Merge branch 'develop' of github.com:matrix-org/synapse into erikj/refactor_state_handler

16 files changed, 445 insertions, 109 deletions

diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 7ea8ce9f94..4a81bd2ba9 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -520,7 +520,7 @@ class AuthHandler(BaseHandler):
         """
         logger.info("Logging in user %s on device %s", user_id, device_id)
         access_token = yield self.issue_access_token(user_id, device_id)
-        yield self.auth.check_auth_blocking()
+        yield self.auth.check_auth_blocking(user_id)
 
         # the device *should* have been registered before we got here; however,
         # it's possible we raced against a DELETE operation. The thing we
@@ -734,7 +734,6 @@ class AuthHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def validate_short_term_login_token_and_get_user_id(self, login_token):
-        yield self.auth.check_auth_blocking()
         auth_api = self.hs.get_auth()
         user_id = None
         try:
@@ -743,6 +742,7 @@ class AuthHandler(BaseHandler):
             auth_api.validate_macaroon(macaroon, "login", True, user_id)
         except Exception:
             raise AuthError(403, "Invalid token", errcode=Codes.FORBIDDEN)
+        yield self.auth.check_auth_blocking(user_id)
         defer.returnValue(user_id)
 
     @defer.inlineCallbacks
@@ -828,12 +828,26 @@ class AuthHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def delete_threepid(self, user_id, medium, address):
+        """Attempts to unbind the 3pid on the identity servers and deletes it
+        from the local database.
+
+        Args:
+            user_id (str)
+            medium (str)
+            address (str)
+
+        Returns:
+            Deferred[bool]: Returns True if successfully unbound the 3pid on
+            the identity server, False if identity server doesn't support the
+            unbind API.
+        """
+
         # 'Canonicalise' email addresses as per above
         if medium == 'email':
             address = address.lower()
 
         identity_handler = self.hs.get_handlers().identity_handler
-        yield identity_handler.unbind_threepid(
+        result = yield identity_handler.try_unbind_threepid(
             user_id,
             {
                 'medium': medium,
@@ -841,10 +855,10 @@ class AuthHandler(BaseHandler):
             },
         )
 
-        ret = yield self.store.user_delete_threepid(
+        yield self.store.user_delete_threepid(
             user_id, medium, address,
         )
-        defer.returnValue(ret)
+        defer.returnValue(result)
 
     def _save_session(self, session):
         # TODO: Persistent storage
diff --git a/synapse/handlers/deactivate_account.py b/synapse/handlers/deactivate_account.py
index b3c5a9ee64..b078df4a76 100644
--- a/synapse/handlers/deactivate_account.py
+++ b/synapse/handlers/deactivate_account.py
@@ -51,7 +51,8 @@ class DeactivateAccountHandler(BaseHandler):
             erase_data (bool): whether to GDPR-erase the user's data
 
         Returns:
-            Deferred
+            Deferred[bool]: True if identity server supports removing
+            threepids, otherwise False.
         """
         # FIXME: Theoretically there is a race here wherein user resets
         # password using threepid.
@@ -60,16 +61,22 @@ class DeactivateAccountHandler(BaseHandler):
         # leave the user still active so they can try again.
         # Ideally we would prevent password resets and then do this in the
         # background thread.
+
+        # This will be set to false if the identity server doesn't support
+        # unbinding
+        identity_server_supports_unbinding = True
+
         threepids = yield self.store.user_get_threepids(user_id)
         for threepid in threepids:
             try:
-                yield self._identity_handler.unbind_threepid(
+                result = yield self._identity_handler.try_unbind_threepid(
                     user_id,
                     {
                         'medium': threepid['medium'],
                         'address': threepid['address'],
                     },
                 )
+                identity_server_supports_unbinding &= result
             except Exception:
                 # Do we want this to be a fatal error or should we carry on?
                 logger.exception("Failed to remove threepid from ID server")
@@ -103,6 +110,8 @@ class DeactivateAccountHandler(BaseHandler):
         # parts users from rooms (if it isn't already running)
         self._start_user_parting()
 
+        defer.returnValue(identity_server_supports_unbinding)
+
     def _start_user_parting(self):
         """
         Start the process that goes through the table of users
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 2d44f15da3..9e017116a9 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -23,7 +23,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import FederationDeniedError
 from synapse.types import RoomStreamToken, get_domain_from_id
 from synapse.util import stringutils
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.metrics import measure_func
 from synapse.util.retryutils import NotRetryingDestination
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 14a10c1229..0ebf0fd188 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -49,10 +49,15 @@ from synapse.crypto.event_signing import (
     compute_event_signature,
 )
 from synapse.events.validator import EventValidator
+from synapse.replication.http.federation import (
+    ReplicationCleanRoomRestServlet,
+    ReplicationFederationSendEventsRestServlet,
+)
+from synapse.replication.http.membership import ReplicationUserJoinedLeftRoomRestServlet
 from synapse.state import resolve_events_with_factory
 from synapse.types import UserID, get_domain_from_id
 from synapse.util import logcontext, unwrapFirstError
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room
 from synapse.util.frozenutils import unfreeze
 from synapse.util.logutils import log_function
@@ -91,6 +96,18 @@ class FederationHandler(BaseHandler):
         self.spam_checker = hs.get_spam_checker()
         self.event_creation_handler = hs.get_event_creation_handler()
         self._server_notices_mxid = hs.config.server_notices_mxid
+        self.config = hs.config
+        self.http_client = hs.get_simple_http_client()
+
+        self._send_events_to_master = (
+            ReplicationFederationSendEventsRestServlet.make_client(hs)
+        )
+        self._notify_user_membership_change = (
+            ReplicationUserJoinedLeftRoomRestServlet.make_client(hs)
+        )
+        self._clean_room_for_join_client = (
+            ReplicationCleanRoomRestServlet.make_client(hs)
+        )
 
         # When joining a room we need to queue any events for that room up
         self.room_queues = {}
@@ -1159,7 +1176,7 @@ class FederationHandler(BaseHandler):
         )
 
         context = yield self.state_handler.compute_event_context(event)
-        yield self._persist_events([(event, context)])
+        yield self.persist_events_and_notify([(event, context)])
 
         defer.returnValue(event)
 
@@ -1190,7 +1207,7 @@ class FederationHandler(BaseHandler):
         )
 
         context = yield self.state_handler.compute_event_context(event)
-        yield self._persist_events([(event, context)])
+        yield self.persist_events_and_notify([(event, context)])
 
         defer.returnValue(event)
 
@@ -1433,7 +1450,7 @@ class FederationHandler(BaseHandler):
                     event, context
                 )
 
-            yield self._persist_events(
+            yield self.persist_events_and_notify(
                 [(event, context)],
                 backfilled=backfilled,
             )
@@ -1471,7 +1488,7 @@ class FederationHandler(BaseHandler):
             ], consumeErrors=True,
         ))
 
-        yield self._persist_events(
+        yield self.persist_events_and_notify(
             [
                 (ev_info["event"], context)
                 for ev_info, context in zip(event_infos, contexts)
@@ -1559,7 +1576,7 @@ class FederationHandler(BaseHandler):
                     raise
                 events_to_context[e.event_id].rejected = RejectedReason.AUTH_ERROR
 
-        yield self._persist_events(
+        yield self.persist_events_and_notify(
             [
                 (e, events_to_context[e.event_id])
                 for e in itertools.chain(auth_events, state)
@@ -1570,7 +1587,7 @@ class FederationHandler(BaseHandler):
             event, old_state=state
         )
 
-        yield self._persist_events(
+        yield self.persist_events_and_notify(
             [(event, new_event_context)],
         )
 
@@ -2301,7 +2318,7 @@ class FederationHandler(BaseHandler):
                 for revocation.
         """
         try:
-            response = yield self.hs.get_simple_http_client().get_json(
+            response = yield self.http_client.get_json(
                 url,
                 {"public_key": public_key}
             )
@@ -2314,7 +2331,7 @@ class FederationHandler(BaseHandler):
             raise AuthError(403, "Third party certificate was invalid")
 
     @defer.inlineCallbacks
-    def _persist_events(self, event_and_contexts, backfilled=False):
+    def persist_events_and_notify(self, event_and_contexts, backfilled=False):
         """Persists events and tells the notifier/pushers about them, if
         necessary.
 
@@ -2326,14 +2343,21 @@ class FederationHandler(BaseHandler):
         Returns:
             Deferred
         """
-        max_stream_id = yield self.store.persist_events(
-            event_and_contexts,
-            backfilled=backfilled,
-        )
+        if self.config.worker_app:
+            yield self._send_events_to_master(
+                store=self.store,
+                event_and_contexts=event_and_contexts,
+                backfilled=backfilled
+            )
+        else:
+            max_stream_id = yield self.store.persist_events(
+                event_and_contexts,
+                backfilled=backfilled,
+            )
 
-        if not backfilled:  # Never notify for backfilled events
-            for event, _ in event_and_contexts:
-                self._notify_persisted_event(event, max_stream_id)
+            if not backfilled:  # Never notify for backfilled events
+                for event, _ in event_and_contexts:
+                    self._notify_persisted_event(event, max_stream_id)
 
     def _notify_persisted_event(self, event, max_stream_id):
         """Checks to see if notifier/pushers should be notified about the
@@ -2366,15 +2390,30 @@ class FederationHandler(BaseHandler):
             extra_users=extra_users
         )
 
-        logcontext.run_in_background(
-            self.pusher_pool.on_new_notifications,
+        self.pusher_pool.on_new_notifications(
             event_stream_id, max_stream_id,
         )
 
     def _clean_room_for_join(self, room_id):
-        return self.store.clean_room_for_join(room_id)
+        """Called to clean up any data in DB for a given room, ready for the
+        server to join the room.
+
+        Args:
+            room_id (str)
+        """
+        if self.config.worker_app:
+            return self._clean_room_for_join_client(room_id)
+        else:
+            return self.store.clean_room_for_join(room_id)
 
     def user_joined_room(self, user, room_id):
         """Called when a new user has joined the room
         """
-        return user_joined_room(self.distributor, user, room_id)
+        if self.config.worker_app:
+            return self._notify_user_membership_change(
+                room_id=room_id,
+                user_id=user.to_string(),
+                change="joined",
+            )
+        else:
+            return user_joined_room(self.distributor, user, room_id)
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 1d36d967c3..5feb3f22a6 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -137,15 +137,19 @@ class IdentityHandler(BaseHandler):
         defer.returnValue(data)
 
     @defer.inlineCallbacks
-    def unbind_threepid(self, mxid, threepid):
-        """
-        Removes a binding from an identity server
+    def try_unbind_threepid(self, mxid, threepid):
+        """Removes a binding from an identity server
+
         Args:
             mxid (str): Matrix user ID of binding to be removed
             threepid (dict): Dict with medium & address of binding to be removed
 
+        Raises:
+            SynapseError: If we failed to contact the identity server
+
         Returns:
-            Deferred[bool]: True on success, otherwise False
+            Deferred[bool]: True on success, otherwise False if the identity
+            server doesn't support unbinding
         """
         logger.debug("unbinding threepid %r from %s", threepid, mxid)
         if not self.trusted_id_servers:
@@ -175,11 +179,21 @@ class IdentityHandler(BaseHandler):
             content=content,
             destination_is=id_server,
         )
-        yield self.http_client.post_json_get_json(
-            url,
-            content,
-            headers,
-        )
+        try:
+            yield self.http_client.post_json_get_json(
+                url,
+                content,
+                headers,
+            )
+        except HttpResponseException as e:
+            if e.code in (400, 404, 501,):
+                # The remote server probably doesn't support unbinding (yet)
+                logger.warn("Received %d response while unbinding threepid", e.code)
+                defer.returnValue(False)
+            else:
+                logger.error("Failed to unbind threepid on identity server: %s", e)
+                raise SynapseError(502, "Failed to contact identity server")
+
         defer.returnValue(True)
 
     @defer.inlineCallbacks
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 40e7580a61..e009395207 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -25,7 +25,7 @@ from synapse.handlers.presence import format_user_presence_state
 from synapse.streams.config import PaginationConfig
 from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.snapshot_cache import SnapshotCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.visibility import filter_events_for_client
@@ -372,6 +372,10 @@ class InitialSyncHandler(BaseHandler):
 
         @defer.inlineCallbacks
         def get_presence():
+            # If presence is disabled, return an empty list
+            if not self.hs.config.use_presence:
+                defer.returnValue([])
+
             states = yield presence_handler.get_states(
                 [m.user_id for m in room_members],
                 as_event=True,
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index bcb093ba3e..e484061cc0 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -25,17 +25,24 @@ from twisted.internet import defer
 from twisted.internet.defer import succeed
 
 from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
-from synapse.api.errors import AuthError, Codes, ConsentNotGivenError, SynapseError
+from synapse.api.errors import (
+    AuthError,
+    Codes,
+    ConsentNotGivenError,
+    NotFoundError,
+    SynapseError,
+)
 from synapse.api.urls import ConsentURIBuilder
 from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
 from synapse.types import RoomAlias, UserID
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import measure_func
+from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
 
@@ -82,28 +89,85 @@ class MessageHandler(object):
         defer.returnValue(data)
 
     @defer.inlineCallbacks
-    def get_state_events(self, user_id, room_id, is_guest=False):
+    def get_state_events(
+        self, user_id, room_id, types=None, filtered_types=None,
+        at_token=None, is_guest=False,
+    ):
         """Retrieve all state events for a given room. If the user is
         joined to the room then return the current state. If the user has
-        left the room return the state events from when they left.
+        left the room return the state events from when they left. If an explicit
+        'at' parameter is passed, return the state events as of that event, if
+        visible.
 
         Args:
             user_id(str): The user requesting state events.
             room_id(str): The room ID to get all state events from.
+            types(list[(str, str|None)]|None): List of (type, state_key) tuples
+                which are used to filter the state fetched. If `state_key` is None,
+                all events are returned of the given type.
+                May be None, which matches any key.
+            filtered_types(list[str]|None): Only apply filtering via `types` to this
+                list of event types.  Other types of events are returned unfiltered.
+                If None, `types` filtering is applied to all events.
+            at_token(StreamToken|None): the stream token of the at which we are requesting
+                the stats. If the user is not allowed to view the state as of that
+                stream token, we raise a 403 SynapseError. If None, returns the current
+                state based on the current_state_events table.
+            is_guest(bool): whether this user is a guest
         Returns:
             A list of dicts representing state events. [{}, {}, {}]
+        Raises:
+            NotFoundError (404) if the at token does not yield an event
+
+            AuthError (403) if the user doesn't have permission to view
+            members of this room.
         """
-        membership, membership_event_id = yield self.auth.check_in_room_or_world_readable(
-            room_id, user_id
-        )
+        if at_token:
+            # FIXME this claims to get the state at a stream position, but
+            # get_recent_events_for_room operates by topo ordering. This therefore
+            # does not reliably give you the state at the given stream position.
+            # (https://github.com/matrix-org/synapse/issues/3305)
+            last_events, _ = yield self.store.get_recent_events_for_room(
+                room_id, end_token=at_token.room_key, limit=1,
+            )
 
-        if membership == Membership.JOIN:
-            room_state = yield self.state.get_current_state(room_id)
-        elif membership == Membership.LEAVE:
-            room_state = yield self.store.get_state_for_events(
-                [membership_event_id], None
+            if not last_events:
+                raise NotFoundError("Can't find event for token %s" % (at_token, ))
+
+            visible_events = yield filter_events_for_client(
+                self.store, user_id, last_events,
             )
-            room_state = room_state[membership_event_id]
+
+            event = last_events[0]
+            if visible_events:
+                room_state = yield self.store.get_state_for_events(
+                    [event.event_id], types, filtered_types=filtered_types,
+                )
+                room_state = room_state[event.event_id]
+            else:
+                raise AuthError(
+                    403,
+                    "User %s not allowed to view events in room %s at token %s" % (
+                        user_id, room_id, at_token,
+                    )
+                )
+        else:
+            membership, membership_event_id = (
+                yield self.auth.check_in_room_or_world_readable(
+                    room_id, user_id,
+                )
+            )
+
+            if membership == Membership.JOIN:
+                state_ids = yield self.store.get_filtered_current_state_ids(
+                    room_id, types, filtered_types=filtered_types,
+                )
+                room_state = yield self.store.get_events(state_ids.values())
+            elif membership == Membership.LEAVE:
+                room_state = yield self.store.get_state_for_events(
+                    [membership_event_id], types, filtered_types=filtered_types,
+                )
+                room_state = room_state[membership_event_id]
 
         now = self.clock.time_msec()
         defer.returnValue(
@@ -212,10 +276,14 @@ class EventCreationHandler(object):
                 where *hashes* is a map from algorithm to hash.
 
                 If None, they will be requested from the database.
-
+        Raises:
+            ResourceLimitError if server is blocked to some resource being
+            exceeded
         Returns:
             Tuple of created event (FrozenEvent), Context
         """
+        yield self.auth.check_auth_blocking(requester.user.to_string())
+
         builder = self.event_builder_factory.new(event_dict)
 
         self.validator.validate_new(builder)
@@ -710,11 +778,8 @@ class EventCreationHandler(object):
             event, context=context
         )
 
-        # this intentionally does not yield: we don't care about the result
-        # and don't need to wait for it.
-        run_in_background(
-            self.pusher_pool.on_new_notifications,
-            event_stream_id, max_stream_id
+        self.pusher_pool.on_new_notifications(
+            event_stream_id, max_stream_id,
         )
 
         def _notify():
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index b2849783ed..5170d093e3 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -18,11 +18,11 @@ import logging
 from twisted.internet import defer
 from twisted.python.failure import Failure
 
-from synapse.api.constants import Membership
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import SynapseError
 from synapse.events.utils import serialize_event
 from synapse.types import RoomStreamToken
-from synapse.util.async import ReadWriteLock
+from synapse.util.async_helpers import ReadWriteLock
 from synapse.util.logcontext import run_in_background
 from synapse.util.stringutils import random_string
 from synapse.visibility import filter_events_for_client
@@ -251,6 +251,33 @@ class PaginationHandler(object):
             is_peeking=(member_event_id is None),
         )
 
+        state = None
+        if event_filter and event_filter.lazy_load_members():
+            # TODO: remove redundant members
+
+            types = [
+                (EventTypes.Member, state_key)
+                for state_key in set(
+                    event.sender  # FIXME: we also care about invite targets etc.
+                    for event in events
+                )
+            ]
+
+            state_ids = yield self.store.get_state_ids_for_event(
+                events[0].event_id, types=types,
+            )
+
+            if state_ids:
+                state = yield self.store.get_events(list(state_ids.values()))
+
+            if state:
+                state = yield filter_events_for_client(
+                    self.store,
+                    user_id,
+                    state.values(),
+                    is_peeking=(member_event_id is None),
+                )
+
         time_now = self.clock.time_msec()
 
         chunk = {
@@ -262,4 +289,10 @@ class PaginationHandler(object):
             "end": next_token.to_string(),
         }
 
+        if state:
+            chunk["state"] = [
+                serialize_event(e, time_now, as_client_event)
+                for e in state
+            ]
+
         defer.returnValue(chunk)
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 3732830194..ba3856674d 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -36,7 +36,7 @@ from synapse.api.errors import SynapseError
 from synapse.metrics import LaterGauge
 from synapse.storage.presence import UserPresenceState
 from synapse.types import UserID, get_domain_from_id
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.logcontext import run_in_background
 from synapse.util.logutils import log_function
@@ -95,6 +95,7 @@ class PresenceHandler(object):
         Args:
             hs (synapse.server.HomeServer):
         """
+        self.hs = hs
         self.is_mine = hs.is_mine
         self.is_mine_id = hs.is_mine_id
         self.clock = hs.get_clock()
@@ -230,6 +231,10 @@ class PresenceHandler(object):
         earlier than they should when synapse is restarted. This affect of this
         is some spurious presence changes that will self-correct.
         """
+        # If the DB pool has already terminated, don't try updating
+        if not self.hs.get_db_pool().running:
+            return
+
         logger.info(
             "Performing _on_shutdown. Persisting %d unpersisted changes",
             len(self.user_to_current_state)
@@ -390,6 +395,10 @@ class PresenceHandler(object):
         """We've seen the user do something that indicates they're interacting
         with the app.
         """
+        # If presence is disabled, no-op
+        if not self.hs.config.use_presence:
+            return
+
         user_id = user.to_string()
 
         bump_active_time_counter.inc()
@@ -419,6 +428,11 @@ class PresenceHandler(object):
                 Useful for streams that are not associated with an actual
                 client that is being used by a user.
         """
+        # Override if it should affect the user's presence, if presence is
+        # disabled.
+        if not self.hs.config.use_presence:
+            affect_presence = False
+
         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
@@ -464,13 +478,16 @@ class PresenceHandler(object):
         Returns:
             set(str): A set of user_id strings.
         """
-        syncing_user_ids = {
-            user_id for user_id, count in self.user_to_num_current_syncs.items()
-            if count
-        }
-        for user_ids in self.external_process_to_current_syncs.values():
-            syncing_user_ids.update(user_ids)
-        return syncing_user_ids
+        if self.hs.config.use_presence:
+            syncing_user_ids = {
+                user_id for user_id, count in self.user_to_num_current_syncs.items()
+                if count
+            }
+            for user_ids in self.external_process_to_current_syncs.values():
+                syncing_user_ids.update(user_ids)
+            return syncing_user_ids
+        else:
+            return set()
 
     @defer.inlineCallbacks
     def update_external_syncs_row(self, process_id, user_id, is_syncing, sync_time_msec):
diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
index 995460f82a..32108568c6 100644
--- a/synapse/handlers/read_marker.py
+++ b/synapse/handlers/read_marker.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 
 from ._base import BaseHandler
 
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index cb905a3903..a6f3181f09 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -18,7 +18,6 @@ from twisted.internet import defer
 
 from synapse.types import get_domain_from_id
 from synapse.util import logcontext
-from synapse.util.logcontext import PreserveLoggingContext
 
 from ._base import BaseHandler
 
@@ -116,16 +115,15 @@ class ReceiptsHandler(BaseHandler):
 
         affected_room_ids = list(set([r["room_id"] for r in receipts]))
 
-        with PreserveLoggingContext():
-            self.notifier.on_new_event(
-                "receipt_key", max_batch_id, rooms=affected_room_ids
-            )
-            # Note that the min here shouldn't be relied upon to be accurate.
-            self.hs.get_pusherpool().on_new_receipts(
-                min_batch_id, max_batch_id, affected_room_ids
-            )
+        self.notifier.on_new_event(
+            "receipt_key", max_batch_id, rooms=affected_room_ids
+        )
+        # Note that the min here shouldn't be relied upon to be accurate.
+        self.hs.get_pusherpool().on_new_receipts(
+            min_batch_id, max_batch_id, affected_room_ids,
+        )
 
-            defer.returnValue(True)
+        defer.returnValue(True)
 
     @logcontext.preserve_fn   # caller should not yield on this
     @defer.inlineCallbacks
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 0e16bbe0ee..f03ee1476b 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -28,7 +28,7 @@ from synapse.api.errors import (
 )
 from synapse.http.client import CaptchaServerHttpClient
 from synapse.types import RoomAlias, RoomID, UserID, create_requester
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.threepids import check_3pid_allowed
 
 from ._base import BaseHandler
@@ -144,7 +144,8 @@ class RegistrationHandler(BaseHandler):
         Raises:
             RegistrationError if there was a problem registering.
         """
-        yield self._check_mau_limits()
+
+        yield self.auth.check_auth_blocking()
         password_hash = None
         if password:
             password_hash = yield self.auth_handler().hash(password)
@@ -289,7 +290,7 @@ class RegistrationHandler(BaseHandler):
                 400,
                 "User ID can only contain characters a-z, 0-9, or '=_-./'",
             )
-        yield self._check_mau_limits()
+        yield self.auth.check_auth_blocking()
         user = UserID(localpart, self.hs.hostname)
         user_id = user.to_string()
 
@@ -439,7 +440,7 @@ class RegistrationHandler(BaseHandler):
         """
         if localpart is None:
             raise SynapseError(400, "Request must include user id")
-        yield self._check_mau_limits()
+        yield self.auth.check_auth_blocking()
         need_register = True
 
         try:
@@ -533,14 +534,3 @@ class RegistrationHandler(BaseHandler):
             remote_room_hosts=remote_room_hosts,
             action="join",
         )
-
-    @defer.inlineCallbacks
-    def _check_mau_limits(self):
-        """
-        Do not accept registrations if monthly active user limits exceeded
-         and limiting is enabled
-        """
-        try:
-            yield self.auth.check_auth_blocking()
-        except AuthError as e:
-            raise RegistrationError(e.code, str(e), e.errcode)
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 6a17c42238..c3f820b975 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -98,9 +98,13 @@ class RoomCreationHandler(BaseHandler):
         Raises:
             SynapseError if the room ID couldn't be stored, or something went
             horribly wrong.
+            ResourceLimitError if server is blocked to some resource being
+            exceeded
         """
         user_id = requester.user.to_string()
 
+        self.auth.check_auth_blocking(user_id)
+
         if not self.spam_checker.user_may_create_room(user_id):
             raise SynapseError(403, "You are not permitted to create rooms")
 
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index 828229f5c3..37e41afd61 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -26,7 +26,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, JoinRules
 from synapse.types import ThirdPartyInstanceID
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.caches.response_cache import ResponseCache
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index b8e1af580b..f643619047 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -30,7 +30,7 @@ import synapse.types
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.types import RoomID, UserID
-from synapse.util.async import Linearizer
+from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room, user_left_room
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index dff1f67dcb..648debc8aa 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -25,7 +25,7 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, Membership
 from synapse.push.clientformat import format_push_rules_for_user
 from synapse.types import RoomStreamToken
-from synapse.util.async import concurrently_execute
+from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.response_cache import ResponseCache
@@ -75,6 +75,7 @@ class JoinedSyncResult(collections.namedtuple("JoinedSyncResult", [
     "ephemeral",
     "account_data",
     "unread_notifications",
+    "summary",
 ])):
     __slots__ = []
 
@@ -184,6 +185,7 @@ class SyncResult(collections.namedtuple("SyncResult", [
 class SyncHandler(object):
 
     def __init__(self, hs):
+        self.hs_config = hs.config
         self.store = hs.get_datastore()
         self.notifier = hs.get_notifier()
         self.presence_handler = hs.get_presence_handler()
@@ -191,6 +193,7 @@ class SyncHandler(object):
         self.clock = hs.get_clock()
         self.response_cache = ResponseCache(hs, "sync")
         self.state = hs.get_state_handler()
+        self.auth = hs.get_auth()
 
         # ExpiringCache((User, Device)) -> LruCache(state_key => event_id)
         self.lazy_loaded_members_cache = ExpiringCache(
@@ -198,19 +201,27 @@ class SyncHandler(object):
             max_len=0, expiry_ms=LAZY_LOADED_MEMBERS_CACHE_MAX_AGE,
         )
 
+    @defer.inlineCallbacks
     def wait_for_sync_for_user(self, sync_config, since_token=None, timeout=0,
                                full_state=False):
         """Get the sync for a client if we have new data for it now. Otherwise
         wait for new data to arrive on the server. If the timeout expires, then
         return an empty sync result.
         Returns:
-            A Deferred SyncResult.
+            Deferred[SyncResult]
         """
-        return self.response_cache.wrap(
+        # If the user is not part of the mau group, then check that limits have
+        # not been exceeded (if not part of the group by this point, almost certain
+        # auth_blocking will occur)
+        user_id = sync_config.user.to_string()
+        yield self.auth.check_auth_blocking(user_id)
+
+        res = yield self.response_cache.wrap(
             sync_config.request_key,
             self._wait_for_sync_for_user,
             sync_config, since_token, timeout, full_state,
         )
+        defer.returnValue(res)
 
     @defer.inlineCallbacks
     def _wait_for_sync_for_user(self, sync_config, since_token, timeout,
@@ -495,9 +506,141 @@ class SyncHandler(object):
         defer.returnValue(state)
 
     @defer.inlineCallbacks
+    def compute_summary(self, room_id, sync_config, batch, state, now_token):
+        """ Works out a room summary block for this room, summarising the number
+        of joined members in the room, and providing the 'hero' members if the
+        room has no name so clients can consistently name rooms.  Also adds
+        state events to 'state' if needed to describe the heroes.
+
+        Args:
+            room_id(str):
+            sync_config(synapse.handlers.sync.SyncConfig):
+            batch(synapse.handlers.sync.TimelineBatch): The timeline batch for
+                the room that will be sent to the user.
+            state(dict): dict of (type, state_key) -> Event as returned by
+                compute_state_delta
+            now_token(str): Token of the end of the current batch.
+
+        Returns:
+             A deferred dict describing the room summary
+        """
+
+        # FIXME: this promulgates https://github.com/matrix-org/synapse/issues/3305
+        last_events, _ = yield self.store.get_recent_event_ids_for_room(
+            room_id, end_token=now_token.room_key, limit=1,
+        )
+
+        if not last_events:
+            defer.returnValue(None)
+            return
+
+        last_event = last_events[-1]
+        state_ids = yield self.store.get_state_ids_for_event(
+            last_event.event_id, [
+                (EventTypes.Member, None),
+                (EventTypes.Name, ''),
+                (EventTypes.CanonicalAlias, ''),
+            ]
+        )
+
+        member_ids = {
+            state_key: event_id
+            for (t, state_key), event_id in state_ids.iteritems()
+            if t == EventTypes.Member
+        }
+        name_id = state_ids.get((EventTypes.Name, ''))
+        canonical_alias_id = state_ids.get((EventTypes.CanonicalAlias, ''))
+
+        summary = {}
+
+        # FIXME: it feels very heavy to load up every single membership event
+        # just to calculate the counts.
+        member_events = yield self.store.get_events(member_ids.values())
+
+        joined_user_ids = []
+        invited_user_ids = []
+
+        for ev in member_events.values():
+            if ev.content.get("membership") == Membership.JOIN:
+                joined_user_ids.append(ev.state_key)
+            elif ev.content.get("membership") == Membership.INVITE:
+                invited_user_ids.append(ev.state_key)
+
+        # TODO: only send these when they change.
+        summary["m.joined_member_count"] = len(joined_user_ids)
+        summary["m.invited_member_count"] = len(invited_user_ids)
+
+        if name_id or canonical_alias_id:
+            defer.returnValue(summary)
+
+        # FIXME: order by stream ordering, not alphabetic
+
+        me = sync_config.user.to_string()
+        if (joined_user_ids or invited_user_ids):
+            summary['m.heroes'] = sorted(
+                [
+                    user_id
+                    for user_id in (joined_user_ids + invited_user_ids)
+                    if user_id != me
+                ]
+            )[0:5]
+        else:
+            summary['m.heroes'] = sorted(
+                [user_id for user_id in member_ids.keys() if user_id != me]
+            )[0:5]
+
+        if not sync_config.filter_collection.lazy_load_members():
+            defer.returnValue(summary)
+
+        # ensure we send membership events for heroes if needed
+        cache_key = (sync_config.user.to_string(), sync_config.device_id)
+        cache = self.get_lazy_loaded_members_cache(cache_key)
+
+        # track which members the client should already know about via LL:
+        # Ones which are already in state...
+        existing_members = set(
+            user_id for (typ, user_id) in state.keys()
+            if typ == EventTypes.Member
+        )
+
+        # ...or ones which are in the timeline...
+        for ev in batch.events:
+            if ev.type == EventTypes.Member:
+                existing_members.add(ev.state_key)
+
+        # ...and then ensure any missing ones get included in state.
+        missing_hero_event_ids = [
+            member_ids[hero_id]
+            for hero_id in summary['m.heroes']
+            if (
+                cache.get(hero_id) != member_ids[hero_id] and
+                hero_id not in existing_members
+            )
+        ]
+
+        missing_hero_state = yield self.store.get_events(missing_hero_event_ids)
+        missing_hero_state = missing_hero_state.values()
+
+        for s in missing_hero_state:
+            cache.set(s.state_key, s.event_id)
+            state[(EventTypes.Member, s.state_key)] = s
+
+        defer.returnValue(summary)
+
+    def get_lazy_loaded_members_cache(self, cache_key):
+        cache = self.lazy_loaded_members_cache.get(cache_key)
+        if cache is None:
+            logger.debug("creating LruCache for %r", cache_key)
+            cache = LruCache(LAZY_LOADED_MEMBERS_CACHE_MAX_SIZE)
+            self.lazy_loaded_members_cache[cache_key] = cache
+        else:
+            logger.debug("found LruCache for %r", cache_key)
+        return cache
+
+    @defer.inlineCallbacks
     def compute_state_delta(self, room_id, batch, sync_config, since_token, now_token,
                             full_state):
-        """ Works out the differnce in state between the start of the timeline
+        """ Works out the difference in state between the start of the timeline
         and the previous sync.
 
         Args:
@@ -511,7 +654,7 @@ class SyncHandler(object):
             full_state(bool): Whether to force returning the full state.
 
         Returns:
-             A deferred new event dictionary
+             A deferred dict of (type, state_key) -> Event
         """
         # TODO(mjark) Check if the state events were received by the server
         # after the previous sync, since we need to include those state
@@ -609,13 +752,7 @@ class SyncHandler(object):
 
             if lazy_load_members and not include_redundant_members:
                 cache_key = (sync_config.user.to_string(), sync_config.device_id)
-                cache = self.lazy_loaded_members_cache.get(cache_key)
-                if cache is None:
-                    logger.debug("creating LruCache for %r", cache_key)
-                    cache = LruCache(LAZY_LOADED_MEMBERS_CACHE_MAX_SIZE)
-                    self.lazy_loaded_members_cache[cache_key] = cache
-                else:
-                    logger.debug("found LruCache for %r", cache_key)
+                cache = self.get_lazy_loaded_members_cache(cache_key)
 
                 # if it's a new sync sequence, then assume the client has had
                 # amnesia and doesn't want any recent lazy-loaded members
@@ -724,7 +861,7 @@ class SyncHandler(object):
             since_token is None and
             sync_config.filter_collection.blocks_all_presence()
         )
-        if not block_all_presence_data:
+        if self.hs_config.use_presence and not block_all_presence_data:
             yield self._generate_sync_entry_for_presence(
                 sync_result_builder, newly_joined_rooms, newly_joined_users
             )
@@ -1416,7 +1553,6 @@ class SyncHandler(object):
             if events == [] and tags is None:
                 return
 
-        since_token = sync_result_builder.since_token
         now_token = sync_result_builder.now_token
         sync_config = sync_result_builder.sync_config
 
@@ -1459,6 +1595,18 @@ class SyncHandler(object):
             full_state=full_state
         )
 
+        summary = {}
+        if (
+            sync_config.filter_collection.lazy_load_members() and
+            (
+                any(ev.type == EventTypes.Member for ev in batch.events) or
+                since_token is None
+            )
+        ):
+            summary = yield self.compute_summary(
+                room_id, sync_config, batch, state, now_token
+            )
+
         if room_builder.rtype == "joined":
             unread_notifications = {}
             room_sync = JoinedSyncResult(
@@ -1468,6 +1616,7 @@ class SyncHandler(object):
                 ephemeral=ephemeral,
                 account_data=account_data_events,
                 unread_notifications=unread_notifications,
+                summary=summary,
             )
 
             if room_sync or always_include: