenceStore
 from synapse.replication.slave.storage.deviceinbox import SlavedDeviceInboxStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.room import RoomStore
+from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
 from synapse.storage.client_ips import ClientIpStore
 from synapse.storage.engines import create_engine
-from synapse.storage.presence import PresenceStore, UserPresenceState
+from synapse.storage.presence import UserPresenceState
 from synapse.storage.roommember import RoomMemberStore
-from synapse.util.async import sleep
 from synapse.util.httpresourcetree import create_resource_tree
-from synapse.util.logcontext import LoggingContext, preserve_fn, \
-    PreserveLoggingContext
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext, preserve_fn
 from synapse.util.manhole import manhole
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.stringutils import random_string
@@ -63,7 +62,6 @@ import sys
 import logging
 import contextlib
 import gc
-import ujson as json
 
 logger = logging.getLogger("synapse.app.synchrotron")
 
@@ -91,27 +89,17 @@ class SynchrotronSlavedStore(
         RoomMemberStore.__dict__["did_forget"]
     )
 
-    # XXX: This is a bit broken because we don't persist the accepted list in a
-    # way that can be replicated. This means that we don't have a way to
-    # invalidate the cache correctly.
-    get_presence_list_accepted = PresenceStore.__dict__[
-        "get_presence_list_accepted"
-    ]
-    get_presence_list_observers_accepted = PresenceStore.__dict__[
-        "get_presence_list_observers_accepted"
-    ]
-
 
 UPDATE_SYNCING_USERS_MS = 10 * 1000
 
 
 class SynchrotronPresence(object):
     def __init__(self, hs):
+        self.hs = hs
         self.is_mine_id = hs.is_mine_id
         self.http_client = hs.get_simple_http_client()
         self.store = hs.get_datastore()
         self.user_to_num_current_syncs = {}
-        self.syncing_users_url = hs.config.worker_replication_url + "/syncing_users"
         self.clock = hs.get_clock()
         self.notifier = hs.get_notifier()
 
@@ -121,17 +109,52 @@ class SynchrotronPresence(object):
             for state in active_presence
         }
 
-        self.process_id = random_string(16)
-        logger.info("Presence process_id is %r", self.process_id)
+        # user_id -> last_sync_ms. Lists the users that have stopped syncing
+        # but we haven't notified the master of that yet
+        self.users_going_offline = {}
 
-        self._sending_sync = False
-        self._need_to_send_sync = False
-        self.clock.looping_call(
-            self._send_syncing_users_regularly,
-            UPDATE_SYNCING_USERS_MS,
+        self._send_stop_syncing_loop = self.clock.looping_call(
+            self.send_stop_syncing, 10 * 1000
         )
 
-        reactor.addSystemEventTrigger("before", "shutdown", self._on_shutdown)
+        self.process_id = random_string(16)
+        logger.info("Presence process_id is %r", self.process_id)
+
+    def send_user_sync(self, user_id, is_syncing, last_sync_ms):
+        self.hs.get_tcp_replication().send_user_sync(user_id, is_syncing, last_sync_ms)
+
+    def mark_as_coming_online(self, user_id):
+        """A user has started syncing. Send a UserSync to the master, unless they
+        had recently stopped syncing.
+
+        Args:
+            user_id (str)
+        """
+        going_offline = self.users_going_offline.pop(user_id, None)
+        if not going_offline:
+            # Safe to skip because we haven't yet told the master they were offline
+            self.send_user_sync(user_id, True, self.clock.time_msec())
+
+    def mark_as_going_offline(self, user_id):
+        """A user has stopped syncing. We wait before notifying the master as
+        its likely they'll come back soon. This allows us to avoid sending
+        a stopped syncing immediately followed by a started syncing notification
+        to the master
+
+        Args:
+            user_id (str)
+        """
+        self.users_going_offline[user_id] = self.clock.time_msec()
+
+    def send_stop_syncing(self):
+        """Check if there are any users who have stopped syncing a while ago
+        and haven't come back yet. If there are poke the master about them.
+        """
+        now = self.clock.time_msec()
+        for user_id, last_sync_ms in self.users_going_offline.items():
+            if now - last_sync_ms > 10 * 1000:
+                self.users_going_offline.pop(user_id, None)
+                self.send_user_sync(user_id, False, last_sync_ms)
 
     def set_state(self, user, state, ignore_status_msg=False):
         # TODO Hows this supposed to work?
@@ -139,18 +162,16 @@ class SynchrotronPresence(object):
 
     get_states = PresenceHandler.get_states.__func__
     get_state = PresenceHandler.get_state.__func__
-    _get_interested_parties = PresenceHandler._get_interested_parties.__func__
     current_state_for_users = PresenceHandler.current_state_for_users.__func__
 
-    @defer.inlineCallbacks
     def user_syncing(self, user_id, affect_presence):
         if affect_presence:
             curr_sync = self.user_to_num_current_syncs.get(user_id, 0)
             self.user_to_num_current_syncs[user_id] = curr_sync + 1
-            prev_states = yield self.current_state_for_users([user_id])
-            if prev_states[user_id].state == PresenceState.OFFLINE:
-                # TODO: Don't block the sync request on this HTTP hit.
-                yield self._send_syncing_users_now()
+
+            # If we went from no in flight sync to some, notify replication
+            if self.user_to_num_current_syncs[user_id] == 1:
+                self.mark_as_coming_online(user_id)
 
         def _end():
             # We check that the user_id is in user_to_num_current_syncs because
@@ -159,6 +180,10 @@ class SynchrotronPresence(object):
             if affect_presence and user_id in self.user_to_num_current_syncs:
                 self.user_to_num_current_syncs[user_id] -= 1
 
+                # If we went from one in flight sync to non, notify replication
+                if self.user_to_num_current_syncs[user_id] == 0:
+                    self.mark_as_going_offline(user_id)
+
         @contextlib.contextmanager
         def _user_syncing():
             try:
@@ -166,56 +191,12 @@ class SynchrotronPresence(object):
             finally:
                 _end()
 
-        defer.returnValue(_user_syncing())
-
-    @defer.inlineCallbacks
-    def _on_shutdown(self):
-        # When the synchrotron is shutdown tell the master to clear the in
-        # progress syncs for this process
-        self.user_to_num_current_syncs.clear()
-        yield self._send_syncing_users_now()
-
-    def _send_syncing_users_regularly(self):
-        # Only send an update if we aren't in the middle of sending one.
-        if not self._sending_sync:
-            preserve_fn(self._send_syncing_users_now)()
-
-    @defer.inlineCallbacks
-    def _send_syncing_users_now(self):
-        if self._sending_sync:
-            # We don't want to race with sending another update.
-            # Instead we wait for that update to finish and send another
-            # update afterwards.
-            self._need_to_send_sync = True
-            return
-
-        # Flag that we are sending an update.
-        self._sending_sync = True
-
-        yield self.http_client.post_json_get_json(self.syncing_users_url, {
-            "process_id": self.process_id,
-            "syncing_users": [
-                user_id for user_id, count in self.user_to_num_current_syncs.items()
-                if count > 0
-            ],
-        })
-
-        # Unset the flag as we are no longer sending an update.
-        self._sending_sync = False
-        if self._need_to_send_sync:
-            # If something happened while we were sending the update then
-            # we might need to send another update.
-            # TODO: Check if the update that was sent matches the current state
-            # as we only need to send an update if they are different.
-            self._need_to_send_sync = False
-            yield self._send_syncing_users_now()
+        return defer.succeed(_user_syncing())
 
     @defer.inlineCallbacks
     def notify_from_replication(self, states, stream_id):
-        parties = yield self._get_interested_parties(
-            states, calculate_remote_hosts=False
-        )
-        room_ids_to_states, users_to_states, _ = parties
+        parties = yield get_interested_parties(self.store, states)
+        room_ids_to_states, users_to_states = parties
 
         self.notifier.on_new_event(
             "presence_key", stream_id, rooms=room_ids_to_states.keys(),
@@ -223,26 +204,24 @@ class SynchrotronPresence(object):
         )
 
     @defer.inlineCallbacks
-    def process_replication(self, result):
-        stream = result.get("presence", {"rows": []})
-        states = []
-        for row in stream["rows"]:
-            (
-                position, user_id, state, last_active_ts,
-                last_federation_update_ts, last_user_sync_ts, status_msg,
-                currently_active
-            ) = row
-            state = UserPresenceState(
-                user_id, state, last_active_ts,
-                last_federation_update_ts, last_user_sync_ts, status_msg,
-                currently_active
-            )
-            self.user_to_current_state[user_id] = state
-            states.append(state)
+    def process_replication_rows(self, token, rows):
+        states = [UserPresenceState(
+            row.user_id, row.state, row.last_active_ts,
+            row.last_federation_update_ts, row.last_user_sync_ts, row.status_msg,
+            row.currently_active
+        ) for row in rows]
+
+        for state in states:
+            self.user_to_current_state[row.user_id] = state
+
+        stream_id = token
+        yield self.notify_from_replication(states, stream_id)
 
-        if states and "position" in stream:
-            stream_id = int(stream["position"])
-            yield self.notify_from_replication(states, stream_id)
+    def get_currently_syncing_users(self):
+        return [
+            user_id for user_id, count in self.user_to_num_current_syncs.iteritems()
+            if count > 0
+        ]
 
 
 class SynchrotronTyping(object):
@@ -257,16 +236,12 @@ class SynchrotronTyping(object):
         # value which we *must* use for the next replication request.
         return {"typing": self._latest_room_serial}
 
-    def process_replication(self, result):
-        stream = result.get("typing")
-        if stream:
-            self._latest_room_serial = int(stream["position"])
+    def process_replication_rows(self, token, rows):
+        self._latest_room_serial = token
 
-            for row in stream["rows"]:
-                position, room_id, typing_json = row
-                typing = json.loads(typing_json)
-                self._room_serials[room_id] = position
-                self._room_typing[room_id] = typing
+        for row in rows:
+            self._room_serials[row.room_id] = token
+            self._room_typing[row.room_id] = row.user_ids
 
 
 class SynchrotronApplicationService(object):
@@ -351,124 +326,89 @@ class SynchrotronServer(HomeServer):
             else:
                 logger.warn("Unrecognized listener type: %s", listener["type"])
 
-    @defer.inlineCallbacks
-    def replicate(self):
-        http_client = self.get_simple_http_client()
-        store = self.get_datastore()
-        replication_url = self.config.worker_replication_url
-        notifier = self.get_notifier()
-        presence_handler = self.get_presence_handler()
-        typing_handler = self.get_typing_handler()
-
-        def notify_from_stream(
-            result, stream_name, stream_key, room=None, user=None
-        ):
-            stream = result.get(stream_name)
-            if stream:
-                position_index = stream["field_names"].index("position")
-                if room:
-                    room_index = stream["field_names"].index(room)
-                if user:
-                    user_index = stream["field_names"].index(user)
-
-                users = ()
-                rooms = ()
-                for row in stream["rows"]:
-                    position = row[position_index]
-
-                    if user:
-                        users = (row[user_index],)
-
-                    if room:
-                        rooms = (row[room_index],)
-
-                    notifier.on_new_event(
-                        stream_key, position, users=users, rooms=rooms
-                    )
+        self.get_tcp_replication().start_replication(self)
 
-        @defer.inlineCallbacks
-        def notify_device_list_update(result):
-            stream = result.get("device_lists")
-            if not stream:
-                return
+    def build_tcp_replication(self):
+        return SyncReplicationHandler(self)
 
-            position_index = stream["field_names"].index("position")
-            user_index = stream["field_names"].index("user_id")
+    def build_presence_handler(self):
+        return SynchrotronPresence(self)
 
-            for row in stream["rows"]:
-                position = row[position_index]
-                user_id = row[user_index]
+    def build_typing_handler(self):
+        return SynchrotronTyping(self)
 
-                room_ids = yield store.get_rooms_for_user(user_id)
 
-                notifier.on_new_event(
-                    "device_list_key", position, rooms=room_ids,
-                )
+class SyncReplicationHandler(ReplicationClientHandler):
+    def __init__(self, hs):
+        super(SyncReplicationHandler, self).__init__(hs.get_datastore())
 
-        @defer.inlineCallbacks
-        def notify(result):
-            stream = result.get("events")
-            if stream:
-                max_position = stream["position"]
-
-                event_map = yield store.get_events([row[1] for row in stream["rows"]])
-
-                for row in stream["rows"]:
-                    position = row[0]
-                    event_id = row[1]
-                    event = event_map.get(event_id, None)
-                    if not event:
-                        continue
-
-                    extra_users = ()
-                    if event.type == EventTypes.Member:
-                        extra_users = (event.state_key,)
-                    notifier.on_new_room_event(
-                        event, position, max_position, extra_users
-                    )
+        self.store = hs.get_datastore()
+        self.typing_handler = hs.get_typing_handler()
+        self.presence_handler = hs.get_presence_handler()
+        self.notifier = hs.get_notifier()
 
-            notify_from_stream(
-                result, "push_rules", "push_rules_key", user="user_id"
-            )
-            notify_from_stream(
-                result, "user_account_data", "account_data_key", user="user_id"
-            )
-            notify_from_stream(
-                result, "room_account_data", "account_data_key", user="user_id"
+        self.presence_handler.sync_callback = self.send_user_sync
+
+    def on_rdata(self, stream_name, token, rows):
+        super(SyncReplicationHandler, self).on_rdata(stream_name, token, rows)
+
+        preserve_fn(self.process_and_notify)(stream_name, token, rows)
+
+    def get_streams_to_replicate(self):
+        args = super(SyncReplicationHandler, self).get_streams_to_replicate()
+        args.update(self.typing_handler.stream_positions())
+        return args
+
+    def get_currently_syncing_users(self):
+        return self.presence_handler.get_currently_syncing_users()
+
+    @defer.inlineCallbacks
+    def process_and_notify(self, stream_name, token, rows):
+        if stream_name == "events":
+            # We shouldn't get multiple rows per token for events stream, so
+            # we don't need to optimise this for multiple rows.
+            for row in rows:
+                event = yield self.store.get_event(row.event_id)
+                extra_users = ()
+                if event.type == EventTypes.Member:
+                    extra_users = (event.state_key,)
+                max_token = self.store.get_room_max_stream_ordering()
+                self.notifier.on_new_room_event(
+                    event, token, max_token, extra_users
+                )
+        elif stream_name == "push_rules":
+            self.notifier.on_new_event(
+                "push_rules_key", token, users=[row.user_id for row in rows],
             )
-            notify_from_stream(
-                result, "tag_account_data", "account_data_key", user="user_id"
+        elif stream_name in ("account_data", "tag_account_data",):
+            self.notifier.on_new_event(
+                "account_data_key", token, users=[row.user_id for row in rows],
             )
-            notify_from_stream(
-                result, "receipts", "receipt_key", room="room_id"
+        elif stream_name == "receipts":
+            self.notifier.on_new_event(
+                "receipt_key", token, rooms=[row.room_id for row in rows],
             )
-            notify_from_stream(
-                result, "typing", "typing_key", room="room_id"
+        elif stream_name == "typing":
+            self.typing_handler.process_replication_rows(token, rows)
+            self.notifier.on_new_event(
+                "typing_key", token, rooms=[row.room_id for row in rows],
             )
-            notify_from_stream(
-                result, "to_device", "to_device_key", user="user_id"
+        elif stream_name == "to_device":
+            entities = [row.entity for row in rows if row.entity.startswith("@")]
+            if entities:
+                self.notifier.on_new_event(
+                    "to_device_key", token, users=entities,
+                )
+        elif stream_name == "device_lists":
+            all_room_ids = set()
+            for row in rows:
+                room_ids = yield self.store.get_rooms_for_user(row.user_id)
+                all_room_ids.update(room_ids)
+            self.notifier.on_new_event(
+                "device_list_key", token, rooms=all_room_ids,
             )
-            yield notify_device_list_update(result)
-
-        while True:
-            try:
-                args = store.stream_positions()
-                args.update(typing_handler.stream_positions())
-                args["timeout"] = 30000
-                result = yield http_client.get_json(replication_url, args=args)
-                yield store.process_replication(result)
-                typing_handler.process_replication(result)
-                yield presence_handler.process_replication(result)
-                yield notify(result)
-            except:
-                logger.exception("Error replicating from %r", replication_url)
-                yield sleep(5)
-
-    def build_presence_handler(self):
-        return SynchrotronPresence(self)
-
-    def build_typing_handler(self):
-        return SynchrotronTyping(self)
+        elif stream_name == "presence":
+            yield self.presence_handler.process_replication_rows(token, rows)
 
 
 def start(config_options):
@@ -514,7 +454,6 @@ def start(config_options):
 
     def start():
         ss.get_datastore().start_profiling()
-        ss.replicate()
         ss.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
diff --git a/synapse/app/synctl.py b/synapse/app/synctl.py
index 23eb6a1ec4..3bd7ef7bba 100755
--- a/synapse/app/synctl.py
+++ b/synapse/app/synctl.py
@@ -125,7 +125,7 @@ def main():
         "configfile",
         nargs="?",
         default="homeserver.yaml",
-        help="the homeserver config file, defaults to homserver.yaml",
+        help="the homeserver config file, defaults to homeserver.yaml",
     )
     parser.add_argument(
         "-w", "--worker",
@@ -202,7 +202,8 @@ def main():
         worker_app = worker_config["worker_app"]
         worker_pidfile = worker_config["worker_pid_file"]
         worker_daemonize = worker_config["worker_daemonize"]
-        assert worker_daemonize  # TODO print something more user friendly
+        assert worker_daemonize, "In config %r: expected '%s' to be True" % (
+            worker_configfile, "worker_daemonize")
         worker_cache_factor = worker_config.get("synctl_cache_factor")
         workers.append(Worker(
             worker_app, worker_configfile, worker_pidfile, worker_cache_factor,
@@ -233,6 +234,9 @@ def main():
 
     if action == "start" or action == "restart":
         if start_stop_synapse:
+            # Check if synapse is already running
+            if os.path.exists(pidfile) and pid_running(int(open(pidfile).read())):
+                abort("synapse.app.homeserver already running")
             start(configfile)
 
         for worker in workers:
diff --git a/synapse/appservice/__init__.py b/synapse/appservice/__init__.py
index b0106a3597..7346206bb1 100644
--- a/synapse/appservice/__init__.py
+++ b/synapse/appservice/__init__.py
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 from synapse.api.constants import EventTypes
+from synapse.util.caches.descriptors import cachedInlineCallbacks
 
 from twisted.internet import defer
 
@@ -124,29 +125,23 @@ class ApplicationService(object):
                     raise ValueError(
                         "Expected bool for 'exclusive' in ns '%s'" % ns
                     )
-                if not isinstance(regex_obj.get("regex"), basestring):
+                regex = regex_obj.get("regex")
+                if isinstance(regex, basestring):
+                    regex_obj["regex"] = re.compile(regex)  # Pre-compile regex
+                else:
                     raise ValueError(
                         "Expected string for 'regex' in ns '%s'" % ns
                     )
         return namespaces
 
-    def _matches_regex(self, test_string, namespace_key, return_obj=False):
-        if not isinstance(test_string, basestring):
-            logger.error(
-                "Expected a string to test regex against, but got %s",
-                test_string
-            )
-            return False
-
+    def _matches_regex(self, test_string, namespace_key):
         for regex_obj in self.namespaces[namespace_key]:
-            if re.match(regex_obj["regex"], test_string):
-                if return_obj:
-                    return regex_obj
-                return True
-        return False
+            if regex_obj["regex"].match(test_string):
+                return regex_obj
+        return None
 
     def _is_exclusive(self, ns_key, test_string):
-        regex_obj = self._matches_regex(test_string, ns_key, return_obj=True)
+        regex_obj = self._matches_regex(test_string, ns_key)
         if regex_obj:
             return regex_obj["exclusive"]
         return False
@@ -166,7 +161,14 @@ class ApplicationService(object):
         if not store:
             defer.returnValue(False)
 
-        member_list = yield store.get_users_in_room(event.room_id)
+        does_match = yield self._matches_user_in_member_list(event.room_id, store)
+        defer.returnValue(does_match)
+
+    @cachedInlineCallbacks(num_args=1, cache_context=True)
+    def _matches_user_in_member_list(self, room_id, store, cache_context):
+        member_list = yield store.get_users_in_room(
+            room_id, on_invalidate=cache_context.invalidate
+        )
 
         # check joined member events
         for user_id in member_list:
@@ -219,10 +221,10 @@ class ApplicationService(object):
         )
 
     def is_interested_in_alias(self, alias):
-        return self._matches_regex(alias, ApplicationService.NS_ALIASES)
+        return bool(self._matches_regex(alias, ApplicationService.NS_ALIASES))
 
     def is_interested_in_room(self, room_id):
-        return self._matches_regex(room_id, ApplicationService.NS_ROOMS)
+        return bool(self._matches_regex(room_id, ApplicationService.NS_ROOMS))
 
     def is_exclusive_user(self, user_id):
         return (
diff --git a/synapse/config/emailconfig.py b/synapse/config/emailconfig.py
index 0030b5db1e..fe156b6930 100644
--- a/synapse/config/emailconfig.py
+++ b/synapse/config/emailconfig.py
@@ -71,6 +71,15 @@ class EmailConfig(Config):
             self.email_riot_base_url = email_config.get(
                 "riot_base_url", None
             )
+            self.email_smtp_user = email_config.get(
+                "smtp_user", None
+            )
+            self.email_smtp_pass = email_config.get(
+                "smtp_pass", None
+            )
+            self.require_transport_security = email_config.get(
+                "require_transport_security", False
+            )
             if "app_name" in email_config:
                 self.email_app_name = email_config["app_name"]
             else:
@@ -91,10 +100,17 @@ class EmailConfig(Config):
         # Defining a custom URL for Riot is only needed if email notifications
         # should contain links to a self-hosted installation of Riot; when set
         # the "app_name" setting is ignored.
+        #
+        # If your SMTP server requires authentication, the optional smtp_user &
+        # smtp_pass variables should be used
+        #
         #email:
         #   enable_notifs: false
         #   smtp_host: "localhost"
         #   smtp_port: 25
+        #   smtp_user: "exampleusername"
+        #   smtp_pass: "examplepassword"
+        #   require_transport_security: False
         #   notif_from: "Your Friendly %(app)s Home Server <noreply@example.com>"
         #   app_name: Matrix
         #   template_dir: res/templates
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index 87e500c97a..f7e03c4cde 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -69,6 +69,7 @@ class RegistrationConfig(Config):
         trusted_third_party_id_servers:
             - matrix.org
             - vector.im
+            - riot.im
         """ % locals()
 
     def add_arguments(self, parser):
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 1f9999d57a..3910b9dc31 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -35,6 +35,8 @@ class ServerConfig(Config):
         # "disable" federation
         self.send_federation = config.get("send_federation", True)
 
+        self.filter_timeline_limit = config.get("filter_timeline_limit", -1)
+
         if self.public_baseurl is not None:
             if self.public_baseurl[-1] != '/':
                 self.public_baseurl += '/'
@@ -144,6 +146,12 @@ class ServerConfig(Config):
         # Whether to serve a web client from the HTTP/HTTPS root resource.
         web_client: True
 
+        # The root directory to server for the above web client.
+        # If left undefined, synapse will serve the matrix-angular-sdk web client.
+        # Make sure matrix-angular-sdk is installed with pip if web_client is True
+        # and web_client_location is undefined
+        # web_client_location: "/path/to/web/root"
+
         # The public-facing base URL for the client API (not including _matrix/...)
         # public_baseurl: https://example.com:8448/
 
@@ -155,6 +163,10 @@ class ServerConfig(Config):
         # The GC threshold parameters to pass to `gc.set_threshold`, if defined
         # gc_thresholds: [700, 10, 10]
 
+        # Set the limit on the returned events in the timeline in the get
+        # and sync operations. The default value is -1, means no upper limit.
+        # filter_timeline_limit: 5000
+
         # List of ports that Synapse should listen on, their purpose and their
         # configuration.
         listeners:
diff --git a/synapse/config/voip.py b/synapse/config/voip.py
index eeb693027b..3a4e16fa96 100644
--- a/synapse/config/voip.py
+++ b/synapse/config/voip.py
@@ -23,6 +23,7 @@ class VoipConfig(Config):
         self.turn_username = config.get("turn_username")
         self.turn_password = config.get("turn_password")
         self.turn_user_lifetime = self.parse_duration(config["turn_user_lifetime"])
+        self.turn_allow_guests = config.get("turn_allow_guests", True)
 
     def default_config(self, **kwargs):
         return """\
@@ -41,4 +42,11 @@ class VoipConfig(Config):
 
         # How long generated TURN credentials last
         turn_user_lifetime: "1h"
+
+        # Whether guests should be allowed to use the TURN server.
+        # This defaults to True, otherwise VoIP will be unreliable for guests.
+        # However, it does introduce a slight security risk as it allows users to
+        # connect to arbitrary endpoints without having first signed up for a
+        # valid account (e.g. by passing a CAPTCHA).
+        turn_allow_guests: True
         """
diff --git a/synapse/config/workers.py b/synapse/config/workers.py
index b165c67ee7..ea48d931a1 100644
--- a/synapse/config/workers.py
+++ b/synapse/config/workers.py
@@ -28,7 +28,9 @@ class WorkerConfig(Config):
         self.worker_pid_file = config.get("worker_pid_file")
         self.worker_log_file = config.get("worker_log_file")
         self.worker_log_config = config.get("worker_log_config")
-        self.worker_replication_url = config.get("worker_replication_url")
+        self.worker_replication_host = config.get("worker_replication_host", None)
+        self.worker_replication_port = config.get("worker_replication_port", None)
+        self.worker_name = config.get("worker_name", self.worker_app)
 
         if self.worker_listeners:
             for listener in self.worker_listeners:
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 6be18880b9..e9a732ff03 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -50,6 +50,7 @@ class EventContext(object):
         "prev_group",
         "delta_ids",
         "prev_state_events",
+        "app_service",
     ]
 
     def __init__(self):
@@ -68,3 +69,5 @@ class EventContext(object):
         self.delta_ids = None
 
         self.prev_state_events = None
+
+        self.app_service = None
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 5bbaef8187..824f4a42e3 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -225,7 +225,22 @@ def format_event_for_client_v2_without_room_id(d):
 
 def serialize_event(e, time_now_ms, as_client_event=True,
                     event_format=format_event_for_client_v1,
-                    token_id=None, only_event_fields=None):
+                    token_id=None, only_event_fields=None, is_invite=False):
+    """Serialize event for clients
+
+    Args:
+        e (EventBase)
+        time_now_ms (int)
+        as_client_event (bool)
+        event_format
+        token_id
+        only_event_fields
+        is_invite (bool): Whether this is an invite that is being sent to the
+            invitee
+
+    Returns:
+        dict
+    """
     # FIXME(erikj): To handle the case of presence events and the like
     if not isinstance(e, EventBase):
         return e
@@ -251,6 +266,12 @@ def serialize_event(e, time_now_ms, as_client_event=True,
             if txn_id is not None:
                 d["unsigned"]["transaction_id"] = txn_id
 
+    # If this is an invite for somebody else, then we don't care about the
+    # invite_room_state as that's meant solely for the invitee. Other clients
+    # will already have the state since they're in the room.
+    if not is_invite:
+        d["unsigned"].pop("invite_room_state", None)
+
     if as_client_event:
         d = event_format(d)
 
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index deee0f4904..861441708b 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -474,8 +474,13 @@ class FederationClient(FederationBase):
             content (object): Any additional data to put into the content field
                 of the event.
         Return:
-            A tuple of (origin (str), event (object)) where origin is the remote
-            homeserver which generated the event.
+            Deferred: resolves to a tuple of (origin (str), event (object))
+            where origin is the remote homeserver which generated the event.
+
+            Fails with a ``CodeMessageException`` if the chosen remote server
+            returns a 300/400 code.
+
+            Fails with a ``RuntimeError`` if no servers were reachable.
         """
         valid_memberships = {Membership.JOIN, Membership.LEAVE}
         if membership not in valid_memberships:
@@ -528,6 +533,27 @@ class FederationClient(FederationBase):
 
     @defer.inlineCallbacks
     def send_join(self, destinations, pdu):
+        """Sends a join event to one of a list of homeservers.
+
+        Doing so will cause the remote server to add the event to the graph,
+        and send the event out to the rest of the federation.
+
+        Args:
+            destinations (str): Candidate homeservers which are probably
+                participating in the room.
+            pdu (BaseEvent): event to be sent
+
+        Return:
+            Deferred: resolves to a dict with members ``origin`` (a string
+            giving the serer the event was sent to, ``state`` (?) and
+            ``auth_chain``.
+
+            Fails with a ``CodeMessageException`` if the chosen remote server
+            returns a 300/400 code.
+
+            Fails with a ``RuntimeError`` if no servers were reachable.
+        """
+
         for destination in destinations:
             if destination == self.server_name:
                 continue
@@ -635,6 +661,26 @@ class FederationClient(FederationBase):
 
     @defer.inlineCallbacks
     def send_leave(self, destinations, pdu):
+        """Sends a leave event to one of a list of homeservers.
+
+        Doing so will cause the remote server to add the event to the graph,
+        and send the event out to the rest of the federation.
+
+        This is mostly useful to reject received invites.
+
+        Args:
+            destinations (str): Candidate homeservers which are probably
+                participating in the room.
+            pdu (BaseEvent): event to be sent
+
+        Return:
+            Deferred: resolves to None.
+
+            Fails with a ``CodeMessageException`` if the chosen remote server
+            returns a non-200 code.
+
+            Fails with a ``RuntimeError`` if no servers were reachable.
+        """
         for destination in destinations:
             if destination == self.server_name:
                 continue
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index bc20b9c201..51e3fdea06 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -440,6 +440,16 @@ class FederationServer(FederationBase):
                         key_id: json.loads(json_bytes)
                     }
 
+        logger.info(
+            "Claimed one-time-keys: %s",
+            ",".join((
+                "%s for %s:%s" % (key_id, user_id, device_id)
+                for user_id, user_keys in json_result.iteritems()
+                for device_id, device_keys in user_keys.iteritems()
+                for key_id, _ in device_keys.iteritems()
+            )),
+        )
+
         defer.returnValue({"one_time_keys": json_result})
 
     @defer.inlineCallbacks
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index bbb0195228..93e5acebc1 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -31,21 +31,19 @@ Events are replicated via a separate events stream.
 
 from .units import Edu
 
+from synapse.storage.presence import UserPresenceState
 from synapse.util.metrics import Measure
 import synapse.metrics
 
 from blist import sorteddict
-import ujson
+from collections import namedtuple
 
+import logging
 
-metrics = synapse.metrics.get_metrics_for(__name__)
+logger = logging.getLogger(__name__)
 
 
-PRESENCE_TYPE = "p"
-KEYED_EDU_TYPE = "k"
-EDU_TYPE = "e"
-FAILURE_TYPE = "f"
-DEVICE_MESSAGE_TYPE = "d"
+metrics = synapse.metrics.get_metrics_for(__name__)
 
 
 class FederationRemoteSendQueue(object):
@@ -55,18 +53,19 @@ class FederationRemoteSendQueue(object):
         self.server_name = hs.hostname
         self.clock = hs.get_clock()
         self.notifier = hs.get_notifier()
+        self.is_mine_id = hs.is_mine_id
 
-        self.presence_map = {}
-        self.presence_changed = sorteddict()
+        self.presence_map = {}  # Pending presence map user_id -> UserPresenceState
+        self.presence_changed = sorteddict()  # Stream position -> user_id
 
-        self.keyed_edu = {}
-        self.keyed_edu_changed = sorteddict()
+        self.keyed_edu = {}  # (destination, key) -> EDU
+        self.keyed_edu_changed = sorteddict()  # stream position -> (destination, key)
 
-        self.edus = sorteddict()
+        self.edus = sorteddict()  # stream position -> Edu
 
-        self.failures = sorteddict()
+        self.failures = sorteddict()  # stream position -> (destination, Failure)
 
-        self.device_messages = sorteddict()
+        self.device_messages = sorteddict()  # stream position -> destination
 
         self.pos = 1
         self.pos_time = sorteddict()
@@ -122,7 +121,9 @@ class FederationRemoteSendQueue(object):
                 del self.presence_changed[key]
 
             user_ids = set(
-                user_id for uids in self.presence_changed.values() for _, user_id in uids
+                user_id
+                for uids in self.presence_changed.itervalues()
+                for user_id in uids
             )
 
             to_del = [
@@ -189,18 +190,20 @@ class FederationRemoteSendQueue(object):
 
         self.notifier.on_new_replication_data()
 
-    def send_presence(self, destination, states):
-        """As per TransactionQueue"""
+    def send_presence(self, states):
+        """As per TransactionQueue
+
+        Args:
+            states (list(UserPresenceState))
+        """
         pos = self._next_pos()
 
-        self.presence_map.update({
-            state.user_id: state
-            for state in states
-        })
+        # We only want to send presence for our own users, so lets always just
+        # filter here just in case.
+        local_states = filter(lambda s: self.is_mine_id(s.user_id), states)
 
-        self.presence_changed[pos] = [
-            (destination, state.user_id) for state in states
-        ]
+        self.presence_map.update({state.user_id: state for state in local_states})
+        self.presence_changed[pos] = [state.user_id for state in local_states]
 
         self.notifier.on_new_replication_data()
 
@@ -220,10 +223,15 @@ class FederationRemoteSendQueue(object):
     def get_current_token(self):
         return self.pos - 1
 
-    def get_replication_rows(self, token, limit, federation_ack=None):
-        """
+    def federation_ack(self, token):
+        self._clear_queue_before_pos(token)
+
+    def get_replication_rows(self, from_token, to_token, limit, federation_ack=None):
+        """Get rows to be sent over federation between the two tokens
+
         Args:
-            token (int)
+            from_token (int)
+            to_token(int)
             limit (int)
             federation_ack (int): Optional. The position where the worker is
                 explicitly acknowledged it has handled. Allows us to drop
@@ -232,9 +240,11 @@ class FederationRemoteSendQueue(object):
         # TODO: Handle limit.
 
         # To handle restarts where we wrap around
-        if token > self.pos:
-            token = -1
+        if from_token > self.pos:
+            from_token = -1
 
+        # list of tuple(int, BaseFederationRow), where the first is the position
+        # of the federation stream.
         rows = []
 
         # There should be only one reader, so lets delete everything its
@@ -244,62 +254,295 @@ class FederationRemoteSendQueue(object):
 
         # Fetch changed presence
         keys = self.presence_changed.keys()
-        i = keys.bisect_right(token)
-        dest_user_ids = set(
-            (pos, dest_user_id)
-            for pos in keys[i:]
-            for dest_user_id in self.presence_changed[pos]
-        )
+        i = keys.bisect_right(from_token)
+        j = keys.bisect_right(to_token) + 1
+        dest_user_ids = [
+            (pos, user_id)
+            for pos in keys[i:j]
+            for user_id in self.presence_changed[pos]
+        ]
 
-        for (key, (dest, user_id)) in dest_user_ids:
-            rows.append((key, PRESENCE_TYPE, ujson.dumps({
-                "destination": dest,
-                "state": self.presence_map[user_id].as_dict(),
-            })))
+        for (key, user_id) in dest_user_ids:
+            rows.append((key, PresenceRow(
+                state=self.presence_map[user_id],
+            )))
 
         # Fetch changes keyed edus
         keys = self.keyed_edu_changed.keys()
-        i = keys.bisect_right(token)
-        keyed_edus = set((k, self.keyed_edu_changed[k]) for k in keys[i:])
-
-        for (pos, (destination, edu_key)) in keyed_edus:
-            rows.append(
-                (pos, KEYED_EDU_TYPE, ujson.dumps({
-                    "key": edu_key,
-                    "edu": self.keyed_edu[(destination, edu_key)].get_internal_dict(),
-                }))
-            )
+        i = keys.bisect_right(from_token)
+        j = keys.bisect_right(to_token) + 1
+        # We purposefully clobber based on the key here, python dict comprehensions
+        # always use the last value, so this will correctly point to the last
+        # stream position.
+        keyed_edus = {self.keyed_edu_changed[k]: k for k in keys[i:j]}
+
+        for ((destination, edu_key), pos) in keyed_edus.iteritems():
+            rows.append((pos, KeyedEduRow(
+                key=edu_key,
+                edu=self.keyed_edu[(destination, edu_key)],
+            )))
 
         # Fetch changed edus
         keys = self.edus.keys()
-        i = keys.bisect_right(token)
-        edus = set((k, self.edus[k]) for k in keys[i:])
+        i = keys.bisect_right(from_token)
+        j = keys.bisect_right(to_token) + 1
+        edus = ((k, self.edus[k]) for k in keys[i:j])
 
         for (pos, edu) in edus:
-            rows.append((pos, EDU_TYPE, ujson.dumps(edu.get_internal_dict())))
+            rows.append((pos, EduRow(edu)))
 
         # Fetch changed failures
         keys = self.failures.keys()
-        i = keys.bisect_right(token)
-        failures = set((k, self.failures[k]) for k in keys[i:])
+        i = keys.bisect_right(from_token)
+        j = keys.bisect_right(to_token) + 1
+        failures = ((k, self.failures[k]) for k in keys[i:j])
 
         for (pos, (destination, failure)) in failures:
-            rows.append((pos, FAILURE_TYPE, ujson.dumps({
-                "destination": destination,
-                "failure": failure,
-            })))
+            rows.append((pos, FailureRow(
+                destination=destination,
+                failure=failure,
+            )))
 
         # Fetch changed device messages
         keys = self.device_messages.keys()
-        i = keys.bisect_right(token)
-        device_messages = set((k, self.device_messages[k]) for k in keys[i:])
+        i = keys.bisect_right(from_token)
+        j = keys.bisect_right(to_token) + 1
+        device_messages = {self.device_messages[k]: k for k in keys[i:j]}
 
-        for (pos, destination) in device_messages:
-            rows.append((pos, DEVICE_MESSAGE_TYPE, ujson.dumps({
-                "destination": destination,
-            })))
+        for (destination, pos) in device_messages.iteritems():
+            rows.append((pos, DeviceRow(
+                destination=destination,
+            )))
 
         # Sort rows based on pos
         rows.sort()
 
-        return rows
+        return [(pos, row.TypeId, row.to_data()) for pos, row in rows]
+
+
+class BaseFederationRow(object):
+    """Base class for rows to be sent in the federation stream.
+
+    Specifies how to identify, serialize and deserialize the different types.
+    """
+
+    TypeId = None  # Unique string that ids the type. Must be overriden in sub classes.
+
+    @staticmethod
+    def from_data(data):
+        """Parse the data from the federation stream into a row.
+
+        Args:
+            data: The value of ``data`` from FederationStreamRow.data, type
+                depends on the type of stream
+        """
+        raise NotImplementedError()
+
+    def to_data(self):
+        """Serialize this row to be sent over the federation stream.
+
+        Returns:
+            The value to be sent in FederationStreamRow.data. The type depends
+            on the type of stream.
+        """
+        raise NotImplementedError()
+
+    def add_to_buffer(self, buff):
+        """Add this row to the appropriate field in the buffer ready for this
+        to be sent over federation.
+
+        We use a buffer so that we can batch up events that have come in at
+        the same time and send them all at once.
+
+        Args:
+            buff (BufferedToSend)
+        """
+        raise NotImplementedError()
+
+
+class PresenceRow(BaseFederationRow, namedtuple("PresenceRow", (
+    "state",  # UserPresenceState
+))):
+    TypeId = "p"
+
+    @staticmethod
+    def from_data(data):
+        return PresenceRow(
+            state=UserPresenceState.from_dict(data)
+        )
+
+    def to_data(self):
+        return self.state.as_dict()
+
+    def add_to_buffer(self, buff):
+        buff.presence.append(self.state)
+
+
+class KeyedEduRow(BaseFederationRow, namedtuple("KeyedEduRow", (
+    "key",  # tuple(str) - the edu key passed to send_edu
+    "edu",  # Edu
+))):
+    """Streams EDUs that have an associated key that is ued to clobber. For example,
+    typing EDUs clobber based on room_id.
+    """
+
+    TypeId = "k"
+
+    @staticmethod
+    def from_data(data):
+        return KeyedEduRow(
+            key=tuple(data["key"]),
+            edu=Edu(**data["edu"]),
+        )
+
+    def to_data(self):
+        return {
+            "key": self.key,
+            "edu": self.edu.get_internal_dict(),
+        }
+
+    def add_to_buffer(self, buff):
+        buff.keyed_edus.setdefault(
+            self.edu.destination, {}
+        )[self.key] = self.edu
+
+
+class EduRow(BaseFederationRow, namedtuple("EduRow", (
+    "edu",  # Edu
+))):
+    """Streams EDUs that don't have keys. See KeyedEduRow
+    """
+    TypeId = "e"
+
+    @staticmethod
+    def from_data(data):
+        return EduRow(Edu(**data))
+
+    def to_data(self):
+        return self.edu.get_internal_dict()
+
+    def add_to_buffer(self, buff):
+        buff.edus.setdefault(self.edu.destination, []).append(self.edu)
+
+
+class FailureRow(BaseFederationRow, namedtuple("FailureRow", (
+    "destination",  # str
+    "failure",
+))):
+    """Streams failures to a remote server. Failures are issued when there was
+    something wrong with a transaction the remote sent us, e.g. it included
+    an event that was invalid.
+    """
+
+    TypeId = "f"
+
+    @staticmethod
+    def from_data(data):
+        return FailureRow(
+            destination=data["destination"],
+            failure=data["failure"],
+        )
+
+    def to_data(self):
+        return {
+            "destination": self.destination,
+            "failure": self.failure,
+        }
+
+    def add_to_buffer(self, buff):
+        buff.failures.setdefault(self.destination, []).append(self.failure)
+
+
+class DeviceRow(BaseFederationRow, namedtuple("DeviceRow", (
+    "destination",  # str
+))):
+    """Streams the fact that either a) there is pending to device messages for
+    users on the remote, or b) a local users device has changed and needs to
+    be sent to the remote.
+    """
+    TypeId = "d"
+
+    @staticmethod
+    def from_data(data):
+        return DeviceRow(destination=data["destination"])
+
+    def to_data(self):
+        return {"destination": self.destination}
+
+    def add_to_buffer(self, buff):
+        buff.device_destinations.add(self.destination)
+
+
+TypeToRow = {
+    Row.TypeId: Row
+    for Row in (
+        PresenceRow,
+        KeyedEduRow,
+        EduRow,
+        FailureRow,
+        DeviceRow,
+    )
+}
+
+
+ParsedFederationStreamData = namedtuple("ParsedFederationStreamData", (
+    "presence",  # list(UserPresenceState)
+    "keyed_edus",  # dict of destination -> { key -> Edu }
+    "edus",  # dict of destination -> [Edu]
+    "failures",  # dict of destination -> [failures]
+    "device_destinations",  # set of destinations
+))
+
+
+def process_rows_for_federation(transaction_queue, rows):
+    """Parse a list of rows from the federation stream and put them in the
+    transaction queue ready for sending to the relevant homeservers.
+
+    Args:
+        transaction_queue (TransactionQueue)
+        rows (list(synapse.replication.tcp.streams.FederationStreamRow))
+    """
+
+    # The federation stream contains a bunch of different types of
+    # rows that need to be handled differently. We parse the rows, put
+    # them into the appropriate collection and then send them off.
+
+    buff = ParsedFederationStreamData(
+        presence=[],
+        keyed_edus={},
+        edus={},
+        failures={},
+        device_destinations=set(),
+    )
+
+    # Parse the rows in the stream and add to the buffer
+    for row in rows:
+        if row.type not in TypeToRow:
+            logger.error("Unrecognized federation row type %r", row.type)
+            continue
+
+        RowType = TypeToRow[row.type]
+        parsed_row = RowType.from_data(row.data)
+        parsed_row.add_to_buffer(buff)
+
+    if buff.presence:
+        transaction_queue.send_presence(buff.presence)
+
+    for destination, edu_map in buff.keyed_edus.iteritems():
+        for key, edu in edu_map.items():
+            transaction_queue.send_edu(
+                edu.destination, edu.edu_type, edu.content, key=key,
+            )
+
+    for destination, edu_list in buff.edus.iteritems():
+        for edu in edu_list:
+            transaction_queue.send_edu(
+                edu.destination, edu.edu_type, edu.content, key=None,
+            )
+
+    for destination, failure_list in buff.failures.iteritems():
+        for failure in failure_list:
+            transaction_queue.send_failure(destination, failure)
+
+    for destination in buff.device_destinations:
+        transaction_queue.send_device_messages(destination)
diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py
index c27ce7c5f3..a15198e05d 100644
--- a/synapse/federation/transaction_queue.py
+++ b/synapse/federation/transaction_queue.py
@@ -21,11 +21,10 @@ from .units import Transaction, Edu
 
 from synapse.api.errors import HttpResponseException
 from synapse.util.async import run_on_reactor
-from synapse.util.logcontext import preserve_context_over_fn
+from synapse.util.logcontext import preserve_context_over_fn, preserve_fn
 from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter
 from synapse.util.metrics import measure_func
-from synapse.types import get_domain_from_id
-from synapse.handlers.presence import format_user_presence_state
+from synapse.handlers.presence import format_user_presence_state, get_interested_remotes
 import synapse.metrics
 
 import logging
@@ -41,6 +40,8 @@ sent_pdus_destination_dist = client_metrics.register_distribution(
 )
 sent_edus_counter = client_metrics.register_counter("sent_edus")
 
+sent_transactions_counter = client_metrics.register_counter("sent_transactions")
+
 
 class TransactionQueue(object):
     """This class makes sure we only have one transaction in flight at
@@ -77,8 +78,18 @@ class TransactionQueue(object):
         # destination -> list of tuple(edu, deferred)
         self.pending_edus_by_dest = edus = {}
 
-        # Presence needs to be separate as we send single aggragate EDUs
+        # Map of user_id -> UserPresenceState for all the pending presence
+        # to be sent out by user_id. Entries here get processed and put in
+        # pending_presence_by_dest
+        self.pending_presence = {}
+
+        # Map of destination -> user_id -> UserPresenceState of pending presence
+        # to be sent to each destinations
         self.pending_presence_by_dest = presence = {}
+
+        # Pending EDUs by their "key". Keyed EDUs are EDUs that get clobbered
+        # based on their key (e.g. typing events by room_id)
+        # Map of destination -> (edu_type, key) -> Edu
         self.pending_edus_keyed_by_dest = edus_keyed = {}
 
         metrics.register_callback(
@@ -113,6 +124,8 @@ class TransactionQueue(object):
         self._is_processing = False
         self._last_poked_id = -1
 
+        self._processing_pending_presence = False
+
     def can_send_to(self, destination):
         """Can we send messages to the given server?
 
@@ -169,15 +182,12 @@ class TransactionQueue(object):
                     # Otherwise if the last member on a server in a room is
                     # banned then it won't receive the event because it won't
                     # be in the room after the ban.
-                    users_in_room = yield self.state.get_current_user_in_room(
+                    destinations = yield self.state.get_current_hosts_in_room(
                         event.room_id, latest_event_ids=[
                             prev_id for prev_id, _ in event.prev_events
                         ],
                     )
 
-                    destinations = set(
-                        get_domain_from_id(user_id) for user_id in users_in_room
-                    )
                     if send_on_behalf_of is not None:
                         # If we are sending the event on behalf of another server
                         # then it already has the event and there is no reason to
@@ -224,17 +234,71 @@ class TransactionQueue(object):
                 self._attempt_new_transaction, destination
             )
 
-    def send_presence(self, destination, states):
-        if not self.can_send_to(destination):
-            return
+    @preserve_fn  # the caller should not yield on this
+    @defer.inlineCallbacks
+    def send_presence(self, states):
+        """Send the new presence states to the appropriate destinations.
 
-        self.pending_presence_by_dest.setdefault(destination, {}).update({
+        This actually queues up the presence states ready for sending and
+        triggers a background task to process them and send out the transactions.
+
+        Args:
+            states (list(UserPresenceState))
+        """
+
+        # First we queue up the new presence by user ID, so multiple presence
+        # updates in quick successtion are correctly handled
+        # We only want to send presence for our own users, so lets always just
+        # filter here just in case.
+        self.pending_presence.update({
             state.user_id: state for state in states
+            if self.is_mine_id(state.user_id)
         })
 
-        preserve_context_over_fn(
-            self._attempt_new_transaction, destination
-        )
+        # We then handle the new pending presence in batches, first figuring
+        # out the destinations we need to send each state to and then poking it
+        # to attempt a new transaction. We linearize this so that we don't
+        # accidentally mess up the ordering and send multiple presence updates
+        # in the wrong order
+        if self._processing_pending_presence:
+            return
+
+        self._processing_pending_presence = True
+        try:
+            while True:
+                states_map = self.pending_presence
+                self.pending_presence = {}
+
+                if not states_map:
+                    break
+
+                yield self._process_presence_inner(states_map.values())
+        finally:
+            self._processing_pending_presence = False
+
+    @measure_func("txnqueue._process_presence")
+    @defer.inlineCallbacks
+    def _process_presence_inner(self, states):
+        """Given a list of states populate self.pending_presence_by_dest and
+        poke to send a new transaction to each destination
+
+        Args:
+            states (list(UserPresenceState))
+        """
+        hosts_and_states = yield get_interested_remotes(self.store, states, self.state)
+
+        for destinations, states in hosts_and_states:
+            for destination in destinations:
+                if not self.can_send_to(destination):
+                    continue
+
+                self.pending_presence_by_dest.setdefault(
+                    destination, {}
+                ).update({
+                    state.user_id: state for state in states
+                })
+
+                preserve_fn(self._attempt_new_transaction)(destination)
 
     def send_edu(self, destination, edu_type, content, key=None):
         edu = Edu(
@@ -374,6 +438,7 @@ class TransactionQueue(object):
                     destination, pending_pdus, pending_edus, pending_failures,
                 )
                 if success:
+                    sent_transactions_counter.inc()
                     # Remove the acknowledged device messages from the database
                     # Only bother if we actually sent some device messages
                     if device_message_edus:
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 15a03378f5..52b2a717d2 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -193,6 +193,26 @@ class TransportLayerClient(object):
     @defer.inlineCallbacks
     @log_function
     def make_membership_event(self, destination, room_id, user_id, membership):
+        """Asks a remote server to build and sign us a membership event
+
+        Note that this does not append any events to any graphs.
+
+        Args:
+            destination (str): address of remote homeserver
+            room_id (str): room to join/leave
+            user_id (str): user to be joined/left
+            membership (str): one of join/leave
+
+        Returns:
+            Deferred: Succeeds when we get a 2xx HTTP response. The result
+            will be the decoded JSON body (ie, the new event).
+
+            Fails with ``HTTPRequestException`` if we get an HTTP response
+            code >= 300.
+
+            Fails with ``NotRetryingDestination`` if we are not yet ready
+            to retry this server.
+        """
         valid_memberships = {Membership.JOIN, Membership.LEAVE}
         if membership not in valid_memberships:
             raise RuntimeError(
@@ -201,11 +221,23 @@ class TransportLayerClient(object):
             )
         path = PREFIX + "/make_%s/%s/%s" % (membership, room_id, user_id)
 
+        ignore_backoff = False
+        retry_on_dns_fail = False
+
+        if membership == Membership.LEAVE:
+            # we particularly want to do our best to send leave events. The
+            # problem is that if it fails, we won't retry it later, so if the
+            # remote server was just having a momentary blip, the room will be
+            # out of sync.
+            ignore_backoff = True
+            retry_on_dns_fail = True
+
         content = yield self.client.get_json(
             destination=destination,
             path=path,
-            retry_on_dns_fail=False,
+            retry_on_dns_fail=retry_on_dns_fail,
             timeout=20000,
+            ignore_backoff=ignore_backoff,
         )
 
         defer.returnValue(content)
@@ -232,6 +264,12 @@ class TransportLayerClient(object):
             destination=destination,
             path=path,
             data=content,
+
+            # we want to do our best to send this through. The problem is
+            # that if it fails, we won't retry it later, so if the remote
+            # server was just having a momentary blip, the room will be out of
+            # sync.
+            ignore_backoff=True,
         )
 
         defer.returnValue(response)
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index c840da834c..3d676e7d8b 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -24,6 +24,7 @@ from synapse.http.servlet import (
 )
 from synapse.util.ratelimitutils import FederationRateLimiter
 from synapse.util.versionstring import get_version_string
+from synapse.util.logcontext import preserve_fn
 from synapse.types import ThirdPartyInstanceID
 
 import functools
@@ -79,6 +80,7 @@ class Authenticator(object):
     def __init__(self, hs):
         self.keyring = hs.get_keyring()
         self.server_name = hs.hostname
+        self.store = hs.get_datastore()
 
     # A method just so we can pass 'self' as the authenticator to the Servlets
     @defer.inlineCallbacks
@@ -138,6 +140,13 @@ class Authenticator(object):
         logger.info("Request from %s", origin)
         request.authenticated_entity = origin
 
+        # If we get a valid signed request from the other side, its probably
+        # alive
+        retry_timings = yield self.store.get_destination_retry_timings(origin)
+        if retry_timings and retry_timings["retry_last_ts"]:
+            logger.info("Marking origin %r as up", origin)
+            preserve_fn(self.store.set_destination_retry_timings)(origin, 0, 0)
+
         defer.returnValue(origin)
 
 
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index e83adc8339..faa5609c0c 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -53,7 +53,20 @@ class BaseHandler(object):
 
         self.event_builder_factory = hs.get_event_builder_factory()
 
-    def ratelimit(self, requester):
+    @defer.inlineCallbacks
+    def ratelimit(self, requester, update=True):
+        """Ratelimits requests.
+
+        Args:
+            requester (Requester)
+            update (bool): Whether to record that a request is being processed.
+                Set to False when doing multiple checks for one request (e.g.
+                to check up front if we would reject the request), and set to
+                True for the last call for a given request.
+
+        Raises:
+            LimitExceededError if the request should be ratelimited
+        """
         time_now = self.clock.time()
         user_id = requester.user.to_string()
 
@@ -67,10 +80,25 @@ class BaseHandler(object):
         if requester.app_service and not requester.app_service.is_rate_limited():
             return
 
+        # Check if there is a per user override in the DB.
+        override = yield self.store.get_ratelimit_for_user(user_id)
+        if override:
+            # If overriden with a null Hz then ratelimiting has been entirely
+            # disabled for the user
+            if not override.messages_per_second:
+                return
+
+            messages_per_second = override.messages_per_second
+            burst_count = override.burst_count
+        else:
+            messages_per_second = self.hs.config.rc_messages_per_second
+            burst_count = self.hs.config.rc_message_burst_count
+
         allowed, time_allowed = self.ratelimiter.send_message(
             user_id, time_now,
-            msg_rate_hz=self.hs.config.rc_messages_per_second,
-            burst_count=self.hs.config.rc_message_burst_count,
+            msg_rate_hz=messages_per_second,
+            burst_count=burst_count,
+            update=update,
         )
         if not allowed:
             raise LimitExceededError(
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index c22f65ce5d..982cda3edf 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -17,6 +17,7 @@ from synapse.api.constants import EventTypes
 from synapse.util import stringutils
 from synapse.util.async import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.retryutils import NotRetryingDestination
 from synapse.util.metrics import measure_func
 from synapse.types import get_domain_from_id, RoomStreamToken
 from twisted.internet import defer
@@ -425,12 +426,38 @@ class DeviceListEduUpdater(object):
                 # This can happen since we batch updates
                 return
 
+            # Given a list of updates we check if we need to resync. This
+            # happens if we've missed updates.
             resync = yield self._need_to_do_resync(user_id, pending_updates)
 
             if resync:
                 # Fetch all devices for the user.
                 origin = get_domain_from_id(user_id)
-                result = yield self.federation.query_user_devices(origin, user_id)
+                try:
+                    result = yield self.federation.query_user_devices(origin, user_id)
+                except NotRetryingDestination:
+                    # TODO: Remember that we are now out of sync and try again
+                    # later
+                    logger.warn(
+                        "Failed to handle device list update for %s,"
+                        " we're not retrying the remote",
+                        user_id,
+                    )
+                    # We abort on exceptions rather than accepting the update
+                    # as otherwise synapse will 'forget' that its device list
+                    # is out of date. If we bail then we will retry the resync
+                    # next time we get a device list update for this user_id.
+                    # This makes it more likely that the device lists will
+                    # eventually become consistent.
+                    return
+                except Exception:
+                    # TODO: Remember that we are now out of sync and try again
+                    # later
+                    logger.exception(
+                        "Failed to handle device list update for %s", user_id
+                    )
+                    return
+
                 stream_id = result["stream_id"]
                 devices = result["devices"]
                 yield self.store.update_remote_device_list_cache(
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index c2b38d72a9..668a90e495 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -21,7 +21,7 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError, CodeMessageException
 from synapse.types import get_domain_from_id
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
+from synapse.util.logcontext import preserve_fn, make_deferred_yieldable
 from synapse.util.retryutils import NotRetryingDestination
 
 logger = logging.getLogger(__name__)
@@ -145,7 +145,7 @@ class E2eKeysHandler(object):
                     "status": 503, "message": e.message
                 }
 
-        yield preserve_context_over_deferred(defer.gatherResults([
+        yield make_deferred_yieldable(defer.gatherResults([
             preserve_fn(do_remote_query)(destination)
             for destination in remote_queries_not_in_cache
         ]))
@@ -257,11 +257,21 @@ class E2eKeysHandler(object):
                     "status": 503, "message": e.message
                 }
 
-        yield preserve_context_over_deferred(defer.gatherResults([
+        yield make_deferred_yieldable(defer.gatherResults([
             preserve_fn(claim_client_keys)(destination)
             for destination in remote_queries
         ]))
 
+        logger.info(
+            "Claimed one-time-keys: %s",
+            ",".join((
+                "%s for %s:%s" % (key_id, user_id, device_id)
+                for user_id, user_keys in json_result.iteritems()
+                for device_id, device_keys in user_keys.iteritems()
+                for key_id, _ in device_keys.iteritems()
+            )),
+        )
+
         defer.returnValue({
             "one_time_keys": json_result,
             "failures": failures
@@ -288,19 +298,8 @@ class E2eKeysHandler(object):
 
         one_time_keys = keys.get("one_time_keys", None)
         if one_time_keys:
-            logger.info(
-                "Adding %d one_time_keys for device %r for user %r at %d",
-                len(one_time_keys), device_id, user_id, time_now
-            )
-            key_list = []
-            for key_id, key_json in one_time_keys.items():
-                algorithm, key_id = key_id.split(":")
-                key_list.append((
-                    algorithm, key_id, encode_canonical_json(key_json)
-                ))
-
-            yield self.store.add_e2e_one_time_keys(
-                user_id, device_id, time_now, key_list
+            yield self._upload_one_time_keys_for_user(
+                user_id, device_id, time_now, one_time_keys,
             )
 
         # the device should have been registered already, but it may have been
@@ -313,3 +312,58 @@ class E2eKeysHandler(object):
         result = yield self.store.count_e2e_one_time_keys(user_id, device_id)
 
         defer.returnValue({"one_time_key_counts": result})
+
+    @defer.inlineCallbacks
+    def _upload_one_time_keys_for_user(self, user_id, device_id, time_now,
+                                       one_time_keys):
+        logger.info(
+            "Adding one_time_keys %r for device %r for user %r at %d",
+            one_time_keys.keys(), device_id, user_id, time_now,
+        )
+
+        # make a list of (alg, id, key) tuples
+        key_list = []
+        for key_id, key_obj in one_time_keys.items():
+            algorithm, key_id = key_id.split(":")
+            key_list.append((
+                algorithm, key_id, key_obj
+            ))
+
+        # First we check if we have already persisted any of the keys.
+        existing_key_map = yield self.store.get_e2e_one_time_keys(
+            user_id, device_id, [k_id for _, k_id, _ in key_list]
+        )
+
+        new_keys = []  # Keys that we need to insert. (alg, id, json) tuples.
+        for algorithm, key_id, key in key_list:
+            ex_json = existing_key_map.get((algorithm, key_id), None)
+            if ex_json:
+                if not _one_time_keys_match(ex_json, key):
+                    raise SynapseError(
+                        400,
+                        ("One time key %s:%s already exists. "
+                         "Old key: %s; new key: %r") %
+                        (algorithm, key_id, ex_json, key)
+                    )
+            else:
+                new_keys.append((algorithm, key_id, encode_canonical_json(key)))
+
+        yield self.store.add_e2e_one_time_keys(
+            user_id, device_id, time_now, new_keys
+        )
+
+
+def _one_time_keys_match(old_key_json, new_key):
+    old_key = json.loads(old_key_json)
+
+    # if either is a string rather than an object, they must match exactly
+    if not isinstance(old_key, dict) or not isinstance(new_key, dict):
+        return old_key == new_key
+
+    # otherwise, we strip off the 'signatures' if any, because it's legitimate
+    # for different upload attempts to have different signatures.
+    old_key.pop("signatures", None)
+    new_key_copy = dict(new_key)
+    new_key_copy.pop("signatures", None)
+
+    return old_key == new_key_copy
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 53f9296399..52d97dfbf3 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -28,7 +28,7 @@ from synapse.api.constants import EventTypes, Membership, RejectedReason
 from synapse.events.validator import EventValidator
 from synapse.util import unwrapFirstError
 from synapse.util.logcontext import (
-    PreserveLoggingContext, preserve_fn, preserve_context_over_deferred
+    preserve_fn, preserve_context_over_deferred
 )
 from synapse.util.metrics import measure_func
 from synapse.util.logutils import log_function
@@ -172,8 +172,22 @@ class FederationHandler(BaseHandler):
                             origin, pdu, prevs, min_depth
                         )
 
-            prevs = {e_id for e_id, _ in pdu.prev_events}
-            seen = set(have_seen.keys())
+                        # Update the set of things we've seen after trying to
+                        # fetch the missing stuff
+                        have_seen = yield self.store.have_events(prevs)
+                        seen = set(have_seen.iterkeys())
+
+                        if not prevs - seen:
+                            logger.info(
+                                "Found all missing prev events for %s", pdu.event_id
+                            )
+                elif prevs - seen:
+                    logger.info(
+                        "Not fetching %d missing events for room %r,event %s: %r...",
+                        len(prevs - seen), pdu.room_id, pdu.event_id,
+                        list(prevs - seen)[:5],
+                    )
+
             if prevs - seen:
                 logger.info(
                     "Still missing %d events for room %r: %r...",
@@ -208,19 +222,15 @@ class FederationHandler(BaseHandler):
         Args:
             origin (str): Origin of the pdu. Will be called to get the missing events
             pdu: received pdu
-            prevs (str[]): List of event ids which we are missing
+            prevs (set(str)): List of event ids which we are missing
             min_depth (int): Minimum depth of events to return.
-
-        Returns:
-            Deferred<dict(str, str?)>: updated have_seen dictionary
         """
         # We recalculate seen, since it may have changed.
         have_seen = yield self.store.have_events(prevs)
         seen = set(have_seen.keys())
 
         if not prevs - seen:
-            # nothing left to do
-            defer.returnValue(have_seen)
+            return
 
         latest = yield self.store.get_latest_event_ids_in_room(
             pdu.room_id
@@ -232,8 +242,8 @@ class FederationHandler(BaseHandler):
         latest |= seen
 
         logger.info(
-            "Missing %d events for room %r: %r...",
-            len(prevs - seen), pdu.room_id, list(prevs - seen)[:5]
+            "Missing %d events for room %r pdu %s: %r...",
+            len(prevs - seen), pdu.room_id, pdu.event_id, list(prevs - seen)[:5]
         )
 
         # XXX: we set timeout to 10s to help workaround
@@ -265,22 +275,23 @@ class FederationHandler(BaseHandler):
             timeout=10000,
         )
 
+        logger.info(
+            "Got %d events: %r...",
+            len(missing_events), [e.event_id for e in missing_events[:5]]
+        )
+
         # We want to sort these by depth so we process them and
         # tell clients about them in order.
         missing_events.sort(key=lambda x: x.depth)
 
         for e in missing_events:
+            logger.info("Handling found event %s", e.event_id)
             yield self.on_receive_pdu(
                 origin,
                 e,
                 get_missing=False
             )
 
-        have_seen = yield self.store.have_events(
-            [ev for ev, _ in pdu.prev_events]
-        )
-        defer.returnValue(have_seen)
-
     @log_function
     @defer.inlineCallbacks
     def _process_received_pdu(self, origin, pdu, state, auth_chain):
@@ -369,13 +380,6 @@ class FederationHandler(BaseHandler):
                     affected=event.event_id,
                 )
 
-        # if we're receiving valid events from an origin,
-        # it's probably a good idea to mark it as not in retry-state
-        # for sending (although this is a bit of a leap)
-        retry_timings = yield self.store.get_destination_retry_timings(origin)
-        if retry_timings and retry_timings["retry_last_ts"]:
-            self.store.set_destination_retry_timings(origin, 0, 0)
-
         room = yield self.store.get_room(event.room_id)
 
         if not room:
@@ -394,11 +398,10 @@ class FederationHandler(BaseHandler):
             target_user = UserID.from_string(target_user_id)
             extra_users.append(target_user)
 
-        with PreserveLoggingContext():
-            self.notifier.on_new_room_event(
-                event, event_stream_id, max_stream_id,
-                extra_users=extra_users
-            )
+        self.notifier.on_new_room_event(
+            event, event_stream_id, max_stream_id,
+            extra_users=extra_users
+        )
 
         if event.type == EventTypes.Member:
             if event.membership == Membership.JOIN:
@@ -916,11 +919,10 @@ class FederationHandler(BaseHandler):
                 origin, auth_chain, state, event
             )
 
-            with PreserveLoggingContext():
-                self.notifier.on_new_room_event(
-                    event, event_stream_id, max_stream_id,
-                    extra_users=[joinee]
-                )
+            self.notifier.on_new_room_event(
+                event, event_stream_id, max_stream_id,
+                extra_users=[joinee]
+            )
 
             logger.debug("Finished joining %s to %s", joinee, room_id)
         finally:
@@ -1035,10 +1037,9 @@ class FederationHandler(BaseHandler):
             target_user = UserID.from_string(target_user_id)
             extra_users.append(target_user)
 
-        with PreserveLoggingContext():
-            self.notifier.on_new_room_event(
-                event, event_stream_id, max_stream_id, extra_users=extra_users
-            )
+        self.notifier.on_new_room_event(
+            event, event_stream_id, max_stream_id, extra_users=extra_users
+        )
 
         if event.type == EventTypes.Member:
             if event.content["membership"] == Membership.JOIN:
@@ -1084,29 +1085,22 @@ class FederationHandler(BaseHandler):
         )
 
         target_user = UserID.from_string(event.state_key)
-        with PreserveLoggingContext():
-            self.notifier.on_new_room_event(
-                event, event_stream_id, max_stream_id,
-                extra_users=[target_user],
-            )
+        self.notifier.on_new_room_event(
+            event, event_stream_id, max_stream_id,
+            extra_users=[target_user],
+        )
 
         defer.returnValue(event)
 
     @defer.inlineCallbacks
     def do_remotely_reject_invite(self, target_hosts, room_id, user_id):
-        try:
-            origin, event = yield self._make_and_verify_event(
-                target_hosts,
-                room_id,
-                user_id,
-                "leave"
-            )
-            event = self._sign_event(event)
-        except SynapseError:
-            raise
-        except CodeMessageException as e:
-            logger.warn("Failed to reject invite: %s", e)
-            raise SynapseError(500, "Failed to reject invite")
+        origin, event = yield self._make_and_verify_event(
+            target_hosts,
+            room_id,
+            user_id,
+            "leave"
+        )
+        event = self._sign_event(event)
 
         # Try the host that we succesfully called /make_leave/ on first for
         # the /send_leave/ request.
@@ -1116,16 +1110,10 @@ class FederationHandler(BaseHandler):
         except ValueError:
             pass
 
-        try:
-            yield self.replication_layer.send_leave(
-                target_hosts,
-                event
-            )
-        except SynapseError:
-            raise
-        except CodeMessageException as e:
-            logger.warn("Failed to reject invite: %s", e)
-            raise SynapseError(500, "Failed to reject invite")
+        yield self.replication_layer.send_leave(
+            target_hosts,
+            event
+        )
 
         context = yield self.state_handler.compute_event_context(event)
 
@@ -1246,10 +1234,9 @@ class FederationHandler(BaseHandler):
             target_user = UserID.from_string(target_user_id)
             extra_users.append(target_user)
 
-        with PreserveLoggingContext():
-            self.notifier.on_new_room_event(
-                event, event_stream_id, max_stream_id, extra_users=extra_users
-            )
+        self.notifier.on_new_room_event(
+            event, event_stream_id, max_stream_id, extra_users=extra_users
+        )
 
         defer.returnValue(None)
 
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 6a53c5eb47..9efcdff1d6 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -18,7 +18,7 @@
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    CodeMessageException
+    MatrixCodeMessageException, CodeMessageException
 )
 from ._base import BaseHandler
 from synapse.util.async import run_on_reactor
@@ -90,6 +90,9 @@ class IdentityHandler(BaseHandler):
                 ),
                 {'sid': creds['sid'], 'client_secret': client_secret}
             )
+        except MatrixCodeMessageException as e:
+            logger.info("getValidated3pid failed with Matrix error: %r", e)
+            raise SynapseError(e.code, e.msg, e.errcode)
         except CodeMessageException as e:
             data = json.loads(e.msg)
 
@@ -159,6 +162,9 @@ class IdentityHandler(BaseHandler):
                 params
             )
             defer.returnValue(data)
+        except MatrixCodeMessageException as e:
+            logger.info("Proxied requestToken failed with Matrix error: %r", e)
+            raise SynapseError(e.code, e.msg, e.errcode)
         except CodeMessageException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e
@@ -193,6 +199,9 @@ class IdentityHandler(BaseHandler):
                 params
             )
             defer.returnValue(data)
+        except MatrixCodeMessageException as e:
+            logger.info("Proxied requestToken failed with Matrix error: %r", e)
+            raise SynapseError(e.code, e.msg, e.errcode)
         except CodeMessageException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 7a498af5a2..196925edad 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -16,7 +16,7 @@
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import AuthError, Codes, SynapseError, LimitExceededError
+from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
@@ -175,7 +175,8 @@ class MessageHandler(BaseHandler):
         defer.returnValue(chunk)
 
     @defer.inlineCallbacks
-    def create_event(self, event_dict, token_id=None, txn_id=None, prev_event_ids=None):
+    def create_event(self, requester, event_dict, token_id=None, txn_id=None,
+                     prev_event_ids=None):
         """
         Given a dict from a client, create a new event.
 
@@ -185,6 +186,7 @@ class MessageHandler(BaseHandler):
         Adds display names to Join membership events.
 
         Args:
+            requester
             event_dict (dict): An entire event
             token_id (str)
             txn_id (str)
@@ -226,6 +228,7 @@ class MessageHandler(BaseHandler):
 
             event, context = yield self._create_new_client_event(
                 builder=builder,
+                requester=requester,
                 prev_event_ids=prev_event_ids,
             )
 
@@ -251,17 +254,7 @@ class MessageHandler(BaseHandler):
         # We check here if we are currently being rate limited, so that we
         # don't do unnecessary work. We check again just before we actually
         # send the event.
-        time_now = self.clock.time()
-        allowed, time_allowed = self.ratelimiter.send_message(
-            event.sender, time_now,
-            msg_rate_hz=self.hs.config.rc_messages_per_second,
-            burst_count=self.hs.config.rc_message_burst_count,
-            update=False,
-        )
-        if not allowed:
-            raise LimitExceededError(
-                retry_after_ms=int(1000 * (time_allowed - time_now)),
-            )
+        yield self.ratelimit(requester, update=False)
 
         user = UserID.from_string(event.sender)
 
@@ -319,6 +312,7 @@ class MessageHandler(BaseHandler):
         See self.create_event and self.send_nonmember_event.
         """
         event, context = yield self.create_event(
+            requester,
             event_dict,
             token_id=requester.access_token_id,
             txn_id=txn_id
@@ -416,7 +410,7 @@ class MessageHandler(BaseHandler):
 
     @measure_func("_create_new_client_event")
     @defer.inlineCallbacks
-    def _create_new_client_event(self, builder, prev_event_ids=None):
+    def _create_new_client_event(self, builder, requester=None, prev_event_ids=None):
         if prev_event_ids:
             prev_events = yield self.store.add_event_hashes(prev_event_ids)
             prev_max_depth = yield self.store.get_max_depth_of_events(prev_event_ids)
@@ -456,6 +450,8 @@ class MessageHandler(BaseHandler):
         state_handler = self.state_handler
 
         context = yield state_handler.compute_event_context(builder)
+        if requester:
+            context.app_service = requester.app_service
 
         if builder.is_state():
             builder.prev_state = yield self.store.add_event_hashes(
@@ -493,7 +489,7 @@ class MessageHandler(BaseHandler):
         # We now need to go and hit out to wherever we need to hit out to.
 
         if ratelimit:
-            self.ratelimit(requester)
+            yield self.ratelimit(requester)
 
         try:
             yield self.auth.check_from_context(event, context)
@@ -531,9 +527,9 @@ class MessageHandler(BaseHandler):
 
                 state_to_include_ids = [
                     e_id
-                    for k, e_id in context.current_state_ids.items()
+                    for k, e_id in context.current_state_ids.iteritems()
                     if k[0] in self.hs.config.room_invite_state_types
-                    or k[0] == EventTypes.Member and k[1] == event.sender
+                    or k == (EventTypes.Member, event.sender)
                 ]
 
                 state_to_include = yield self.store.get_events(state_to_include_ids)
@@ -545,7 +541,7 @@ class MessageHandler(BaseHandler):
                         "content": e.content,
                         "sender": e.sender,
                     }
-                    for e in state_to_include.values()
+                    for e in state_to_include.itervalues()
                 ]
 
                 invitee = UserID.from_string(event.state_key)
@@ -612,12 +608,9 @@ class MessageHandler(BaseHandler):
         @defer.inlineCallbacks
         def _notify():
             yield run_on_reactor()
-            yield self.notifier.on_new_room_event(
+            self.notifier.on_new_room_event(
                 event, event_stream_id, max_stream_id,
                 extra_users=extra_users
             )
 
         preserve_fn(_notify)()
-
-        # If invite, remove room_state from unsigned before sending.
-        event.unsigned.pop("invite_room_state", None)
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 1ede117c79..c7c0b0a1e2 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -30,6 +30,7 @@ from synapse.api.constants import PresenceState
 from synapse.storage.presence import UserPresenceState
 
 from synapse.util.caches.descriptors import cachedInlineCallbacks
+from synapse.util.async import Linearizer
 from synapse.util.logcontext import preserve_fn
 from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
@@ -187,6 +188,7 @@ class PresenceHandler(object):
         # process_id to millisecond timestamp last updated.
         self.external_process_to_current_syncs = {}
         self.external_process_last_updated_ms = {}
+        self.external_sync_linearizer = Linearizer(name="external_sync_linearizer")
 
         # Start a LoopingCall in 30s that fires every 5s.
         # The initial delay is to allow disconnected clients a chance to
@@ -316,11 +318,7 @@ class PresenceHandler(object):
             if to_federation_ping:
                 federation_presence_out_counter.inc_by(len(to_federation_ping))
 
-                _, _, hosts_to_states = yield self._get_interested_parties(
-                    to_federation_ping.values()
-                )
-
-                self._push_to_remotes(hosts_to_states)
+                self._push_to_remotes(to_federation_ping.values())
 
     def _handle_timeouts(self):
         """Checks the presence of users that have timed out and updates as
@@ -509,6 +507,73 @@ class PresenceHandler(object):
         self.external_process_to_current_syncs[process_id] = syncing_user_ids
 
     @defer.inlineCallbacks
+    def update_external_syncs_row(self, process_id, user_id, is_syncing, sync_time_msec):
+        """Update the syncing users for an external process as a delta.
+
+        Args:
+            process_id (str): An identifier for the process the users are
+                syncing against. This allows synapse to process updates
+                as user start and stop syncing against a given process.
+            user_id (str): The user who has started or stopped syncing
+            is_syncing (bool): Whether or not the user is now syncing
+            sync_time_msec(int): Time in ms when the user was last syncing
+        """
+        with (yield self.external_sync_linearizer.queue(process_id)):
+            prev_state = yield self.current_state_for_user(user_id)
+
+            process_presence = self.external_process_to_current_syncs.setdefault(
+                process_id, set()
+            )
+
+            updates = []
+            if is_syncing and user_id not in process_presence:
+                if prev_state.state == PresenceState.OFFLINE:
+                    updates.append(prev_state.copy_and_replace(
+                        state=PresenceState.ONLINE,
+                        last_active_ts=sync_time_msec,
+                        last_user_sync_ts=sync_time_msec,
+                    ))
+                else:
+                    updates.append(prev_state.copy_and_replace(
+                        last_user_sync_ts=sync_time_msec,
+                    ))
+                process_presence.add(user_id)
+            elif user_id in process_presence:
+                updates.append(prev_state.copy_and_replace(
+                    last_user_sync_ts=sync_time_msec,
+                ))
+
+            if not is_syncing:
+                process_presence.discard(user_id)
+
+            if updates:
+                yield self._update_states(updates)
+
+            self.external_process_last_updated_ms[process_id] = self.clock.time_msec()
+
+    @defer.inlineCallbacks
+    def update_external_syncs_clear(self, process_id):
+        """Marks all users that had been marked as syncing by a given process
+        as offline.
+
+        Used when the process has stopped/disappeared.
+        """
+        with (yield self.external_sync_linearizer.queue(process_id)):
+            process_presence = self.external_process_to_current_syncs.pop(
+                process_id, set()
+            )
+            prev_states = yield self.current_state_for_users(process_presence)
+            time_now_ms = self.clock.time_msec()
+
+            yield self._update_states([
+                prev_state.copy_and_replace(
+                    last_user_sync_ts=time_now_ms,
+                )
+                for prev_state in prev_states.itervalues()
+            ])
+            self.external_process_last_updated_ms.pop(process_id, None)
+
+    @defer.inlineCallbacks
     def current_state_for_user(self, user_id):
         """Get the current presence state for a user.
         """
@@ -527,14 +592,14 @@ class PresenceHandler(object):
             for user_id in user_ids
         }
 
-        missing = [user_id for user_id, state in states.items() if not state]
+        missing = [user_id for user_id, state in states.iteritems() if not state]
         if missing:
             # There are things not in our in memory cache. Lets pull them out of
             # the database.
             res = yield self.store.get_presence_for_users(missing)
             states.update(res)
 
-            missing = [user_id for user_id, state in states.items() if not state]
+            missing = [user_id for user_id, state in states.iteritems() if not state]
             if missing:
                 new = {
                     user_id: UserPresenceState.default(user_id)
@@ -546,88 +611,39 @@ class PresenceHandler(object):
         defer.returnValue(states)
 
     @defer.inlineCallbacks
-    def _get_interested_parties(self, states, calculate_remote_hosts=True):
-        """Given a list of states return which entities (rooms, users, servers)
-        are interested in the given states.
-
-        Returns:
-            3-tuple: `(room_ids_to_states, users_to_states, hosts_to_states)`,
-            with each item being a dict of `entity_name` -> `[UserPresenceState]`
-        """
-        room_ids_to_states = {}
-        users_to_states = {}
-        for state in states:
-            room_ids = yield self.store.get_rooms_for_user(state.user_id)
-            for room_id in room_ids:
-                room_ids_to_states.setdefault(room_id, []).append(state)
-
-            plist = yield self.store.get_presence_list_observers_accepted(state.user_id)
-            for u in plist:
-                users_to_states.setdefault(u, []).append(state)
-
-            # Always notify self
-            users_to_states.setdefault(state.user_id, []).append(state)
-
-        hosts_to_states = {}
-        if calculate_remote_hosts:
-            for room_id, states in room_ids_to_states.items():
-                local_states = filter(lambda s: self.is_mine_id(s.user_id), states)
-                if not local_states:
-                    continue
-
-                hosts = yield self.store.get_hosts_in_room(room_id)
-
-                for host in hosts:
-                    hosts_to_states.setdefault(host, []).extend(local_states)
-
-        for user_id, states in users_to_states.items():
-            local_states = filter(lambda s: self.is_mine_id(s.user_id), states)
-            if not local_states:
-                continue
-
-            host = get_domain_from_id(user_id)
-            hosts_to_states.setdefault(host, []).extend(local_states)
-
-        # TODO: de-dup hosts_to_states, as a single host might have multiple
-        # of same presence
-
-        defer.returnValue((room_ids_to_states, users_to_states, hosts_to_states))
-
-    @defer.inlineCallbacks
     def _persist_and_notify(self, states):
         """Persist states in the database, poke the notifier and send to
         interested remote servers
         """
         stream_id, max_token = yield self.store.update_presence(states)
 
-        parties = yield self._get_interested_parties(states)
-        room_ids_to_states, users_to_states, hosts_to_states = parties
+        parties = yield get_interested_parties(self.store, states)
+        room_ids_to_states, users_to_states = parties
 
         self.notifier.on_new_event(
             "presence_key", stream_id, rooms=room_ids_to_states.keys(),
-            users=[UserID.from_string(u) for u in users_to_states.keys()]
+            users=[UserID.from_string(u) for u in users_to_states]
         )
 
-        self._push_to_remotes(hosts_to_states)
+        self._push_to_remotes(states)
 
     @defer.inlineCallbacks
     def notify_for_states(self, state, stream_id):
-        parties = yield self._get_interested_parties([state])
-        room_ids_to_states, users_to_states, hosts_to_states = parties
+        parties = yield get_interested_parties(self.store, [state])
+        room_ids_to_states, users_to_states = parties
 
         self.notifier.on_new_event(
             "presence_key", stream_id, rooms=room_ids_to_states.keys(),
-            users=[UserID.from_string(u) for u in users_to_states.keys()]
+            users=[UserID.from_string(u) for u in users_to_states]
         )
 
-    def _push_to_remotes(self, hosts_to_states):
+    def _push_to_remotes(self, states):
         """Sends state updates to remote servers.
 
         Args:
-            hosts_to_states (dict): Mapping `server_name` -> `[UserPresenceState]`
+            states (list(UserPresenceState))
         """
-        for host, states in hosts_to_states.items():
-            self.federation.send_presence(host, states)
+        self.federation.send_presence(states)
 
     @defer.inlineCallbacks
     def incoming_presence(self, origin, content):
@@ -764,18 +780,17 @@ class PresenceHandler(object):
         # don't need to send to local clients here, as that is done as part
         # of the event stream/sync.
         # TODO: Only send to servers not already in the room.
-        user_ids = yield self.store.get_users_in_room(room_id)
         if self.is_mine(user):
             state = yield self.current_state_for_user(user.to_string())
 
-            hosts = set(get_domain_from_id(u) for u in user_ids)
-            self._push_to_remotes({host: (state,) for host in hosts})
+            self._push_to_remotes([state])
         else:
+            user_ids = yield self.store.get_users_in_room(room_id)
             user_ids = filter(self.is_mine_id, user_ids)
 
             states = yield self.current_state_for_users(user_ids)
 
-            self._push_to_remotes({user.domain: states.values()})
+            self._push_to_remotes(states.values())
 
     @defer.inlineCallbacks
     def get_presence_list(self, observer_user, accepted=None):
@@ -1275,3 +1290,66 @@ def handle_update(prev_state, new_state, is_mine, wheel_timer, now):
         persist_and_notify = True
 
     return new_state, persist_and_notify, federation_ping
+
+
+@defer.inlineCallbacks
+def get_interested_parties(store, states):
+    """Given a list of states return which entities (rooms, users)
+    are interested in the given states.
+
+    Args:
+        states (list(UserPresenceState))
+
+    Returns:
+        2-tuple: `(room_ids_to_states, users_to_states)`,
+        with each item being a dict of `entity_name` -> `[UserPresenceState]`
+    """
+    room_ids_to_states = {}
+    users_to_states = {}
+    for state in states:
+        room_ids = yield store.get_rooms_for_user(state.user_id)
+        for room_id in room_ids:
+            room_ids_to_states.setdefault(room_id, []).append(state)
+
+        plist = yield store.get_presence_list_observers_accepted(state.user_id)
+        for u in plist:
+            users_to_states.setdefault(u, []).append(state)
+
+        # Always notify self
+        users_to_states.setdefault(state.user_id, []).append(state)
+
+    defer.returnValue((room_ids_to_states, users_to_states))
+
+
+@defer.inlineCallbacks
+def get_interested_remotes(store, states, state_handler):
+    """Given a list of presence states figure out which remote servers
+    should be sent which.
+
+    All the presence states should be for local users only.
+
+    Args:
+        store (DataStore)
+        states (list(UserPresenceState))
+
+    Returns:
+        Deferred list of ([destinations], [UserPresenceState]), where for
+        each row the list of UserPresenceState should be sent to each
+        destination
+    """
+    hosts_and_states = []
+
+    # First we look up the rooms each user is in (as well as any explicit
+    # subscriptions), then for each distinct room we look up the remote
+    # hosts in those rooms.
+    room_ids_to_states, users_to_states = yield get_interested_parties(store, states)
+
+    for room_id, states in room_ids_to_states.iteritems():
+        hosts = yield state_handler.get_current_hosts_in_room(room_id)
+        hosts_and_states.append((hosts, states))
+
+    for user_id, states in users_to_states.iteritems():
+        host = get_domain_from_id(user_id)
+        hosts_and_states.append(([host], states))
+
+    defer.returnValue(hosts_and_states)
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 9bf638f818..7abee98dea 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -156,7 +156,7 @@ class ProfileHandler(BaseHandler):
         if not self.hs.is_mine(user):
             return
 
-        self.ratelimit(requester)
+        yield self.ratelimit(requester)
 
         room_ids = yield self.store.get_rooms_for_user(
             user.to_string(),
diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
new file mode 100644
index 0000000000..b5b0303d54
--- /dev/null
+++ b/synapse/handlers/read_marker.py
@@ -0,0 +1,64 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ._base import BaseHandler
+
+from twisted.internet import defer
+
+from synapse.util.async import Linearizer
+
+import logging
+logger = logging.getLogger(__name__)
+
+
+class ReadMarkerHandler(BaseHandler):
+    def __init__(self, hs):
+        super(ReadMarkerHandler, self).__init__(hs)
+        self.server_name = hs.config.server_name
+        self.store = hs.get_datastore()
+        self.read_marker_linearizer = Linearizer(name="read_marker")
+        self.notifier = hs.get_notifier()
+
+    @defer.inlineCallbacks
+    def received_client_read_marker(self, room_id, user_id, event_id):
+        """Updates the read marker for a given user in a given room if the event ID given
+        is ahead in the stream relative to the current read marker.
+
+        This uses a notifier to indicate that account data should be sent down /sync if
+        the read marker has changed.
+        """
+
+        with (yield self.read_marker_linearizer.queue((room_id, user_id))):
+            account_data = yield self.store.get_account_data_for_room(user_id, room_id)
+
+            existing_read_marker = account_data.get("m.fully_read", None)
+
+            should_update = True
+
+            if existing_read_marker:
+                # Only update if the new marker is ahead in the stream
+                should_update = yield self.store.is_event_after(
+                    event_id,
+                    existing_read_marker['event_id']
+                )
+
+            if should_update:
+                content = {
+                    "event_id": event_id
+                }
+                max_id = yield self.store.add_account_data_to_room(
+                    user_id, room_id, "m.fully_read", content
+                )
+                self.notifier.on_new_event("account_data_key", max_id, users=[user_id])
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 03c6a85fc6..ee3a2269a8 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -54,6 +54,13 @@ class RegistrationHandler(BaseHandler):
                 Codes.INVALID_USERNAME
             )
 
+        if not localpart:
+            raise SynapseError(
+                400,
+                "User ID cannot be empty",
+                Codes.INVALID_USERNAME
+            )
+
         if localpart[0] == '_':
             raise SynapseError(
                 400,
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 99cb7db0db..d2a0d6520a 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -75,7 +75,7 @@ class RoomCreationHandler(BaseHandler):
         """
         user_id = requester.user.to_string()
 
-        self.ratelimit(requester)
+        yield self.ratelimit(requester)
 
         if "room_alias_name" in config:
             for wchar in string.whitespace:
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 2052d6d05f..1ca88517a2 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -70,6 +70,7 @@ class RoomMemberHandler(BaseHandler):
             content["kind"] = "guest"
 
         event, context = yield msg_handler.create_event(
+            requester,
             {
                 "type": EventTypes.Member,
                 "content": content,
@@ -139,13 +140,6 @@ class RoomMemberHandler(BaseHandler):
         )
         yield user_joined_room(self.distributor, user, room_id)
 
-    def reject_remote_invite(self, user_id, room_id, remote_room_hosts):
-        return self.hs.get_handlers().federation_handler.do_remotely_reject_invite(
-            remote_room_hosts,
-            room_id,
-            user_id
-        )
-
     @defer.inlineCallbacks
     def update_membership(
             self,
@@ -286,13 +280,21 @@ class RoomMemberHandler(BaseHandler):
                 else:
                     # send the rejection to the inviter's HS.
                     remote_room_hosts = remote_room_hosts + [inviter.domain]
-
+                    fed_handler = self.hs.get_handlers().federation_handler
                     try:
-                        ret = yield self.reject_remote_invite(
-                            target.to_string(), room_id, remote_room_hosts
+                        ret = yield fed_handler.do_remotely_reject_invite(
+                            remote_room_hosts,
+                            room_id,
+                            target.to_string(),
                         )
                         defer.returnValue(ret)
-                    except SynapseError as e:
+                    except Exception as e:
+                        # if we were unable to reject the exception, just mark
+                        # it as rejected on our end and plough ahead.
+                        #
+                        # The 'except' clause is very broad, but we need to
+                        # capture everything from DNS failures upwards
+                        #
                         logger.warn("Failed to reject invite: %s", e)
 
                         yield self.store.locally_reject_invite(
@@ -737,10 +739,11 @@ class RoomMemberHandler(BaseHandler):
         if len(current_state_ids) == 1 and create_event_id:
             defer.returnValue(self.hs.is_mine_id(create_event_id))
 
-        for (etype, state_key), event_id in current_state_ids.items():
+        for etype, state_key in current_state_ids:
             if etype != EventTypes.Member or not self.hs.is_mine_id(state_key):
                 continue
 
+            event_id = current_state_ids[(etype, state_key)]
             event = yield self.store.get_event(event_id, allow_none=True)
             if not event:
                 continue
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index 0eea7f8f9c..3b7818af5c 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -24,7 +24,6 @@ from synapse.types import UserID, get_domain_from_id
 import logging
 
 from collections import namedtuple
-import ujson as json
 
 logger = logging.getLogger(__name__)
 
@@ -288,11 +287,13 @@ class TypingHandler(object):
         for room_id, serial in self._room_serials.items():
             if last_id < serial and serial <= current_id:
                 typing = self._room_typing[room_id]
-                typing_bytes = json.dumps(list(typing), ensure_ascii=False)
-                rows.append((serial, room_id, typing_bytes))
+                rows.append((serial, room_id, list(typing)))
         rows.sort()
         return rows
 
+    def get_current_token(self):
+        return self._latest_room_serial
+
 
 class TypingNotificationEventSource(object):
     def __init__(self, hs):
diff --git a/synapse/http/client.py b/synapse/http/client.py
index ca2f770f5d..9eba046bbf 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -16,9 +16,10 @@ from OpenSSL import SSL
 from OpenSSL.SSL import VERIFY_NONE
 
 from synapse.api.errors import (
-    CodeMessageException, SynapseError, Codes,
+    CodeMessageException, MatrixCodeMessageException, SynapseError, Codes,
 )
 from synapse.util.logcontext import preserve_context_over_fn
+from synapse.util import logcontext
 import synapse.metrics
 from synapse.http.endpoint import SpiderEndpoint
 
@@ -72,39 +73,45 @@ class SimpleHttpClient(object):
             contextFactory=hs.get_http_client_context_factory()
         )
         self.user_agent = hs.version_string
+        self.clock = hs.get_clock()
         if hs.config.user_agent_suffix:
             self.user_agent = "%s %s" % (self.user_agent, hs.config.user_agent_suffix,)
 
+    @defer.inlineCallbacks
     def request(self, method, uri, *args, **kwargs):
         # A small wrapper around self.agent.request() so we can easily attach
         # counters to it
         outgoing_requests_counter.inc(method)
-        d = preserve_context_over_fn(
-            self.agent.request,
-            method, uri, *args, **kwargs
-        )
+
+        def send_request():
+            request_deferred = self.agent.request(
+                method, uri, *args, **kwargs
+            )
+
+            return self.clock.time_bound_deferred(
+                request_deferred,
+                time_out=60,
+            )
 
         logger.info("Sending request %s %s", method, uri)
 
-        def _cb(response):
+        try:
+            with logcontext.PreserveLoggingContext():
+                response = yield send_request()
+
             incoming_responses_counter.inc(method, response.code)
             logger.info(
                 "Received response to  %s %s: %s",
                 method, uri, response.code
             )
-            return response
-
-        def _eb(failure):
+            defer.returnValue(response)
+        except Exception as e:
             incoming_responses_counter.inc(method, "ERR")
             logger.info(
                 "Error sending request to  %s %s: %s %s",
-                method, uri, failure.type, failure.getErrorMessage()
+                method, uri, type(e).__name__, e.message
             )
-            return failure
-
-        d.addCallbacks(_cb, _eb)
-
-        return d
+            raise e
 
     @defer.inlineCallbacks
     def post_urlencoded_get_json(self, uri, args={}):
@@ -145,6 +152,11 @@ class SimpleHttpClient(object):
 
         body = yield preserve_context_over_fn(readBody, response)
 
+        if 200 <= response.code < 300:
+            defer.returnValue(json.loads(body))
+        else:
+            raise self._exceptionFromFailedRequest(response, body)
+
         defer.returnValue(json.loads(body))
 
     @defer.inlineCallbacks
@@ -164,8 +176,11 @@ class SimpleHttpClient(object):
             On a non-2xx HTTP response. The response body will be used as the
             error message.
         """
-        body = yield self.get_raw(uri, args)
-        defer.returnValue(json.loads(body))
+        try:
+            body = yield self.get_raw(uri, args)
+            defer.returnValue(json.loads(body))
+        except CodeMessageException as e:
+            raise self._exceptionFromFailedRequest(e.code, e.msg)
 
     @defer.inlineCallbacks
     def put_json(self, uri, json_body, args={}):
@@ -246,6 +261,15 @@ class SimpleHttpClient(object):
         else:
             raise CodeMessageException(response.code, body)
 
+    def _exceptionFromFailedRequest(self, response, body):
+        try:
+            jsonBody = json.loads(body)
+            errcode = jsonBody['errcode']
+            error = jsonBody['error']
+            return MatrixCodeMessageException(response.code, error, errcode)
+        except (ValueError, KeyError):
+            return CodeMessageException(response.code, body)
+
     # XXX: FIXME: This is horribly copy-pasted from matrixfederationclient.
     # The two should be factored out.
 
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 62b4d7e93d..747a791f83 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -125,6 +125,8 @@ class MatrixFederationHttpClient(object):
                 code >= 300.
             Fails with ``NotRetryingDestination`` if we are not yet ready
                 to retry this server.
+            (May also fail with plenty of other Exceptions for things like DNS
+                failures, connection failures, SSL failures.)
         """
         limiter = yield synapse.util.retryutils.get_retry_limiter(
             destination,
@@ -302,8 +304,10 @@ class MatrixFederationHttpClient(object):
 
         Returns:
             Deferred: Succeeds when we get a 2xx HTTP response. The result
-            will be the decoded JSON body. On a 4xx or 5xx error response a
-            CodeMessageException is raised.
+            will be the decoded JSON body.
+
+            Fails with ``HTTPRequestException`` if we get an HTTP response
+            code >= 300.
 
             Fails with ``NotRetryingDestination`` if we are not yet ready
             to retry this server.
@@ -360,8 +364,10 @@ class MatrixFederationHttpClient(object):
                 try the request anyway.
         Returns:
             Deferred: Succeeds when we get a 2xx HTTP response. The result
-            will be the decoded JSON body. On a 4xx or 5xx error response a
-            CodeMessageException is raised.
+            will be the decoded JSON body.
+
+            Fails with ``HTTPRequestException`` if we get an HTTP response
+            code >= 300.
 
             Fails with ``NotRetryingDestination`` if we are not yet ready
             to retry this server.
@@ -410,10 +416,11 @@ class MatrixFederationHttpClient(object):
             ignore_backoff (bool): true to ignore the historical backoff data
                 and try the request anyway.
         Returns:
-            Deferred: Succeeds when we get *any* HTTP response.
+            Deferred: Succeeds when we get a 2xx HTTP response. The result
+            will be the decoded JSON body.
 
-            The result of the deferred is a tuple of `(code, response)`,
-            where `response` is a dict representing the decoded JSON body.
+            Fails with ``HTTPRequestException`` if we get an HTTP response
+            code >= 300.
 
             Fails with ``NotRetryingDestination`` if we are not yet ready
             to retry this server.
diff --git a/synapse/notifier.py b/synapse/notifier.py
index 7eeba6d28e..48566187ab 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -163,6 +163,8 @@ class Notifier(object):
         self.store = hs.get_datastore()
         self.pending_new_room_events = []
 
+        self.replication_callbacks = []
+
         self.clock = hs.get_clock()
         self.appservice_handler = hs.get_application_service_handler()
 
@@ -202,7 +204,12 @@ class Notifier(object):
             lambda: len(self.user_to_user_stream),
         )
 
-    @preserve_fn
+    def add_replication_callback(self, cb):
+        """Add a callback that will be called when some new data is available.
+        Callback is not given any arguments.
+        """
+        self.replication_callbacks.append(cb)
+
     def on_new_room_event(self, event, room_stream_id, max_room_stream_id,
                           extra_users=[]):
         """ Used by handlers to inform the notifier something has happened
@@ -216,15 +223,13 @@ class Notifier(object):
         until all previous events have been persisted before notifying
         the client streams.
         """
-        with PreserveLoggingContext():
-            self.pending_new_room_events.append((
-                room_stream_id, event, extra_users
-            ))
-            self._notify_pending_new_room_events(max_room_stream_id)
+        self.pending_new_room_events.append((
+            room_stream_id, event, extra_users
+        ))
+        self._notify_pending_new_room_events(max_room_stream_id)
 
-            self.notify_replication()
+        self.notify_replication()
 
-    @preserve_fn
     def _notify_pending_new_room_events(self, max_room_stream_id):
         """Notify for the room events that were queued waiting for a previous
         event to be persisted.
@@ -242,14 +247,16 @@ class Notifier(object):
             else:
                 self._on_new_room_event(event, room_stream_id, extra_users)
 
-    @preserve_fn
     def _on_new_room_event(self, event, room_stream_id, extra_users=[]):
         """Notify any user streams that are interested in this room event"""
         # poke any interested application service.
-        self.appservice_handler.notify_interested_services(room_stream_id)
+        preserve_fn(self.appservice_handler.notify_interested_services)(
+            room_stream_id)
 
         if self.federation_sender:
-            self.federation_sender.notify_new_events(room_stream_id)
+            preserve_fn(self.federation_sender.notify_new_events)(
+                room_stream_id
+            )
 
         if event.type == EventTypes.Member and event.membership == Membership.JOIN:
             self._user_joined_room(event.state_key, event.room_id)
@@ -260,7 +267,6 @@ class Notifier(object):
             rooms=[event.room_id],
         )
 
-    @preserve_fn
     def on_new_event(self, stream_key, new_token, users=[], rooms=[]):
         """ Used to inform listeners that something has happend event wise.
 
@@ -287,7 +293,6 @@ class Notifier(object):
 
                 self.notify_replication()
 
-    @preserve_fn
     def on_new_replication_data(self):
         """Used to inform replication listeners that something has happend
         without waking up any of the normal user event streams"""
@@ -510,6 +515,9 @@ class Notifier(object):
             self.replication_deferred = ObservableDeferred(defer.Deferred())
             deferred.callback(None)
 
+        for cb in self.replication_callbacks:
+            preserve_fn(cb)()
+
     @defer.inlineCallbacks
     def wait_for_replication(self, callback, timeout):
         """Wait for an event to happen.
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 78b095c903..f943ff640f 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -87,7 +87,11 @@ class BulkPushRuleEvaluator:
         condition_cache = {}
 
         for uid, rules in self.rules_by_user.items():
-            display_name = room_members.get(uid, {}).get("display_name", None)
+            display_name = None
+            profile_info = room_members.get(uid)
+            if profile_info:
+                display_name = profile_info.display_name
+
             if not display_name:
                 # Handle the case where we are pushing a membership event to
                 # that user, as they might not be already joined.
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index 3a50c72e0b..f83aa7625c 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -200,7 +200,11 @@ class Mailer(object):
         yield sendmail(
             self.hs.config.email_smtp_host,
             raw_from, raw_to, multipart_msg.as_string(),
-            port=self.hs.config.email_smtp_port
+            port=self.hs.config.email_smtp_port,
+            requireAuthentication=self.hs.config.email_smtp_user is not None,
+            username=self.hs.config.email_smtp_user,
+            password=self.hs.config.email_smtp_pass,
+            requireTransportSecurity=self.hs.config.require_transport_security
         )
 
     @defer.inlineCallbacks
diff --git a/synapse/push/push_tools.py b/synapse/push/push_tools.py
index 287df94b4f..6835f54e97 100644
--- a/synapse/push/push_tools.py
+++ b/synapse/push/push_tools.py
@@ -17,15 +17,12 @@ from twisted.internet import defer
 from synapse.push.presentable_names import (
     calculate_room_name, name_from_member_event
 )
-from synapse.util.logcontext import preserve_fn, preserve_context_over_deferred
 
 
 @defer.inlineCallbacks
 def get_badge_count(store, user_id):
-    invites, joins = yield preserve_context_over_deferred(defer.gatherResults([
-        preserve_fn(store.get_invited_rooms_for_user)(user_id),
-        preserve_fn(store.get_rooms_for_user)(user_id),
-    ], consumeErrors=True))
+    invites = yield store.get_invited_rooms_for_user(user_id)
+    joins = yield store.get_rooms_for_user(user_id)
 
     my_receipts_by_room = yield store.get_receipts_for_user(
         user_id, "m.read",
diff --git a/synapse/replication/expire_cache.py b/synapse/replication/expire_cache.py
deleted file mode 100644
index c05a50d7a6..0000000000
--- a/synapse/replication/expire_cache.py
+++ /dev/null
@@ -1,60 +0,0 @@
-# Copyright 2016 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from synapse.http.server import respond_with_json_bytes, request_handler
-from synapse.http.servlet import parse_json_object_from_request
-
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-
-
-class ExpireCacheResource(Resource):
-    """
-    HTTP endpoint for expiring storage caches.
-
-    POST /_synapse/replication/expire_cache HTTP/1.1
-    Content-Type: application/json
-
-    {
-        "invalidate": [
-            {
-                "name": "func_name",
-                "keys": ["key1", "key2"]
-            }
-        ]
-    }
-    """
-
-    def __init__(self, hs):
-        Resource.__init__(self)  # Resource is old-style, so no super()
-
-        self.store = hs.get_datastore()
-        self.version_string = hs.version_string
-        self.clock = hs.get_clock()
-
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
-    @request_handler()
-    def _async_render_POST(self, request):
-        content = parse_json_object_from_request(request)
-
-        for row in content["invalidate"]:
-            name = row["name"]
-            keys = tuple(row["keys"])
-
-            getattr(self.store, name).invalidate(keys)
-
-        respond_with_json_bytes(request, 200, "{}")
diff --git a/synapse/replication/presence_resource.py b/synapse/replication/presence_resource.py
deleted file mode 100644
index fc18130ab4..0000000000
--- a/synapse/replication/presence_resource.py
+++ /dev/null
@@ -1,59 +0,0 @@
-# Copyright 2016 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from synapse.http.server import respond_with_json_bytes, request_handler
-from synapse.http.servlet import parse_json_object_from_request
-
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-from twisted.internet import defer
-
-
-class PresenceResource(Resource):
-    """
-    HTTP endpoint for marking users as syncing.
-
-    POST /_synapse/replication/presence HTTP/1.1
-    Content-Type: application/json
-
-    {
-        "process_id": "<process_id>",
-        "syncing_users": ["<user_id>"]
-    }
-    """
-
-    def __init__(self, hs):
-        Resource.__init__(self)  # Resource is old-style, so no super()
-
-        self.version_string = hs.version_string
-        self.clock = hs.get_clock()
-        self.presence_handler = hs.get_presence_handler()
-
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
-    @request_handler()
-    @defer.inlineCallbacks
-    def _async_render_POST(self, request):
-        content = parse_json_object_from_request(request)
-
-        process_id = content["process_id"]
-        syncing_user_ids = content["syncing_users"]
-
-        yield self.presence_handler.update_external_syncs(
-            process_id, set(syncing_user_ids)
-        )
-
-        respond_with_json_bytes(request, 200, "{}")
diff --git a/synapse/replication/pusher_resource.py b/synapse/replication/pusher_resource.py
deleted file mode 100644
index 9b01ab3c13..0000000000
--- a/synapse/replication/pusher_resource.py
+++ /dev/null
@@ -1,54 +0,0 @@
-# Copyright 2016 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from synapse.http.server import respond_with_json_bytes, request_handler
-from synapse.http.servlet import parse_json_object_from_request
-
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-from twisted.internet import defer
-
-
-class PusherResource(Resource):
-    """
-    HTTP endpoint for deleting rejected pushers
-    """
-
-    def __init__(self, hs):
-        Resource.__init__(self)  # Resource is old-style, so no super()
-
-        self.version_string = hs.version_string
-        self.store = hs.get_datastore()
-        self.notifier = hs.get_notifier()
-        self.clock = hs.get_clock()
-
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
-    @request_handler()
-    @defer.inlineCallbacks
-    def _async_render_POST(self, request):
-        content = parse_json_object_from_request(request)
-
-        for remove in content["remove"]:
-            yield self.store.delete_pusher_by_app_id_pushkey_user_id(
-                remove["app_id"],
-                remove["push_key"],
-                remove["user_id"],
-            )
-
-        self.notifier.on_new_replication_data()
-
-        respond_with_json_bytes(request, 200, "{}")
diff --git a/synapse/replication/resource.py b/synapse/replication/resource.py
deleted file mode 100644
index 03930fe958..0000000000
--- a/synapse/replication/resource.py
+++ /dev/null
@@ -1,576 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015 OpenMarket Ltd
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from synapse.http.servlet import parse_integer, parse_string
-from synapse.http.server import request_handler, finish_request
-from synapse.replication.pusher_resource import PusherResource
-from synapse.replication.presence_resource import PresenceResource
-from synapse.replication.expire_cache import ExpireCacheResource
-from synapse.api.errors import SynapseError
-
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-from twisted.internet import defer
-
-import ujson as json
-
-import collections
-import logging
-
-logger = logging.getLogger(__name__)
-
-REPLICATION_PREFIX = "/_synapse/replication"
-
-STREAM_NAMES = (
-    ("events",),
-    ("presence",),
-    ("typing",),
-    ("receipts",),
-    ("user_account_data", "room_account_data", "tag_account_data",),
-    ("backfill",),
-    ("push_rules",),
-    ("pushers",),
-    ("caches",),
-    ("to_device",),
-    ("public_rooms",),
-    ("federation",),
-    ("device_lists",),
-)
-
-
-class ReplicationResource(Resource):
-    """
-    HTTP endpoint for extracting data from synapse.
-
-    The streams of data returned by the endpoint are controlled by the
-    parameters given to the API. To return a given stream pass a query
-    parameter with a position in the stream to return data from or the
-    special value "-1" to return data from the start of the stream.
-
-    If there is no data for any of the supplied streams after the given
-    position then the request will block until there is data for one
-    of the streams. This allows clients to long-poll this API.
-
-    The possible streams are:
-
-    * "streams": A special stream returing the positions of other streams.
-    * "events": The new events seen on the server.
-    * "presence": Presence updates.
-    * "typing": Typing updates.
-    * "receipts": Receipt updates.
-    * "user_account_data": Top-level per user account data.
-    * "room_account_data: Per room per user account data.
-    * "tag_account_data": Per room per user tags.
-    * "backfill": Old events that have been backfilled from other servers.
-    * "push_rules": Per user changes to push rules.
-    * "pushers": Per user changes to their pushers.
-    * "caches": Cache invalidations.
-
-    The API takes two additional query parameters:
-
-    * "timeout": How long to wait before returning an empty response.
-    * "limit": The maximum number of rows to return for the selected streams.
-
-    The response is a JSON object with keys for each stream with updates. Under
-    each key is a JSON object with:
-
-    * "position": The current position of the stream.
-    * "field_names": The names of the fields in each row.
-    * "rows": The updates as an array of arrays.
-
-    There are a number of ways this API could be used:
-
-    1) To replicate the contents of the backing database to another database.
-    2) To be notified when the contents of a shared backing database changes.
-    3) To "tail" the activity happening on a server for debugging.
-
-    In the first case the client would track all of the streams and store it's
-    own copy of the data.
-
-    In the second case the client might theoretically just be able to follow
-    the "streams" stream to track where the other streams are. However in
-    practise it will probably need to get the contents of the streams in
-    order to expire the any in-memory caches. Whether it gets the contents
-    of the streams from this replication API or directly from the backing
-    store is a matter of taste.
-
-    In the third case the client would use the "streams" stream to find what
-    streams are available and their current positions. Then it can start
-    long-polling this replication API for new data on those streams.
-    """
-
-    def __init__(self, hs):
-        Resource.__init__(self)  # Resource is old-style, so no super()
-
-        self.version_string = hs.version_string
-        self.store = hs.get_datastore()
-        self.sources = hs.get_event_sources()
-        self.presence_handler = hs.get_presence_handler()
-        self.typing_handler = hs.get_typing_handler()
-        self.federation_sender = hs.get_federation_sender()
-        self.notifier = hs.notifier
-        self.clock = hs.get_clock()
-        self.config = hs.get_config()
-
-        self.putChild("remove_pushers", PusherResource(hs))
-        self.putChild("syncing_users", PresenceResource(hs))
-        self.putChild("expire_cache", ExpireCacheResource(hs))
-
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
-    @defer.inlineCallbacks
-    def current_replication_token(self):
-        stream_token = yield self.sources.get_current_token()
-        backfill_token = yield self.store.get_current_backfill_token()
-        push_rules_token, room_stream_token = self.store.get_push_rules_stream_token()
-        pushers_token = self.store.get_pushers_stream_token()
-        caches_token = self.store.get_cache_stream_token()
-        public_rooms_token = self.store.get_current_public_room_stream_id()
-        federation_token = self.federation_sender.get_current_token()
-        device_list_token = self.store.get_device_stream_token()
-
-        defer.returnValue(_ReplicationToken(
-            room_stream_token,
-            int(stream_token.presence_key),
-            int(stream_token.typing_key),
-            int(stream_token.receipt_key),
-            int(stream_token.account_data_key),
-            backfill_token,
-            push_rules_token,
-            pushers_token,
-            0,  # State stream is no longer a thing
-            caches_token,
-            int(stream_token.to_device_key),
-            int(public_rooms_token),
-            int(federation_token),
-            int(device_list_token),
-        ))
-
-    @request_handler()
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
-        limit = parse_integer(request, "limit", 100)
-        timeout = parse_integer(request, "timeout", 10 * 1000)
-
-        request.setHeader(b"Content-Type", b"application/json")
-
-        request_streams = {
-            name: parse_integer(request, name)
-            for names in STREAM_NAMES for name in names
-        }
-        request_streams["streams"] = parse_string(request, "streams")
-
-        federation_ack = parse_integer(request, "federation_ack", None)
-
-        def replicate():
-            return self.replicate(
-                request_streams, limit,
-                federation_ack=federation_ack
-            )
-
-        writer = yield self.notifier.wait_for_replication(replicate, timeout)
-        result = writer.finish()
-
-        for stream_name, stream_content in result.items():
-            logger.info(
-                "Replicating %d rows of %s from %s -> %s",
-                len(stream_content["rows"]),
-                stream_name,
-                request_streams.get(stream_name),
-                stream_content["position"],
-            )
-
-        request.write(json.dumps(result, ensure_ascii=False))
-        finish_request(request)
-
-    @defer.inlineCallbacks
-    def replicate(self, request_streams, limit, federation_ack=None):
-        writer = _Writer()
-        current_token = yield self.current_replication_token()
-        logger.debug("Replicating up to %r", current_token)
-
-        if limit == 0:
-            raise SynapseError(400, "Limit cannot be 0")
-
-        yield self.account_data(writer, current_token, limit, request_streams)
-        yield self.events(writer, current_token, limit, request_streams)
-        # TODO: implement limit
-        yield self.presence(writer, current_token, request_streams)
-        yield self.typing(writer, current_token, request_streams)
-        yield self.receipts(writer, current_token, limit, request_streams)
-        yield self.push_rules(writer, current_token, limit, request_streams)
-        yield self.pushers(writer, current_token, limit, request_streams)
-        yield self.caches(writer, current_token, limit, request_streams)
-        yield self.to_device(writer, current_token, limit, request_streams)
-        yield self.public_rooms(writer, current_token, limit, request_streams)
-        yield self.device_lists(writer, current_token, limit, request_streams)
-        self.federation(writer, current_token, limit, request_streams, federation_ack)
-        self.streams(writer, current_token, request_streams)
-
-        logger.debug("Replicated %d rows", writer.total)
-        defer.returnValue(writer)
-
-    def streams(self, writer, current_token, request_streams):
-        request_token = request_streams.get("streams")
-
-        streams = []
-
-        if request_token is not None:
-            if request_token == "-1":
-                for names, position in zip(STREAM_NAMES, current_token):
-                    streams.extend((name, position) for name in names)
-            else:
-                items = zip(
-                    STREAM_NAMES,
-                    current_token,
-                    _ReplicationToken(request_token)
-                )
-                for names, current_id, last_id in items:
-                    if last_id < current_id:
-                        streams.extend((name, current_id) for name in names)
-
-            if streams:
-                writer.write_header_and_rows(
-                    "streams", streams, ("name", "position"),
-                    position=str(current_token)
-                )
-
-    @defer.inlineCallbacks
-    def events(self, writer, current_token, limit, request_streams):
-        request_events = request_streams.get("events")
-        request_backfill = request_streams.get("backfill")
-
-        if request_events is not None or request_backfill is not None:
-            if request_events is None:
-                request_events = current_token.events
-            if request_backfill is None:
-                request_backfill = current_token.backfill
-
-            no_new_tokens = (
-                request_events == current_token.events
-                and request_backfill == current_token.backfill
-            )
-            if no_new_tokens:
-                return
-
-            res = yield self.store.get_all_new_events(
-                request_backfill, request_events,
-                current_token.backfill, current_token.events,
-                limit
-            )
-
-            upto_events_token = _position_from_rows(
-                res.new_forward_events, current_token.events
-            )
-
-            upto_backfill_token = _position_from_rows(
-                res.new_backfill_events, current_token.backfill
-            )
-
-            if request_events != upto_events_token:
-                writer.write_header_and_rows("events", res.new_forward_events, (
-                    "position", "event_id", "room_id", "type", "state_key",
-                ), position=upto_events_token)
-
-            if request_backfill != upto_backfill_token:
-                writer.write_header_and_rows("backfill", res.new_backfill_events, (
-                    "position", "event_id", "room_id", "type", "state_key", "redacts",
-                ), position=upto_backfill_token)
-
-            writer.write_header_and_rows(
-                "forward_ex_outliers", res.forward_ex_outliers,
-                ("position", "event_id", "state_group"),
-            )
-            writer.write_header_and_rows(
-                "backward_ex_outliers", res.backward_ex_outliers,
-                ("position", "event_id", "state_group"),
-            )
-
-    @defer.inlineCallbacks
-    def presence(self, writer, current_token, request_streams):
-        current_position = current_token.presence
-
-        request_presence = request_streams.get("presence")
-
-        if request_presence is not None and request_presence != current_position:
-            presence_rows = yield self.presence_handler.get_all_presence_updates(
-                request_presence, current_position
-            )
-            upto_token = _position_from_rows(presence_rows, current_position)
-            writer.write_header_and_rows("presence", presence_rows, (
-                "position", "user_id", "state", "last_active_ts",
-                "last_federation_update_ts", "last_user_sync_ts",
-                "status_msg", "currently_active",
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def typing(self, writer, current_token, request_streams):
-        current_position = current_token.typing
-
-        request_typing = request_streams.get("typing")
-
-        if request_typing is not None and request_typing != current_position:
-            # If they have a higher token than current max, we can assume that
-            # they had been talking to a previous instance of the master. Since
-            # we reset the token on restart, the best (but hacky) thing we can
-            # do is to simply resend down all the typing notifications.
-            if request_typing > current_position:
-                request_typing = 0
-
-            typing_rows = yield self.typing_handler.get_all_typing_updates(
-                request_typing, current_position
-            )
-            upto_token = _position_from_rows(typing_rows, current_position)
-            writer.write_header_and_rows("typing", typing_rows, (
-                "position", "room_id", "typing"
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def receipts(self, writer, current_token, limit, request_streams):
-        current_position = current_token.receipts
-
-        request_receipts = request_streams.get("receipts")
-
-        if request_receipts is not None and request_receipts != current_position:
-            receipts_rows = yield self.store.get_all_updated_receipts(
-                request_receipts, current_position, limit
-            )
-            upto_token = _position_from_rows(receipts_rows, current_position)
-            writer.write_header_and_rows("receipts", receipts_rows, (
-                "position", "room_id", "receipt_type", "user_id", "event_id", "data"
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def account_data(self, writer, current_token, limit, request_streams):
-        current_position = current_token.account_data
-
-        user_account_data = request_streams.get("user_account_data")
-        room_account_data = request_streams.get("room_account_data")
-        tag_account_data = request_streams.get("tag_account_data")
-
-        if user_account_data is not None or room_account_data is not None:
-            if user_account_data is None:
-                user_account_data = current_position
-            if room_account_data is None:
-                room_account_data = current_position
-
-            no_new_tokens = (
-                user_account_data == current_position
-                and room_account_data == current_position
-            )
-            if no_new_tokens:
-                return
-
-            user_rows, room_rows = yield self.store.get_all_updated_account_data(
-                user_account_data, room_account_data, current_position, limit
-            )
-
-            upto_users_token = _position_from_rows(user_rows, current_position)
-            upto_rooms_token = _position_from_rows(room_rows, current_position)
-
-            writer.write_header_and_rows("user_account_data", user_rows, (
-                "position", "user_id", "type", "content"
-            ), position=upto_users_token)
-            writer.write_header_and_rows("room_account_data", room_rows, (
-                "position", "user_id", "room_id", "type", "content"
-            ), position=upto_rooms_token)
-
-        if tag_account_data is not None:
-            tag_rows = yield self.store.get_all_updated_tags(
-                tag_account_data, current_position, limit
-            )
-            upto_tag_token = _position_from_rows(tag_rows, current_position)
-            writer.write_header_and_rows("tag_account_data", tag_rows, (
-                "position", "user_id", "room_id", "tags"
-            ), position=upto_tag_token)
-
-    @defer.inlineCallbacks
-    def push_rules(self, writer, current_token, limit, request_streams):
-        current_position = current_token.push_rules
-
-        push_rules = request_streams.get("push_rules")
-
-        if push_rules is not None and push_rules != current_position:
-            rows = yield self.store.get_all_push_rule_updates(
-                push_rules, current_position, limit
-            )
-            upto_token = _position_from_rows(rows, current_position)
-            writer.write_header_and_rows("push_rules", rows, (
-                "position", "event_stream_ordering", "user_id", "rule_id", "op",
-                "priority_class", "priority", "conditions", "actions"
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def pushers(self, writer, current_token, limit, request_streams):
-        current_position = current_token.pushers
-
-        pushers = request_streams.get("pushers")
-
-        if pushers is not None and pushers != current_position:
-            updated, deleted = yield self.store.get_all_updated_pushers(
-                pushers, current_position, limit
-            )
-            upto_token = _position_from_rows(updated, current_position)
-            writer.write_header_and_rows("pushers", updated, (
-                "position", "user_id", "access_token", "profile_tag", "kind",
-                "app_id", "app_display_name", "device_display_name", "pushkey",
-                "ts", "lang", "data"
-            ), position=upto_token)
-            writer.write_header_and_rows("deleted_pushers", deleted, (
-                "position", "user_id", "app_id", "pushkey"
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def caches(self, writer, current_token, limit, request_streams):
-        current_position = current_token.caches
-
-        caches = request_streams.get("caches")
-
-        if caches is not None and caches != current_position:
-            updated_caches = yield self.store.get_all_updated_caches(
-                caches, current_position, limit
-            )
-            upto_token = _position_from_rows(updated_caches, current_position)
-            writer.write_header_and_rows("caches", updated_caches, (
-                "position", "cache_func", "keys", "invalidation_ts"
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def to_device(self, writer, current_token, limit, request_streams):
-        current_position = current_token.to_device
-
-        to_device = request_streams.get("to_device")
-
-        if to_device is not None and to_device != current_position:
-            to_device_rows = yield self.store.get_all_new_device_messages(
-                to_device, current_position, limit
-            )
-            upto_token = _position_from_rows(to_device_rows, current_position)
-            writer.write_header_and_rows("to_device", to_device_rows, (
-                "position", "user_id", "device_id", "message_json"
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def public_rooms(self, writer, current_token, limit, request_streams):
-        current_position = current_token.public_rooms
-
-        public_rooms = request_streams.get("public_rooms")
-
-        if public_rooms is not None and public_rooms != current_position:
-            public_rooms_rows = yield self.store.get_all_new_public_rooms(
-                public_rooms, current_position, limit
-            )
-            upto_token = _position_from_rows(public_rooms_rows, current_position)
-            writer.write_header_and_rows("public_rooms", public_rooms_rows, (
-                "position", "room_id", "visibility", "appservice_id", "network_id",
-            ), position=upto_token)
-
-    def federation(self, writer, current_token, limit, request_streams, federation_ack):
-        if self.config.send_federation:
-            return
-
-        current_position = current_token.federation
-
-        federation = request_streams.get("federation")
-
-        if federation is not None and federation != current_position:
-            federation_rows = self.federation_sender.get_replication_rows(
-                federation, limit, federation_ack=federation_ack,
-            )
-            upto_token = _position_from_rows(federation_rows, current_position)
-            writer.write_header_and_rows("federation", federation_rows, (
-                "position", "type", "content",
-            ), position=upto_token)
-
-    @defer.inlineCallbacks
-    def device_lists(self, writer, current_token, limit, request_streams):
-        current_position = current_token.device_lists
-
-        device_lists = request_streams.get("device_lists")
-
-        if device_lists is not None and device_lists != current_position:
-            changes = yield self.store.get_all_device_list_changes_for_remotes(
-                device_lists,
-            )
-            writer.write_header_and_rows("device_lists", changes, (
-                "position", "user_id", "destination",
-            ), position=current_position)
-
-
-class _Writer(object):
-    """Writes the streams as a JSON object as the response to the request"""
-    def __init__(self):
-        self.streams = {}
-        self.total = 0
-
-    def write_header_and_rows(self, name, rows, fields, position=None):
-        if position is None:
-            if rows:
-                position = rows[-1][0]
-            else:
-                return
-
-        self.streams[name] = {
-            "position": position if type(position) is int else str(position),
-            "field_names": fields,
-            "rows": rows,
-        }
-
-        self.total += len(rows)
-
-    def __nonzero__(self):
-        return bool(self.total)
-
-    def finish(self):
-        return self.streams
-
-
-class _ReplicationToken(collections.namedtuple("_ReplicationToken", (
-    "events", "presence", "typing", "receipts", "account_data", "backfill",
-    "push_rules", "pushers", "state", "caches", "to_device", "public_rooms",
-    "federation", "device_lists",
-))):
-    __slots__ = []
-
-    def __new__(cls, *args):
-        if len(args) == 1:
-            streams = [int(value) for value in args[0].split("_")]
-            if len(streams) < len(cls._fields):
-                streams.extend([0] * (len(cls._fields) - len(streams)))
-            return cls(*streams)
-        else:
-            return super(_ReplicationToken, cls).__new__(cls, *args)
-
-    def __str__(self):
-        return "_".join(str(value) for value in self)
-
-
-def _position_from_rows(rows, current_position):
-    """Calculates a position to return for a stream. Ideally we want to return the
-    position of the last row, as that will be the most correct. However, if there
-    are no rows we fall back to using the current position to stop us from
-    repeatedly hitting the storage layer unncessarily thinking there are updates.
-    (Not all advances of the token correspond to an actual update)
-
-    We can't just always return the current position, as we often limit the
-    number of rows we replicate, and so the stream may lag. The assumption is
-    that if the storage layer returns no new rows then we are not lagging and
-    we are at the `current_position`.
-    """
-    if rows:
-        return rows[-1][0]
-    return current_position
diff --git a/synapse/replication/slave/storage/_base.py b/synapse/replication/slave/storage/_base.py
index ab133db872..b962641166 100644
--- a/synapse/replication/slave/storage/_base.py
+++ b/synapse/replication/slave/storage/_base.py
@@ -15,7 +15,6 @@
 
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.engines import PostgresEngine
-from twisted.internet import defer
 
 from ._slaved_id_tracker import SlavedIdTracker
 
@@ -34,8 +33,7 @@ class BaseSlavedStore(SQLBaseStore):
         else:
             self._cache_id_gen = None
 
-        self.expire_cache_url = hs.config.worker_replication_url + "/expire_cache"
-        self.http_client = hs.get_simple_http_client()
+        self.hs = hs
 
     def stream_positions(self):
         pos = {}
@@ -43,35 +41,20 @@ class BaseSlavedStore(SQLBaseStore):
             pos["caches"] = self._cache_id_gen.get_current_token()
         return pos
 
-    def process_replication(self, result):
-        stream = result.get("caches")
-        if stream:
-            for row in stream["rows"]:
-                (
-                    position, cache_func, keys, invalidation_ts,
-                ) = row
-
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "caches":
+            self._cache_id_gen.advance(token)
+            for row in rows:
                 try:
-                    getattr(self, cache_func).invalidate(tuple(keys))
+                    getattr(self, row.cache_func).invalidate(tuple(row.keys))
                 except AttributeError:
                     # We probably haven't pulled in the cache in this worker,
                     # which is fine.
                     pass
-            self._cache_id_gen.advance(int(stream["position"]))
-        return defer.succeed(None)
 
     def _invalidate_cache_and_stream(self, txn, cache_func, keys):
         txn.call_after(cache_func.invalidate, keys)
         txn.call_after(self._send_invalidation_poke, cache_func, keys)
 
-    @defer.inlineCallbacks
     def _send_invalidation_poke(self, cache_func, keys):
-        try:
-            yield self.http_client.post_json_get_json(self.expire_cache_url, {
-                "invalidate": [{
-                    "name": cache_func.__name__,
-                    "keys": list(keys),
-                }]
-            })
-        except:
-            logger.exception("Failed to poke on expire_cache")
+        self.hs.get_tcp_replication().send_invalidate_cache(cache_func, keys)
diff --git a/synapse/replication/slave/storage/account_data.py b/synapse/replication/slave/storage/account_data.py
index 77c64722c7..efbd87918e 100644
--- a/synapse/replication/slave/storage/account_data.py
+++ b/synapse/replication/slave/storage/account_data.py
@@ -69,38 +69,25 @@ class SlavedAccountDataStore(BaseSlavedStore):
         result["tag_account_data"] = position
         return result
 
-    def process_replication(self, result):
-        stream = result.get("user_account_data")
-        if stream:
-            self._account_data_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                position, user_id, data_type = row[:3]
-                self.get_global_account_data_by_type_for_user.invalidate(
-                    (data_type, user_id,)
-                )
-                self.get_account_data_for_user.invalidate((user_id,))
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "tag_account_data":
+            self._account_data_id_gen.advance(token)
+            for row in rows:
+                self.get_tags_for_user.invalidate((row.user_id,))
                 self._account_data_stream_cache.entity_has_changed(
-                    user_id, position
+                    row.user_id, token
                 )
-
-        stream = result.get("room_account_data")
-        if stream:
-            self._account_data_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                position, user_id = row[:2]
-                self.get_account_data_for_user.invalidate((user_id,))
+        elif stream_name == "account_data":
+            self._account_data_id_gen.advance(token)
+            for row in rows:
+                if not row.room_id:
+                    self.get_global_account_data_by_type_for_user.invalidate(
+                        (row.data_type, row.user_id,)
+                    )
+                self.get_account_data_for_user.invalidate((row.user_id,))
                 self._account_data_stream_cache.entity_has_changed(
-                    user_id, position
+                    row.user_id, token
                 )
-
-        stream = result.get("tag_account_data")
-        if stream:
-            self._account_data_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                position, user_id = row[:2]
-                self.get_tags_for_user.invalidate((user_id,))
-                self._account_data_stream_cache.entity_has_changed(
-                    user_id, position
-                )
-
-        return super(SlavedAccountDataStore, self).process_replication(result)
+        return super(SlavedAccountDataStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/deviceinbox.py b/synapse/replication/slave/storage/deviceinbox.py
index f9102e0d89..6f3fb64770 100644
--- a/synapse/replication/slave/storage/deviceinbox.py
+++ b/synapse/replication/slave/storage/deviceinbox.py
@@ -53,21 +53,18 @@ class SlavedDeviceInboxStore(BaseSlavedStore):
         result["to_device"] = self._device_inbox_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("to_device")
-        if stream:
-            self._device_inbox_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                stream_id = row[0]
-                entity = row[1]
-
-                if entity.startswith("@"):
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "to_device":
+            self._device_inbox_id_gen.advance(token)
+            for row in rows:
+                if row.entity.startswith("@"):
                     self._device_inbox_stream_cache.entity_has_changed(
-                        entity, stream_id
+                        row.entity, token
                     )
                 else:
                     self._device_federation_outbox_stream_cache.entity_has_changed(
-                        entity, stream_id
+                        row.entity, token
                     )
-
-        return super(SlavedDeviceInboxStore, self).process_replication(result)
+        return super(SlavedDeviceInboxStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/devices.py b/synapse/replication/slave/storage/devices.py
index ca46aa17b6..4d4a435471 100644
--- a/synapse/replication/slave/storage/devices.py
+++ b/synapse/replication/slave/storage/devices.py
@@ -51,22 +51,18 @@ class SlavedDeviceStore(BaseSlavedStore):
         result["device_lists"] = self._device_list_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("device_lists")
-        if stream:
-            self._device_list_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                stream_id = row[0]
-                user_id = row[1]
-                destination = row[2]
-
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "device_lists":
+            self._device_list_id_gen.advance(token)
+            for row in rows:
                 self._device_list_stream_cache.entity_has_changed(
-                    user_id, stream_id
+                    row.user_id, token
                 )
 
-                if destination:
+                if row.destination:
                     self._device_list_federation_stream_cache.entity_has_changed(
-                        destination, stream_id
+                        row.destination, token
                     )
-
-        return super(SlavedDeviceStore, self).process_replication(result)
+        return super(SlavedDeviceStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/events.py b/synapse/replication/slave/storage/events.py
index d4db1e452e..fcaf58b93b 100644
--- a/synapse/replication/slave/storage/events.py
+++ b/synapse/replication/slave/storage/events.py
@@ -71,6 +71,7 @@ class SlavedEventStore(BaseSlavedStore):
     # to reach inside the __dict__ to extract them.
     get_rooms_for_user = RoomMemberStore.__dict__["get_rooms_for_user"]
     get_users_in_room = RoomMemberStore.__dict__["get_users_in_room"]
+    get_hosts_in_room = RoomMemberStore.__dict__["get_hosts_in_room"]
     get_users_who_share_room_with_user = (
         RoomMemberStore.__dict__["get_users_who_share_room_with_user"]
     )
@@ -101,9 +102,6 @@ class SlavedEventStore(BaseSlavedStore):
     _get_state_groups_from_groups_txn = (
         DataStore._get_state_groups_from_groups_txn.__func__
     )
-    _get_state_group_from_group = (
-        StateStore.__dict__["_get_state_group_from_group"]
-    )
     get_recent_event_ids_for_room = (
         StreamStore.__dict__["get_recent_event_ids_for_room"]
     )
@@ -146,6 +144,9 @@ class SlavedEventStore(BaseSlavedStore):
         RoomMemberStore.__dict__["_get_joined_users_from_context"]
     )
 
+    get_joined_hosts = DataStore.get_joined_hosts.__func__
+    _get_joined_hosts = RoomMemberStore.__dict__["_get_joined_hosts"]
+
     get_recent_events_for_room = DataStore.get_recent_events_for_room.__func__
     get_room_events_stream_for_rooms = (
         DataStore.get_room_events_stream_for_rooms.__func__
@@ -201,48 +202,25 @@ class SlavedEventStore(BaseSlavedStore):
         result["backfill"] = -self._backfill_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("events")
-        if stream:
-            self._stream_id_gen.advance(int(stream["position"]))
-
-            if stream["rows"]:
-                logger.info("Got %d event rows", len(stream["rows"]))
-
-            for row in stream["rows"]:
-                self._process_replication_row(
-                    row, backfilled=False,
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "events":
+            self._stream_id_gen.advance(token)
+            for row in rows:
+                self.invalidate_caches_for_event(
+                    token, row.event_id, row.room_id, row.type, row.state_key,
+                    row.redacts,
+                    backfilled=False,
                 )
-
-        stream = result.get("backfill")
-        if stream:
-            self._backfill_id_gen.advance(-int(stream["position"]))
-            for row in stream["rows"]:
-                self._process_replication_row(
-                    row, backfilled=True,
+        elif stream_name == "backfill":
+            self._backfill_id_gen.advance(-token)
+            for row in rows:
+                self.invalidate_caches_for_event(
+                    -token, row.event_id, row.room_id, row.type, row.state_key,
+                    row.redacts,
+                    backfilled=True,
                 )
-
-        stream = result.get("forward_ex_outliers")
-        if stream:
-            self._stream_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                event_id = row[1]
-                self._invalidate_get_event_cache(event_id)
-
-        stream = result.get("backward_ex_outliers")
-        if stream:
-            self._backfill_id_gen.advance(-int(stream["position"]))
-            for row in stream["rows"]:
-                event_id = row[1]
-                self._invalidate_get_event_cache(event_id)
-
-        return super(SlavedEventStore, self).process_replication(result)
-
-    def _process_replication_row(self, row, backfilled):
-        stream_ordering = row[0] if not backfilled else -row[0]
-        self.invalidate_caches_for_event(
-            stream_ordering, row[1], row[2], row[3], row[4], row[5],
-            backfilled=backfilled,
+        return super(SlavedEventStore, self).process_replication_rows(
+            stream_name, token, rows
         )
 
     def invalidate_caches_for_event(self, stream_ordering, event_id, room_id,
diff --git a/synapse/replication/slave/storage/presence.py b/synapse/replication/slave/storage/presence.py
index e4a2414d78..cfb9280181 100644
--- a/synapse/replication/slave/storage/presence.py
+++ b/synapse/replication/slave/storage/presence.py
@@ -39,6 +39,16 @@ class SlavedPresenceStore(BaseSlavedStore):
     _get_presence_for_user = PresenceStore.__dict__["_get_presence_for_user"]
     get_presence_for_users = PresenceStore.__dict__["get_presence_for_users"]
 
+    # XXX: This is a bit broken because we don't persist the accepted list in a
+    # way that can be replicated. This means that we don't have a way to
+    # invalidate the cache correctly.
+    get_presence_list_accepted = PresenceStore.__dict__[
+        "get_presence_list_accepted"
+    ]
+    get_presence_list_observers_accepted = PresenceStore.__dict__[
+        "get_presence_list_observers_accepted"
+    ]
+
     def get_current_presence_token(self):
         return self._presence_id_gen.get_current_token()
 
@@ -48,15 +58,14 @@ class SlavedPresenceStore(BaseSlavedStore):
         result["presence"] = position
         return result
 
-    def process_replication(self, result):
-        stream = result.get("presence")
-        if stream:
-            self._presence_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                position, user_id = row[:2]
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "presence":
+            self._presence_id_gen.advance(token)
+            for row in rows:
                 self.presence_stream_cache.entity_has_changed(
-                    user_id, position
+                    row.user_id, token
                 )
-                self._get_presence_for_user.invalidate((user_id,))
-
-        return super(SlavedPresenceStore, self).process_replication(result)
+                self._get_presence_for_user.invalidate((row.user_id,))
+        return super(SlavedPresenceStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/push_rule.py b/synapse/replication/slave/storage/push_rule.py
index 21ceb0213a..83e880fdd2 100644
--- a/synapse/replication/slave/storage/push_rule.py
+++ b/synapse/replication/slave/storage/push_rule.py
@@ -50,18 +50,15 @@ class SlavedPushRuleStore(SlavedEventStore):
         result["push_rules"] = self._push_rules_stream_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("push_rules")
-        if stream:
-            for row in stream["rows"]:
-                position = row[0]
-                user_id = row[2]
-                self.get_push_rules_for_user.invalidate((user_id,))
-                self.get_push_rules_enabled_for_user.invalidate((user_id,))
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "push_rules":
+            self._push_rules_stream_id_gen.advance(token)
+            for row in rows:
+                self.get_push_rules_for_user.invalidate((row.user_id,))
+                self.get_push_rules_enabled_for_user.invalidate((row.user_id,))
                 self.push_rules_stream_cache.entity_has_changed(
-                    user_id, position
+                    row.user_id, token
                 )
-
-            self._push_rules_stream_id_gen.advance(int(stream["position"]))
-
-        return super(SlavedPushRuleStore, self).process_replication(result)
+        return super(SlavedPushRuleStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/pushers.py b/synapse/replication/slave/storage/pushers.py
index d88206b3bb..4e8d68ece9 100644
--- a/synapse/replication/slave/storage/pushers.py
+++ b/synapse/replication/slave/storage/pushers.py
@@ -40,13 +40,9 @@ class SlavedPusherStore(BaseSlavedStore):
         result["pushers"] = self._pushers_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("pushers")
-        if stream:
-            self._pushers_id_gen.advance(int(stream["position"]))
-
-        stream = result.get("deleted_pushers")
-        if stream:
-            self._pushers_id_gen.advance(int(stream["position"]))
-
-        return super(SlavedPusherStore, self).process_replication(result)
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "pushers":
+            self._pushers_id_gen.advance(token)
+        return super(SlavedPusherStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/receipts.py b/synapse/replication/slave/storage/receipts.py
index ac9662d399..b371574ece 100644
--- a/synapse/replication/slave/storage/receipts.py
+++ b/synapse/replication/slave/storage/receipts.py
@@ -65,20 +65,22 @@ class SlavedReceiptsStore(BaseSlavedStore):
         result["receipts"] = self._receipts_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("receipts")
-        if stream:
-            self._receipts_id_gen.advance(int(stream["position"]))
-            for row in stream["rows"]:
-                position, room_id, receipt_type, user_id = row[:4]
-                self.invalidate_caches_for_receipt(room_id, receipt_type, user_id)
-                self._receipts_stream_cache.entity_has_changed(room_id, position)
-
-        return super(SlavedReceiptsStore, self).process_replication(result)
-
     def invalidate_caches_for_receipt(self, room_id, receipt_type, user_id):
         self.get_receipts_for_user.invalidate((user_id, receipt_type))
         self.get_linearized_receipts_for_room.invalidate_many((room_id,))
         self.get_last_receipt_event_id_for_user.invalidate(
             (user_id, room_id, receipt_type)
         )
+
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "receipts":
+            self._receipts_id_gen.advance(token)
+            for row in rows:
+                self.invalidate_caches_for_receipt(
+                    row.room_id, row.receipt_type, row.user_id
+                )
+                self._receipts_stream_cache.entity_has_changed(row.room_id, token)
+
+        return super(SlavedReceiptsStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/slave/storage/room.py b/synapse/replication/slave/storage/room.py
index 6df9a25ef3..f510384033 100644
--- a/synapse/replication/slave/storage/room.py
+++ b/synapse/replication/slave/storage/room.py
@@ -46,9 +46,10 @@ class RoomStore(BaseSlavedStore):
         result["public_rooms"] = self._public_room_id_gen.get_current_token()
         return result
 
-    def process_replication(self, result):
-        stream = result.get("public_rooms")
-        if stream:
-            self._public_room_id_gen.advance(int(stream["position"]))
+    def process_replication_rows(self, stream_name, token, rows):
+        if stream_name == "public_rooms":
+            self._public_room_id_gen.advance(token)
 
-        return super(RoomStore, self).process_replication(result)
+        return super(RoomStore, self).process_replication_rows(
+            stream_name, token, rows
+        )
diff --git a/synapse/replication/tcp/__init__.py b/synapse/replication/tcp/__init__.py
new file mode 100644
index 0000000000..81c2ea7ee9
--- /dev/null
+++ b/synapse/replication/tcp/__init__.py
@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""This module implements the TCP replication protocol used by synapse to
+communicate between the master process and its workers (when they're enabled).
+
+Further details can be found in docs/tcp_replication.rst
+
+
+Structure of the module:
+ * client.py   - the client classes used for workers to connect to master
+ * command.py  - the definitions of all the valid commands
+ * protocol.py - contains bot the client and server protocol implementations,
+                 these should not be used directly
+ * resource.py - the server classes that accepts and handle client connections
+ * streams.py  - the definitons of all the valid streams
+
+"""
diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
new file mode 100644
index 0000000000..90fb6c1336
--- /dev/null
+++ b/synapse/replication/tcp/client.py
@@ -0,0 +1,196 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""A replication client for use by synapse workers.
+"""
+
+from twisted.internet import reactor, defer
+from twisted.internet.protocol import ReconnectingClientFactory
+
+from .commands import (
+    FederationAckCommand, UserSyncCommand, RemovePusherCommand, InvalidateCacheCommand,
+)
+from .protocol import ClientReplicationStreamProtocol
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class ReplicationClientFactory(ReconnectingClientFactory):
+    """Factory for building connections to the master. Will reconnect if the
+    connection is lost.
+
+    Accepts a handler that will be called when new data is available or data
+    is required.
+    """
+    maxDelay = 5  # Try at least once every N seconds
+
+    def __init__(self, hs, client_name, handler):
+        self.client_name = client_name
+        self.handler = handler
+        self.server_name = hs.config.server_name
+        self._clock = hs.get_clock()  # As self.clock is defined in super class
+
+        reactor.addSystemEventTrigger("before", "shutdown", self.stopTrying)
+
+    def startedConnecting(self, connector):
+        logger.info("Connecting to replication: %r", connector.getDestination())
+
+    def buildProtocol(self, addr):
+        logger.info("Connected to replication: %r", addr)
+        self.resetDelay()
+        return ClientReplicationStreamProtocol(
+            self.client_name, self.server_name, self._clock, self.handler
+        )
+
+    def clientConnectionLost(self, connector, reason):
+        logger.error("Lost replication conn: %r", reason)
+        ReconnectingClientFactory.clientConnectionLost(self, connector, reason)
+
+    def clientConnectionFailed(self, connector, reason):
+        logger.error("Failed to connect to replication: %r", reason)
+        ReconnectingClientFactory.clientConnectionFailed(
+            self, connector, reason
+        )
+
+
+class ReplicationClientHandler(object):
+    """A base handler that can be passed to the ReplicationClientFactory.
+
+    By default proxies incoming replication data to the SlaveStore.
+    """
+    def __init__(self, store):
+        self.store = store
+
+        # The current connection. None if we are currently (re)connecting
+        self.connection = None
+
+        # Any pending commands to be sent once a new connection has been
+        # established
+        self.pending_commands = []
+
+        # Map from string -> deferred, to wake up when receiveing a SYNC with
+        # the given string.
+        # Used for tests.
+        self.awaiting_syncs = {}
+
+    def start_replication(self, hs):
+        """Helper method to start a replication connection to the remote server
+        using TCP.
+        """
+        client_name = hs.config.worker_name
+        factory = ReplicationClientFactory(hs, client_name, self)
+        host = hs.config.worker_replication_host
+        port = hs.config.worker_replication_port
+        reactor.connectTCP(host, port, factory)
+
+    def on_rdata(self, stream_name, token, rows):
+        """Called when we get new replication data. By default this just pokes
+        the slave store.
+
+        Can be overriden in subclasses to handle more.
+        """
+        logger.info("Received rdata %s -> %s", stream_name, token)
+        self.store.process_replication_rows(stream_name, token, rows)
+
+    def on_position(self, stream_name, token):
+        """Called when we get new position data. By default this just pokes
+        the slave store.
+
+        Can be overriden in subclasses to handle more.
+        """
+        self.store.process_replication_rows(stream_name, token, [])
+
+    def on_sync(self, data):
+        """When we received a SYNC we wake up any deferreds that were waiting
+        for the sync with the given data.
+
+        Used by tests.
+        """
+        d = self.awaiting_syncs.pop(data, None)
+        if d:
+            d.callback(data)
+
+    def get_streams_to_replicate(self):
+        """Called when a new connection has been established and we need to
+        subscribe to streams.
+
+        Returns a dictionary of stream name to token.
+        """
+        args = self.store.stream_positions()
+        user_account_data = args.pop("user_account_data", None)
+        room_account_data = args.pop("room_account_data", None)
+        if user_account_data:
+            args["account_data"] = user_account_data
+        elif room_account_data:
+            args["account_data"] = room_account_data
+        return args
+
+    def get_currently_syncing_users(self):
+        """Get the list of currently syncing users (if any). This is called
+        when a connection has been established and we need to send the
+        currently syncing users. (Overriden by the synchrotron's only)
+        """
+        return []
+
+    def send_command(self, cmd):
+        """Send a command to master (when we get establish a connection if we
+        don't have one already.)
+        """
+        if self.connection:
+            self.connection.send_command(cmd)
+        else:
+            logger.warn("Queuing command as not connected: %r", cmd.NAME)
+            self.pending_commands.append(cmd)
+
+    def send_federation_ack(self, token):
+        """Ack data for the federation stream. This allows the master to drop
+        data stored purely in memory.
+        """
+        self.send_command(FederationAckCommand(token))
+
+    def send_user_sync(self, user_id, is_syncing, last_sync_ms):
+        """Poke the master that a user has started/stopped syncing.
+        """
+        self.send_command(UserSyncCommand(user_id, is_syncing, last_sync_ms))
+
+    def send_remove_pusher(self, app_id, push_key, user_id):
+        """Poke the master to remove a pusher for a user
+        """
+        cmd = RemovePusherCommand(app_id, push_key, user_id)
+        self.send_command(cmd)
+
+    def send_invalidate_cache(self, cache_func, keys):
+        """Poke the master to invalidate a cache.
+        """
+        cmd = InvalidateCacheCommand(cache_func.__name__, keys)
+        self.send_command(cmd)
+
+    def await_sync(self, data):
+        """Returns a deferred that is resolved when we receive a SYNC command
+        with given data.
+
+        Used by tests.
+        """
+        return self.awaiting_syncs.setdefault(data, defer.Deferred())
+
+    def update_connection(self, connection):
+        """Called when a connection has been established (or lost with None).
+        """
+        self.connection = connection
+        if connection:
+            for cmd in self.pending_commands:
+                connection.send_command(cmd)
+            self.pending_commands = []
diff --git a/synapse/replication/tcp/commands.py b/synapse/replication/tcp/commands.py
new file mode 100644
index 0000000000..84d2a2272a
--- /dev/null
+++ b/synapse/replication/tcp/commands.py
@@ -0,0 +1,346 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Defines the various valid commands
+
+The VALID_SERVER_COMMANDS and VALID_CLIENT_COMMANDS define which commands are
+allowed to be sent by which side.
+"""
+
+import logging
+import ujson as json
+
+
+logger = logging.getLogger(__name__)
+
+
+class Command(object):
+    """The base command class.
+
+    All subclasses must set the NAME variable which equates to the name of the
+    command on the wire.
+
+    A full command line on the wire is constructed from `NAME + " " + to_line()`
+
+    The default implementation creates a command of form `<NAME> <data>`
+    """
+    NAME = None
+
+    def __init__(self, data):
+        self.data = data
+
+    @classmethod
+    def from_line(cls, line):
+        """Deserialises a line from the wire into this command. `line` does not
+        include the command.
+        """
+        return cls(line)
+
+    def to_line(self):
+        """Serialises the comamnd for the wire. Does not include the command
+        prefix.
+        """
+        return self.data
+
+
+class ServerCommand(Command):
+    """Sent by the server on new connection and includes the server_name.
+
+    Format::
+
+        SERVER <server_name>
+    """
+    NAME = "SERVER"
+
+
+class RdataCommand(Command):
+    """Sent by server when a subscribed stream has an update.
+
+    Format::
+
+        RDATA <stream_name> <token> <row_json>
+
+    The `<token>` may either be a numeric stream id OR "batch". The latter case
+    is used to support sending multiple updates with the same stream ID. This
+    is done by sending an RDATA for each row, with all but the last RDATA having
+    a token of "batch" and the last having the final stream ID.
+
+    The client should batch all incoming RDATA with a token of "batch" (per
+    stream_name) until it sees an RDATA with a numeric stream ID.
+
+    `<token>` of "batch" maps to the instance variable `token` being None.
+
+    An example of a batched series of RDATA::
+
+        RDATA presence batch ["@foo:example.com", "online", ...]
+        RDATA presence batch ["@bar:example.com", "online", ...]
+        RDATA presence 59 ["@baz:example.com", "online", ...]
+    """
+    NAME = "RDATA"
+
+    def __init__(self, stream_name, token, row):
+        self.stream_name = stream_name
+        self.token = token
+        self.row = row
+
+    @classmethod
+    def from_line(cls, line):
+        stream_name, token, row_json = line.split(" ", 2)
+        return cls(
+            stream_name,
+            None if token == "batch" else int(token),
+            json.loads(row_json)
+        )
+
+    def to_line(self):
+        return " ".join((
+            self.stream_name,
+            str(self.token) if self.token is not None else "batch",
+            json.dumps(self.row),
+        ))
+
+
+class PositionCommand(Command):
+    """Sent by the client to tell the client the stream postition without
+    needing to send an RDATA.
+    """
+    NAME = "POSITION"
+
+    def __init__(self, stream_name, token):
+        self.stream_name = stream_name
+        self.token = token
+
+    @classmethod
+    def from_line(cls, line):
+        stream_name, token = line.split(" ", 1)
+        return cls(stream_name, int(token))
+
+    def to_line(self):
+        return " ".join((self.stream_name, str(self.token),))
+
+
+class ErrorCommand(Command):
+    """Sent by either side if there was an ERROR. The data is a string describing
+    the error.
+    """
+    NAME = "ERROR"
+
+
+class PingCommand(Command):
+    """Sent by either side as a keep alive. The data is arbitary (often timestamp)
+    """
+    NAME = "PING"
+
+
+class NameCommand(Command):
+    """Sent by client to inform the server of the client's identity. The data
+    is the name
+    """
+    NAME = "NAME"
+
+
+class ReplicateCommand(Command):
+    """Sent by the client to subscribe to the stream.
+
+    Format::
+
+        REPLICATE <stream_name> <token>
+
+    Where <token> may be either:
+        * a numeric stream_id to stream updates from
+        * "NOW" to stream all subsequent updates.
+
+    The <stream_name> can be "ALL" to subscribe to all known streams, in which
+    case the <token> must be set to "NOW", i.e.::
+
+        REPLICATE ALL NOW
+    """
+    NAME = "REPLICATE"
+
+    def __init__(self, stream_name, token):
+        self.stream_name = stream_name
+        self.token = token
+
+    @classmethod
+    def from_line(cls, line):
+        stream_name, token = line.split(" ", 1)
+        if token in ("NOW", "now"):
+            token = "NOW"
+        else:
+            token = int(token)
+        return cls(stream_name, token)
+
+    def to_line(self):
+        return " ".join((self.stream_name, str(self.token),))
+
+
+class UserSyncCommand(Command):
+    """Sent by the client to inform the server that a user has started or
+    stopped syncing. Used to calculate presence on the master.
+
+    Includes a timestamp of when the last user sync was.
+
+    Format::
+
+        USER_SYNC <user_id> <state> <last_sync_ms>
+
+    Where <state> is either "start" or "stop"
+    """
+    NAME = "USER_SYNC"
+
+    def __init__(self, user_id, is_syncing, last_sync_ms):
+        self.user_id = user_id
+        self.is_syncing = is_syncing
+        self.last_sync_ms = last_sync_ms
+
+    @classmethod
+    def from_line(cls, line):
+        user_id, state, last_sync_ms = line.split(" ", 2)
+
+        if state not in ("start", "end"):
+            raise Exception("Invalid USER_SYNC state %r" % (state,))
+
+        return cls(user_id, state == "start", int(last_sync_ms))
+
+    def to_line(self):
+        return " ".join((
+            self.user_id, "start" if self.is_syncing else "end", str(self.last_sync_ms),
+        ))
+
+
+class FederationAckCommand(Command):
+    """Sent by the client when it has processed up to a given point in the
+    federation stream. This allows the master to drop in-memory caches of the
+    federation stream.
+
+    This must only be sent from one worker (i.e. the one sending federation)
+
+    Format::
+
+        FEDERATION_ACK <token>
+    """
+    NAME = "FEDERATION_ACK"
+
+    def __init__(self, token):
+        self.token = token
+
+    @classmethod
+    def from_line(cls, line):
+        return cls(int(line))
+
+    def to_line(self):
+        return str(self.token)
+
+
+class SyncCommand(Command):
+    """Used for testing. The client protocol implementation allows waiting
+    on a SYNC command with a specified data.
+    """
+    NAME = "SYNC"
+
+
+class RemovePusherCommand(Command):
+    """Sent by the client to request the master remove the given pusher.
+
+    Format::
+
+        REMOVE_PUSHER <app_id> <push_key> <user_id>
+    """
+    NAME = "REMOVE_PUSHER"
+
+    def __init__(self, app_id, push_key, user_id):
+        self.user_id = user_id
+        self.app_id = app_id
+        self.push_key = push_key
+
+    @classmethod
+    def from_line(cls, line):
+        app_id, push_key, user_id = line.split(" ", 2)
+
+        return cls(app_id, push_key, user_id)
+
+    def to_line(self):
+        return " ".join((self.app_id, self.push_key, self.user_id))
+
+
+class InvalidateCacheCommand(Command):
+    """Sent by the client to invalidate an upstream cache.
+
+    THIS IS NOT RELIABLE, AND SHOULD *NOT* BE USED ACCEPT FOR THINGS THAT ARE
+    NOT DISASTROUS IF WE DROP ON THE FLOOR.
+
+    Mainly used to invalidate destination retry timing caches.
+
+    Format::
+
+        INVALIDATE_CACHE <cache_func> <keys_json>
+
+    Where <keys_json> is a json list.
+    """
+    NAME = "INVALIDATE_CACHE"
+
+    def __init__(self, cache_func, keys):
+        self.cache_func = cache_func
+        self.keys = keys
+
+    @classmethod
+    def from_line(cls, line):
+        cache_func, keys_json = line.split(" ", 1)
+
+        return cls(cache_func, json.loads(keys_json))
+
+    def to_line(self):
+        return " ".join((self.cache_func, json.dumps(self.keys)))
+
+
+# Map of command name to command type.
+COMMAND_MAP = {
+    cmd.NAME: cmd
+    for cmd in (
+        ServerCommand,
+        RdataCommand,
+        PositionCommand,
+        ErrorCommand,
+        PingCommand,
+        NameCommand,
+        ReplicateCommand,
+        UserSyncCommand,
+        FederationAckCommand,
+        SyncCommand,
+        RemovePusherCommand,
+        InvalidateCacheCommand,
+    )
+}
+
+# The commands the server is allowed to send
+VALID_SERVER_COMMANDS = (
+    ServerCommand.NAME,
+    RdataCommand.NAME,
+    PositionCommand.NAME,
+    ErrorCommand.NAME,
+    PingCommand.NAME,
+    SyncCommand.NAME,
+)
+
+# The commands the client is allowed to send
+VALID_CLIENT_COMMANDS = (
+    NameCommand.NAME,
+    ReplicateCommand.NAME,
+    PingCommand.NAME,
+    UserSyncCommand.NAME,
+    FederationAckCommand.NAME,
+    RemovePusherCommand.NAME,
+    InvalidateCacheCommand.NAME,
+    ErrorCommand.NAME,
+)
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
new file mode 100644
index 0000000000..9fee2a484b
--- /dev/null
+++ b/synapse/replication/tcp/protocol.py
@@ -0,0 +1,640 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""This module contains the implementation of both the client and server
+protocols.
+
+The basic structure of the protocol is line based, where the initial word of
+each line specifies the command. The rest of the line is parsed based on the
+command. For example, the `RDATA` command is defined as::
+
+    RDATA <stream_name> <token> <row_json>
+
+(Note that `<row_json>` may contains spaces, but cannot contain newlines.)
+
+Blank lines are ignored.
+
+# Example
+
+An example iteraction is shown below. Each line is prefixed with '>' or '<' to
+indicate which side is sending, these are *not* included on the wire::
+
+    * connection established *
+    > SERVER localhost:8823
+    > PING 1490197665618
+    < NAME synapse.app.appservice
+    < PING 1490197665618
+    < REPLICATE events 1
+    < REPLICATE backfill 1
+    < REPLICATE caches 1
+    > POSITION events 1
+    > POSITION backfill 1
+    > POSITION caches 1
+    > RDATA caches 2 ["get_user_by_id",["@01register-user:localhost:8823"],1490197670513]
+    > RDATA events 14 ["$149019767112vOHxz:localhost:8823",
+        "!AFDCvgApUmpdfVjIXm:localhost:8823","m.room.guest_access","",null]
+    < PING 1490197675618
+    > ERROR server stopping
+    * connection closed by server *
+"""
+
+from twisted.internet import defer
+from twisted.protocols.basic import LineOnlyReceiver
+from twisted.python.failure import Failure
+
+from commands import (
+    COMMAND_MAP, VALID_CLIENT_COMMANDS, VALID_SERVER_COMMANDS,
+    ErrorCommand, ServerCommand, RdataCommand, PositionCommand, PingCommand,
+    NameCommand, ReplicateCommand, UserSyncCommand, SyncCommand,
+)
+from streams import STREAMS_MAP
+
+from synapse.util.stringutils import random_string
+from synapse.metrics.metric import CounterMetric
+
+import logging
+import synapse.metrics
+import struct
+import fcntl
+
+
+metrics = synapse.metrics.get_metrics_for(__name__)
+
+connection_close_counter = metrics.register_counter(
+    "close_reason", labels=["reason_type"],
+)
+
+
+# A list of all connected protocols. This allows us to send metrics about the
+# connections.
+connected_connections = []
+
+
+logger = logging.getLogger(__name__)
+
+
+PING_TIME = 5000
+PING_TIMEOUT_MULTIPLIER = 5
+PING_TIMEOUT_MS = PING_TIME * PING_TIMEOUT_MULTIPLIER
+
+
+class ConnectionStates(object):
+    CONNECTING = "connecting"
+    ESTABLISHED = "established"
+    PAUSED = "paused"
+    CLOSED = "closed"
+
+
+class BaseReplicationStreamProtocol(LineOnlyReceiver):
+    """Base replication protocol shared between client and server.
+
+    Reads lines (ignoring blank ones) and parses them into command classes,
+    asserting that they are valid for the given direction, i.e. server commands
+    are only sent by the server.
+
+    On receiving a new command it calls `on_<COMMAND_NAME>` with the parsed
+    command.
+
+    It also sends `PING` periodically, and correctly times out remote connections
+    (if they send a `PING` command)
+    """
+    delimiter = b'\n'
+
+    VALID_INBOUND_COMMANDS = []  # Valid commands we expect to receive
+    VALID_OUTBOUND_COMMANDS = []  # Valid commans we can send
+
+    max_line_buffer = 10000
+
+    def __init__(self, clock):
+        self.clock = clock
+
+        self.last_received_command = self.clock.time_msec()
+        self.last_sent_command = 0
+        self.time_we_closed = None  # When we requested the connection be closed
+
+        self.received_ping = False  # Have we reecived a ping from the other side
+
+        self.state = ConnectionStates.CONNECTING
+
+        self.name = "anon"  # The name sent by a client.
+        self.conn_id = random_string(5)  # To dedupe in case of name clashes.
+
+        # List of pending commands to send once we've established the connection
+        self.pending_commands = []
+
+        # The LoopingCall for sending pings.
+        self._send_ping_loop = None
+
+        self.inbound_commands_counter = CounterMetric(
+            "inbound_commands", labels=["command"],
+        )
+        self.outbound_commands_counter = CounterMetric(
+            "outbound_commands", labels=["command"],
+        )
+
+    def connectionMade(self):
+        logger.info("[%s] Connection established", self.id())
+
+        self.state = ConnectionStates.ESTABLISHED
+
+        connected_connections.append(self)  # Register connection for metrics
+
+        self.transport.registerProducer(self, True)  # For the *Producing callbacks
+
+        self._send_pending_commands()
+
+        # Starts sending pings
+        self._send_ping_loop = self.clock.looping_call(self.send_ping, 5000)
+
+        # Always send the initial PING so that the other side knows that they
+        # can time us out.
+        self.send_command(PingCommand(self.clock.time_msec()))
+
+    def send_ping(self):
+        """Periodically sends a ping and checks if we should close the connection
+        due to the other side timing out.
+        """
+        now = self.clock.time_msec()
+
+        if self.time_we_closed:
+            if now - self.time_we_closed > PING_TIMEOUT_MS:
+                logger.info(
+                    "[%s] Failed to close connection gracefully, aborting", self.id()
+                )
+                self.transport.abortConnection()
+        else:
+            if now - self.last_sent_command >= PING_TIME:
+                self.send_command(PingCommand(now))
+
+            if self.received_ping and now - self.last_received_command > PING_TIMEOUT_MS:
+                logger.info(
+                    "[%s] Connection hasn't received command in %r ms. Closing.",
+                    self.id(), now - self.last_received_command
+                )
+                self.send_error("ping timeout")
+
+    def lineReceived(self, line):
+        """Called when we've received a line
+        """
+        if line.strip() == "":
+            # Ignore blank lines
+            return
+
+        line = line.decode("utf-8")
+        cmd_name, rest_of_line = line.split(" ", 1)
+
+        if cmd_name not in self.VALID_INBOUND_COMMANDS:
+            logger.error("[%s] invalid command %s", self.id(), cmd_name)
+            self.send_error("invalid command: %s", cmd_name)
+            return
+
+        self.last_received_command = self.clock.time_msec()
+
+        self.inbound_commands_counter.inc(cmd_name)
+
+        cmd_cls = COMMAND_MAP[cmd_name]
+        try:
+            cmd = cmd_cls.from_line(rest_of_line)
+        except Exception as e:
+            logger.exception(
+                "[%s] failed to parse line %r: %r", self.id(), cmd_name, rest_of_line
+            )
+            self.send_error(
+                "failed to parse line for  %r: %r (%r):" % (cmd_name, e, rest_of_line)
+            )
+            return
+
+        # Now lets try and call on_<CMD_NAME> function
+        try:
+            getattr(self, "on_%s" % (cmd_name,))(cmd)
+        except Exception:
+            logger.exception("[%s] Failed to handle line: %r", self.id(), line)
+
+    def close(self):
+        logger.warn("[%s] Closing connection", self.id())
+        self.time_we_closed = self.clock.time_msec()
+        self.transport.loseConnection()
+        self.on_connection_closed()
+
+    def send_error(self, error_string, *args):
+        """Send an error to remote and close the connection.
+        """
+        self.send_command(ErrorCommand(error_string % args))
+        self.close()
+
+    def send_command(self, cmd, do_buffer=True):
+        """Send a command if connection has been established.
+
+        Args:
+            cmd (Command)
+            do_buffer (bool): Whether to buffer the message or always attempt
+                to send the command. This is mostly used to send an error
+                message if we're about to close the connection due our buffers
+                becoming full.
+        """
+        if self.state == ConnectionStates.CLOSED:
+            logger.info("[%s] Not sending, connection closed", self.id())
+            return
+
+        if do_buffer and self.state != ConnectionStates.ESTABLISHED:
+            self._queue_command(cmd)
+            return
+
+        self.outbound_commands_counter.inc(cmd.NAME)
+
+        string = "%s %s" % (cmd.NAME, cmd.to_line(),)
+        if "\n" in string:
+            raise Exception("Unexpected newline in command: %r", string)
+
+        self.sendLine(string.encode("utf-8"))
+
+        self.last_sent_command = self.clock.time_msec()
+
+    def _queue_command(self, cmd):
+        """Queue the command until the connection is ready to write to again.
+        """
+        logger.info("[%s] Queing as conn %r, cmd: %r", self.id(), self.state, cmd)
+        self.pending_commands.append(cmd)
+
+        if len(self.pending_commands) > self.max_line_buffer:
+            # The other side is failing to keep up and out buffers are becoming
+            # full, so lets close the connection.
+            # XXX: should we squawk more loudly?
+            logger.error("[%s] Remote failed to keep up", self.id())
+            self.send_command(ErrorCommand("Failed to keep up"), do_buffer=False)
+            self.close()
+
+    def _send_pending_commands(self):
+        """Send any queued commandes
+        """
+        pending = self.pending_commands
+        self.pending_commands = []
+        for cmd in pending:
+            self.send_command(cmd)
+
+    def on_PING(self, line):
+        self.received_ping = True
+
+    def on_ERROR(self, cmd):
+        logger.error("[%s] Remote reported error: %r", self.id(), cmd.data)
+
+    def pauseProducing(self):
+        """This is called when both the kernel send buffer and the twisted
+        tcp connection send buffers have become full.
+
+        We don't actually have any control over those sizes, so we buffer some
+        commands ourselves before knifing the connection due to the remote
+        failing to keep up.
+        """
+        logger.info("[%s] Pause producing", self.id())
+        self.state = ConnectionStates.PAUSED
+
+    def resumeProducing(self):
+        """The remote has caught up after we started buffering!
+        """
+        logger.info("[%s] Resume producing", self.id())
+        self.state = ConnectionStates.ESTABLISHED
+        self._send_pending_commands()
+
+    def stopProducing(self):
+        """We're never going to send any more data (normally because either
+        we or the remote has closed the connection)
+        """
+        logger.info("[%s] Stop producing", self.id())
+        self.on_connection_closed()
+
+    def connectionLost(self, reason):
+        logger.info("[%s] Replication connection closed: %r", self.id(), reason)
+        if isinstance(reason, Failure):
+            connection_close_counter.inc(reason.type.__name__)
+        else:
+            connection_close_counter.inc(reason.__class__.__name__)
+
+        try:
+            # Remove us from list of connections to be monitored
+            connected_connections.remove(self)
+        except ValueError:
+            pass
+
+        # Stop the looping call sending pings.
+        if self._send_ping_loop and self._send_ping_loop.running:
+            self._send_ping_loop.stop()
+
+        self.on_connection_closed()
+
+    def on_connection_closed(self):
+        logger.info("[%s] Connection was closed", self.id())
+
+        self.state = ConnectionStates.CLOSED
+        self.pending_commands = []
+
+        if self.transport:
+            self.transport.unregisterProducer()
+
+    def __str__(self):
+        return "ReplicationConnection<name=%s,conn_id=%s,addr=%s>" % (
+            self.name, self.conn_id, self.addr,
+        )
+
+    def id(self):
+        return "%s-%s" % (self.name, self.conn_id)
+
+
+class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol):
+    VALID_INBOUND_COMMANDS = VALID_CLIENT_COMMANDS
+    VALID_OUTBOUND_COMMANDS = VALID_SERVER_COMMANDS
+
+    def __init__(self, server_name, clock, streamer, addr):
+        BaseReplicationStreamProtocol.__init__(self, clock)  # Old style class
+
+        self.server_name = server_name
+        self.streamer = streamer
+        self.addr = addr
+
+        # The streams the client has subscribed to and is up to date with
+        self.replication_streams = set()
+
+        # The streams the client is currently subscribing to.
+        self.connecting_streams = set()
+
+        # Map from stream name to list of updates to send once we've finished
+        # subscribing the client to the stream.
+        self.pending_rdata = {}
+
+    def connectionMade(self):
+        self.send_command(ServerCommand(self.server_name))
+        BaseReplicationStreamProtocol.connectionMade(self)
+        self.streamer.new_connection(self)
+
+    def on_NAME(self, cmd):
+        logger.info("[%s] Renamed to %r", self.id(), cmd.data)
+        self.name = cmd.data
+
+    def on_USER_SYNC(self, cmd):
+        self.streamer.on_user_sync(
+            self.conn_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms,
+        )
+
+    def on_REPLICATE(self, cmd):
+        stream_name = cmd.stream_name
+        token = cmd.token
+
+        if stream_name == "ALL":
+            # Subscribe to all streams we're publishing to.
+            for stream in self.streamer.streams_by_name.iterkeys():
+                self.subscribe_to_stream(stream, token)
+        else:
+            self.subscribe_to_stream(stream_name, token)
+
+    def on_FEDERATION_ACK(self, cmd):
+        self.streamer.federation_ack(cmd.token)
+
+    def on_REMOVE_PUSHER(self, cmd):
+        self.streamer.on_remove_pusher(cmd.app_id, cmd.push_key, cmd.user_id)
+
+    def on_INVALIDATE_CACHE(self, cmd):
+        self.streamer.on_invalidate_cache(cmd.cache_func, cmd.keys)
+
+    @defer.inlineCallbacks
+    def subscribe_to_stream(self, stream_name, token):
+        """Subscribe the remote to a streams.
+
+        This invloves checking if they've missed anything and sending those
+        updates down if they have. During that time new updates for the stream
+        are queued and sent once we've sent down any missed updates.
+        """
+        self.replication_streams.discard(stream_name)
+        self.connecting_streams.add(stream_name)
+
+        try:
+            # Get missing updates
+            updates, current_token = yield self.streamer.get_stream_updates(
+                stream_name, token,
+            )
+
+            # Send all the missing updates
+            for update in updates:
+                token, row = update[0], update[1]
+                self.send_command(RdataCommand(stream_name, token, row))
+
+            # We send a POSITION command to ensure that they have an up to
+            # date token (especially useful if we didn't send any updates
+            # above)
+            self.send_command(PositionCommand(stream_name, current_token))
+
+            # Now we can send any updates that came in while we were subscribing
+            pending_rdata = self.pending_rdata.pop(stream_name, [])
+            for token, update in pending_rdata:
+                # Only send updates newer than the current token
+                if token > current_token:
+                    self.send_command(RdataCommand(stream_name, token, update))
+
+            # They're now fully subscribed
+            self.replication_streams.add(stream_name)
+        except Exception as e:
+            logger.exception("[%s] Failed to handle REPLICATE command", self.id())
+            self.send_error("failed to handle replicate: %r", e)
+        finally:
+            self.connecting_streams.discard(stream_name)
+
+    def stream_update(self, stream_name, token, data):
+        """Called when a new update is available to stream to clients.
+
+        We need to check if the client is interested in the stream or not
+        """
+        if stream_name in self.replication_streams:
+            # The client is subscribed to the stream
+            self.send_command(RdataCommand(stream_name, token, data))
+        elif stream_name in self.connecting_streams:
+            # The client is being subscribed to the stream
+            logger.debug("[%s] Queuing RDATA %r %r", self.id(), stream_name, token)
+            self.pending_rdata.setdefault(stream_name, []).append((token, data))
+        else:
+            # The client isn't subscribed
+            logger.debug("[%s] Dropping RDATA %r %r", self.id(), stream_name, token)
+
+    def send_sync(self, data):
+        self.send_command(SyncCommand(data))
+
+    def on_connection_closed(self):
+        BaseReplicationStreamProtocol.on_connection_closed(self)
+        self.streamer.lost_connection(self)
+
+
+class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol):
+    VALID_INBOUND_COMMANDS = VALID_SERVER_COMMANDS
+    VALID_OUTBOUND_COMMANDS = VALID_CLIENT_COMMANDS
+
+    def __init__(self, client_name, server_name, clock, handler):
+        BaseReplicationStreamProtocol.__init__(self, clock)
+
+        self.client_name = client_name
+        self.server_name = server_name
+        self.handler = handler
+
+        # Map of stream to batched updates. See RdataCommand for info on how
+        # batching works.
+        self.pending_batches = {}
+
+    def connectionMade(self):
+        self.send_command(NameCommand(self.client_name))
+        BaseReplicationStreamProtocol.connectionMade(self)
+
+        # Once we've connected subscribe to the necessary streams
+        for stream_name, token in self.handler.get_streams_to_replicate().iteritems():
+            self.replicate(stream_name, token)
+
+        # Tell the server if we have any users currently syncing (should only
+        # happen on synchrotrons)
+        currently_syncing = self.handler.get_currently_syncing_users()
+        now = self.clock.time_msec()
+        for user_id in currently_syncing:
+            self.send_command(UserSyncCommand(user_id, True, now))
+
+        # We've now finished connecting to so inform the client handler
+        self.handler.update_connection(self)
+
+    def on_SERVER(self, cmd):
+        if cmd.data != self.server_name:
+            logger.error("[%s] Connected to wrong remote: %r", self.id(), cmd.data)
+            self.send_error("Wrong remote")
+
+    def on_RDATA(self, cmd):
+        try:
+            row = STREAMS_MAP[cmd.stream_name].ROW_TYPE(*cmd.row)
+        except Exception:
+            logger.exception(
+                "[%s] Failed to parse RDATA: %r %r",
+                self.id(), cmd.stream_name, cmd.row
+            )
+            raise
+
+        if cmd.token is None:
+            # I.e. this is part of a batch of updates for this stream. Batch
+            # until we get an update for the stream with a non None token
+            self.pending_batches.setdefault(cmd.stream_name, []).append(row)
+        else:
+            # Check if this is the last of a batch of updates
+            rows = self.pending_batches.pop(cmd.stream_name, [])
+            rows.append(row)
+
+            self.handler.on_rdata(cmd.stream_name, cmd.token, rows)
+
+    def on_POSITION(self, cmd):
+        self.handler.on_position(cmd.stream_name, cmd.token)
+
+    def on_SYNC(self, cmd):
+        self.handler.on_sync(cmd.data)
+
+    def replicate(self, stream_name, token):
+        """Send the subscription request to the server
+        """
+        if stream_name not in STREAMS_MAP:
+            raise Exception("Invalid stream name %r" % (stream_name,))
+
+        logger.info(
+            "[%s] Subscribing to replication stream: %r from %r",
+            self.id(), stream_name, token
+        )
+
+        self.send_command(ReplicateCommand(stream_name, token))
+
+    def on_connection_closed(self):
+        BaseReplicationStreamProtocol.on_connection_closed(self)
+        self.handler.update_connection(None)
+
+
+# The following simply registers metrics for the replication connections
+
+metrics.register_callback(
+    "pending_commands",
+    lambda: {
+        (p.name, p.conn_id): len(p.pending_commands)
+        for p in connected_connections
+    },
+    labels=["name", "conn_id"],
+)
+
+
+def transport_buffer_size(protocol):
+    if protocol.transport:
+        size = len(protocol.transport.dataBuffer) + protocol.transport._tempDataLen
+        return size
+    return 0
+
+
+metrics.register_callback(
+    "transport_send_buffer",
+    lambda: {
+        (p.name, p.conn_id): transport_buffer_size(p)
+        for p in connected_connections
+    },
+    labels=["name", "conn_id"],
+)
+
+
+def transport_kernel_read_buffer_size(protocol, read=True):
+    SIOCINQ = 0x541B
+    SIOCOUTQ = 0x5411
+
+    if protocol.transport:
+        fileno = protocol.transport.getHandle().fileno()
+        if read:
+            op = SIOCINQ
+        else:
+            op = SIOCOUTQ
+        size = struct.unpack("I", fcntl.ioctl(fileno, op, '\0\0\0\0'))[0]
+        return size
+    return 0
+
+
+metrics.register_callback(
+    "transport_kernel_send_buffer",
+    lambda: {
+        (p.name, p.conn_id): transport_kernel_read_buffer_size(p, False)
+        for p in connected_connections
+    },
+    labels=["name", "conn_id"],
+)
+
+
+metrics.register_callback(
+    "transport_kernel_read_buffer",
+    lambda: {
+        (p.name, p.conn_id): transport_kernel_read_buffer_size(p, True)
+        for p in connected_connections
+    },
+    labels=["name", "conn_id"],
+)
+
+
+metrics.register_callback(
+    "inbound_commands",
+    lambda: {
+        (k[0], p.name, p.conn_id): count
+        for p in connected_connections
+        for k, count in p.inbound_commands_counter.counts.iteritems()
+    },
+    labels=["command", "name", "conn_id"],
+)
+
+metrics.register_callback(
+    "outbound_commands",
+    lambda: {
+        (k[0], p.name, p.conn_id): count
+        for p in connected_connections
+        for k, count in p.outbound_commands_counter.counts.iteritems()
+    },
+    labels=["command", "name", "conn_id"],
+)
diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py
new file mode 100644
index 0000000000..8b2c4c3043
--- /dev/null
+++ b/synapse/replication/tcp/resource.py
@@ -0,0 +1,290 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""The server side of the replication stream.
+"""
+
+from twisted.internet import defer, reactor
+from twisted.internet.protocol import Factory
+
+from streams import STREAMS_MAP, FederationStream
+from protocol import ServerReplicationStreamProtocol
+
+from synapse.util.metrics import Measure, measure_func
+
+import logging
+import synapse.metrics
+
+
+metrics = synapse.metrics.get_metrics_for(__name__)
+stream_updates_counter = metrics.register_counter(
+    "stream_updates", labels=["stream_name"]
+)
+user_sync_counter = metrics.register_counter("user_sync")
+federation_ack_counter = metrics.register_counter("federation_ack")
+remove_pusher_counter = metrics.register_counter("remove_pusher")
+invalidate_cache_counter = metrics.register_counter("invalidate_cache")
+
+logger = logging.getLogger(__name__)
+
+
+class ReplicationStreamProtocolFactory(Factory):
+    """Factory for new replication connections.
+    """
+    def __init__(self, hs):
+        self.streamer = ReplicationStreamer(hs)
+        self.clock = hs.get_clock()
+        self.server_name = hs.config.server_name
+
+    def buildProtocol(self, addr):
+        return ServerReplicationStreamProtocol(
+            self.server_name,
+            self.clock,
+            self.streamer,
+            addr
+        )
+
+
+class ReplicationStreamer(object):
+    """Handles replication connections.
+
+    This needs to be poked when new replication data may be available. When new
+    data is available it will propagate to all connected clients.
+    """
+
+    def __init__(self, hs):
+        self.store = hs.get_datastore()
+        self.presence_handler = hs.get_presence_handler()
+        self.clock = hs.get_clock()
+
+        # Current connections.
+        self.connections = []
+
+        metrics.register_callback("total_connections", lambda: len(self.connections))
+
+        # List of streams that clients can subscribe to.
+        # We only support federation stream if federation sending hase been
+        # disabled on the master.
+        self.streams = [
+            stream(hs) for stream in STREAMS_MAP.itervalues()
+            if stream != FederationStream or not hs.config.send_federation
+        ]
+
+        self.streams_by_name = {stream.NAME: stream for stream in self.streams}
+
+        metrics.register_callback(
+            "connections_per_stream",
+            lambda: {
+                (stream_name,): len([
+                    conn for conn in self.connections
+                    if stream_name in conn.replication_streams
+                ])
+                for stream_name in self.streams_by_name
+            },
+            labels=["stream_name"],
+        )
+
+        self.federation_sender = None
+        if not hs.config.send_federation:
+            self.federation_sender = hs.get_federation_sender()
+
+        hs.get_notifier().add_replication_callback(self.on_notifier_poke)
+
+        # Keeps track of whether we are currently checking for updates
+        self.is_looping = False
+        self.pending_updates = False
+
+        reactor.addSystemEventTrigger("before", "shutdown", self.on_shutdown)
+
+    def on_shutdown(self):
+        # close all connections on shutdown
+        for conn in self.connections:
+            conn.send_error("server shutting down")
+
+    @defer.inlineCallbacks
+    def on_notifier_poke(self):
+        """Checks if there is actually any new data and sends it to the
+        connections if there are.
+
+        This should get called each time new data is available, even if it
+        is currently being executed, so that nothing gets missed
+        """
+        if not self.connections:
+            # Don't bother if nothing is listening. We still need to advance
+            # the stream tokens otherwise they'll fall beihind forever
+            for stream in self.streams:
+                stream.discard_updates_and_advance()
+            return
+
+        # If we're in the process of checking for new updates, mark that fact
+        # and return
+        if self.is_looping:
+            logger.debug("Noitifier poke loop already running")
+            self.pending_updates = True
+            return
+
+        self.pending_updates = True
+        self.is_looping = True
+
+        try:
+            # Keep looping while there have been pokes about potential updates.
+            # This protects against the race where a stream we already checked
+            # gets an update while we're handling other streams.
+            while self.pending_updates:
+                self.pending_updates = False
+
+                with Measure(self.clock, "repl.stream.get_updates"):
+                    # First we tell the streams that they should update their
+                    # current tokens.
+                    for stream in self.streams:
+                        stream.advance_current_token()
+
+                    for stream in self.streams:
+                        if stream.last_token == stream.upto_token:
+                            continue
+
+                        logger.debug(
+                            "Getting stream: %s: %s -> %s",
+                            stream.NAME, stream.last_token, stream.upto_token
+                        )
+                        updates, current_token = yield stream.get_updates()
+
+                        logger.debug(
+                            "Sending %d updates to %d connections",
+                            len(updates), len(self.connections),
+                        )
+
+                        if updates:
+                            logger.info(
+                                "Streaming: %s -> %s", stream.NAME, updates[-1][0]
+                            )
+                            stream_updates_counter.inc_by(len(updates), stream.NAME)
+
+                        # Some streams return multiple rows with the same stream IDs,
+                        # we need to make sure they get sent out in batches. We do
+                        # this by setting the current token to all but the last of
+                        # a series of updates with the same token to have a None
+                        # token. See RdataCommand for more details.
+                        batched_updates = _batch_updates(updates)
+
+                        for conn in self.connections:
+                            for token, row in batched_updates:
+                                try:
+                                    conn.stream_update(stream.NAME, token, row)
+                                except Exception:
+                                    logger.exception("Failed to replicate")
+
+            logger.debug("No more pending updates, breaking poke loop")
+        finally:
+            self.pending_updates = False
+            self.is_looping = False
+
+    @measure_func("repl.get_stream_updates")
+    def get_stream_updates(self, stream_name, token):
+        """For a given stream get all updates since token. This is called when
+        a client first subscribes to a stream.
+        """
+        stream = self.streams_by_name.get(stream_name, None)
+        if not stream:
+            raise Exception("unknown stream %s", stream_name)
+
+        return stream.get_updates_since(token)
+
+    @measure_func("repl.federation_ack")
+    def federation_ack(self, token):
+        """We've received an ack for federation stream from a client.
+        """
+        federation_ack_counter.inc()
+        if self.federation_sender:
+            self.federation_sender.federation_ack(token)
+
+    @measure_func("repl.on_user_sync")
+    def on_user_sync(self, conn_id, user_id, is_syncing, last_sync_ms):
+        """A client has started/stopped syncing on a worker.
+        """
+        user_sync_counter.inc()
+        self.presence_handler.update_external_syncs_row(
+            conn_id, user_id, is_syncing, last_sync_ms,
+        )
+
+    @measure_func("repl.on_remove_pusher")
+    @defer.inlineCallbacks
+    def on_remove_pusher(self, app_id, push_key, user_id):
+        """A client has asked us to remove a pusher
+        """
+        remove_pusher_counter.inc()
+        yield self.store.delete_pusher_by_app_id_pushkey_user_id(
+            app_id=app_id, pushkey=push_key, user_id=user_id
+        )
+
+        self.notifier.on_new_replication_data()
+
+    @measure_func("repl.on_invalidate_cache")
+    def on_invalidate_cache(self, cache_func, keys):
+        """The client has asked us to invalidate a cache
+        """
+        invalidate_cache_counter.inc()
+        getattr(self.store, cache_func).invalidate(tuple(keys))
+
+    def send_sync_to_all_connections(self, data):
+        """Sends a SYNC command to all clients.
+
+        Used in tests.
+        """
+        for conn in self.connections:
+            conn.send_sync(data)
+
+    def new_connection(self, connection):
+        """A new client connection has been established
+        """
+        self.connections.append(connection)
+
+    def lost_connection(self, connection):
+        """A client connection has been lost
+        """
+        try:
+            self.connections.remove(connection)
+        except ValueError:
+            pass
+
+        # We need to tell the presence handler that the connection has been
+        # lost so that it can handle any ongoing syncs on that connection.
+        self.presence_handler.update_external_syncs_clear(connection.conn_id)
+
+
+def _batch_updates(updates):
+    """Takes a list of updates of form [(token, row)] and sets the token to
+    None for all rows where the next row has the same token. This is used to
+    implement batching.
+
+    For example:
+
+        [(1, _), (1, _), (2, _), (3, _), (3, _)]
+
+    becomes:
+
+        [(None, _), (1, _), (2, _), (None, _), (3, _)]
+    """
+    if not updates:
+        return []
+
+    new_updates = []
+    for i, update in enumerate(updates[:-1]):
+        if update[0] == updates[i + 1][0]:
+            new_updates.append((None, update[1]))
+        else:
+            new_updates.append(update)
+
+    new_updates.append(updates[-1])
+    return new_updates
diff --git a/synapse/replication/tcp/streams.py b/synapse/replication/tcp/streams.py
new file mode 100644
index 0000000000..369d5f2428
--- /dev/null
+++ b/synapse/replication/tcp/streams.py
@@ -0,0 +1,464 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Defines all the valid streams that clients can subscribe to, and the format
+of the rows returned by each stream.
+
+Each stream is defined by the following information:
+
+    stream name:        The name of the stream
+    row type:           The type that is used to serialise/deserialse the row
+    current_token:      The function that returns the current token for the stream
+    update_function:    The function that returns a list of updates between two tokens
+"""
+
+from twisted.internet import defer
+from collections import namedtuple
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+MAX_EVENTS_BEHIND = 10000
+
+
+EventStreamRow = namedtuple("EventStreamRow", (
+    "event_id",  # str
+    "room_id",  # str
+    "type",  # str
+    "state_key",  # str, optional
+    "redacts",  # str, optional
+))
+BackfillStreamRow = namedtuple("BackfillStreamRow", (
+    "event_id",  # str
+    "room_id",  # str
+    "type",  # str
+    "state_key",  # str, optional
+    "redacts",  # str, optional
+))
+PresenceStreamRow = namedtuple("PresenceStreamRow", (
+    "user_id",  # str
+    "state",  # str
+    "last_active_ts",  # int
+    "last_federation_update_ts",  # int
+    "last_user_sync_ts",  # int
+    "status_msg",   # str
+    "currently_active",  # bool
+))
+TypingStreamRow = namedtuple("TypingStreamRow", (
+    "room_id",  # str
+    "user_ids",  # list(str)
+))
+ReceiptsStreamRow = namedtuple("ReceiptsStreamRow", (
+    "room_id",  # str
+    "receipt_type",  # str
+    "user_id",  # str
+    "event_id",  # str
+    "data",  # dict
+))
+PushRulesStreamRow = namedtuple("PushRulesStreamRow", (
+    "user_id",  # str
+))
+PushersStreamRow = namedtuple("PushersStreamRow", (
+    "user_id",  # str
+    "app_id",  # str
+    "pushkey",  # str
+    "deleted",  # bool
+))
+CachesStreamRow = namedtuple("CachesStreamRow", (
+    "cache_func",  # str
+    "keys",  # list(str)
+    "invalidation_ts",  # int
+))
+PublicRoomsStreamRow = namedtuple("PublicRoomsStreamRow", (
+    "room_id",  # str
+    "visibility",  # str
+    "appservice_id",  # str, optional
+    "network_id",  # str, optional
+))
+DeviceListsStreamRow = namedtuple("DeviceListsStreamRow", (
+    "user_id",  # str
+    "destination",  # str
+))
+ToDeviceStreamRow = namedtuple("ToDeviceStreamRow", (
+    "entity",  # str
+))
+FederationStreamRow = namedtuple("FederationStreamRow", (
+    "type",  # str, the type of data as defined in the BaseFederationRows
+    "data",  # dict, serialization of a federation.send_queue.BaseFederationRow
+))
+TagAccountDataStreamRow = namedtuple("TagAccountDataStreamRow", (
+    "user_id",  # str
+    "room_id",  # str
+    "data",  # dict
+))
+AccountDataStreamRow = namedtuple("AccountDataStream", (
+    "user_id",  # str
+    "room_id",  # str
+    "data_type",  # str
+    "data",  # dict
+))
+
+
+class Stream(object):
+    """Base class for the streams.
+
+    Provides a `get_updates()` function that returns new updates since the last
+    time it was called up until the point `advance_current_token` was called.
+    """
+    NAME = None  # The name of the stream
+    ROW_TYPE = None  # The type of the row
+    _LIMITED = True  # Whether the update function takes a limit
+
+    def __init__(self, hs):
+        # The token from which we last asked for updates
+        self.last_token = self.current_token()
+
+        # The token that we will get updates up to
+        self.upto_token = self.current_token()
+
+    def advance_current_token(self):
+        """Updates `upto_token` to "now", which updates up until which point
+        get_updates[_since] will fetch rows till.
+        """
+        self.upto_token = self.current_token()
+
+    def discard_updates_and_advance(self):
+        """Called when the stream should advance but the updates would be discarded,
+        e.g. when there are no currently connected workers.
+        """
+        self.upto_token = self.current_token()
+        self.last_token = self.upto_token
+
+    @defer.inlineCallbacks
+    def get_updates(self):
+        """Gets all updates since the last time this function was called (or
+        since the stream was constructed if it hadn't been called before),
+        until the `upto_token`
+
+        Returns:
+            (list(ROW_TYPE), int): list of updates plus the token used as an
+                upper bound of the updates (i.e. the "current token")
+        """
+        updates, current_token = yield self.get_updates_since(self.last_token)
+        self.last_token = current_token
+
+        defer.returnValue((updates, current_token))
+
+    @defer.inlineCallbacks
+    def get_updates_since(self, from_token):
+        """Like get_updates except allows specifying from when we should
+        stream updates
+
+        Returns:
+            (list(ROW_TYPE), int): list of updates plus the token used as an
+                upper bound of the updates (i.e. the "current token")
+        """
+        if from_token in ("NOW", "now"):
+            defer.returnValue(([], self.upto_token))
+
+        current_token = self.upto_token
+
+        from_token = int(from_token)
+
+        if from_token == current_token:
+            defer.returnValue(([], current_token))
+
+        if self._LIMITED:
+            rows = yield self.update_function(
+                from_token, current_token,
+                limit=MAX_EVENTS_BEHIND + 1,
+            )
+
+            if len(rows) >= MAX_EVENTS_BEHIND:
+                raise Exception("stream %s has fallen behined" % (self.NAME))
+        else:
+            rows = yield self.update_function(
+                from_token, current_token,
+            )
+
+        updates = [(row[0], self.ROW_TYPE(*row[1:])) for row in rows]
+
+        defer.returnValue((updates, current_token))
+
+    def current_token(self):
+        """Gets the current token of the underlying streams. Should be provided
+        by the sub classes
+
+        Returns:
+            int
+        """
+        raise NotImplementedError()
+
+    def update_function(self, from_token, current_token, limit=None):
+        """Get updates between from_token and to_token. If Stream._LIMITED is
+        True then limit is provided, otherwise it's not.
+
+        Returns:
+            Deferred(list(tuple)): the first entry in the tuple is the token for
+                that update, and the rest of the tuple gets used to construct
+                a ``ROW_TYPE`` instance
+        """
+        raise NotImplementedError()
+
+
+class EventsStream(Stream):
+    """We received a new event, or an event went from being an outlier to not
+    """
+    NAME = "events"
+    ROW_TYPE = EventStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+        self.current_token = store.get_current_events_token
+        self.update_function = store.get_all_new_forward_event_rows
+
+        super(EventsStream, self).__init__(hs)
+
+
+class BackfillStream(Stream):
+    """We fetched some old events and either we had never seen that event before
+    or it went from being an outlier to not.
+    """
+    NAME = "backfill"
+    ROW_TYPE = BackfillStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+        self.current_token = store.get_current_backfill_token
+        self.update_function = store.get_all_new_backfill_event_rows
+
+        super(BackfillStream, self).__init__(hs)
+
+
+class PresenceStream(Stream):
+    NAME = "presence"
+    _LIMITED = False
+    ROW_TYPE = PresenceStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+        presence_handler = hs.get_presence_handler()
+
+        self.current_token = store.get_current_presence_token
+        self.update_function = presence_handler.get_all_presence_updates
+
+        super(PresenceStream, self).__init__(hs)
+
+
+class TypingStream(Stream):
+    NAME = "typing"
+    _LIMITED = False
+    ROW_TYPE = TypingStreamRow
+
+    def __init__(self, hs):
+        typing_handler = hs.get_typing_handler()
+
+        self.current_token = typing_handler.get_current_token
+        self.update_function = typing_handler.get_all_typing_updates
+
+        super(TypingStream, self).__init__(hs)
+
+
+class ReceiptsStream(Stream):
+    NAME = "receipts"
+    ROW_TYPE = ReceiptsStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_max_receipt_stream_id
+        self.update_function = store.get_all_updated_receipts
+
+        super(ReceiptsStream, self).__init__(hs)
+
+
+class PushRulesStream(Stream):
+    """A user has changed their push rules
+    """
+    NAME = "push_rules"
+    ROW_TYPE = PushRulesStreamRow
+
+    def __init__(self, hs):
+        self.store = hs.get_datastore()
+        super(PushRulesStream, self).__init__(hs)
+
+    def current_token(self):
+        push_rules_token, _ = self.store.get_push_rules_stream_token()
+        return push_rules_token
+
+    @defer.inlineCallbacks
+    def update_function(self, from_token, to_token, limit):
+        rows = yield self.store.get_all_push_rule_updates(from_token, to_token, limit)
+        defer.returnValue([(row[0], row[2]) for row in rows])
+
+
+class PushersStream(Stream):
+    """A user has added/changed/removed a pusher
+    """
+    NAME = "pushers"
+    ROW_TYPE = PushersStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_pushers_stream_token
+        self.update_function = store.get_all_updated_pushers_rows
+
+        super(PushersStream, self).__init__(hs)
+
+
+class CachesStream(Stream):
+    """A cache was invalidated on the master and no other stream would invalidate
+    the cache on the workers
+    """
+    NAME = "caches"
+    ROW_TYPE = CachesStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_cache_stream_token
+        self.update_function = store.get_all_updated_caches
+
+        super(CachesStream, self).__init__(hs)
+
+
+class PublicRoomsStream(Stream):
+    """The public rooms list changed
+    """
+    NAME = "public_rooms"
+    ROW_TYPE = PublicRoomsStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_current_public_room_stream_id
+        self.update_function = store.get_all_new_public_rooms
+
+        super(PublicRoomsStream, self).__init__(hs)
+
+
+class DeviceListsStream(Stream):
+    """Someone added/changed/removed a device
+    """
+    NAME = "device_lists"
+    _LIMITED = False
+    ROW_TYPE = DeviceListsStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_device_stream_token
+        self.update_function = store.get_all_device_list_changes_for_remotes
+
+        super(DeviceListsStream, self).__init__(hs)
+
+
+class ToDeviceStream(Stream):
+    """New to_device messages for a client
+    """
+    NAME = "to_device"
+    ROW_TYPE = ToDeviceStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_to_device_stream_token
+        self.update_function = store.get_all_new_device_messages
+
+        super(ToDeviceStream, self).__init__(hs)
+
+
+class FederationStream(Stream):
+    """Data to be sent over federation. Only available when master has federation
+    sending disabled.
+    """
+    NAME = "federation"
+    ROW_TYPE = FederationStreamRow
+
+    def __init__(self, hs):
+        federation_sender = hs.get_federation_sender()
+
+        self.current_token = federation_sender.get_current_token
+        self.update_function = federation_sender.get_replication_rows
+
+        super(FederationStream, self).__init__(hs)
+
+
+class TagAccountDataStream(Stream):
+    """Someone added/removed a tag for a room
+    """
+    NAME = "tag_account_data"
+    ROW_TYPE = TagAccountDataStreamRow
+
+    def __init__(self, hs):
+        store = hs.get_datastore()
+
+        self.current_token = store.get_max_account_data_stream_id
+        self.update_function = store.get_all_updated_tags
+
+        super(TagAccountDataStream, self).__init__(hs)
+
+
+class AccountDataStream(Stream):
+    """Global or per room account data was changed
+    """
+    NAME = "account_data"
+    ROW_TYPE = AccountDataStreamRow
+
+    def __init__(self, hs):
+        self.store = hs.get_datastore()
+
+        self.current_token = self.store.get_max_account_data_stream_id
+
+        super(AccountDataStream, self).__init__(hs)
+
+    @defer.inlineCallbacks
+    def update_function(self, from_token, to_token, limit):
+        global_results, room_results = yield self.store.get_all_updated_account_data(
+            from_token, from_token, to_token, limit
+        )
+
+        results = list(room_results)
+        results.extend(
+            (stream_id, user_id, None, account_data_type, content,)
+            for stream_id, user_id, account_data_type, content in global_results
+        )
+
+        defer.returnValue(results)
+
+
+STREAMS_MAP = {
+    stream.NAME: stream
+    for stream in (
+        EventsStream,
+        BackfillStream,
+        PresenceStream,
+        TypingStream,
+        ReceiptsStream,
+        PushRulesStream,
+        PushersStream,
+        CachesStream,
+        PublicRoomsStream,
+        DeviceListsStream,
+        ToDeviceStream,
+        FederationStream,
+        TagAccountDataStream,
+        AccountDataStream,
+    )
+}
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index f9f5a3e077..aa8d874f96 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -40,6 +40,7 @@ from synapse.rest.client.v2_alpha import (
     register,
     auth,
     receipts,
+    read_marker,
     keys,
     tokenrefresh,
     tags,
@@ -88,6 +89,7 @@ class ClientRestResource(JsonResource):
         register.register_servlets(hs, client_resource)
         auth.register_servlets(hs, client_resource)
         receipts.register_servlets(hs, client_resource)
+        read_marker.register_servlets(hs, client_resource)
         keys.register_servlets(hs, client_resource)
         tokenrefresh.register_servlets(hs, client_resource)
         tags.register_servlets(hs, client_resource)
diff --git a/synapse/rest/client/v1/directory.py b/synapse/rest/client/v1/directory.py
index 8930f1826f..f15aa5c13f 100644
--- a/synapse/rest/client/v1/directory.py
+++ b/synapse/rest/client/v1/directory.py
@@ -39,6 +39,7 @@ class ClientDirectoryServer(ClientV1RestServlet):
 
     def __init__(self, hs):
         super(ClientDirectoryServer, self).__init__(hs)
+        self.store = hs.get_datastore()
         self.handlers = hs.get_handlers()
 
     @defer.inlineCallbacks
@@ -70,7 +71,10 @@ class ClientDirectoryServer(ClientV1RestServlet):
         logger.debug("Got servers: %s", servers)
 
         # TODO(erikj): Check types.
-        # TODO(erikj): Check that room exists
+
+        room = yield self.store.get_room(room_id)
+        if room is None:
+            raise SynapseError(400, "Room does not exist")
 
         dir_handler = self.handlers.directory_handler
 
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 0bdd6b5b36..cd388770c8 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -164,6 +164,7 @@ class RoomStateEventRestServlet(ClientV1RestServlet):
         else:
             msg_handler = self.handlers.message_handler
             event, context = yield msg_handler.create_event(
+                requester,
                 event_dict,
                 token_id=requester.access_token_id,
                 txn_id=txn_id,
@@ -406,7 +407,13 @@ class JoinedRoomMemberListRestServlet(ClientV1RestServlet):
         users_with_profile = yield self.state.get_current_user_in_room(room_id)
 
         defer.returnValue((200, {
-            "joined": users_with_profile
+            "joined": {
+                user_id: {
+                    "avatar_url": profile.avatar_url,
+                    "display_name": profile.display_name,
+                }
+                for user_id, profile in users_with_profile.iteritems()
+            }
         }))
 
 
diff --git a/synapse/rest/client/v1/voip.py b/synapse/rest/client/v1/voip.py
index 03141c623c..c43b30b73a 100644
--- a/synapse/rest/client/v1/voip.py
+++ b/synapse/rest/client/v1/voip.py
@@ -28,7 +28,10 @@ class VoipRestServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request):
-        requester = yield self.auth.get_user_by_req(request)
+        requester = yield self.auth.get_user_by_req(
+            request,
+            self.hs.config.turn_allow_guests
+        )
 
         turnUris = self.hs.config.turn_uris
         turnSecret = self.hs.config.turn_shared_secret
diff --git a/synapse/rest/client/v2_alpha/_base.py b/synapse/rest/client/v2_alpha/_base.py
index 20e765f48f..1f5bc24cc3 100644
--- a/synapse/rest/client/v2_alpha/_base.py
+++ b/synapse/rest/client/v2_alpha/_base.py
@@ -47,3 +47,13 @@ def client_v2_patterns(path_regex, releases=(0,),
         new_prefix = CLIENT_V2_ALPHA_PREFIX.replace("/v2_alpha", "/r%d" % release)
         patterns.append(re.compile("^" + new_prefix + path_regex))
     return patterns
+
+
+def set_timeline_upper_limit(filter_json, filter_timeline_limit):
+    if filter_timeline_limit < 0:
+        return  # no upper limits
+    timeline = filter_json.get('room', {}).get('timeline', {})
+    if 'limit' in timeline:
+        filter_json['room']['timeline']["limit"] = min(
+            filter_json['room']['timeline']['limit'],
+            filter_timeline_limit)
diff --git a/synapse/rest/client/v2_alpha/account_data.py b/synapse/rest/client/v2_alpha/account_data.py
index b16079cece..0e0a187efd 100644
--- a/synapse/rest/client/v2_alpha/account_data.py
+++ b/synapse/rest/client/v2_alpha/account_data.py
@@ -16,7 +16,7 @@
 from ._base import client_v2_patterns
 
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.api.errors import AuthError
+from synapse.api.errors import AuthError, SynapseError
 
 from twisted.internet import defer
 
@@ -82,6 +82,13 @@ class RoomAccountDataServlet(RestServlet):
 
         body = parse_json_object_from_request(request)
 
+        if account_data_type == "m.fully_read":
+            raise SynapseError(
+                405,
+                "Cannot set m.fully_read through this API."
+                " Use /rooms/!roomId:server.name/read_markers"
+            )
+
         max_id = yield self.store.add_account_data_to_room(
             user_id, room_id, account_data_type, body
         )
diff --git a/synapse/rest/client/v2_alpha/filter.py b/synapse/rest/client/v2_alpha/filter.py
index b4084fec62..d2b2fd66e6 100644
--- a/synapse/rest/client/v2_alpha/filter.py
+++ b/synapse/rest/client/v2_alpha/filter.py
@@ -20,6 +20,7 @@ from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.types import UserID
 
 from ._base import client_v2_patterns
+from ._base import set_timeline_upper_limit
 
 import logging
 
@@ -85,6 +86,11 @@ class CreateFilterRestServlet(RestServlet):
             raise AuthError(403, "Can only create filters for local users")
 
         content = parse_json_object_from_request(request)
+        set_timeline_upper_limit(
+            content,
+            self.hs.config.filter_timeline_limit
+        )
+
         filter_id = yield self.filtering.add_user_filter(
             user_localpart=target_user.localpart,
             user_filter=content,
diff --git a/synapse/rest/client/v2_alpha/read_marker.py b/synapse/rest/client/v2_alpha/read_marker.py
new file mode 100644
index 0000000000..2f8784fe06
--- /dev/null
+++ b/synapse/rest/client/v2_alpha/read_marker.py
@@ -0,0 +1,66 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from twisted.internet import defer
+
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from ._base import client_v2_patterns
+
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+class ReadMarkerRestServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/rooms/(?P<room_id>[^/]*)/read_markers$")
+
+    def __init__(self, hs):
+        super(ReadMarkerRestServlet, self).__init__()
+        self.auth = hs.get_auth()
+        self.receipts_handler = hs.get_receipts_handler()
+        self.read_marker_handler = hs.get_read_marker_handler()
+        self.presence_handler = hs.get_presence_handler()
+
+    @defer.inlineCallbacks
+    def on_POST(self, request, room_id):
+        requester = yield self.auth.get_user_by_req(request)
+
+        yield self.presence_handler.bump_presence_active_time(requester.user)
+
+        body = parse_json_object_from_request(request)
+
+        read_event_id = body.get("m.read", None)
+        if read_event_id:
+            yield self.receipts_handler.received_client_receipt(
+                room_id,
+                "m.read",
+                user_id=requester.user.to_string(),
+                event_id=read_event_id
+            )
+
+        read_marker_event_id = body.get("m.fully_read", None)
+        if read_marker_event_id:
+            yield self.read_marker_handler.received_client_read_marker(
+                room_id,
+                user_id=requester.user.to_string(),
+                event_id=read_marker_event_id
+            )
+
+        defer.returnValue((200, {}))
+
+
+def register_servlets(hs, http_server):
+    ReadMarkerRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index 3acf4eacdd..1421c18152 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -21,7 +21,7 @@ from synapse.api.auth import get_access_token_from_request, has_access_token
 from synapse.api.constants import LoginType
 from synapse.api.errors import SynapseError, Codes, UnrecognizedRequestError
 from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request, assert_params_in_request
+    RestServlet, parse_json_object_from_request, assert_params_in_request, parse_string
 )
 from synapse.util.msisdn import phone_number_to_msisdn
 
@@ -31,6 +31,7 @@ import logging
 import hmac
 from hashlib import sha1
 from synapse.util.async import run_on_reactor
+from synapse.util.ratelimitutils import FederationRateLimiter
 
 
 # We ought to be using hmac.compare_digest() but on older pythons it doesn't
@@ -115,6 +116,44 @@ class MsisdnRegisterRequestTokenRestServlet(RestServlet):
         defer.returnValue((200, ret))
 
 
+class UsernameAvailabilityRestServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/register/available")
+
+    def __init__(self, hs):
+        """
+        Args:
+            hs (synapse.server.HomeServer): server
+        """
+        super(UsernameAvailabilityRestServlet, self).__init__()
+        self.hs = hs
+        self.registration_handler = hs.get_handlers().registration_handler
+        self.ratelimiter = FederationRateLimiter(
+            hs.get_clock(),
+            # Time window of 2s
+            window_size=2000,
+            # Artificially delay requests if rate > sleep_limit/window_size
+            sleep_limit=1,
+            # Amount of artificial delay to apply
+            sleep_msec=1000,
+            # Error with 429 if more than reject_limit requests are queued
+            reject_limit=1,
+            # Allow 1 request at a time
+            concurrent_requests=1,
+        )
+
+    @defer.inlineCallbacks
+    def on_GET(self, request):
+        ip = self.hs.get_ip_from_request(request)
+        with self.ratelimiter.ratelimit(ip) as wait_deferred:
+            yield wait_deferred
+
+            username = parse_string(request, "username", required=True)
+
+            yield self.registration_handler.check_username(username)
+
+            defer.returnValue((200, {"available": True}))
+
+
 class RegisterRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/register$")
 
@@ -555,4 +594,5 @@ class RegisterRestServlet(RestServlet):
 def register_servlets(hs, http_server):
     EmailRegisterRequestTokenRestServlet(hs).register(http_server)
     MsisdnRegisterRequestTokenRestServlet(hs).register(http_server)
+    UsernameAvailabilityRestServlet(hs).register(http_server)
     RegisterRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index a7a9e0a794..771e127ab9 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -28,6 +28,7 @@ from synapse.api.filtering import FilterCollection, DEFAULT_FILTER_COLLECTION
 from synapse.api.errors import SynapseError
 from synapse.api.constants import PresenceState
 from ._base import client_v2_patterns
+from ._base import set_timeline_upper_limit
 
 import itertools
 import logging
@@ -78,6 +79,7 @@ class SyncRestServlet(RestServlet):
 
     def __init__(self, hs):
         super(SyncRestServlet, self).__init__()
+        self.hs = hs
         self.auth = hs.get_auth()
         self.sync_handler = hs.get_sync_handler()
         self.clock = hs.get_clock()
@@ -121,6 +123,8 @@ class SyncRestServlet(RestServlet):
             if filter_id.startswith('{'):
                 try:
                     filter_object = json.loads(filter_id)
+                    set_timeline_upper_limit(filter_object,
+                                             self.hs.config.filter_timeline_limit)
                 except:
                     raise SynapseError(400, "Invalid filter JSON")
                 self.filtering.check_valid_filter(filter_object)
@@ -253,6 +257,7 @@ class SyncRestServlet(RestServlet):
             invite = serialize_event(
                 room.invite, time_now, token_id=token_id,
                 event_format=format_event_for_client_v2_without_room_id,
+                is_invite=True,
             )
             unsigned = dict(invite.get("unsigned", {}))
             invite["unsigned"] = unsigned
diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
index 31f94bc6e9..6fceb23e26 100644
--- a/synapse/rest/client/v2_alpha/thirdparty.py
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -36,7 +36,7 @@ class ThirdPartyProtocolsServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request):
-        yield self.auth.get_user_by_req(request)
+        yield self.auth.get_user_by_req(request, allow_guest=True)
 
         protocols = yield self.appservice_handler.get_3pe_protocols()
         defer.returnValue((200, protocols))
@@ -54,7 +54,7 @@ class ThirdPartyProtocolServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request, protocol):
-        yield self.auth.get_user_by_req(request)
+        yield self.auth.get_user_by_req(request, allow_guest=True)
 
         protocols = yield self.appservice_handler.get_3pe_protocols(
             only_protocol=protocol,
@@ -77,7 +77,7 @@ class ThirdPartyUserServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request, protocol):
-        yield self.auth.get_user_by_req(request)
+        yield self.auth.get_user_by_req(request, allow_guest=True)
 
         fields = request.args
         fields.pop("access_token", None)
@@ -101,7 +101,7 @@ class ThirdPartyLocationServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request, protocol):
-        yield self.auth.get_user_by_req(request)
+        yield self.auth.get_user_by_req(request, allow_guest=True)
 
         fields = request.args
         fields.pop("access_token", None)
diff --git a/synapse/rest/key/v2/local_key_resource.py b/synapse/rest/key/v2/local_key_resource.py
index ff95269ba8..be68d9a096 100644
--- a/synapse/rest/key/v2/local_key_resource.py
+++ b/synapse/rest/key/v2/local_key_resource.py
@@ -84,12 +84,11 @@ class LocalKey(Resource):
             }
 
         old_verify_keys = {}
-        for key in self.config.old_signing_keys:
-            key_id = "%s:%s" % (key.alg, key.version)
+        for key_id, key in self.config.old_signing_keys.items():
             verify_key_bytes = key.encode()
             old_verify_keys[key_id] = {
                 u"key": encode_base64(verify_key_bytes),
-                u"expired_ts": key.expired,
+                u"expired_ts": key.expired_ts,
             }
 
         tls_fingerprints = self.config.tls_fingerprints
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index c43b185e08..caca96c222 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -34,6 +34,7 @@ from synapse.api.errors import SynapseError, HttpResponseException, \
 from synapse.util.async import Linearizer
 from synapse.util.stringutils import is_ascii
 from synapse.util.logcontext import preserve_context_over_fn
+from synapse.util.retryutils import NotRetryingDestination
 
 import os
 import errno
@@ -181,7 +182,8 @@ class MediaRepository(object):
                     logger.exception("Failed to fetch remote media %s/%s",
                                      server_name, media_id)
                     raise
-
+                except NotRetryingDestination:
+                    logger.warn("Not retrying destination %r", server_name)
                 except Exception:
                     logger.exception("Failed to fetch remote media %s/%s",
                                      server_name, media_id)
diff --git a/synapse/server.py b/synapse/server.py
index c577032041..12754c89ae 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -48,6 +48,7 @@ from synapse.handlers.typing import TypingHandler
 from synapse.handlers.events import EventHandler, EventStreamHandler
 from synapse.handlers.initial_sync import InitialSyncHandler
 from synapse.handlers.receipts import ReceiptsHandler
+from synapse.handlers.read_marker import ReadMarkerHandler
 from synapse.http.client import SimpleHttpClient, InsecureInterceptableContextFactory
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.notifier import Notifier
@@ -132,6 +133,8 @@ class HomeServer(object):
         'federation_sender',
         'receipts_handler',
         'macaroon_generator',
+        'tcp_replication',
+        'read_marker_handler',
     ]
 
     def __init__(self, hostname, **kwargs):
@@ -290,6 +293,12 @@ class HomeServer(object):
     def build_receipts_handler(self):
         return ReceiptsHandler(self)
 
+    def build_read_marker_handler(self):
+        return ReadMarkerHandler(self)
+
+    def build_tcp_replication(self):
+        raise NotImplementedError()
+
     def remove_pusher(self, app_id, push_key, user_id):
         return self.get_pusherpool().remove_pusher(app_id, push_key, user_id)
 
diff --git a/synapse/state.py b/synapse/state.py
index f6b83d888a..02fee47f39 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -176,6 +176,17 @@ class StateHandler(object):
         defer.returnValue(joined_users)
 
     @defer.inlineCallbacks
+    def get_current_hosts_in_room(self, room_id, latest_event_ids=None):
+        if not latest_event_ids:
+            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
+        logger.debug("calling resolve_state_groups from get_current_hosts_in_room")
+        entry = yield self.resolve_state_groups(room_id, latest_event_ids)
+        joined_hosts = yield self.store.get_joined_hosts(
+            room_id, entry.state_id, entry.state
+        )
+        defer.returnValue(joined_hosts)
+
+    @defer.inlineCallbacks
     def compute_event_context(self, event, old_state=None):
         """Build an EventContext structure for the event.
 
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index c659004e8d..58b73af7d2 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -60,12 +60,12 @@ class LoggingTransaction(object):
         object.__setattr__(self, "database_engine", database_engine)
         object.__setattr__(self, "after_callbacks", after_callbacks)
 
-    def call_after(self, callback, *args):
+    def call_after(self, callback, *args, **kwargs):
         """Call the given callback on the main twisted thread after the
         transaction has finished. Used to invalidate the caches on the
         correct thread.
         """
-        self.after_callbacks.append((callback, args))
+        self.after_callbacks.append((callback, args, kwargs))
 
     def __getattr__(self, name):
         return getattr(self.txn, name)
@@ -319,8 +319,8 @@ class SQLBaseStore(object):
                     inner_func, *args, **kwargs
                 )
         finally:
-            for after_callback, after_args in after_callbacks:
-                after_callback(*after_args)
+            for after_callback, after_args, after_kwargs in after_callbacks:
+                after_callback(*after_args, **after_kwargs)
         defer.returnValue(result)
 
     @defer.inlineCallbacks
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index 813ad59e56..7157fb1dfb 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -210,7 +210,9 @@ class BackgroundUpdateStore(SQLBaseStore):
         self._background_update_handlers[update_name] = update_handler
 
     def register_background_index_update(self, update_name, index_name,
-                                         table, columns, where_clause=None):
+                                         table, columns, where_clause=None,
+                                         unique=False,
+                                         psql_only=False):
         """Helper for store classes to do a background index addition
 
         To use:
@@ -226,48 +228,80 @@ class BackgroundUpdateStore(SQLBaseStore):
             index_name (str): name of index to add
             table (str): table to add index to
             columns (list[str]): columns/expressions to include in index
+            unique (bool): true to make a UNIQUE index
+            psql_only: true to only create this index on psql databases (useful
+                for virtual sqlite tables)
         """
 
-        # if this is postgres, we add the indexes concurrently. Otherwise
-        # we fall back to doing it inline
-        if isinstance(self.database_engine, engines.PostgresEngine):
-            conc = True
-        else:
-            conc = False
-            # We don't use partial indices on SQLite as it wasn't introduced
-            # until 3.8, and wheezy has 3.7
-            where_clause = None
-
-        sql = (
-            "CREATE INDEX %(conc)s %(name)s ON %(table)s (%(columns)s)"
-            " %(where_clause)s"
-        ) % {
-            "conc": "CONCURRENTLY" if conc else "",
-            "name": index_name,
-            "table": table,
-            "columns": ", ".join(columns),
-            "where_clause": "WHERE " + where_clause if where_clause else ""
-        }
-
-        def create_index_concurrently(conn):
+        def create_index_psql(conn):
             conn.rollback()
             # postgres insists on autocommit for the index
             conn.set_session(autocommit=True)
-            c = conn.cursor()
-            c.execute(sql)
-            conn.set_session(autocommit=False)
 
-        def create_index(conn):
+            try:
+                c = conn.cursor()
+
+                # If a previous attempt to create the index was interrupted,
+                # we may already have a half-built index. Let's just drop it
+                # before trying to create it again.
+
+                sql = "DROP INDEX IF EXISTS %s" % (index_name,)
+                logger.debug("[SQL] %s", sql)
+                c.execute(sql)
+
+                sql = (
+                    "CREATE %(unique)s INDEX CONCURRENTLY %(name)s"
+                    " ON %(table)s"
+                    " (%(columns)s) %(where_clause)s"
+                ) % {
+                    "unique": "UNIQUE" if unique else "",
+                    "name": index_name,
+                    "table": table,
+                    "columns": ", ".join(columns),
+                    "where_clause": "WHERE " + where_clause if where_clause else ""
+                }
+                logger.debug("[SQL] %s", sql)
+                c.execute(sql)
+            finally:
+                conn.set_session(autocommit=False)
+
+        def create_index_sqlite(conn):
+            # Sqlite doesn't support concurrent creation of indexes.
+            #
+            # We don't use partial indices on SQLite as it wasn't introduced
+            # until 3.8, and wheezy has 3.7
+            #
+            # We assume that sqlite doesn't give us invalid indices; however
+            # we may still end up with the index existing but the
+            # background_updates not having been recorded if synapse got shut
+            # down at the wrong moment - hance we use IF NOT EXISTS. (SQLite
+            # has supported CREATE TABLE|INDEX IF NOT EXISTS since 3.3.0.)
+            sql = (
+                "CREATE %(unique)s INDEX IF NOT EXISTS %(name)s ON %(table)s"
+                " (%(columns)s)"
+            ) % {
+                "unique": "UNIQUE" if unique else "",
+                "name": index_name,
+                "table": table,
+                "columns": ", ".join(columns),
+            }
+
             c = conn.cursor()
+            logger.debug("[SQL] %s", sql)
             c.execute(sql)
 
+        if isinstance(self.database_engine, engines.PostgresEngine):
+            runner = create_index_psql
+        elif psql_only:
+            runner = None
+        else:
+            runner = create_index_sqlite
+
         @defer.inlineCallbacks
         def updater(progress, batch_size):
-            logger.info("Adding index %s to %s", index_name, table)
-            if conc:
-                yield self.runWithConnection(create_index_concurrently)
-            else:
-                yield self.runWithConnection(create_index)
+            if runner is not None:
+                logger.info("Adding index %s to %s", index_name, table)
+                yield self.runWithConnection(runner)
             yield self._end_background_update(update_name)
             defer.returnValue(1)
 
diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py
index 71e5ea112f..747d2df622 100644
--- a/synapse/storage/client_ips.py
+++ b/synapse/storage/client_ips.py
@@ -33,6 +33,7 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
         self.client_ip_last_seen = Cache(
             name="client_ip_last_seen",
             keylen=4,
+            max_entries=5000,
         )
 
         super(ClientIpStore, self).__init__(hs)
@@ -120,6 +121,9 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
                 where_clauses.append("(user_id = ? AND device_id = ?)")
                 bindings.extend((user_id, device_id))
 
+        if not where_clauses:
+            return []
+
         inner_select = (
             "SELECT MAX(last_seen) mls, user_id, device_id FROM user_ips "
             "WHERE %(where)s "
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index 2714519d21..0b62b493d5 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -325,23 +325,26 @@ class DeviceInboxStore(BackgroundUpdateStore):
             # we return.
             upper_pos = min(current_pos, last_pos + limit)
             sql = (
-                "SELECT stream_id, user_id"
+                "SELECT max(stream_id), user_id"
                 " FROM device_inbox"
                 " WHERE ? < stream_id AND stream_id <= ?"
-                " ORDER BY stream_id ASC"
+                " GROUP BY user_id"
             )
             txn.execute(sql, (last_pos, upper_pos))
             rows = txn.fetchall()
 
             sql = (
-                "SELECT stream_id, destination"
+                "SELECT max(stream_id), destination"
                 " FROM device_federation_outbox"
                 " WHERE ? < stream_id AND stream_id <= ?"
-                " ORDER BY stream_id ASC"
+                " GROUP BY destination"
             )
             txn.execute(sql, (last_pos, upper_pos))
             rows.extend(txn)
 
+            # Order by ascending stream ordering
+            rows.sort()
+
             return rows
 
         return self.runInteraction(
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index 53e36791d5..d9936c88bb 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -18,7 +18,7 @@ import ujson as json
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
-from ._base import SQLBaseStore
+from ._base import SQLBaseStore, Cache
 from synapse.util.caches.descriptors import cached, cachedList, cachedInlineCallbacks
 
 
@@ -29,6 +29,14 @@ class DeviceStore(SQLBaseStore):
     def __init__(self, hs):
         super(DeviceStore, self).__init__(hs)
 
+        # Map of (user_id, device_id) -> bool. If there is an entry that implies
+        # the device exists.
+        self.device_id_exists_cache = Cache(
+            name="device_id_exists",
+            keylen=2,
+            max_entries=10000,
+        )
+
         self._clock.looping_call(
             self._prune_old_outbound_device_pokes, 60 * 60 * 1000
         )
@@ -54,6 +62,10 @@ class DeviceStore(SQLBaseStore):
             defer.Deferred: boolean whether the device was inserted or an
                 existing device existed with that ID.
         """
+        key = (user_id, device_id)
+        if self.device_id_exists_cache.get(key, None):
+            defer.returnValue(False)
+
         try:
             inserted = yield self._simple_insert(
                 "devices",
@@ -65,6 +77,7 @@ class DeviceStore(SQLBaseStore):
                 desc="store_device",
                 or_ignore=True,
             )
+            self.device_id_exists_cache.prefill(key, True)
             defer.returnValue(inserted)
         except Exception as e:
             logger.error("store_device with device_id=%s(%r) user_id=%s(%r)"
@@ -93,6 +106,7 @@ class DeviceStore(SQLBaseStore):
             desc="get_device",
         )
 
+    @defer.inlineCallbacks
     def delete_device(self, user_id, device_id):
         """Delete a device.
 
@@ -102,12 +116,15 @@ class DeviceStore(SQLBaseStore):
         Returns:
             defer.Deferred
         """
-        return self._simple_delete_one(
+        yield self._simple_delete_one(
             table="devices",
             keyvalues={"user_id": user_id, "device_id": device_id},
             desc="delete_device",
         )
 
+        self.device_id_exists_cache.invalidate((user_id, device_id))
+
+    @defer.inlineCallbacks
     def delete_devices(self, user_id, device_ids):
         """Deletes several devices.
 
@@ -117,13 +134,15 @@ class DeviceStore(SQLBaseStore):
         Returns:
             defer.Deferred
         """
-        return self._simple_delete_many(
+        yield self._simple_delete_many(
             table="devices",
             column="device_id",
             iterable=device_ids,
             keyvalues={"user_id": user_id},
             desc="delete_devices",
         )
+        for device_id in device_ids:
+            self.device_id_exists_cache.invalidate((user_id, device_id))
 
     def update_device(self, user_id, device_id, new_display_name=None):
         """Update a device.
@@ -533,7 +552,7 @@ class DeviceStore(SQLBaseStore):
         rows = yield self._execute("get_user_whose_devices_changed", None, sql, from_key)
         defer.returnValue(set(row[0] for row in rows))
 
-    def get_all_device_list_changes_for_remotes(self, from_key):
+    def get_all_device_list_changes_for_remotes(self, from_key, to_key):
         """Return a list of `(stream_id, user_id, destination)` which is the
         combined list of changes to devices, and which destinations need to be
         poked. `destination` may be None if no destinations need to be poked.
@@ -541,11 +560,11 @@ class DeviceStore(SQLBaseStore):
         sql = """
             SELECT stream_id, user_id, destination FROM device_lists_stream
             LEFT JOIN device_lists_outbound_pokes USING (stream_id, user_id, device_id)
-            WHERE stream_id > ?
+            WHERE ? < stream_id AND stream_id <= ?
         """
         return self._execute(
             "get_all_device_list_changes_for_remotes", None,
-            sql, from_key,
+            sql, from_key, to_key
         )
 
     @defer.inlineCallbacks
diff --git a/synapse/storage/end_to_end_keys.py b/synapse/storage/end_to_end_keys.py
index 7cbc1470fd..e00f31da2b 100644
--- a/synapse/storage/end_to_end_keys.py
+++ b/synapse/storage/end_to_end_keys.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError
+from synapse.util.caches.descriptors import cached
 
 from canonicaljson import encode_canonical_json
 import ujson as json
@@ -123,18 +123,24 @@ class EndToEndKeyStore(SQLBaseStore):
         return result
 
     @defer.inlineCallbacks
-    def add_e2e_one_time_keys(self, user_id, device_id, time_now, key_list):
-        """Insert some new one time keys for a device.
+    def get_e2e_one_time_keys(self, user_id, device_id, key_ids):
+        """Retrieve a number of one-time keys for a user
 
-        Checks if any of the keys are already inserted, if they are then check
-        if they match. If they don't then we raise an error.
+        Args:
+            user_id(str): id of user to get keys for
+            device_id(str): id of device to get keys for
+            key_ids(list[str]): list of key ids (excluding algorithm) to
+                retrieve
+
+        Returns:
+            deferred resolving to Dict[(str, str), str]: map from (algorithm,
+            key_id) to json string for key
         """
 
-        # First we check if we have already persisted any of the keys.
         rows = yield self._simple_select_many_batch(
             table="e2e_one_time_keys_json",
             column="key_id",
-            iterable=[key_id for _, key_id, _ in key_list],
+            iterable=key_ids,
             retcols=("algorithm", "key_id", "key_json",),
             keyvalues={
                 "user_id": user_id,
@@ -143,20 +149,22 @@ class EndToEndKeyStore(SQLBaseStore):
             desc="add_e2e_one_time_keys_check",
         )
 
-        existing_key_map = {
+        defer.returnValue({
             (row["algorithm"], row["key_id"]): row["key_json"] for row in rows
-        }
-
-        new_keys = []  # Keys that we need to insert
-        for algorithm, key_id, json_bytes in key_list:
-            ex_bytes = existing_key_map.get((algorithm, key_id), None)
-            if ex_bytes:
-                if json_bytes != ex_bytes:
-                    raise SynapseError(
-                        400, "One time key with key_id %r already exists" % (key_id,)
-                    )
-            else:
-                new_keys.append((algorithm, key_id, json_bytes))
+        })
+
+    @defer.inlineCallbacks
+    def add_e2e_one_time_keys(self, user_id, device_id, time_now, new_keys):
+        """Insert some new one time keys for a device. Errors if any of the
+        keys already exist.
+
+        Args:
+            user_id(str): id of user to get keys for
+            device_id(str): id of device to get keys for
+            time_now(long): insertion time to record (ms since epoch)
+            new_keys(iterable[(str, str, str)]: keys to add - each a tuple of
+                (algorithm, key_id, key json)
+        """
 
         def _add_e2e_one_time_keys(txn):
             # We are protected from race between lookup and insertion due to
@@ -177,10 +185,14 @@ class EndToEndKeyStore(SQLBaseStore):
                     for algorithm, key_id, json_bytes in new_keys
                 ],
             )
+            txn.call_after(
+                self.count_e2e_one_time_keys.invalidate, (user_id, device_id,)
+            )
         yield self.runInteraction(
             "add_e2e_one_time_keys_insert", _add_e2e_one_time_keys
         )
 
+    @cached(max_entries=10000)
     def count_e2e_one_time_keys(self, user_id, device_id):
         """ Count the number of one time keys the server has for a device
         Returns:
@@ -225,6 +237,9 @@ class EndToEndKeyStore(SQLBaseStore):
             )
             for user_id, device_id, algorithm, key_id in delete:
                 txn.execute(sql, (user_id, device_id, algorithm, key_id))
+                txn.call_after(
+                    self.count_e2e_one_time_keys.invalidate, (user_id, device_id,)
+                )
             return result
         return self.runInteraction(
             "claim_e2e_one_time_keys", _claim_e2e_one_time_keys
@@ -242,3 +257,4 @@ class EndToEndKeyStore(SQLBaseStore):
             keyvalues={"user_id": user_id, "device_id": device_id},
             desc="delete_e2e_one_time_keys_by_device"
         )
+        self.count_e2e_one_time_keys.invalidate((user_id, device_id,))
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 3f6833fad2..c4aeb48800 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -29,6 +29,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import SynapseError
 from synapse.state import resolve_events
 from synapse.util.caches.descriptors import cached
+from synapse.types import get_domain_from_id
 
 from canonicaljson import encode_canonical_json
 from collections import deque, namedtuple, OrderedDict
@@ -49,6 +50,9 @@ logger = logging.getLogger(__name__)
 
 metrics = synapse.metrics.get_metrics_for(__name__)
 persist_event_counter = metrics.register_counter("persisted_events")
+event_counter = metrics.register_counter(
+    "persisted_events_sep", labels=["type", "origin_type", "origin_entity"]
+)
 
 
 def encode_json(json_object):
@@ -203,6 +207,18 @@ class EventsStore(SQLBaseStore):
             where_clause="contains_url = true AND outlier = false",
         )
 
+        # an event_id index on event_search is useful for the purge_history
+        # api. Plus it means we get to enforce some integrity with a UNIQUE
+        # clause
+        self.register_background_index_update(
+            "event_search_event_id_idx",
+            index_name="event_search_event_id_idx",
+            table="event_search",
+            columns=["event_id"],
+            unique=True,
+            psql_only=True,
+        )
+
         self._event_persist_queue = _EventPeristenceQueue()
 
     def persist_events(self, events_and_contexts, backfilled=False):
@@ -370,6 +386,23 @@ class EventsStore(SQLBaseStore):
                     new_forward_extremeties=new_forward_extremeties,
                 )
                 persist_event_counter.inc_by(len(chunk))
+                for event, context in chunk:
+                    if context.app_service:
+                        origin_type = "local"
+                        origin_entity = context.app_service.id
+                    elif self.hs.is_mine_id(event.sender):
+                        origin_type = "local"
+                        origin_entity = "*client*"
+                    else:
+                        origin_type = "remote"
+                        origin_entity = get_domain_from_id(event.sender)
+
+                    event_counter.inc(event.type, origin_type, origin_entity)
+
+                for room_id, (_, _, new_state) in current_state_for_room.iteritems():
+                    self.get_current_state_ids.prefill(
+                        (room_id, ), new_state
+                    )
 
     @defer.inlineCallbacks
     def _calculate_new_extremeties(self, room_id, event_contexts, latest_event_ids):
@@ -419,10 +452,10 @@ class EventsStore(SQLBaseStore):
         Assumes that we are only persisting events for one room at a time.
 
         Returns:
-            2-tuple (to_delete, to_insert) where both are state dicts, i.e.
-            (type, state_key) -> event_id. `to_delete` are the entries to
+            3-tuple (to_delete, to_insert, new_state) where both are state dicts,
+            i.e. (type, state_key) -> event_id. `to_delete` are the entries to
             first be deleted from current_state_events, `to_insert` are entries
-            to insert.
+            to insert. `new_state` is the full set of state.
             May return None if there are no changes to be applied.
         """
         # Now we need to work out the different state sets for
@@ -529,7 +562,7 @@ class EventsStore(SQLBaseStore):
             if ev_id in events_to_insert
         }
 
-        defer.returnValue((to_delete, to_insert))
+        defer.returnValue((to_delete, to_insert, current_state))
 
     @defer.inlineCallbacks
     def get_event(self, event_id, check_redacted=True,
@@ -682,7 +715,7 @@ class EventsStore(SQLBaseStore):
 
     def _update_current_state_txn(self, txn, state_delta_by_room):
         for room_id, current_state_tuple in state_delta_by_room.iteritems():
-                to_delete, to_insert = current_state_tuple
+                to_delete, to_insert, _ = current_state_tuple
                 txn.executemany(
                     "DELETE FROM current_state_events WHERE event_id = ?",
                     [(ev_id,) for ev_id in to_delete.itervalues()],
@@ -1327,11 +1360,26 @@ class EventsStore(SQLBaseStore):
     def _invalidate_get_event_cache(self, event_id):
             self._get_event_cache.invalidate((event_id,))
 
-    def _get_events_from_cache(self, events, allow_rejected):
+    def _get_events_from_cache(self, events, allow_rejected, update_metrics=True):
+        """Fetch events from the caches
+
+        Args:
+            events (list(str)): list of event_ids to fetch
+            allow_rejected (bool): Whether to teturn events that were rejected
+            update_metrics (bool): Whether to update the cache hit ratio metrics
+
+        Returns:
+            dict of event_id -> _EventCacheEntry for each event_id in cache. If
+            allow_rejected is `False` then there will still be an entry but it
+            will be `None`
+        """
         event_map = {}
 
         for event_id in events:
-            ret = self._get_event_cache.get((event_id,), None)
+            ret = self._get_event_cache.get(
+                (event_id,), None,
+                update_metrics=update_metrics,
+            )
             if not ret:
                 continue
 
@@ -1771,6 +1819,94 @@ class EventsStore(SQLBaseStore):
         """The current minimum token that backfilled events have reached"""
         return -self._backfill_id_gen.get_current_token()
 
+    def get_current_events_token(self):
+        """The current maximum token that events have reached"""
+        return self._stream_id_gen.get_current_token()
+
+    def get_all_new_forward_event_rows(self, last_id, current_id, limit):
+        if last_id == current_id:
+            return defer.succeed([])
+
+        def get_all_new_forward_event_rows(txn):
+            sql = (
+                "SELECT e.stream_ordering, e.event_id, e.room_id, e.type,"
+                " state_key, redacts"
+                " FROM events AS e"
+                " LEFT JOIN redactions USING (event_id)"
+                " LEFT JOIN state_events USING (event_id)"
+                " WHERE ? < stream_ordering AND stream_ordering <= ?"
+                " ORDER BY stream_ordering ASC"
+                " LIMIT ?"
+            )
+            txn.execute(sql, (last_id, current_id, limit))
+            new_event_updates = txn.fetchall()
+
+            if len(new_event_updates) == limit:
+                upper_bound = new_event_updates[-1][0]
+            else:
+                upper_bound = current_id
+
+            sql = (
+                "SELECT event_stream_ordering, e.event_id, e.room_id, e.type,"
+                " state_key, redacts"
+                " FROM events AS e"
+                " INNER JOIN ex_outlier_stream USING (event_id)"
+                " LEFT JOIN redactions USING (event_id)"
+                " LEFT JOIN state_events USING (event_id)"
+                " WHERE ? < event_stream_ordering"
+                " AND event_stream_ordering <= ?"
+                " ORDER BY event_stream_ordering DESC"
+            )
+            txn.execute(sql, (last_id, upper_bound))
+            new_event_updates.extend(txn)
+
+            return new_event_updates
+        return self.runInteraction(
+            "get_all_new_forward_event_rows", get_all_new_forward_event_rows
+        )
+
+    def get_all_new_backfill_event_rows(self, last_id, current_id, limit):
+        if last_id == current_id:
+            return defer.succeed([])
+
+        def get_all_new_backfill_event_rows(txn):
+            sql = (
+                "SELECT -e.stream_ordering, e.event_id, e.room_id, e.type,"
+                " state_key, redacts"
+                " FROM events AS e"
+                " LEFT JOIN redactions USING (event_id)"
+                " LEFT JOIN state_events USING (event_id)"
+                " WHERE ? > stream_ordering AND stream_ordering >= ?"
+                " ORDER BY stream_ordering ASC"
+                " LIMIT ?"
+            )
+            txn.execute(sql, (-last_id, -current_id, limit))
+            new_event_updates = txn.fetchall()
+
+            if len(new_event_updates) == limit:
+                upper_bound = new_event_updates[-1][0]
+            else:
+                upper_bound = current_id
+
+            sql = (
+                "SELECT -event_stream_ordering, e.event_id, e.room_id, e.type,"
+                " state_key, redacts"
+                " FROM events AS e"
+                " INNER JOIN ex_outlier_stream USING (event_id)"
+                " LEFT JOIN redactions USING (event_id)"
+                " LEFT JOIN state_events USING (event_id)"
+                " WHERE ? > event_stream_ordering"
+                " AND event_stream_ordering >= ?"
+                " ORDER BY event_stream_ordering DESC"
+            )
+            txn.execute(sql, (-last_id, -upper_bound))
+            new_event_updates.extend(txn.fetchall())
+
+            return new_event_updates
+        return self.runInteraction(
+            "get_all_new_backfill_event_rows", get_all_new_backfill_event_rows
+        )
+
     @cached(num_args=5, max_entries=10)
     def get_all_new_events(self, last_backfill_id, last_forward_id,
                            current_backfill_id, current_forward_id, limit):
@@ -1903,6 +2039,8 @@ class EventsStore(SQLBaseStore):
                 400, "topological_ordering is greater than forward extremeties"
             )
 
+        logger.debug("[purge] looking for events to delete")
+
         txn.execute(
             "SELECT event_id, state_key FROM events"
             " LEFT JOIN state_events USING (room_id, event_id)"
@@ -1911,9 +2049,19 @@ class EventsStore(SQLBaseStore):
         )
         event_rows = txn.fetchall()
 
+        to_delete = [
+            (event_id,) for event_id, state_key in event_rows
+            if state_key is None and not self.hs.is_mine_id(event_id)
+        ]
+        logger.info(
+            "[purge] found %i events before cutoff, of which %i are remote"
+            " non-state events to delete", len(event_rows), len(to_delete))
+
         for event_id, state_key in event_rows:
             txn.call_after(self._get_state_group_for_event.invalidate, (event_id,))
 
+        logger.debug("[purge] Finding new backward extremities")
+
         # We calculate the new entries for the backward extremeties by finding
         # all events that point to events that are to be purged
         txn.execute(
@@ -1926,6 +2074,8 @@ class EventsStore(SQLBaseStore):
         )
         new_backwards_extrems = txn.fetchall()
 
+        logger.debug("[purge] replacing backward extremities: %r", new_backwards_extrems)
+
         txn.execute(
             "DELETE FROM event_backward_extremities WHERE room_id = ?",
             (room_id,)
@@ -1940,6 +2090,8 @@ class EventsStore(SQLBaseStore):
             ]
         )
 
+        logger.debug("[purge] finding redundant state groups")
+
         # Get all state groups that are only referenced by events that are
         # to be deleted.
         txn.execute(
@@ -1955,15 +2107,20 @@ class EventsStore(SQLBaseStore):
         )
 
         state_rows = txn.fetchall()
-        state_groups_to_delete = [sg for sg, in state_rows]
+        logger.debug("[purge] found %i redundant state groups", len(state_rows))
+
+        # make a set of the redundant state groups, so that we can look them up
+        # efficiently
+        state_groups_to_delete = set([sg for sg, in state_rows])
 
         # Now we get all the state groups that rely on these state groups
-        new_state_edges = []
-        chunks = [
-            state_groups_to_delete[i:i + 100]
-            for i in xrange(0, len(state_groups_to_delete), 100)
-        ]
-        for chunk in chunks:
+        logger.debug("[purge] finding state groups which depend on redundant"
+                     " state groups")
+        remaining_state_groups = []
+        for i in xrange(0, len(state_rows), 100):
+            chunk = [sg for sg, in state_rows[i:i + 100]]
+            # look for state groups whose prev_state_group is one we are about
+            # to delete
             rows = self._simple_select_many_txn(
                 txn,
                 table="state_group_edges",
@@ -1972,21 +2129,28 @@ class EventsStore(SQLBaseStore):
                 retcols=["state_group"],
                 keyvalues={},
             )
-            new_state_edges.extend(row["state_group"] for row in rows)
+            remaining_state_groups.extend(
+                row["state_group"] for row in rows
+
+                # exclude state groups we are about to delete: no point in
+                # updating them
+                if row["state_group"] not in state_groups_to_delete
+            )
 
-        # Now we turn the state groups that reference to-be-deleted state groups
-        # to non delta versions.
-        for new_state_edge in new_state_edges:
+        # Now we turn the state groups that reference to-be-deleted state
+        # groups to non delta versions.
+        for sg in remaining_state_groups:
+            logger.debug("[purge] de-delta-ing remaining state group %s", sg)
             curr_state = self._get_state_groups_from_groups_txn(
-                txn, [new_state_edge], types=None
+                txn, [sg], types=None
             )
-            curr_state = curr_state[new_state_edge]
+            curr_state = curr_state[sg]
 
             self._simple_delete_txn(
                 txn,
                 table="state_groups_state",
                 keyvalues={
-                    "state_group": new_state_edge,
+                    "state_group": sg,
                 }
             )
 
@@ -1994,7 +2158,7 @@ class EventsStore(SQLBaseStore):
                 txn,
                 table="state_group_edges",
                 keyvalues={
-                    "state_group": new_state_edge,
+                    "state_group": sg,
                 }
             )
 
@@ -2003,7 +2167,7 @@ class EventsStore(SQLBaseStore):
                 table="state_groups_state",
                 values=[
                     {
-                        "state_group": new_state_edge,
+                        "state_group": sg,
                         "room_id": room_id,
                         "type": key[0],
                         "state_key": key[1],
@@ -2013,6 +2177,7 @@ class EventsStore(SQLBaseStore):
                 ],
             )
 
+        logger.debug("[purge] removing redundant state groups")
         txn.executemany(
             "DELETE FROM state_groups_state WHERE state_group = ?",
             state_rows
@@ -2021,22 +2186,21 @@ class EventsStore(SQLBaseStore):
             "DELETE FROM state_groups WHERE id = ?",
             state_rows
         )
+
         # Delete all non-state
+        logger.debug("[purge] removing events from event_to_state_groups")
         txn.executemany(
             "DELETE FROM event_to_state_groups WHERE event_id = ?",
             [(event_id,) for event_id, _ in event_rows]
         )
 
+        logger.debug("[purge] updating room_depth")
         txn.execute(
             "UPDATE room_depth SET min_depth = ? WHERE room_id = ?",
             (topological_ordering, room_id,)
         )
 
         # Delete all remote non-state events
-        to_delete = [
-            (event_id,) for event_id, state_key in event_rows
-            if state_key is None and not self.hs.is_mine_id(event_id)
-        ]
         for table in (
             "events",
             "event_json",
@@ -2052,16 +2216,15 @@ class EventsStore(SQLBaseStore):
             "event_signatures",
             "rejections",
         ):
+            logger.debug("[purge] removing remote non-state events from %s", table)
+
             txn.executemany(
                 "DELETE FROM %s WHERE event_id = ?" % (table,),
                 to_delete
             )
 
-        txn.executemany(
-            "DELETE FROM events WHERE event_id = ?",
-            to_delete
-        )
         # Mark all state and own events as outliers
+        logger.debug("[purge] marking remaining events as outliers")
         txn.executemany(
             "UPDATE events SET outlier = ?"
             " WHERE event_id = ?",
@@ -2071,6 +2234,30 @@ class EventsStore(SQLBaseStore):
             ]
         )
 
+        logger.info("[purge] done")
+
+    @defer.inlineCallbacks
+    def is_event_after(self, event_id1, event_id2):
+        """Returns True if event_id1 is after event_id2 in the stream
+        """
+        to_1, so_1 = yield self._get_event_ordering(event_id1)
+        to_2, so_2 = yield self._get_event_ordering(event_id2)
+        defer.returnValue((to_1, so_1) > (to_2, so_2))
+
+    @defer.inlineCallbacks
+    def _get_event_ordering(self, event_id):
+        res = yield self._simple_select_one(
+            table="events",
+            retcols=["topological_ordering", "stream_ordering"],
+            keyvalues={"event_id": event_id},
+            allow_none=True
+        )
+
+        if not res:
+            raise SynapseError(404, "Could not find event %s" % (event_id,))
+
+        defer.returnValue((int(res["topological_ordering"]), int(res["stream_ordering"])))
+
 
 AllNewEventsResult = namedtuple("AllNewEventsResult", [
     "new_forward_events", "new_backfill_events",
diff --git a/synapse/storage/push_rule.py b/synapse/storage/push_rule.py
index cbec255966..0a819d32c5 100644
--- a/synapse/storage/push_rule.py
+++ b/synapse/storage/push_rule.py
@@ -16,6 +16,7 @@
 from ._base import SQLBaseStore
 from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList
 from synapse.push.baserules import list_with_base_rules
+from synapse.api.constants import EventTypes
 from twisted.internet import defer
 
 import logging
@@ -184,6 +185,18 @@ class PushRuleStore(SQLBaseStore):
             if uid in local_users_in_room:
                 user_ids.add(uid)
 
+        forgotten = yield self.who_forgot_in_room(
+            event.room_id, on_invalidate=cache_context.invalidate,
+        )
+
+        for row in forgotten:
+            user_id = row["user_id"]
+            event_id = row["event_id"]
+
+            mem_id = current_state_ids.get((EventTypes.Member, user_id), None)
+            if event_id == mem_id:
+                user_ids.discard(user_id)
+
         rules_by_user = yield self.bulk_get_push_rules(
             user_ids, on_invalidate=cache_context.invalidate,
         )
diff --git a/synapse/storage/pusher.py b/synapse/storage/pusher.py
index 8cc9f0353b..34d2f82b7f 100644
--- a/synapse/storage/pusher.py
+++ b/synapse/storage/pusher.py
@@ -135,6 +135,48 @@ class PusherStore(SQLBaseStore):
             "get_all_updated_pushers", get_all_updated_pushers_txn
         )
 
+    def get_all_updated_pushers_rows(self, last_id, current_id, limit):
+        """Get all the pushers that have changed between the given tokens.
+
+        Returns:
+            Deferred(list(tuple)): each tuple consists of:
+                stream_id (str)
+                user_id (str)
+                app_id (str)
+                pushkey (str)
+                was_deleted (bool): whether the pusher was added/updated (False)
+                    or deleted (True)
+        """
+
+        if last_id == current_id:
+            return defer.succeed([])
+
+        def get_all_updated_pushers_rows_txn(txn):
+            sql = (
+                "SELECT id, user_name, app_id, pushkey"
+                " FROM pushers"
+                " WHERE ? < id AND id <= ?"
+                " ORDER BY id ASC LIMIT ?"
+            )
+            txn.execute(sql, (last_id, current_id, limit))
+            results = [list(row) + [False] for row in txn]
+
+            sql = (
+                "SELECT stream_id, user_id, app_id, pushkey"
+                " FROM deleted_pushers"
+                " WHERE ? < stream_id AND stream_id <= ?"
+                " ORDER BY stream_id ASC LIMIT ?"
+            )
+            txn.execute(sql, (last_id, current_id, limit))
+
+            results.extend(list(row) + [True] for row in txn)
+            results.sort()  # Sort so that they're ordered by stream id
+
+            return results
+        return self.runInteraction(
+            "get_all_updated_pushers_rows", get_all_updated_pushers_rows_txn
+        )
+
     @cachedInlineCallbacks(num_args=1, max_entries=15000)
     def get_if_user_has_pusher(self, user_id):
         # This only exists for the cachedList decorator
diff --git a/synapse/storage/receipts.py b/synapse/storage/receipts.py
index 6b0f8c2787..efb90c3c91 100644
--- a/synapse/storage/receipts.py
+++ b/synapse/storage/receipts.py
@@ -47,10 +47,13 @@ class ReceiptsStore(SQLBaseStore):
         # Returns an ObservableDeferred
         res = self.get_users_with_read_receipts_in_room.cache.get((room_id,), None)
 
-        if res and res.called and user_id in res.result:
-            # We'd only be adding to the set, so no point invalidating if the
-            # user is already there
-            return
+        if res:
+            if isinstance(res, defer.Deferred) and res.called:
+                res = res.result
+            if user_id in res:
+                # We'd only be adding to the set, so no point invalidating if the
+                # user is already there
+                return
 
         self.get_users_with_read_receipts_in_room.invalidate((room_id,))
 
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index e4c56cc175..5d543652bb 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -16,7 +16,7 @@
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
-from synapse.util.caches.descriptors import cached
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
 from ._base import SQLBaseStore
 from .engines import PostgresEngine, Sqlite3Engine
@@ -33,6 +33,11 @@ OpsLevel = collections.namedtuple(
     ("ban_level", "kick_level", "redact_level",)
 )
 
+RatelimitOverride = collections.namedtuple(
+    "RatelimitOverride",
+    ("messages_per_second", "burst_count",)
+)
+
 
 class RoomStore(SQLBaseStore):
 
@@ -473,3 +478,32 @@ class RoomStore(SQLBaseStore):
         return self.runInteraction(
             "get_all_new_public_rooms", get_all_new_public_rooms
         )
+
+    @cachedInlineCallbacks(max_entries=10000)
+    def get_ratelimit_for_user(self, user_id):
+        """Check if there are any overrides for ratelimiting for the given
+        user
+
+        Args:
+            user_id (str)
+
+        Returns:
+            RatelimitOverride if there is an override, else None. If the contents
+            of RatelimitOverride are None or 0 then ratelimitng has been
+            disabled for that user entirely.
+        """
+        row = yield self._simple_select_one(
+            table="ratelimit_override",
+            keyvalues={"user_id": user_id},
+            retcols=("messages_per_second", "burst_count"),
+            allow_none=True,
+            desc="get_ratelimit_for_user",
+        )
+
+        if row:
+            defer.returnValue(RatelimitOverride(
+                messages_per_second=row["messages_per_second"],
+                burst_count=row["burst_count"],
+            ))
+        else:
+            defer.returnValue(None)
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 367dbbbcf6..0829ae5bee 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -18,7 +18,9 @@ from twisted.internet import defer
 from collections import namedtuple
 
 from ._base import SQLBaseStore
+from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
+from synapse.util.stringutils import to_ascii
 
 from synapse.api.constants import Membership, EventTypes
 from synapse.types import get_domain_from_id
@@ -35,6 +37,13 @@ RoomsForUser = namedtuple(
 )
 
 
+# We store this using a namedtuple so that we save about 3x space over using a
+# dict.
+ProfileInfo = namedtuple(
+    "ProfileInfo", ("avatar_url", "display_name")
+)
+
+
 _MEMBERSHIP_PROFILE_UPDATE_NAME = "room_membership_profile_update"
 
 
@@ -139,7 +148,7 @@ class RoomMemberStore(SQLBaseStore):
         hosts = frozenset(get_domain_from_id(user_id) for user_id in user_ids)
         defer.returnValue(hosts)
 
-    @cached(max_entries=500000, iterable=True)
+    @cached(max_entries=100000, iterable=True)
     def get_users_in_room(self, room_id):
         def f(txn):
             sql = (
@@ -152,7 +161,7 @@ class RoomMemberStore(SQLBaseStore):
             )
 
             txn.execute(sql, (room_id, Membership.JOIN,))
-            return [r[0] for r in txn]
+            return [to_ascii(r[0]) for r in txn]
         return self.runInteraction("get_users_in_room", f)
 
     @cached()
@@ -378,7 +387,9 @@ class RoomMemberStore(SQLBaseStore):
             state_group = object()
 
         return self._get_joined_users_from_context(
-            event.room_id, state_group, context.current_state_ids, event=event,
+            event.room_id, state_group, context.current_state_ids,
+            event=event,
+            context=context,
         )
 
     def get_joined_users_from_state(self, room_id, state_group, state_ids):
@@ -396,46 +407,95 @@ class RoomMemberStore(SQLBaseStore):
     @cachedInlineCallbacks(num_args=2, cache_context=True, iterable=True,
                            max_entries=100000)
     def _get_joined_users_from_context(self, room_id, state_group, current_state_ids,
-                                       cache_context, event=None):
+                                       cache_context, event=None, context=None):
         # We don't use `state_group`, it's there so that we can cache based
         # on it. However, it's important that it's never None, since two current_states
         # with a state_group of None are likely to be different.
         # See bulk_get_push_rules_for_room for how we work around this.
         assert state_group is not None
 
+        users_in_room = {}
         member_event_ids = [
             e_id
             for key, e_id in current_state_ids.iteritems()
             if key[0] == EventTypes.Member
         ]
 
-        rows = yield self._simple_select_many_batch(
-            table="room_memberships",
-            column="event_id",
-            iterable=member_event_ids,
-            retcols=['user_id', 'display_name', 'avatar_url'],
-            keyvalues={
-                "membership": Membership.JOIN,
-            },
-            batch_size=500,
-            desc="_get_joined_users_from_context",
+        if context is not None:
+            # If we have a context with a delta from a previous state group,
+            # check if we also have the result from the previous group in cache.
+            # If we do then we can reuse that result and simply update it with
+            # any membership changes in `delta_ids`
+            if context.prev_group and context.delta_ids:
+                prev_res = self._get_joined_users_from_context.cache.get(
+                    (room_id, context.prev_group), None
+                )
+                if prev_res and isinstance(prev_res, dict):
+                    users_in_room = dict(prev_res)
+                    member_event_ids = [
+                        e_id
+                        for key, e_id in context.delta_ids.iteritems()
+                        if key[0] == EventTypes.Member
+                    ]
+                    for etype, state_key in context.delta_ids:
+                        users_in_room.pop(state_key, None)
+
+        # We check if we have any of the member event ids in the event cache
+        # before we ask the DB
+
+        # We don't update the event cache hit ratio as it completely throws off
+        # the hit ratio counts. After all, we don't populate the cache if we
+        # miss it here
+        event_map = self._get_events_from_cache(
+            member_event_ids,
+            allow_rejected=False,
+            update_metrics=False,
         )
 
-        users_in_room = {
-            row["user_id"]: {
-                "display_name": row["display_name"],
-                "avatar_url": row["avatar_url"],
-            }
-            for row in rows
-        }
+        missing_member_event_ids = []
+        for event_id in member_event_ids:
+            ev_entry = event_map.get(event_id)
+            if ev_entry:
+                if ev_entry.event.membership == Membership.JOIN:
+                    users_in_room[to_ascii(ev_entry.event.state_key)] = ProfileInfo(
+                        display_name=to_ascii(
+                            ev_entry.event.content.get("displayname", None)
+                        ),
+                        avatar_url=to_ascii(
+                            ev_entry.event.content.get("avatar_url", None)
+                        ),
+                    )
+            else:
+                missing_member_event_ids.append(event_id)
+
+        if missing_member_event_ids:
+            rows = yield self._simple_select_many_batch(
+                table="room_memberships",
+                column="event_id",
+                iterable=missing_member_event_ids,
+                retcols=('user_id', 'display_name', 'avatar_url',),
+                keyvalues={
+                    "membership": Membership.JOIN,
+                },
+                batch_size=500,
+                desc="_get_joined_users_from_context",
+            )
+
+            users_in_room.update({
+                to_ascii(row["user_id"]): ProfileInfo(
+                    avatar_url=to_ascii(row["avatar_url"]),
+                    display_name=to_ascii(row["display_name"]),
+                )
+                for row in rows
+            })
 
         if event is not None and event.type == EventTypes.Member:
             if event.membership == Membership.JOIN:
                 if event.event_id in member_event_ids:
-                    users_in_room[event.state_key] = {
-                        "display_name": event.content.get("displayname", None),
-                        "avatar_url": event.content.get("avatar_url", None),
-                    }
+                    users_in_room[to_ascii(event.state_key)] = ProfileInfo(
+                        display_name=to_ascii(event.content.get("displayname", None)),
+                        avatar_url=to_ascii(event.content.get("avatar_url", None)),
+                    )
 
         defer.returnValue(users_in_room)
 
@@ -474,6 +534,45 @@ class RoomMemberStore(SQLBaseStore):
 
         defer.returnValue(False)
 
+    def get_joined_hosts(self, room_id, state_group, state_ids):
+        if not state_group:
+            # If state_group is None it means it has yet to be assigned a
+            # state group, i.e. we need to make sure that calls with a state_group
+            # of None don't hit previous cached calls with a None state_group.
+            # To do this we set the state_group to a new object as object() != object()
+            state_group = object()
+
+        return self._get_joined_hosts(
+            room_id, state_group, state_ids
+        )
+
+    @cachedInlineCallbacks(num_args=2, max_entries=10000, iterable=True)
+    def _get_joined_hosts(self, room_id, state_group, current_state_ids):
+        # We don't use `state_group`, its there so that we can cache based
+        # on it. However, its important that its never None, since two current_state's
+        # with a state_group of None are likely to be different.
+        # See bulk_get_push_rules_for_room for how we work around this.
+        assert state_group is not None
+
+        joined_hosts = set()
+        for etype, state_key in current_state_ids:
+            if etype == EventTypes.Member:
+                try:
+                    host = get_domain_from_id(state_key)
+                except:
+                    logger.warn("state_key not user_id: %s", state_key)
+                    continue
+
+                if host in joined_hosts:
+                    continue
+
+                event_id = current_state_ids[(etype, state_key)]
+                event = yield self.get_event(event_id, allow_none=True)
+                if event and event.content["membership"] == Membership.JOIN:
+                    joined_hosts.add(intern_string(host))
+
+        defer.returnValue(joined_hosts)
+
     @defer.inlineCallbacks
     def _background_add_membership_profile(self, progress, batch_size):
         target_min_stream_id = progress.get(
diff --git a/synapse/storage/schema/delta/37/remove_auth_idx.py b/synapse/storage/schema/delta/37/remove_auth_idx.py
index 784f3b348f..20ad8bd5a6 100644
--- a/synapse/storage/schema/delta/37/remove_auth_idx.py
+++ b/synapse/storage/schema/delta/37/remove_auth_idx.py
@@ -36,6 +36,10 @@ DROP INDEX IF EXISTS transactions_have_ref;
 -- and is used incredibly rarely.
 DROP INDEX IF EXISTS events_order_topo_stream_room;
 
+-- an equivalent index to this actually gets re-created in delta 41, because it
+-- turned out that deleting it wasn't a great plan :/. In any case, let's
+-- delete it here, and delta 41 will create a new one with an added UNIQUE
+-- constraint
 DROP INDEX IF EXISTS event_search_ev_idx;
 """
 
diff --git a/synapse/storage/schema/delta/41/event_search_event_id_idx.sql b/synapse/storage/schema/delta/41/event_search_event_id_idx.sql
new file mode 100644
index 0000000000..5d9cfecf36
--- /dev/null
+++ b/synapse/storage/schema/delta/41/event_search_event_id_idx.sql
@@ -0,0 +1,17 @@
+/* Copyright 2017 Vector Creations Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+INSERT into background_updates (update_name, progress_json)
+    VALUES ('event_search_event_id_idx', '{}');
diff --git a/synapse/storage/schema/delta/41/ratelimit.sql b/synapse/storage/schema/delta/41/ratelimit.sql
new file mode 100644
index 0000000000..a194bf0238
--- /dev/null
+++ b/synapse/storage/schema/delta/41/ratelimit.sql
@@ -0,0 +1,22 @@
+/* Copyright 2017 Vector Creations Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+CREATE TABLE ratelimit_override (
+    user_id TEXT NOT NULL,
+    messages_per_second BIGINT,
+    burst_count BIGINT
+);
+
+CREATE UNIQUE INDEX ratelimit_override_idx ON ratelimit_override(user_id);
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index fb23f6f462..85acf2ad1e 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -14,8 +14,9 @@
 # limitations under the License.
 
 from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cached, cachedList, cachedInlineCallbacks
+from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches import intern_string
+from synapse.util.stringutils import to_ascii
 from synapse.storage.engines import PostgresEngine
 
 from twisted.internet import defer
@@ -69,17 +70,33 @@ class StateStore(SQLBaseStore):
             where_clause="type='m.room.member'",
         )
 
-    @cachedInlineCallbacks(max_entries=100000, iterable=True)
+    @cached(max_entries=100000, iterable=True)
     def get_current_state_ids(self, room_id):
-        rows = yield self._simple_select_list(
-            table="current_state_events",
-            keyvalues={"room_id": room_id},
-            retcols=["event_id", "type", "state_key"],
-            desc="_calculate_state_delta",
+        """Get the current state event ids for a room based on the
+        current_state_events table.
+
+        Args:
+            room_id (str)
+
+        Returns:
+            deferred: dict of (type, state_key) -> event_id
+        """
+        def _get_current_state_ids_txn(txn):
+            txn.execute(
+                """SELECT type, state_key, event_id FROM current_state_events
+                WHERE room_id = ?
+                """,
+                (room_id,)
+            )
+
+            return {
+                (intern_string(r[0]), intern_string(r[1])): to_ascii(r[2]) for r in txn
+            }
+
+        return self.runInteraction(
+            "get_current_state_ids",
+            _get_current_state_ids_txn,
         )
-        defer.returnValue({
-            (r["type"], r["state_key"]): r["event_id"] for r in rows
-        })
 
     @defer.inlineCallbacks
     def get_state_groups_ids(self, room_id, event_ids):
@@ -210,6 +227,18 @@ class StateStore(SQLBaseStore):
                     ],
                 )
 
+            # Prefill the state group cache with this group.
+            # It's fine to use the sequence like this as the state group map
+            # is immutable. (If the map wasn't immutable then this prefill could
+            # race with another update)
+            txn.call_after(
+                self._state_group_cache.update,
+                self._state_group_cache.sequence,
+                key=context.state_group,
+                value=dict(context.current_state_ids),
+                full=True,
+            )
+
         self._simple_insert_many_txn(
             txn,
             table="event_to_state_groups",
@@ -263,12 +292,7 @@ class StateStore(SQLBaseStore):
 
             return count
 
-    @cached(num_args=2, max_entries=100000, iterable=True)
-    def _get_state_group_from_group(self, group, types):
-        raise NotImplementedError()
-
-    @cachedList(cached_method_name="_get_state_group_from_group",
-                list_name="groups", num_args=2, inlineCallbacks=True)
+    @defer.inlineCallbacks
     def _get_state_groups_from_groups(self, groups, types):
         """Returns dictionary state_group -> (dict of (type, state_key) -> event id)
         """
@@ -496,7 +520,7 @@ class StateStore(SQLBaseStore):
         state_map = yield self.get_state_ids_for_events([event_id], types)
         defer.returnValue(state_map[event_id])
 
-    @cached(num_args=2, max_entries=100000)
+    @cached(num_args=2, max_entries=50000)
     def _get_state_group_for_event(self, room_id, event_id):
         return self._simple_select_one_onecol(
             table="event_to_state_groups",
@@ -644,7 +668,7 @@ class StateStore(SQLBaseStore):
                     state_dict = results[group]
 
                 state_dict.update(
-                    ((intern_string(k[0]), intern_string(k[1])), v)
+                    ((intern_string(k[0]), intern_string(k[1])), to_ascii(v))
                     for k, v in group_state_dict.iteritems()
                 )
 
diff --git a/synapse/types.py b/synapse/types.py
index 9666f9d73f..445bdcb4d7 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -56,10 +56,10 @@ def create_requester(user_id, access_token_id=None, is_guest=False,
 
 
 def get_domain_from_id(string):
-    try:
-        return string.split(":", 1)[1]
-    except IndexError:
+    idx = string.find(":")
+    if idx == -1:
         raise SynapseError(400, "Invalid ID: %r" % (string,))
+    return string[idx + 1:]
 
 
 class DomainSpecificString(
@@ -216,9 +216,7 @@ class StreamToken(
             return self
 
     def copy_and_replace(self, key, new_value):
-        d = self._asdict()
-        d[key] = new_value
-        return StreamToken(**d)
+        return self._replace(**{key: new_value})
 
 
 StreamToken.START = StreamToken(
diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py
index 98a5a26ac5..2a2360ab5d 100644
--- a/synapse/util/__init__.py
+++ b/synapse/util/__init__.py
@@ -26,7 +26,7 @@ logger = logging.getLogger(__name__)
 
 class DeferredTimedOutError(SynapseError):
     def __init__(self):
-        super(SynapseError, self).__init__(504, "Timed out")
+        super(DeferredTimedOutError, self).__init__(504, "Timed out")
 
 
 def unwrapFirstError(failure):
diff --git a/synapse/util/async.py b/synapse/util/async.py
index 35380bf8ed..1453faf0ef 100644
--- a/synapse/util/async.py
+++ b/synapse/util/async.py
@@ -89,6 +89,11 @@ class ObservableDeferred(object):
         deferred.addCallbacks(callback, errback)
 
     def observe(self):
+        """Observe the underlying deferred.
+
+        Can return either a deferred if the underlying deferred is still pending
+        (or has failed), or the actual value. Callers may need to use maybeDeferred.
+        """
         if not self._result:
             d = defer.Deferred()
 
@@ -101,7 +106,7 @@ class ObservableDeferred(object):
             return d
         else:
             success, res = self._result
-            return defer.succeed(res) if success else defer.fail(res)
+            return res if success else defer.fail(res)
 
     def observers(self):
         return self._observers
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 8a7774a88e..4a83c46d98 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -14,13 +14,10 @@
 # limitations under the License.
 
 import synapse.metrics
-from lrucache import LruCache
 import os
 
 CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.1))
 
-DEBUG_CACHES = False
-
 metrics = synapse.metrics.get_metrics_for("synapse.util.caches")
 
 caches_by_name = {}
@@ -40,10 +37,6 @@ def register_cache(name, cache):
     )
 
 
-_string_cache = LruCache(int(100000 * CACHE_SIZE_FACTOR))
-_stirng_cache_metrics = register_cache("string_cache", _string_cache)
-
-
 KNOWN_KEYS = {
     key: key for key in
     (
@@ -67,14 +60,16 @@ KNOWN_KEYS = {
 
 
 def intern_string(string):
-    """Takes a (potentially) unicode string and interns using custom cache
+    """Takes a (potentially) unicode string and interns it if it's ascii
     """
-    new_str = _string_cache.setdefault(string, string)
-    if new_str is string:
-        _stirng_cache_metrics.inc_hits()
-    else:
-        _stirng_cache_metrics.inc_misses()
-    return new_str
+    if string is None:
+        return None
+
+    try:
+        string = string.encode("ascii")
+        return intern(string)
+    except UnicodeEncodeError:
+        return string
 
 
 def intern_dict(dictionary):
@@ -87,13 +82,9 @@ def intern_dict(dictionary):
 
 
 def _intern_known_values(key, value):
-    intern_str_keys = ("event_id", "room_id")
-    intern_unicode_keys = ("sender", "user_id", "type", "state_key")
-
-    if key in intern_str_keys:
-        return intern(value.encode('ascii'))
+    intern_keys = ("event_id", "room_id", "sender", "user_id", "type", "state_key",)
 
-    if key in intern_unicode_keys:
+    if key in intern_keys:
         return intern_string(value)
 
     return value
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 5c30ed235d..48dcbafeef 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -18,8 +18,9 @@ from synapse.util.async import ObservableDeferred
 from synapse.util import unwrapFirstError, logcontext
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
+from synapse.util.stringutils import to_ascii
 
-from . import DEBUG_CACHES, register_cache
+from . import register_cache
 
 from twisted.internet import defer
 from collections import namedtuple
@@ -76,7 +77,7 @@ class Cache(object):
 
         self.cache = LruCache(
             max_size=max_entries, keylen=keylen, cache_type=cache_type,
-            size_callback=(lambda d: len(d.result)) if iterable else None,
+            size_callback=(lambda d: len(d)) if iterable else None,
         )
 
         self.name = name
@@ -95,13 +96,26 @@ class Cache(object):
                     "Cache objects can only be accessed from the main thread"
                 )
 
-    def get(self, key, default=_CacheSentinel, callback=None):
+    def get(self, key, default=_CacheSentinel, callback=None, update_metrics=True):
+        """Looks the key up in the caches.
+
+        Args:
+            key(tuple)
+            default: What is returned if key is not in the caches. If not
+                specified then function throws KeyError instead
+            callback(fn): Gets called when the entry in the cache is invalidated
+            update_metrics (bool): whether to update the cache hit rate metrics
+
+        Returns:
+            Either a Deferred or the raw result
+        """
         callbacks = [callback] if callback else []
         val = self._pending_deferred_cache.get(key, _CacheSentinel)
         if val is not _CacheSentinel:
             if val.sequence == self.sequence:
                 val.callbacks.update(callbacks)
-                self.metrics.inc_hits()
+                if update_metrics:
+                    self.metrics.inc_hits()
                 return val.deferred
 
         val = self.cache.get(key, _CacheSentinel, callbacks=callbacks)
@@ -109,7 +123,8 @@ class Cache(object):
             self.metrics.inc_hits()
             return val
 
-        self.metrics.inc_misses()
+        if update_metrics:
+            self.metrics.inc_misses()
 
         if default is _CacheSentinel:
             raise KeyError()
@@ -137,7 +152,7 @@ class Cache(object):
             if self.sequence == entry.sequence:
                 existing_entry = self._pending_deferred_cache.pop(key, None)
                 if existing_entry is entry:
-                    self.cache.set(key, entry.deferred, entry.callbacks)
+                    self.cache.set(key, result, entry.callbacks)
                 else:
                     entry.invalidate()
             else:
@@ -152,10 +167,6 @@ class Cache(object):
 
     def invalidate(self, key):
         self.check_thread()
-        if not isinstance(key, tuple):
-            raise TypeError(
-                "The cache key must be a tuple not %r" % (type(key),)
-            )
 
         # Increment the sequence number so that any SELECT statements that
         # raced with the INSERT don't update the cache (SYN-369)
@@ -224,8 +235,20 @@ class _CacheDescriptorBase(object):
             )
 
         self.num_args = num_args
+
+        # list of the names of the args used as the cache key
         self.arg_names = all_args[1:num_args + 1]
 
+        # self.arg_defaults is a map of arg name to its default value for each
+        # argument that has a default value
+        if arg_spec.defaults:
+            self.arg_defaults = dict(zip(
+                all_args[-len(arg_spec.defaults):],
+                arg_spec.defaults
+            ))
+        else:
+            self.arg_defaults = {}
+
         if "cache_context" in self.arg_names:
             raise Exception(
                 "cache_context arg cannot be included among the cache keys"
@@ -289,18 +312,47 @@ class CacheDescriptor(_CacheDescriptorBase):
             iterable=self.iterable,
         )
 
+        def get_cache_key_gen(args, kwargs):
+            """Given some args/kwargs return a generator that resolves into
+            the cache_key.
+
+            We loop through each arg name, looking up if its in the `kwargs`,
+            otherwise using the next argument in `args`. If there are no more
+            args then we try looking the arg name up in the defaults
+            """
+            pos = 0
+            for nm in self.arg_names:
+                if nm in kwargs:
+                    yield kwargs[nm]
+                elif pos < len(args):
+                    yield args[pos]
+                    pos += 1
+                else:
+                    yield self.arg_defaults[nm]
+
+        # By default our cache key is a tuple, but if there is only one item
+        # then don't bother wrapping in a tuple.  This is to save memory.
+        if self.num_args == 1:
+            nm = self.arg_names[0]
+
+            def get_cache_key(args, kwargs):
+                if nm in kwargs:
+                    return kwargs[nm]
+                elif len(args):
+                    return args[0]
+                else:
+                    return self.arg_defaults[nm]
+        else:
+            def get_cache_key(args, kwargs):
+                return tuple(get_cache_key_gen(args, kwargs))
+
         @functools.wraps(self.orig)
         def wrapped(*args, **kwargs):
             # If we're passed a cache_context then we'll want to call its invalidate()
             # whenever we are invalidated
             invalidate_callback = kwargs.pop("on_invalidate", None)
 
-            # Add temp cache_context so inspect.getcallargs doesn't explode
-            if self.add_cache_context:
-                kwargs["cache_context"] = None
-
-            arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs)
-            cache_key = tuple(arg_dict[arg_nm] for arg_nm in self.arg_names)
+            cache_key = get_cache_key(args, kwargs)
 
             # Add our own `cache_context` to argument list if the wrapped function
             # has asked for one
@@ -310,20 +362,10 @@ class CacheDescriptor(_CacheDescriptorBase):
             try:
                 cached_result_d = cache.get(cache_key, callback=invalidate_callback)
 
-                observer = cached_result_d.observe()
-                if DEBUG_CACHES:
-                    @defer.inlineCallbacks
-                    def check_result(cached_result):
-                        actual_result = yield self.function_to_call(obj, *args, **kwargs)
-                        if actual_result != cached_result:
-                            logger.error(
-                                "Stale cache entry %s%r: cached: %r, actual %r",
-                                self.orig.__name__, cache_key,
-                                cached_result, actual_result,
-                            )
-                            raise ValueError("Stale cache entry")
-                        defer.returnValue(cached_result)
-                    observer.addCallback(check_result)
+                if isinstance(cached_result_d, ObservableDeferred):
+                    observer = cached_result_d.observe()
+                else:
+                    observer = cached_result_d
 
             except KeyError:
                 ret = defer.maybeDeferred(
@@ -337,16 +379,30 @@ class CacheDescriptor(_CacheDescriptorBase):
 
                 ret.addErrback(onErr)
 
+                # If our cache_key is a string, try to convert to ascii to save
+                # a bit of space in large caches
+                if isinstance(cache_key, basestring):
+                    cache_key = to_ascii(cache_key)
+
                 result_d = ObservableDeferred(ret, consumeErrors=True)
                 cache.set(cache_key, result_d, callback=invalidate_callback)
                 observer = result_d.observe()
 
-            return logcontext.make_deferred_yieldable(observer)
+            if isinstance(observer, defer.Deferred):
+                return logcontext.make_deferred_yieldable(observer)
+            else:
+                return observer
+
+        if self.num_args == 1:
+            wrapped.invalidate = lambda key: cache.invalidate(key[0])
+            wrapped.prefill = lambda key, val: cache.prefill(key[0], val)
+        else:
+            wrapped.invalidate = cache.invalidate
+            wrapped.invalidate_all = cache.invalidate_all
+            wrapped.invalidate_many = cache.invalidate_many
+            wrapped.prefill = cache.prefill
 
-        wrapped.invalidate = cache.invalidate
         wrapped.invalidate_all = cache.invalidate_all
-        wrapped.invalidate_many = cache.invalidate_many
-        wrapped.prefill = cache.prefill
         wrapped.cache = cache
 
         obj.__dict__[self.orig.__name__] = wrapped
@@ -419,7 +475,9 @@ class CacheListDescriptor(_CacheDescriptorBase):
 
                 try:
                     res = cache.get(tuple(key), callback=invalidate_callback)
-                    if not res.has_succeeded():
+                    if not isinstance(res, ObservableDeferred):
+                        results[arg] = res
+                    elif not res.has_succeeded():
                         res = res.observe()
                         res.addCallback(lambda r, arg: (arg, r), arg)
                         cached_defers[arg] = res
diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py
index 857afee7cb..990216145e 100644
--- a/synapse/util/logcontext.py
+++ b/synapse/util/logcontext.py
@@ -334,12 +334,8 @@ def preserve_fn(f):
         LoggingContext.set_current_context(LoggingContext.sentinel)
         return result
 
-    # XXX: why is this here rather than inside g? surely we want to preserve
-    # the context from the time the function was called, not when it was
-    # wrapped?
-    current = LoggingContext.current_context()
-
     def g(*args, **kwargs):
+        current = LoggingContext.current_context()
         res = f(*args, **kwargs)
         if isinstance(res, defer.Deferred) and not res.called:
             # The function will have reset the context before returning, so
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index a100f151d4..95a6168e16 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -40,3 +40,17 @@ def is_ascii(s):
         return False
     else:
         return True
+
+
+def to_ascii(s):
+    """Converts a string to ascii if it is ascii, otherwise leave it alone.
+
+    If given None then will return None.
+    """
+    if s is None:
+        return None
+
+    try:
+        return s.encode("ascii")
+    except UnicodeEncodeError:
+        return s
diff --git a/synapse/visibility.py b/synapse/visibility.py
index 31659156ae..c4dd9ae2c7 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -56,7 +56,8 @@ def filter_events_for_clients(store, user_tuples, events, event_id_to_state):
         events ([synapse.events.EventBase]): list of events to filter
     """
     forgotten = yield preserve_context_over_deferred(defer.gatherResults([
-        preserve_fn(store.who_forgot_in_room)(
+        defer.maybeDeferred(
+            preserve_fn(store.who_forgot_in_room),
             room_id,
         )
         for room_id in frozenset(e.room_id for e in events)