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-rw-r--r--synapse/app/admin_cmd.py5
-rw-r--r--synapse/app/appservice.py5
-rw-r--r--synapse/app/client_reader.py5
-rw-r--r--synapse/app/event_creator.py5
-rw-r--r--synapse/app/federation_reader.py5
-rw-r--r--synapse/app/federation_sender.py5
-rw-r--r--synapse/app/frontend_proxy.py5
-rw-r--r--synapse/app/homeserver.py13
-rw-r--r--synapse/app/media_repository.py5
-rw-r--r--synapse/app/pusher.py5
-rw-r--r--synapse/app/synchrotron.py5
-rw-r--r--synapse/app/user_dir.py5
-rw-r--r--synapse/config/emailconfig.py3
-rw-r--r--synapse/config/ratelimiting.py3
-rw-r--r--synapse/config/saml2_config.py186
-rw-r--r--synapse/config/server.py15
-rw-r--r--synapse/event_auth.py8
-rw-r--r--synapse/federation/federation_client.py88
-rw-r--r--synapse/federation/federation_server.py15
-rw-r--r--synapse/federation/transport/client.py33
-rw-r--r--synapse/federation/transport/server.py32
-rw-r--r--synapse/groups/groups_server.py5
-rw-r--r--synapse/handlers/account_data.py15
-rw-r--r--synapse/handlers/account_validity.py86
-rw-r--r--synapse/handlers/e2e_keys.py35
-rw-r--r--synapse/handlers/federation.py209
-rw-r--r--synapse/handlers/initial_sync.py115
-rw-r--r--synapse/handlers/message.py5
-rw-r--r--synapse/handlers/pagination.py27
-rw-r--r--synapse/handlers/profile.py6
-rw-r--r--synapse/handlers/room.py12
-rw-r--r--synapse/handlers/saml_handler.py198
-rw-r--r--synapse/handlers/search.py34
-rw-r--r--synapse/handlers/typing.py3
-rw-r--r--synapse/logging/_terse_json.py2
-rw-r--r--synapse/logging/context.py14
-rw-r--r--synapse/server.py12
-rw-r--r--synapse/state/__init__.py3
-rw-r--r--synapse/storage/data_stores/main/client_ips.py8
-rw-r--r--synapse/storage/data_stores/main/end_to_end_keys.py217
-rw-r--r--synapse/storage/data_stores/main/events_worker.py97
-rw-r--r--synapse/storage/data_stores/main/schema/delta/56/nuke_empty_communities_from_db.sql29
-rw-r--r--synapse/storage/data_stores/main/schema/full_schemas/README.md13
-rw-r--r--synapse/storage/data_stores/main/schema/full_schemas/README.txt19
-rw-r--r--synapse/storage/data_stores/main/search.py19
-rw-r--r--synapse/storage/data_stores/main/state.py18
-rw-r--r--synapse/streams/events.py4
-rw-r--r--synapse/util/caches/descriptors.py2
-rw-r--r--synapse/util/caches/snapshot_cache.py94
49 files changed, 1114 insertions, 638 deletions
diff --git a/synapse/app/admin_cmd.py b/synapse/app/admin_cmd.py
index 04751a6a5e..51a909419f 100644
--- a/synapse/app/admin_cmd.py
+++ b/synapse/app/admin_cmd.py
@@ -45,7 +45,6 @@ from synapse.replication.slave.storage.registration import SlavedRegistrationSto
 from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
-from synapse.storage.engines import create_engine
 from synapse.util.logcontext import LoggingContext
 from synapse.util.versionstring import get_version_string
 
@@ -229,14 +228,10 @@ def start(config_options):
 
     synapse.events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = AdminCmdServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index 02b900f382..e82e0f11e3 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -34,7 +34,6 @@ from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -143,8 +142,6 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     if config.notify_appservices:
         sys.stderr.write(
             "\nThe appservices must be disabled in the main synapse process"
@@ -159,10 +156,8 @@ def start(config_options):
 
     ps = AppserviceServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ps, config, use_worker_options=True)
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index dadb487d5f..3edfe19567 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -62,7 +62,6 @@ from synapse.rest.client.v2_alpha.keys import KeyChangesServlet, KeyQueryServlet
 from synapse.rest.client.v2_alpha.register import RegisterRestServlet
 from synapse.rest.client.versions import VersionsRestServlet
 from synapse.server import HomeServer
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -181,14 +180,10 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = ClientReaderServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/event_creator.py b/synapse/app/event_creator.py
index d110599a35..d0ddbe38fc 100644
--- a/synapse/app/event_creator.py
+++ b/synapse/app/event_creator.py
@@ -57,7 +57,6 @@ from synapse.rest.client.v1.room import (
 )
 from synapse.server import HomeServer
 from synapse.storage.data_stores.main.user_directory import UserDirectoryStore
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -180,14 +179,10 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = EventCreatorServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index 418c086254..311523e0ed 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -46,7 +46,6 @@ from synapse.replication.slave.storage.transactions import SlavedTransactionStor
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.key.v2 import KeyApiV2Resource
 from synapse.server import HomeServer
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -162,14 +161,10 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = FederationReaderServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index f24920a7d6..83c436229c 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -41,7 +41,6 @@ from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.replication.tcp.streams._base import ReceiptsStream
 from synapse.server import HomeServer
 from synapse.storage.database import Database
-from synapse.storage.engines import create_engine
 from synapse.types import ReadReceipt
 from synapse.util.async_helpers import Linearizer
 from synapse.util.httpresourcetree import create_resource_tree
@@ -174,8 +173,6 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     if config.send_federation:
         sys.stderr.write(
             "\nThe send_federation must be disabled in the main synapse process"
@@ -190,10 +187,8 @@ def start(config_options):
 
     ss = FederationSenderServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index e647459d0e..30e435eead 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -39,7 +39,6 @@ from synapse.replication.slave.storage.registration import SlavedRegistrationSto
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.client.v2_alpha._base import client_patterns
 from synapse.server import HomeServer
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -234,14 +233,10 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = FrontendProxyServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index df65d0a989..b8661457e2 100644
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -69,7 +69,7 @@ from synapse.rest.media.v0.content_repository import ContentRepoResource
 from synapse.rest.well_known import WellKnownResource
 from synapse.server import HomeServer
 from synapse.storage import DataStore
-from synapse.storage.engines import IncorrectDatabaseSetup, create_engine
+from synapse.storage.engines import IncorrectDatabaseSetup
 from synapse.storage.prepare_database import UpgradeDatabaseException
 from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.httpresourcetree import create_resource_tree
@@ -328,15 +328,10 @@ def setup(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-    config.database_config["args"]["cp_openfun"] = database_engine.on_new_connection
-
     hs = SynapseHomeServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     synapse.config.logger.setup_logging(hs, config, use_worker_options=False)
@@ -519,8 +514,10 @@ def phone_stats_home(hs, stats, stats_process=_stats_process):
     # Database version
     #
 
-    stats["database_engine"] = hs.database_engine.module.__name__
-    stats["database_server_version"] = hs.database_engine.server_version
+    # This only reports info about the *main* database.
+    stats["database_engine"] = hs.get_datastore().db.engine.module.__name__
+    stats["database_server_version"] = hs.get_datastore().db.engine.server_version
+
     logger.info("Reporting stats to %s: %s" % (hs.config.report_stats_endpoint, stats))
     try:
         yield hs.get_proxied_http_client().put_json(
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index 2c6dd3ef02..4c80f257e2 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -40,7 +40,6 @@ from synapse.rest.admin import register_servlets_for_media_repo
 from synapse.rest.media.v0.content_repository import ContentRepoResource
 from synapse.server import HomeServer
 from synapse.storage.data_stores.main.media_repository import MediaRepositoryStore
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -157,14 +156,10 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = MediaRepositoryServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index dd52a9fc2d..09e639040a 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -37,7 +37,6 @@ from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
 from synapse.storage import DataStore
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
@@ -203,14 +202,10 @@ def start(config_options):
     # Force the pushers to start since they will be disabled in the main config
     config.start_pushers = True
 
-    database_engine = create_engine(config.database_config)
-
     ps = PusherServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ps, config, use_worker_options=True)
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 288ee64b42..dd2132e608 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -55,7 +55,6 @@ from synapse.rest.client.v1.room import RoomInitialSyncRestServlet
 from synapse.rest.client.v2_alpha import sync
 from synapse.server import HomeServer
 from synapse.storage.data_stores.main.presence import UserPresenceState
-from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
 from synapse.util.stringutils import random_string
@@ -437,14 +436,10 @@ def start(config_options):
 
     synapse.events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     ss = SynchrotronServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
         application_service_handler=SynchrotronApplicationService(),
     )
 
diff --git a/synapse/app/user_dir.py b/synapse/app/user_dir.py
index c01fb34a9b..1257098f92 100644
--- a/synapse/app/user_dir.py
+++ b/synapse/app/user_dir.py
@@ -44,7 +44,6 @@ from synapse.rest.client.v2_alpha import user_directory
 from synapse.server import HomeServer
 from synapse.storage.data_stores.main.user_directory import UserDirectoryStore
 from synapse.storage.database import Database
-from synapse.storage.engines import create_engine
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.manhole import manhole
@@ -200,8 +199,6 @@ def start(config_options):
 
     events.USE_FROZEN_DICTS = config.use_frozen_dicts
 
-    database_engine = create_engine(config.database_config)
-
     if config.update_user_directory:
         sys.stderr.write(
             "\nThe update_user_directory must be disabled in the main synapse process"
@@ -216,10 +213,8 @@ def start(config_options):
 
     ss = UserDirectoryServer(
         config.server_name,
-        db_config=config.database_config,
         config=config,
         version_string="Synapse/" + get_version_string(synapse),
-        database_engine=database_engine,
     )
 
     setup_logging(ss, config, use_worker_options=True)
diff --git a/synapse/config/emailconfig.py b/synapse/config/emailconfig.py
index 18f42a87f9..35756bed87 100644
--- a/synapse/config/emailconfig.py
+++ b/synapse/config/emailconfig.py
@@ -21,6 +21,7 @@ from __future__ import print_function
 import email.utils
 import os
 from enum import Enum
+from typing import Optional
 
 import pkg_resources
 
@@ -101,7 +102,7 @@ class EmailConfig(Config):
                 # both in RegistrationConfig and here. We should factor this bit out
                 self.account_threepid_delegate_email = self.trusted_third_party_id_servers[
                     0
-                ]
+                ]  # type: Optional[str]
                 self.using_identity_server_from_trusted_list = True
             else:
                 raise ConfigError(
diff --git a/synapse/config/ratelimiting.py b/synapse/config/ratelimiting.py
index 947f653e03..4a3bfc4354 100644
--- a/synapse/config/ratelimiting.py
+++ b/synapse/config/ratelimiting.py
@@ -83,10 +83,9 @@ class RatelimitConfig(Config):
         )
 
         rc_admin_redaction = config.get("rc_admin_redaction")
+        self.rc_admin_redaction = None
         if rc_admin_redaction:
             self.rc_admin_redaction = RateLimitConfig(rc_admin_redaction)
-        else:
-            self.rc_admin_redaction = None
 
     def generate_config_section(self, **kwargs):
         return """\
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index c5ea2d43a1..b91414aa35 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -14,17 +14,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import re
+import logging
 
 from synapse.python_dependencies import DependencyException, check_requirements
-from synapse.types import (
-    map_username_to_mxid_localpart,
-    mxid_localpart_allowed_characters,
-)
-from synapse.util.module_loader import load_python_module
+from synapse.util.module_loader import load_module, load_python_module
 
 from ._base import Config, ConfigError
 
+logger = logging.getLogger(__name__)
+
+DEFAULT_USER_MAPPING_PROVIDER = (
+    "synapse.handlers.saml_handler.DefaultSamlMappingProvider"
+)
+
 
 def _dict_merge(merge_dict, into_dict):
     """Do a deep merge of two dicts
@@ -75,15 +77,69 @@ class SAML2Config(Config):
 
         self.saml2_enabled = True
 
-        self.saml2_mxid_source_attribute = saml2_config.get(
-            "mxid_source_attribute", "uid"
-        )
-
         self.saml2_grandfathered_mxid_source_attribute = saml2_config.get(
             "grandfathered_mxid_source_attribute", "uid"
         )
 
-        saml2_config_dict = self._default_saml_config_dict()
+        # user_mapping_provider may be None if the key is present but has no value
+        ump_dict = saml2_config.get("user_mapping_provider") or {}
+
+        # Use the default user mapping provider if not set
+        ump_dict.setdefault("module", DEFAULT_USER_MAPPING_PROVIDER)
+
+        # Ensure a config is present
+        ump_dict["config"] = ump_dict.get("config") or {}
+
+        if ump_dict["module"] == DEFAULT_USER_MAPPING_PROVIDER:
+            # Load deprecated options for use by the default module
+            old_mxid_source_attribute = saml2_config.get("mxid_source_attribute")
+            if old_mxid_source_attribute:
+                logger.warning(
+                    "The config option saml2_config.mxid_source_attribute is deprecated. "
+                    "Please use saml2_config.user_mapping_provider.config"
+                    ".mxid_source_attribute instead."
+                )
+                ump_dict["config"]["mxid_source_attribute"] = old_mxid_source_attribute
+
+            old_mxid_mapping = saml2_config.get("mxid_mapping")
+            if old_mxid_mapping:
+                logger.warning(
+                    "The config option saml2_config.mxid_mapping is deprecated. Please "
+                    "use saml2_config.user_mapping_provider.config.mxid_mapping instead."
+                )
+                ump_dict["config"]["mxid_mapping"] = old_mxid_mapping
+
+        # Retrieve an instance of the module's class
+        # Pass the config dictionary to the module for processing
+        (
+            self.saml2_user_mapping_provider_class,
+            self.saml2_user_mapping_provider_config,
+        ) = load_module(ump_dict)
+
+        # Ensure loaded user mapping module has defined all necessary methods
+        # Note parse_config() is already checked during the call to load_module
+        required_methods = [
+            "get_saml_attributes",
+            "saml_response_to_user_attributes",
+        ]
+        missing_methods = [
+            method
+            for method in required_methods
+            if not hasattr(self.saml2_user_mapping_provider_class, method)
+        ]
+        if missing_methods:
+            raise ConfigError(
+                "Class specified by saml2_config."
+                "user_mapping_provider.module is missing required "
+                "methods: %s" % (", ".join(missing_methods),)
+            )
+
+        # Get the desired saml auth response attributes from the module
+        saml2_config_dict = self._default_saml_config_dict(
+            *self.saml2_user_mapping_provider_class.get_saml_attributes(
+                self.saml2_user_mapping_provider_config
+            )
+        )
         _dict_merge(
             merge_dict=saml2_config.get("sp_config", {}), into_dict=saml2_config_dict
         )
@@ -103,22 +159,27 @@ class SAML2Config(Config):
             saml2_config.get("saml_session_lifetime", "5m")
         )
 
-        mapping = saml2_config.get("mxid_mapping", "hexencode")
-        try:
-            self.saml2_mxid_mapper = MXID_MAPPER_MAP[mapping]
-        except KeyError:
-            raise ConfigError("%s is not a known mxid_mapping" % (mapping,))
-
-    def _default_saml_config_dict(self):
+    def _default_saml_config_dict(
+        self, required_attributes: set, optional_attributes: set
+    ):
+        """Generate a configuration dictionary with required and optional attributes that
+        will be needed to process new user registration
+
+        Args:
+            required_attributes: SAML auth response attributes that are
+                necessary to function
+            optional_attributes: SAML auth response attributes that can be used to add
+                additional information to Synapse user accounts, but are not required
+
+        Returns:
+            dict: A SAML configuration dictionary
+        """
         import saml2
 
         public_baseurl = self.public_baseurl
         if public_baseurl is None:
             raise ConfigError("saml2_config requires a public_baseurl to be set")
 
-        required_attributes = {"uid", self.saml2_mxid_source_attribute}
-
-        optional_attributes = {"displayName"}
         if self.saml2_grandfathered_mxid_source_attribute:
             optional_attributes.add(self.saml2_grandfathered_mxid_source_attribute)
         optional_attributes -= required_attributes
@@ -207,33 +268,58 @@ class SAML2Config(Config):
           #
           #config_path: "%(config_dir_path)s/sp_conf.py"
 
-          # the lifetime of a SAML session. This defines how long a user has to
+          # The lifetime of a SAML session. This defines how long a user has to
           # complete the authentication process, if allow_unsolicited is unset.
           # The default is 5 minutes.
           #
           #saml_session_lifetime: 5m
 
-          # The SAML attribute (after mapping via the attribute maps) to use to derive
-          # the Matrix ID from. 'uid' by default.
+          # An external module can be provided here as a custom solution to
+          # mapping attributes returned from a saml provider onto a matrix user.
           #
-          #mxid_source_attribute: displayName
-
-          # The mapping system to use for mapping the saml attribute onto a matrix ID.
-          # Options include:
-          #  * 'hexencode' (which maps unpermitted characters to '=xx')
-          #  * 'dotreplace' (which replaces unpermitted characters with '.').
-          # The default is 'hexencode'.
-          #
-          #mxid_mapping: dotreplace
-
-          # In previous versions of synapse, the mapping from SAML attribute to MXID was
-          # always calculated dynamically rather than stored in a table. For backwards-
-          # compatibility, we will look for user_ids matching such a pattern before
-          # creating a new account.
+          user_mapping_provider:
+            # The custom module's class. Uncomment to use a custom module.
+            #
+            #module: mapping_provider.SamlMappingProvider
+
+            # Custom configuration values for the module. Below options are
+            # intended for the built-in provider, they should be changed if
+            # using a custom module. This section will be passed as a Python
+            # dictionary to the module's `parse_config` method.
+            #
+            config:
+              # The SAML attribute (after mapping via the attribute maps) to use
+              # to derive the Matrix ID from. 'uid' by default.
+              #
+              # Note: This used to be configured by the
+              # saml2_config.mxid_source_attribute option. If that is still
+              # defined, its value will be used instead.
+              #
+              #mxid_source_attribute: displayName
+
+              # The mapping system to use for mapping the saml attribute onto a
+              # matrix ID.
+              #
+              # Options include:
+              #  * 'hexencode' (which maps unpermitted characters to '=xx')
+              #  * 'dotreplace' (which replaces unpermitted characters with
+              #     '.').
+              # The default is 'hexencode'.
+              #
+              # Note: This used to be configured by the
+              # saml2_config.mxid_mapping option. If that is still defined, its
+              # value will be used instead.
+              #
+              #mxid_mapping: dotreplace
+
+          # In previous versions of synapse, the mapping from SAML attribute to
+          # MXID was always calculated dynamically rather than stored in a
+          # table. For backwards- compatibility, we will look for user_ids
+          # matching such a pattern before creating a new account.
           #
           # This setting controls the SAML attribute which will be used for this
-          # backwards-compatibility lookup. Typically it should be 'uid', but if the
-          # attribute maps are changed, it may be necessary to change it.
+          # backwards-compatibility lookup. Typically it should be 'uid', but if
+          # the attribute maps are changed, it may be necessary to change it.
           #
           # The default is 'uid'.
           #
@@ -241,23 +327,3 @@ class SAML2Config(Config):
         """ % {
             "config_dir_path": config_dir_path
         }
-
-
-DOT_REPLACE_PATTERN = re.compile(
-    ("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
-)
-
-
-def dot_replace_for_mxid(username: str) -> str:
-    username = username.lower()
-    username = DOT_REPLACE_PATTERN.sub(".", username)
-
-    # regular mxids aren't allowed to start with an underscore either
-    username = re.sub("^_", "", username)
-    return username
-
-
-MXID_MAPPER_MAP = {
-    "hexencode": map_username_to_mxid_localpart,
-    "dotreplace": dot_replace_for_mxid,
-}
diff --git a/synapse/config/server.py b/synapse/config/server.py
index a4bef00936..38f6ff9edc 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -102,6 +102,12 @@ class ServerConfig(Config):
             "require_auth_for_profile_requests", False
         )
 
+        # Whether to require sharing a room with a user to retrieve their
+        # profile data
+        self.limit_profile_requests_to_users_who_share_rooms = config.get(
+            "limit_profile_requests_to_users_who_share_rooms", False,
+        )
+
         if "restrict_public_rooms_to_local_users" in config and (
             "allow_public_rooms_without_auth" in config
             or "allow_public_rooms_over_federation" in config
@@ -200,7 +206,7 @@ class ServerConfig(Config):
         self.admin_contact = config.get("admin_contact", None)
 
         # FIXME: federation_domain_whitelist needs sytests
-        self.federation_domain_whitelist = None
+        self.federation_domain_whitelist = None  # type: Optional[dict]
         federation_domain_whitelist = config.get("federation_domain_whitelist", None)
 
         if federation_domain_whitelist is not None:
@@ -621,6 +627,13 @@ class ServerConfig(Config):
         #
         #require_auth_for_profile_requests: true
 
+        # Uncomment to require a user to share a room with another user in order
+        # to retrieve their profile information. Only checked on Client-Server
+        # requests. Profile requests from other servers should be checked by the
+        # requesting server. Defaults to 'false'.
+        #
+        #limit_profile_requests_to_users_who_share_rooms: true
+
         # If set to 'true', removes the need for authentication to access the server's
         # public rooms directory through the client API, meaning that anyone can
         # query the room directory. Defaults to 'false'.
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index 350ed9351f..1033e5e121 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -43,6 +43,8 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
     Returns:
          if the auth checks pass.
     """
+    assert isinstance(auth_events, dict)
+
     if do_size_check:
         _check_size_limits(event)
 
@@ -87,12 +89,6 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
             if not event.signatures.get(event_id_domain):
                 raise AuthError(403, "Event not signed by sending server")
 
-    if auth_events is None:
-        # Oh, we don't know what the state of the room was, so we
-        # are trusting that this is allowed (at least for now)
-        logger.warning("Trusting event: %s", event.event_id)
-        return
-
     if event.type == EventTypes.Create:
         sender_domain = get_domain_from_id(event.sender)
         room_id_domain = get_domain_from_id(event.room_id)
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index d396e6564f..af652a7659 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -526,13 +526,7 @@ class FederationClient(FederationBase):
 
         @defer.inlineCallbacks
         def send_request(destination):
-            time_now = self._clock.time_msec()
-            _, content = yield self.transport_layer.send_join(
-                destination=destination,
-                room_id=pdu.room_id,
-                event_id=pdu.event_id,
-                content=pdu.get_pdu_json(time_now),
-            )
+            content = yield self._do_send_join(destination, pdu)
 
             logger.debug("Got content: %s", content)
 
@@ -600,6 +594,44 @@ class FederationClient(FederationBase):
         return self._try_destination_list("send_join", destinations, send_request)
 
     @defer.inlineCallbacks
+    def _do_send_join(self, destination, pdu):
+        time_now = self._clock.time_msec()
+
+        try:
+            content = yield self.transport_layer.send_join_v2(
+                destination=destination,
+                room_id=pdu.room_id,
+                event_id=pdu.event_id,
+                content=pdu.get_pdu_json(time_now),
+            )
+
+            return content
+        except HttpResponseException as e:
+            if e.code in [400, 404]:
+                err = e.to_synapse_error()
+
+                # If we receive an error response that isn't a generic error, or an
+                # unrecognised endpoint error, we  assume that the remote understands
+                # the v2 invite API and this is a legitimate error.
+                if err.errcode not in [Codes.UNKNOWN, Codes.UNRECOGNIZED]:
+                    raise err
+            else:
+                raise e.to_synapse_error()
+
+        logger.debug("Couldn't send_join with the v2 API, falling back to the v1 API")
+
+        resp = yield self.transport_layer.send_join_v1(
+            destination=destination,
+            room_id=pdu.room_id,
+            event_id=pdu.event_id,
+            content=pdu.get_pdu_json(time_now),
+        )
+
+        # We expect the v1 API to respond with [200, content], so we only return the
+        # content.
+        return resp[1]
+
+    @defer.inlineCallbacks
     def send_invite(self, destination, room_id, event_id, pdu):
         room_version = yield self.store.get_room_version(room_id)
 
@@ -708,18 +740,50 @@ class FederationClient(FederationBase):
 
         @defer.inlineCallbacks
         def send_request(destination):
-            time_now = self._clock.time_msec()
-            _, content = yield self.transport_layer.send_leave(
+            content = yield self._do_send_leave(destination, pdu)
+
+            logger.debug("Got content: %s", content)
+            return None
+
+        return self._try_destination_list("send_leave", destinations, send_request)
+
+    @defer.inlineCallbacks
+    def _do_send_leave(self, destination, pdu):
+        time_now = self._clock.time_msec()
+
+        try:
+            content = yield self.transport_layer.send_leave_v2(
                 destination=destination,
                 room_id=pdu.room_id,
                 event_id=pdu.event_id,
                 content=pdu.get_pdu_json(time_now),
             )
 
-            logger.debug("Got content: %s", content)
-            return None
+            return content
+        except HttpResponseException as e:
+            if e.code in [400, 404]:
+                err = e.to_synapse_error()
 
-        return self._try_destination_list("send_leave", destinations, send_request)
+                # If we receive an error response that isn't a generic error, or an
+                # unrecognised endpoint error, we  assume that the remote understands
+                # the v2 invite API and this is a legitimate error.
+                if err.errcode not in [Codes.UNKNOWN, Codes.UNRECOGNIZED]:
+                    raise err
+            else:
+                raise e.to_synapse_error()
+
+        logger.debug("Couldn't send_leave with the v2 API, falling back to the v1 API")
+
+        resp = yield self.transport_layer.send_leave_v1(
+            destination=destination,
+            room_id=pdu.room_id,
+            event_id=pdu.event_id,
+            content=pdu.get_pdu_json(time_now),
+        )
+
+        # We expect the v1 API to respond with [200, content], so we only return the
+        # content.
+        return resp[1]
 
     def get_public_rooms(
         self,
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 84d4eca041..d7ce333822 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -384,15 +384,10 @@ class FederationServer(FederationBase):
 
         res_pdus = await self.handler.on_send_join_request(origin, pdu)
         time_now = self._clock.time_msec()
-        return (
-            200,
-            {
-                "state": [p.get_pdu_json(time_now) for p in res_pdus["state"]],
-                "auth_chain": [
-                    p.get_pdu_json(time_now) for p in res_pdus["auth_chain"]
-                ],
-            },
-        )
+        return {
+            "state": [p.get_pdu_json(time_now) for p in res_pdus["state"]],
+            "auth_chain": [p.get_pdu_json(time_now) for p in res_pdus["auth_chain"]],
+        }
 
     async def on_make_leave_request(self, origin, room_id, user_id):
         origin_host, _ = parse_server_name(origin)
@@ -419,7 +414,7 @@ class FederationServer(FederationBase):
         pdu = await self._check_sigs_and_hash(room_version, pdu)
 
         await self.handler.on_send_leave_request(origin, pdu)
-        return 200, {}
+        return {}
 
     async def on_event_auth(self, origin, room_id, event_id):
         with (await self._server_linearizer.queue((origin, room_id))):
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 46dba84cac..198257414b 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -243,7 +243,7 @@ class TransportLayerClient(object):
 
     @defer.inlineCallbacks
     @log_function
-    def send_join(self, destination, room_id, event_id, content):
+    def send_join_v1(self, destination, room_id, event_id, content):
         path = _create_v1_path("/send_join/%s/%s", room_id, event_id)
 
         response = yield self.client.put_json(
@@ -254,7 +254,18 @@ class TransportLayerClient(object):
 
     @defer.inlineCallbacks
     @log_function
-    def send_leave(self, destination, room_id, event_id, content):
+    def send_join_v2(self, destination, room_id, event_id, content):
+        path = _create_v2_path("/send_join/%s/%s", room_id, event_id)
+
+        response = yield self.client.put_json(
+            destination=destination, path=path, data=content
+        )
+
+        return response
+
+    @defer.inlineCallbacks
+    @log_function
+    def send_leave_v1(self, destination, room_id, event_id, content):
         path = _create_v1_path("/send_leave/%s/%s", room_id, event_id)
 
         response = yield self.client.put_json(
@@ -272,6 +283,24 @@ class TransportLayerClient(object):
 
     @defer.inlineCallbacks
     @log_function
+    def send_leave_v2(self, destination, room_id, event_id, content):
+        path = _create_v2_path("/send_leave/%s/%s", room_id, event_id)
+
+        response = yield self.client.put_json(
+            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,
+        )
+
+        return response
+
+    @defer.inlineCallbacks
+    @log_function
     def send_invite_v1(self, destination, room_id, event_id, content):
         path = _create_v1_path("/invite/%s/%s", room_id, event_id)
 
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index fefc789c85..b4cbf23394 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -506,11 +506,21 @@ class FederationMakeLeaveServlet(BaseFederationServlet):
         return 200, content
 
 
-class FederationSendLeaveServlet(BaseFederationServlet):
+class FederationV1SendLeaveServlet(BaseFederationServlet):
     PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
     async def on_PUT(self, origin, content, query, room_id, event_id):
         content = await self.handler.on_send_leave_request(origin, content, room_id)
+        return 200, (200, content)
+
+
+class FederationV2SendLeaveServlet(BaseFederationServlet):
+    PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+
+    PREFIX = FEDERATION_V2_PREFIX
+
+    async def on_PUT(self, origin, content, query, room_id, event_id):
+        content = await self.handler.on_send_leave_request(origin, content, room_id)
         return 200, content
 
 
@@ -521,9 +531,21 @@ class FederationEventAuthServlet(BaseFederationServlet):
         return await self.handler.on_event_auth(origin, context, event_id)
 
 
-class FederationSendJoinServlet(BaseFederationServlet):
+class FederationV1SendJoinServlet(BaseFederationServlet):
+    PATH = "/send_join/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+
+    async def on_PUT(self, origin, content, query, context, event_id):
+        # TODO(paul): assert that context/event_id parsed from path actually
+        #   match those given in content
+        content = await self.handler.on_send_join_request(origin, content, context)
+        return 200, (200, content)
+
+
+class FederationV2SendJoinServlet(BaseFederationServlet):
     PATH = "/send_join/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
 
+    PREFIX = FEDERATION_V2_PREFIX
+
     async def on_PUT(self, origin, content, query, context, event_id):
         # TODO(paul): assert that context/event_id parsed from path actually
         #   match those given in content
@@ -1367,8 +1389,10 @@ FEDERATION_SERVLET_CLASSES = (
     FederationMakeJoinServlet,
     FederationMakeLeaveServlet,
     FederationEventServlet,
-    FederationSendJoinServlet,
-    FederationSendLeaveServlet,
+    FederationV1SendJoinServlet,
+    FederationV2SendJoinServlet,
+    FederationV1SendLeaveServlet,
+    FederationV2SendLeaveServlet,
     FederationV1InviteServlet,
     FederationV2InviteServlet,
     FederationQueryAuthServlet,
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
index 29e8ffc295..0ec9be3cb5 100644
--- a/synapse/groups/groups_server.py
+++ b/synapse/groups/groups_server.py
@@ -773,6 +773,11 @@ class GroupsServerHandler(object):
         if not self.hs.is_mine_id(user_id):
             yield self.store.maybe_delete_remote_profile_cache(user_id)
 
+        # Delete group if the last user has left
+        users = yield self.store.get_users_in_group(group_id, include_private=True)
+        if not users:
+            yield self.store.delete_group(group_id)
+
         return {}
 
     @defer.inlineCallbacks
diff --git a/synapse/handlers/account_data.py b/synapse/handlers/account_data.py
index 2d7e6df6e4..a8d3fbc6de 100644
--- a/synapse/handlers/account_data.py
+++ b/synapse/handlers/account_data.py
@@ -13,8 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
 
 class AccountDataEventSource(object):
     def __init__(self, hs):
@@ -23,15 +21,14 @@ class AccountDataEventSource(object):
     def get_current_key(self, direction="f"):
         return self.store.get_max_account_data_stream_id()
 
-    @defer.inlineCallbacks
-    def get_new_events(self, user, from_key, **kwargs):
+    async def get_new_events(self, user, from_key, **kwargs):
         user_id = user.to_string()
         last_stream_id = from_key
 
-        current_stream_id = yield self.store.get_max_account_data_stream_id()
+        current_stream_id = self.store.get_max_account_data_stream_id()
 
         results = []
-        tags = yield self.store.get_updated_tags(user_id, last_stream_id)
+        tags = await self.store.get_updated_tags(user_id, last_stream_id)
 
         for room_id, room_tags in tags.items():
             results.append(
@@ -41,7 +38,7 @@ class AccountDataEventSource(object):
         (
             account_data,
             room_account_data,
-        ) = yield self.store.get_updated_account_data_for_user(user_id, last_stream_id)
+        ) = await self.store.get_updated_account_data_for_user(user_id, last_stream_id)
 
         for account_data_type, content in account_data.items():
             results.append({"type": account_data_type, "content": content})
@@ -53,7 +50,3 @@ class AccountDataEventSource(object):
                 )
 
         return results, current_stream_id
-
-    @defer.inlineCallbacks
-    def get_pagination_rows(self, user, config, key):
-        return [], config.to_id
diff --git a/synapse/handlers/account_validity.py b/synapse/handlers/account_validity.py
index d04e0fe576..829f52eca1 100644
--- a/synapse/handlers/account_validity.py
+++ b/synapse/handlers/account_validity.py
@@ -18,8 +18,7 @@ import email.utils
 import logging
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
-
-from twisted.internet import defer
+from typing import List
 
 from synapse.api.errors import StoreError
 from synapse.logging.context import make_deferred_yieldable
@@ -78,42 +77,39 @@ class AccountValidityHandler(object):
                 # run as a background process to make sure that the database transactions
                 # have a logcontext to report to
                 return run_as_background_process(
-                    "send_renewals", self.send_renewal_emails
+                    "send_renewals", self._send_renewal_emails
                 )
 
             self.clock.looping_call(send_emails, 30 * 60 * 1000)
 
-    @defer.inlineCallbacks
-    def send_renewal_emails(self):
+    async def _send_renewal_emails(self):
         """Gets the list of users whose account is expiring in the amount of time
         configured in the ``renew_at`` parameter from the ``account_validity``
         configuration, and sends renewal emails to all of these users as long as they
         have an email 3PID attached to their account.
         """
-        expiring_users = yield self.store.get_users_expiring_soon()
+        expiring_users = await self.store.get_users_expiring_soon()
 
         if expiring_users:
             for user in expiring_users:
-                yield self._send_renewal_email(
+                await self._send_renewal_email(
                     user_id=user["user_id"], expiration_ts=user["expiration_ts_ms"]
                 )
 
-    @defer.inlineCallbacks
-    def send_renewal_email_to_user(self, user_id):
-        expiration_ts = yield self.store.get_expiration_ts_for_user(user_id)
-        yield self._send_renewal_email(user_id, expiration_ts)
+    async def send_renewal_email_to_user(self, user_id: str):
+        expiration_ts = await self.store.get_expiration_ts_for_user(user_id)
+        await self._send_renewal_email(user_id, expiration_ts)
 
-    @defer.inlineCallbacks
-    def _send_renewal_email(self, user_id, expiration_ts):
+    async def _send_renewal_email(self, user_id: str, expiration_ts: int):
         """Sends out a renewal email to every email address attached to the given user
         with a unique link allowing them to renew their account.
 
         Args:
-            user_id (str): ID of the user to send email(s) to.
-            expiration_ts (int): Timestamp in milliseconds for the expiration date of
+            user_id: ID of the user to send email(s) to.
+            expiration_ts: Timestamp in milliseconds for the expiration date of
                 this user's account (used in the email templates).
         """
-        addresses = yield self._get_email_addresses_for_user(user_id)
+        addresses = await self._get_email_addresses_for_user(user_id)
 
         # Stop right here if the user doesn't have at least one email address.
         # In this case, they will have to ask their server admin to renew their
@@ -125,7 +121,7 @@ class AccountValidityHandler(object):
             return
 
         try:
-            user_display_name = yield self.store.get_profile_displayname(
+            user_display_name = await self.store.get_profile_displayname(
                 UserID.from_string(user_id).localpart
             )
             if user_display_name is None:
@@ -133,7 +129,7 @@ class AccountValidityHandler(object):
         except StoreError:
             user_display_name = user_id
 
-        renewal_token = yield self._get_renewal_token(user_id)
+        renewal_token = await self._get_renewal_token(user_id)
         url = "%s_matrix/client/unstable/account_validity/renew?token=%s" % (
             self.hs.config.public_baseurl,
             renewal_token,
@@ -165,7 +161,7 @@ class AccountValidityHandler(object):
 
             logger.info("Sending renewal email to %s", address)
 
-            yield make_deferred_yieldable(
+            await make_deferred_yieldable(
                 self.sendmail(
                     self.hs.config.email_smtp_host,
                     self._raw_from,
@@ -180,19 +176,18 @@ class AccountValidityHandler(object):
                 )
             )
 
-        yield self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
+        await self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
 
-    @defer.inlineCallbacks
-    def _get_email_addresses_for_user(self, user_id):
+    async def _get_email_addresses_for_user(self, user_id: str) -> List[str]:
         """Retrieve the list of email addresses attached to a user's account.
 
         Args:
-            user_id (str): ID of the user to lookup email addresses for.
+            user_id: ID of the user to lookup email addresses for.
 
         Returns:
-            defer.Deferred[list[str]]: Email addresses for this account.
+            Email addresses for this account.
         """
-        threepids = yield self.store.user_get_threepids(user_id)
+        threepids = await self.store.user_get_threepids(user_id)
 
         addresses = []
         for threepid in threepids:
@@ -201,16 +196,15 @@ class AccountValidityHandler(object):
 
         return addresses
 
-    @defer.inlineCallbacks
-    def _get_renewal_token(self, user_id):
+    async def _get_renewal_token(self, user_id: str) -> str:
         """Generates a 32-byte long random string that will be inserted into the
         user's renewal email's unique link, then saves it into the database.
 
         Args:
-            user_id (str): ID of the user to generate a string for.
+            user_id: ID of the user to generate a string for.
 
         Returns:
-            defer.Deferred[str]: The generated string.
+            The generated string.
 
         Raises:
             StoreError(500): Couldn't generate a unique string after 5 attempts.
@@ -219,52 +213,52 @@ class AccountValidityHandler(object):
         while attempts < 5:
             try:
                 renewal_token = stringutils.random_string(32)
-                yield self.store.set_renewal_token_for_user(user_id, renewal_token)
+                await self.store.set_renewal_token_for_user(user_id, renewal_token)
                 return renewal_token
             except StoreError:
                 attempts += 1
         raise StoreError(500, "Couldn't generate a unique string as refresh string.")
 
-    @defer.inlineCallbacks
-    def renew_account(self, renewal_token):
+    async def renew_account(self, renewal_token: str) -> bool:
         """Renews the account attached to a given renewal token by pushing back the
         expiration date by the current validity period in the server's configuration.
 
         Args:
-            renewal_token (str): Token sent with the renewal request.
+            renewal_token: Token sent with the renewal request.
         Returns:
-            bool: Whether the provided token is valid.
+            Whether the provided token is valid.
         """
         try:
-            user_id = yield self.store.get_user_from_renewal_token(renewal_token)
+            user_id = await self.store.get_user_from_renewal_token(renewal_token)
         except StoreError:
-            defer.returnValue(False)
+            return False
 
         logger.debug("Renewing an account for user %s", user_id)
-        yield self.renew_account_for_user(user_id)
+        await self.renew_account_for_user(user_id)
 
-        defer.returnValue(True)
+        return True
 
-    @defer.inlineCallbacks
-    def renew_account_for_user(self, user_id, expiration_ts=None, email_sent=False):
+    async def renew_account_for_user(
+        self, user_id: str, expiration_ts: int = None, email_sent: bool = False
+    ) -> int:
         """Renews the account attached to a given user by pushing back the
         expiration date by the current validity period in the server's
         configuration.
 
         Args:
-            renewal_token (str): Token sent with the renewal request.
-            expiration_ts (int): New expiration date. Defaults to now + validity period.
-            email_sent (bool): Whether an email has been sent for this validity period.
+            renewal_token: Token sent with the renewal request.
+            expiration_ts: New expiration date. Defaults to now + validity period.
+            email_sen: Whether an email has been sent for this validity period.
                 Defaults to False.
 
         Returns:
-            defer.Deferred[int]: New expiration date for this account, as a timestamp
-                in milliseconds since epoch.
+            New expiration date for this account, as a timestamp in
+            milliseconds since epoch.
         """
         if expiration_ts is None:
             expiration_ts = self.clock.time_msec() + self._account_validity.period
 
-        yield self.store.set_account_validity_for_user(
+        await self.store.set_account_validity_for_user(
             user_id=user_id, expiration_ts=expiration_ts, email_sent=email_sent
         )
 
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 57a10daefd..2d889364d4 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -264,6 +264,7 @@ class E2eKeysHandler(object):
 
         return ret
 
+    @defer.inlineCallbacks
     def get_cross_signing_keys_from_cache(self, query, from_user_id):
         """Get cross-signing keys for users from the database
 
@@ -283,14 +284,32 @@ class E2eKeysHandler(object):
         self_signing_keys = {}
         user_signing_keys = {}
 
-        # Currently a stub, implementation coming in https://github.com/matrix-org/synapse/pull/6486
-        return defer.succeed(
-            {
-                "master_keys": master_keys,
-                "self_signing_keys": self_signing_keys,
-                "user_signing_keys": user_signing_keys,
-            }
-        )
+        user_ids = list(query)
+
+        keys = yield self.store.get_e2e_cross_signing_keys_bulk(user_ids, from_user_id)
+
+        for user_id, user_info in keys.items():
+            if user_info is None:
+                continue
+            if "master" in user_info:
+                master_keys[user_id] = user_info["master"]
+            if "self_signing" in user_info:
+                self_signing_keys[user_id] = user_info["self_signing"]
+
+        if (
+            from_user_id in keys
+            and keys[from_user_id] is not None
+            and "user_signing" in keys[from_user_id]
+        ):
+            # users can see other users' master and self-signing keys, but can
+            # only see their own user-signing keys
+            user_signing_keys[from_user_id] = keys[from_user_id]["user_signing"]
+
+        return {
+            "master_keys": master_keys,
+            "self_signing_keys": self_signing_keys,
+            "user_signing_keys": user_signing_keys,
+        }
 
     @trace
     @defer.inlineCallbacks
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index abe02907b9..60bb00fc6a 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -19,7 +19,7 @@
 
 import itertools
 import logging
-from typing import Dict, Iterable, Optional, Sequence, Tuple
+from typing import Dict, Iterable, List, Optional, Sequence, Tuple
 
 import six
 from six import iteritems, itervalues
@@ -63,6 +63,7 @@ from synapse.replication.http.federation import (
 )
 from synapse.replication.http.membership import ReplicationUserJoinedLeftRoomRestServlet
 from synapse.state import StateResolutionStore, resolve_events_with_store
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.types import UserID, get_domain_from_id
 from synapse.util.async_helpers import Linearizer, concurrently_execute
 from synapse.util.distributor import user_joined_room
@@ -163,8 +164,7 @@ class FederationHandler(BaseHandler):
 
         self._ephemeral_messages_enabled = hs.config.enable_ephemeral_messages
 
-    @defer.inlineCallbacks
-    def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False):
+    async def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False) -> None:
         """ Process a PDU received via a federation /send/ transaction, or
         via backfill of missing prev_events
 
@@ -174,17 +174,15 @@ class FederationHandler(BaseHandler):
             pdu (FrozenEvent): received PDU
             sent_to_us_directly (bool): True if this event was pushed to us; False if
                 we pulled it as the result of a missing prev_event.
-
-        Returns (Deferred): completes with None
         """
 
         room_id = pdu.room_id
         event_id = pdu.event_id
 
-        logger.info("[%s %s] handling received PDU: %s", room_id, event_id, pdu)
+        logger.info("handling received PDU: %s", pdu)
 
         # We reprocess pdus when we have seen them only as outliers
-        existing = yield self.store.get_event(
+        existing = await self.store.get_event(
             event_id, allow_none=True, allow_rejected=True
         )
 
@@ -228,7 +226,7 @@ class FederationHandler(BaseHandler):
         #
         # Note that if we were never in the room then we would have already
         # dropped the event, since we wouldn't know the room version.
-        is_in_room = yield self.auth.check_host_in_room(room_id, self.server_name)
+        is_in_room = await self.auth.check_host_in_room(room_id, self.server_name)
         if not is_in_room:
             logger.info(
                 "[%s %s] Ignoring PDU from %s as we're not in the room",
@@ -243,12 +241,12 @@ class FederationHandler(BaseHandler):
         # Get missing pdus if necessary.
         if not pdu.internal_metadata.is_outlier():
             # We only backfill backwards to the min depth.
-            min_depth = yield self.get_min_depth_for_context(pdu.room_id)
+            min_depth = await self.get_min_depth_for_context(pdu.room_id)
 
             logger.debug("[%s %s] min_depth: %d", room_id, event_id, min_depth)
 
             prevs = set(pdu.prev_event_ids())
-            seen = yield self.store.have_seen_events(prevs)
+            seen = await self.store.have_seen_events(prevs)
 
             if min_depth and pdu.depth < min_depth:
                 # This is so that we don't notify the user about this
@@ -268,7 +266,7 @@ class FederationHandler(BaseHandler):
                         len(missing_prevs),
                         shortstr(missing_prevs),
                     )
-                    with (yield self._room_pdu_linearizer.queue(pdu.room_id)):
+                    with (await self._room_pdu_linearizer.queue(pdu.room_id)):
                         logger.info(
                             "[%s %s] Acquired room lock to fetch %d missing prev_events",
                             room_id,
@@ -276,13 +274,19 @@ class FederationHandler(BaseHandler):
                             len(missing_prevs),
                         )
 
-                        yield self._get_missing_events_for_pdu(
-                            origin, pdu, prevs, min_depth
-                        )
+                        try:
+                            await self._get_missing_events_for_pdu(
+                                origin, pdu, prevs, min_depth
+                            )
+                        except Exception as e:
+                            raise Exception(
+                                "Error fetching missing prev_events for %s: %s"
+                                % (event_id, e)
+                            )
 
                         # Update the set of things we've seen after trying to
                         # fetch the missing stuff
-                        seen = yield self.store.have_seen_events(prevs)
+                        seen = await self.store.have_seen_events(prevs)
 
                         if not prevs - seen:
                             logger.info(
@@ -290,14 +294,6 @@ class FederationHandler(BaseHandler):
                                 room_id,
                                 event_id,
                             )
-                elif missing_prevs:
-                    logger.info(
-                        "[%s %s] Not recursively fetching %d missing prev_events: %s",
-                        room_id,
-                        event_id,
-                        len(missing_prevs),
-                        shortstr(missing_prevs),
-                    )
 
             if prevs - seen:
                 # We've still not been able to get all of the prev_events for this event.
@@ -342,12 +338,18 @@ class FederationHandler(BaseHandler):
                         affected=pdu.event_id,
                     )
 
+                logger.info(
+                    "Event %s is missing prev_events: calculating state for a "
+                    "backwards extremity",
+                    event_id,
+                )
+
                 # Calculate the state after each of the previous events, and
                 # resolve them to find the correct state at the current event.
                 event_map = {event_id: pdu}
                 try:
                     # Get the state of the events we know about
-                    ours = yield self.state_store.get_state_groups_ids(room_id, seen)
+                    ours = await self.state_store.get_state_groups_ids(room_id, seen)
 
                     # state_maps is a list of mappings from (type, state_key) to event_id
                     state_maps = list(
@@ -361,17 +363,14 @@ class FederationHandler(BaseHandler):
                     # know about
                     for p in prevs - seen:
                         logger.info(
-                            "[%s %s] Requesting state at missing prev_event %s",
-                            room_id,
-                            event_id,
-                            p,
+                            "Requesting state at missing prev_event %s", event_id,
                         )
 
                         with nested_logging_context(p):
                             # note that if any of the missing prevs share missing state or
                             # auth events, the requests to fetch those events are deduped
                             # by the get_pdu_cache in federation_client.
-                            (remote_state, _,) = yield self._get_state_for_room(
+                            (remote_state, _,) = await self._get_state_for_room(
                                 origin, room_id, p, include_event_in_state=True
                             )
 
@@ -383,8 +382,8 @@ class FederationHandler(BaseHandler):
                             for x in remote_state:
                                 event_map[x.event_id] = x
 
-                    room_version = yield self.store.get_room_version(room_id)
-                    state_map = yield resolve_events_with_store(
+                    room_version = await self.store.get_room_version(room_id)
+                    state_map = await resolve_events_with_store(
                         room_id,
                         room_version,
                         state_maps,
@@ -397,10 +396,10 @@ class FederationHandler(BaseHandler):
 
                     # First though we need to fetch all the events that are in
                     # state_map, so we can build up the state below.
-                    evs = yield self.store.get_events(
+                    evs = await self.store.get_events(
                         list(state_map.values()),
                         get_prev_content=False,
-                        check_redacted=False,
+                        redact_behaviour=EventRedactBehaviour.AS_IS,
                     )
                     event_map.update(evs)
 
@@ -420,10 +419,9 @@ class FederationHandler(BaseHandler):
                         affected=event_id,
                     )
 
-        yield self._process_received_pdu(origin, pdu, state=state)
+        await self._process_received_pdu(origin, pdu, state=state)
 
-    @defer.inlineCallbacks
-    def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
+    async def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
         """
         Args:
             origin (str): Origin of the pdu. Will be called to get the missing events
@@ -435,12 +433,12 @@ class FederationHandler(BaseHandler):
         room_id = pdu.room_id
         event_id = pdu.event_id
 
-        seen = yield self.store.have_seen_events(prevs)
+        seen = await self.store.have_seen_events(prevs)
 
         if not prevs - seen:
             return
 
-        latest = yield self.store.get_latest_event_ids_in_room(room_id)
+        latest = await self.store.get_latest_event_ids_in_room(room_id)
 
         # We add the prev events that we have seen to the latest
         # list to ensure the remote server doesn't give them to us
@@ -504,7 +502,7 @@ class FederationHandler(BaseHandler):
         # All that said: Let's try increasing the timout to 60s and see what happens.
 
         try:
-            missing_events = yield self.federation_client.get_missing_events(
+            missing_events = await self.federation_client.get_missing_events(
                 origin,
                 room_id,
                 earliest_events_ids=list(latest),
@@ -543,7 +541,7 @@ class FederationHandler(BaseHandler):
             )
             with nested_logging_context(ev.event_id):
                 try:
-                    yield self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
+                    await self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
                 except FederationError as e:
                     if e.code == 403:
                         logger.warning(
@@ -555,29 +553,30 @@ class FederationHandler(BaseHandler):
                     else:
                         raise
 
-    @defer.inlineCallbacks
-    @log_function
-    def _get_state_for_room(
-        self, destination, room_id, event_id, include_event_in_state
-    ):
+    async def _get_state_for_room(
+        self,
+        destination: str,
+        room_id: str,
+        event_id: str,
+        include_event_in_state: bool = False,
+    ) -> Tuple[List[EventBase], List[EventBase]]:
         """Requests all of the room state at a given event from a remote homeserver.
 
         Args:
-            destination (str): The remote homeserver to query for the state.
-            room_id (str): The id of the room we're interested in.
-            event_id (str): The id of the event we want the state at.
+            destination: The remote homeserver to query for the state.
+            room_id: The id of the room we're interested in.
+            event_id: The id of the event we want the state at.
             include_event_in_state: if true, the event itself will be included in the
                 returned state event list.
 
         Returns:
-            Deferred[Tuple[List[EventBase], List[EventBase]]]:
-                A list of events in the state, and a list of events in the auth chain
-                for the given event.
+            A list of events in the state, possibly including the event itself, and
+            a list of events in the auth chain for the given event.
         """
         (
             state_event_ids,
             auth_event_ids,
-        ) = yield self.federation_client.get_room_state_ids(
+        ) = await self.federation_client.get_room_state_ids(
             destination, room_id, event_id=event_id
         )
 
@@ -586,15 +585,15 @@ class FederationHandler(BaseHandler):
         if include_event_in_state:
             desired_events.add(event_id)
 
-        event_map = yield self._get_events_from_store_or_dest(
+        event_map = await self._get_events_from_store_or_dest(
             destination, room_id, desired_events
         )
 
         failed_to_fetch = desired_events - event_map.keys()
         if failed_to_fetch:
             logger.warning(
-                "Failed to fetch missing state/auth events for %s: %s",
-                room_id,
+                "Failed to fetch missing state/auth events for %s %s",
+                event_id,
                 failed_to_fetch,
             )
 
@@ -614,15 +613,11 @@ class FederationHandler(BaseHandler):
 
         return remote_state, auth_chain
 
-    @defer.inlineCallbacks
-    def _get_events_from_store_or_dest(self, destination, room_id, event_ids):
+    async def _get_events_from_store_or_dest(
+        self, destination: str, room_id: str, event_ids: Iterable[str]
+    ) -> Dict[str, EventBase]:
         """Fetch events from a remote destination, checking if we already have them.
 
-        Args:
-            destination (str)
-            room_id (str)
-            event_ids (Iterable[str])
-
         Persists any events we don't already have as outliers.
 
         If we fail to fetch any of the events, a warning will be logged, and the event
@@ -630,10 +625,9 @@ class FederationHandler(BaseHandler):
         be in the given room.
 
         Returns:
-            Deferred[dict[str, EventBase]]: A deferred resolving to a map
-            from event_id to event
+            map from event_id to event
         """
-        fetched_events = yield self.store.get_events(event_ids, allow_rejected=True)
+        fetched_events = await self.store.get_events(event_ids, allow_rejected=True)
 
         missing_events = set(event_ids) - fetched_events.keys()
 
@@ -644,14 +638,14 @@ class FederationHandler(BaseHandler):
                 room_id,
             )
 
-            yield self._get_events_and_persist(
+            await self._get_events_and_persist(
                 destination=destination, room_id=room_id, events=missing_events
             )
 
             # we need to make sure we re-load from the database to get the rejected
             # state correct.
             fetched_events.update(
-                (yield self.store.get_events(missing_events, allow_rejected=True))
+                (await self.store.get_events(missing_events, allow_rejected=True))
             )
 
         # check for events which were in the wrong room.
@@ -677,12 +671,14 @@ class FederationHandler(BaseHandler):
                 bad_room_id,
                 room_id,
             )
+
             del fetched_events[bad_event_id]
 
         return fetched_events
 
-    @defer.inlineCallbacks
-    def _process_received_pdu(self, origin, event, state):
+    async def _process_received_pdu(
+        self, origin: str, event: EventBase, state: Optional[Iterable[EventBase]],
+    ):
         """ Called when we have a new pdu. We need to do auth checks and put it
         through the StateHandler.
 
@@ -701,15 +697,15 @@ class FederationHandler(BaseHandler):
         logger.debug("[%s %s] Processing event: %s", room_id, event_id, event)
 
         try:
-            context = yield self._handle_new_event(origin, event, state=state)
+            context = await self._handle_new_event(origin, event, state=state)
         except AuthError as e:
             raise FederationError("ERROR", e.code, e.msg, affected=event.event_id)
 
-        room = yield self.store.get_room(room_id)
+        room = await self.store.get_room(room_id)
 
         if not room:
             try:
-                yield self.store.store_room(
+                await self.store.store_room(
                     room_id=room_id, room_creator_user_id="", is_public=False
                 )
             except StoreError:
@@ -722,11 +718,11 @@ class FederationHandler(BaseHandler):
                 # changing their profile info.
                 newly_joined = True
 
-                prev_state_ids = yield context.get_prev_state_ids(self.store)
+                prev_state_ids = await context.get_prev_state_ids(self.store)
 
                 prev_state_id = prev_state_ids.get((event.type, event.state_key))
                 if prev_state_id:
-                    prev_state = yield self.store.get_event(
+                    prev_state = await self.store.get_event(
                         prev_state_id, allow_none=True
                     )
                     if prev_state and prev_state.membership == Membership.JOIN:
@@ -734,11 +730,10 @@ class FederationHandler(BaseHandler):
 
                 if newly_joined:
                     user = UserID.from_string(event.state_key)
-                    yield self.user_joined_room(user, room_id)
+                    await self.user_joined_room(user, room_id)
 
     @log_function
-    @defer.inlineCallbacks
-    def backfill(self, dest, room_id, limit, extremities):
+    async def backfill(self, dest, room_id, limit, extremities):
         """ Trigger a backfill request to `dest` for the given `room_id`
 
         This will attempt to get more events from the remote. If the other side
@@ -755,7 +750,7 @@ class FederationHandler(BaseHandler):
         if dest == self.server_name:
             raise SynapseError(400, "Can't backfill from self.")
 
-        events = yield self.federation_client.backfill(
+        events = await self.federation_client.backfill(
             dest, room_id, limit=limit, extremities=extremities
         )
 
@@ -770,7 +765,7 @@ class FederationHandler(BaseHandler):
         #     self._sanity_check_event(ev)
 
         # Don't bother processing events we already have.
-        seen_events = yield self.store.have_events_in_timeline(
+        seen_events = await self.store.have_events_in_timeline(
             set(e.event_id for e in events)
         )
 
@@ -796,7 +791,7 @@ class FederationHandler(BaseHandler):
         state_events = {}
         events_to_state = {}
         for e_id in edges:
-            state, auth = yield self._get_state_for_room(
+            state, auth = await self._get_state_for_room(
                 destination=dest, room_id=room_id, event_id=e_id
             )
             auth_events.update({a.event_id: a for a in auth})
@@ -840,7 +835,7 @@ class FederationHandler(BaseHandler):
                 )
             )
 
-        yield self._handle_new_events(dest, ev_infos, backfilled=True)
+        await self._handle_new_events(dest, ev_infos, backfilled=True)
 
         # Step 2: Persist the rest of the events in the chunk one by one
         events.sort(key=lambda e: e.depth)
@@ -856,16 +851,15 @@ class FederationHandler(BaseHandler):
             # We store these one at a time since each event depends on the
             # previous to work out the state.
             # TODO: We can probably do something more clever here.
-            yield self._handle_new_event(dest, event, backfilled=True)
+            await self._handle_new_event(dest, event, backfilled=True)
 
         return events
 
-    @defer.inlineCallbacks
-    def maybe_backfill(self, room_id, current_depth):
+    async def maybe_backfill(self, room_id, current_depth):
         """Checks the database to see if we should backfill before paginating,
         and if so do.
         """
-        extremities = yield self.store.get_oldest_events_with_depth_in_room(room_id)
+        extremities = await self.store.get_oldest_events_with_depth_in_room(room_id)
 
         if not extremities:
             logger.debug("Not backfilling as no extremeties found.")
@@ -897,15 +891,17 @@ class FederationHandler(BaseHandler):
         #   state *before* the event, ignoring the special casing certain event
         #   types have.
 
-        forward_events = yield self.store.get_successor_events(list(extremities))
+        forward_events = await self.store.get_successor_events(list(extremities))
 
-        extremities_events = yield self.store.get_events(
-            forward_events, check_redacted=False, get_prev_content=False
+        extremities_events = await self.store.get_events(
+            forward_events,
+            redact_behaviour=EventRedactBehaviour.AS_IS,
+            get_prev_content=False,
         )
 
         # We set `check_history_visibility_only` as we might otherwise get false
         # positives from users having been erased.
-        filtered_extremities = yield filter_events_for_server(
+        filtered_extremities = await filter_events_for_server(
             self.storage,
             self.server_name,
             list(extremities_events.values()),
@@ -935,7 +931,7 @@ class FederationHandler(BaseHandler):
         # First we try hosts that are already in the room
         # TODO: HEURISTIC ALERT.
 
-        curr_state = yield self.state_handler.get_current_state(room_id)
+        curr_state = await self.state_handler.get_current_state(room_id)
 
         def get_domains_from_state(state):
             """Get joined domains from state
@@ -974,12 +970,11 @@ class FederationHandler(BaseHandler):
             domain for domain, depth in curr_domains if domain != self.server_name
         ]
 
-        @defer.inlineCallbacks
-        def try_backfill(domains):
+        async def try_backfill(domains):
             # TODO: Should we try multiple of these at a time?
             for dom in domains:
                 try:
-                    yield self.backfill(
+                    await self.backfill(
                         dom, room_id, limit=100, extremities=extremities
                     )
                     # If this succeeded then we probably already have the
@@ -1010,7 +1005,7 @@ class FederationHandler(BaseHandler):
 
             return False
 
-        success = yield try_backfill(likely_domains)
+        success = await try_backfill(likely_domains)
         if success:
             return True
 
@@ -1024,7 +1019,7 @@ class FederationHandler(BaseHandler):
 
         logger.debug("calling resolve_state_groups in _maybe_backfill")
         resolve = preserve_fn(self.state_handler.resolve_state_groups_for_events)
-        states = yield make_deferred_yieldable(
+        states = await make_deferred_yieldable(
             defer.gatherResults(
                 [resolve(room_id, [e]) for e in event_ids], consumeErrors=True
             )
@@ -1034,7 +1029,7 @@ class FederationHandler(BaseHandler):
         # event_ids.
         states = dict(zip(event_ids, [s.state for s in states]))
 
-        state_map = yield self.store.get_events(
+        state_map = await self.store.get_events(
             [e_id for ids in itervalues(states) for e_id in itervalues(ids)],
             get_prev_content=False,
         )
@@ -1050,7 +1045,7 @@ class FederationHandler(BaseHandler):
         for e_id, _ in sorted_extremeties_tuple:
             likely_domains = get_domains_from_state(states[e_id])
 
-            success = yield try_backfill(
+            success = await try_backfill(
                 [dom for dom, _ in likely_domains if dom not in tried_domains]
             )
             if success:
@@ -1060,8 +1055,7 @@ class FederationHandler(BaseHandler):
 
         return False
 
-    @defer.inlineCallbacks
-    def _get_events_and_persist(
+    async def _get_events_and_persist(
         self, destination: str, room_id: str, events: Iterable[str]
     ):
         """Fetch the given events from a server, and persist them as outliers.
@@ -1069,7 +1063,7 @@ class FederationHandler(BaseHandler):
         Logs a warning if we can't find the given event.
         """
 
-        room_version = yield self.store.get_room_version(room_id)
+        room_version = await self.store.get_room_version(room_id)
 
         event_infos = []
 
@@ -1105,9 +1099,9 @@ class FederationHandler(BaseHandler):
                         e,
                     )
 
-        yield concurrently_execute(get_event, events, 5)
+        await concurrently_execute(get_event, events, 5)
 
-        yield self._handle_new_events(
+        await self._handle_new_events(
             destination, event_infos,
         )
 
@@ -1250,7 +1244,7 @@ class FederationHandler(BaseHandler):
             # Check whether this room is the result of an upgrade of a room we already know
             # about. If so, migrate over user information
             predecessor = yield self.store.get_room_predecessor(room_id)
-            if not predecessor:
+            if not predecessor or not isinstance(predecessor.get("room_id"), str):
                 return
             old_room_id = predecessor["room_id"]
             logger.debug(
@@ -1278,8 +1272,7 @@ class FederationHandler(BaseHandler):
 
         return True
 
-    @defer.inlineCallbacks
-    def _handle_queued_pdus(self, room_queue):
+    async def _handle_queued_pdus(self, room_queue):
         """Process PDUs which got queued up while we were busy send_joining.
 
         Args:
@@ -1295,7 +1288,7 @@ class FederationHandler(BaseHandler):
                     p.room_id,
                 )
                 with nested_logging_context(p.event_id):
-                    yield self.on_receive_pdu(origin, p, sent_to_us_directly=True)
+                    await self.on_receive_pdu(origin, p, sent_to_us_directly=True)
             except Exception as e:
                 logger.warning(
                     "Error handling queued PDU %s from %s: %s", p.event_id, origin, e
@@ -1493,7 +1486,7 @@ class FederationHandler(BaseHandler):
     @defer.inlineCallbacks
     def do_remotely_reject_invite(self, target_hosts, room_id, user_id, content):
         origin, event, event_format_version = yield self._make_and_verify_event(
-            target_hosts, room_id, user_id, "leave", content=content,
+            target_hosts, room_id, user_id, "leave", content=content
         )
         # Mark as outlier as we don't have any state for this event; we're not
         # even in the room.
@@ -2854,7 +2847,7 @@ class FederationHandler(BaseHandler):
                 room_id=room_id, user_id=user.to_string(), change="joined"
             )
         else:
-            return user_joined_room(self.distributor, user, room_id)
+            return defer.succeed(user_joined_room(self.distributor, user, room_id))
 
     @defer.inlineCallbacks
     def get_room_complexity(self, remote_room_hosts, room_id):
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 81dce96f4b..44ec3e66ae 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -26,7 +26,7 @@ from synapse.streams.config import PaginationConfig
 from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
 from synapse.util.async_helpers import concurrently_execute
-from synapse.util.caches.snapshot_cache import SnapshotCache
+from synapse.util.caches.response_cache import ResponseCache
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
@@ -41,7 +41,7 @@ class InitialSyncHandler(BaseHandler):
         self.state = hs.get_state_handler()
         self.clock = hs.get_clock()
         self.validator = EventValidator()
-        self.snapshot_cache = SnapshotCache()
+        self.snapshot_cache = ResponseCache(hs, "initial_sync_cache")
         self._event_serializer = hs.get_event_client_serializer()
         self.storage = hs.get_storage()
         self.state_store = self.storage.state
@@ -79,21 +79,17 @@ class InitialSyncHandler(BaseHandler):
             as_client_event,
             include_archived,
         )
-        now_ms = self.clock.time_msec()
-        result = self.snapshot_cache.get(now_ms, key)
-        if result is not None:
-            return result
 
-        return self.snapshot_cache.set(
-            now_ms,
+        return self.snapshot_cache.wrap(
             key,
-            self._snapshot_all_rooms(
-                user_id, pagin_config, as_client_event, include_archived
-            ),
+            self._snapshot_all_rooms,
+            user_id,
+            pagin_config,
+            as_client_event,
+            include_archived,
         )
 
-    @defer.inlineCallbacks
-    def _snapshot_all_rooms(
+    async def _snapshot_all_rooms(
         self,
         user_id=None,
         pagin_config=None,
@@ -105,7 +101,7 @@ class InitialSyncHandler(BaseHandler):
         if include_archived:
             memberships.append(Membership.LEAVE)
 
-        room_list = yield self.store.get_rooms_for_user_where_membership_is(
+        room_list = await self.store.get_rooms_for_user_where_membership_is(
             user_id=user_id, membership_list=memberships
         )
 
@@ -113,33 +109,32 @@ class InitialSyncHandler(BaseHandler):
 
         rooms_ret = []
 
-        now_token = yield self.hs.get_event_sources().get_current_token()
+        now_token = await self.hs.get_event_sources().get_current_token()
 
         presence_stream = self.hs.get_event_sources().sources["presence"]
         pagination_config = PaginationConfig(from_token=now_token)
-        presence, _ = yield presence_stream.get_pagination_rows(
+        presence, _ = await presence_stream.get_pagination_rows(
             user, pagination_config.get_source_config("presence"), None
         )
 
         receipt_stream = self.hs.get_event_sources().sources["receipt"]
-        receipt, _ = yield receipt_stream.get_pagination_rows(
+        receipt, _ = await receipt_stream.get_pagination_rows(
             user, pagination_config.get_source_config("receipt"), None
         )
 
-        tags_by_room = yield self.store.get_tags_for_user(user_id)
+        tags_by_room = await self.store.get_tags_for_user(user_id)
 
-        account_data, account_data_by_room = yield self.store.get_account_data_for_user(
+        account_data, account_data_by_room = await self.store.get_account_data_for_user(
             user_id
         )
 
-        public_room_ids = yield self.store.get_public_room_ids()
+        public_room_ids = await self.store.get_public_room_ids()
 
         limit = pagin_config.limit
         if limit is None:
             limit = 10
 
-        @defer.inlineCallbacks
-        def handle_room(event):
+        async def handle_room(event):
             d = {
                 "room_id": event.room_id,
                 "membership": event.membership,
@@ -152,8 +147,8 @@ class InitialSyncHandler(BaseHandler):
                 time_now = self.clock.time_msec()
                 d["inviter"] = event.sender
 
-                invite_event = yield self.store.get_event(event.event_id)
-                d["invite"] = yield self._event_serializer.serialize_event(
+                invite_event = await self.store.get_event(event.event_id)
+                d["invite"] = await self._event_serializer.serialize_event(
                     invite_event, time_now, as_client_event
                 )
 
@@ -177,7 +172,7 @@ class InitialSyncHandler(BaseHandler):
                         lambda states: states[event.event_id]
                     )
 
-                (messages, token), current_state = yield make_deferred_yieldable(
+                (messages, token), current_state = await make_deferred_yieldable(
                     defer.gatherResults(
                         [
                             run_in_background(
@@ -191,7 +186,7 @@ class InitialSyncHandler(BaseHandler):
                     )
                 ).addErrback(unwrapFirstError)
 
-                messages = yield filter_events_for_client(
+                messages = await filter_events_for_client(
                     self.storage, user_id, messages
                 )
 
@@ -201,7 +196,7 @@ class InitialSyncHandler(BaseHandler):
 
                 d["messages"] = {
                     "chunk": (
-                        yield self._event_serializer.serialize_events(
+                        await self._event_serializer.serialize_events(
                             messages, time_now=time_now, as_client_event=as_client_event
                         )
                     ),
@@ -209,7 +204,7 @@ class InitialSyncHandler(BaseHandler):
                     "end": end_token.to_string(),
                 }
 
-                d["state"] = yield self._event_serializer.serialize_events(
+                d["state"] = await self._event_serializer.serialize_events(
                     current_state.values(),
                     time_now=time_now,
                     as_client_event=as_client_event,
@@ -232,7 +227,7 @@ class InitialSyncHandler(BaseHandler):
             except Exception:
                 logger.exception("Failed to get snapshot")
 
-        yield concurrently_execute(handle_room, room_list, 10)
+        await concurrently_execute(handle_room, room_list, 10)
 
         account_data_events = []
         for account_data_type, content in account_data.items():
@@ -256,8 +251,7 @@ class InitialSyncHandler(BaseHandler):
 
         return ret
 
-    @defer.inlineCallbacks
-    def room_initial_sync(self, requester, room_id, pagin_config=None):
+    async def room_initial_sync(self, requester, room_id, pagin_config=None):
         """Capture the a snapshot of a room. If user is currently a member of
         the room this will be what is currently in the room. If the user left
         the room this will be what was in the room when they left.
@@ -274,32 +268,32 @@ class InitialSyncHandler(BaseHandler):
             A JSON serialisable dict with the snapshot of the room.
         """
 
-        blocked = yield self.store.is_room_blocked(room_id)
+        blocked = await self.store.is_room_blocked(room_id)
         if blocked:
             raise SynapseError(403, "This room has been blocked on this server")
 
         user_id = requester.user.to_string()
 
-        membership, member_event_id = yield self._check_in_room_or_world_readable(
+        membership, member_event_id = await self._check_in_room_or_world_readable(
             room_id, user_id
         )
         is_peeking = member_event_id is None
 
         if membership == Membership.JOIN:
-            result = yield self._room_initial_sync_joined(
+            result = await self._room_initial_sync_joined(
                 user_id, room_id, pagin_config, membership, is_peeking
             )
         elif membership == Membership.LEAVE:
-            result = yield self._room_initial_sync_parted(
+            result = await self._room_initial_sync_parted(
                 user_id, room_id, pagin_config, membership, member_event_id, is_peeking
             )
 
         account_data_events = []
-        tags = yield self.store.get_tags_for_room(user_id, room_id)
+        tags = await self.store.get_tags_for_room(user_id, room_id)
         if tags:
             account_data_events.append({"type": "m.tag", "content": {"tags": tags}})
 
-        account_data = yield self.store.get_account_data_for_room(user_id, room_id)
+        account_data = await self.store.get_account_data_for_room(user_id, room_id)
         for account_data_type, content in account_data.items():
             account_data_events.append({"type": account_data_type, "content": content})
 
@@ -307,11 +301,10 @@ class InitialSyncHandler(BaseHandler):
 
         return result
 
-    @defer.inlineCallbacks
-    def _room_initial_sync_parted(
+    async def _room_initial_sync_parted(
         self, user_id, room_id, pagin_config, membership, member_event_id, is_peeking
     ):
-        room_state = yield self.state_store.get_state_for_events([member_event_id])
+        room_state = await self.state_store.get_state_for_events([member_event_id])
 
         room_state = room_state[member_event_id]
 
@@ -319,13 +312,13 @@ class InitialSyncHandler(BaseHandler):
         if limit is None:
             limit = 10
 
-        stream_token = yield self.store.get_stream_token_for_event(member_event_id)
+        stream_token = await self.store.get_stream_token_for_event(member_event_id)
 
-        messages, token = yield self.store.get_recent_events_for_room(
+        messages, token = await self.store.get_recent_events_for_room(
             room_id, limit=limit, end_token=stream_token
         )
 
-        messages = yield filter_events_for_client(
+        messages = await filter_events_for_client(
             self.storage, user_id, messages, is_peeking=is_peeking
         )
 
@@ -339,13 +332,13 @@ class InitialSyncHandler(BaseHandler):
             "room_id": room_id,
             "messages": {
                 "chunk": (
-                    yield self._event_serializer.serialize_events(messages, time_now)
+                    await self._event_serializer.serialize_events(messages, time_now)
                 ),
                 "start": start_token.to_string(),
                 "end": end_token.to_string(),
             },
             "state": (
-                yield self._event_serializer.serialize_events(
+                await self._event_serializer.serialize_events(
                     room_state.values(), time_now
                 )
             ),
@@ -353,19 +346,18 @@ class InitialSyncHandler(BaseHandler):
             "receipts": [],
         }
 
-    @defer.inlineCallbacks
-    def _room_initial_sync_joined(
+    async def _room_initial_sync_joined(
         self, user_id, room_id, pagin_config, membership, is_peeking
     ):
-        current_state = yield self.state.get_current_state(room_id=room_id)
+        current_state = await self.state.get_current_state(room_id=room_id)
 
         # TODO: These concurrently
         time_now = self.clock.time_msec()
-        state = yield self._event_serializer.serialize_events(
+        state = await self._event_serializer.serialize_events(
             current_state.values(), time_now
         )
 
-        now_token = yield self.hs.get_event_sources().get_current_token()
+        now_token = await self.hs.get_event_sources().get_current_token()
 
         limit = pagin_config.limit if pagin_config else None
         if limit is None:
@@ -380,28 +372,26 @@ class InitialSyncHandler(BaseHandler):
 
         presence_handler = self.hs.get_presence_handler()
 
-        @defer.inlineCallbacks
-        def get_presence():
+        async def get_presence():
             # If presence is disabled, return an empty list
             if not self.hs.config.use_presence:
                 return []
 
-            states = yield presence_handler.get_states(
+            states = await presence_handler.get_states(
                 [m.user_id for m in room_members], as_event=True
             )
 
             return states
 
-        @defer.inlineCallbacks
-        def get_receipts():
-            receipts = yield self.store.get_linearized_receipts_for_room(
+        async def get_receipts():
+            receipts = await self.store.get_linearized_receipts_for_room(
                 room_id, to_key=now_token.receipt_key
             )
             if not receipts:
                 receipts = []
             return receipts
 
-        presence, receipts, (messages, token) = yield make_deferred_yieldable(
+        presence, receipts, (messages, token) = await make_deferred_yieldable(
             defer.gatherResults(
                 [
                     run_in_background(get_presence),
@@ -417,7 +407,7 @@ class InitialSyncHandler(BaseHandler):
             ).addErrback(unwrapFirstError)
         )
 
-        messages = yield filter_events_for_client(
+        messages = await filter_events_for_client(
             self.storage, user_id, messages, is_peeking=is_peeking
         )
 
@@ -430,7 +420,7 @@ class InitialSyncHandler(BaseHandler):
             "room_id": room_id,
             "messages": {
                 "chunk": (
-                    yield self._event_serializer.serialize_events(messages, time_now)
+                    await self._event_serializer.serialize_events(messages, time_now)
                 ),
                 "start": start_token.to_string(),
                 "end": end_token.to_string(),
@@ -444,18 +434,17 @@ class InitialSyncHandler(BaseHandler):
 
         return ret
 
-    @defer.inlineCallbacks
-    def _check_in_room_or_world_readable(self, room_id, user_id):
+    async def _check_in_room_or_world_readable(self, room_id, user_id):
         try:
             # check_user_was_in_room will return the most recent membership
             # event for the user if:
             #  * The user is a non-guest user, and was ever in the room
             #  * The user is a guest user, and has joined the room
             # else it will throw.
-            member_event = yield self.auth.check_user_was_in_room(room_id, user_id)
+            member_event = await self.auth.check_user_was_in_room(room_id, user_id)
             return member_event.membership, member_event.event_id
         except AuthError:
-            visibility = yield self.state_handler.get_current_state(
+            visibility = await self.state_handler.get_current_state(
                 room_id, EventTypes.RoomHistoryVisibility, ""
             )
             if (
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 54fa216d83..bf9add7fe2 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -46,6 +46,7 @@ from synapse.events.validator import EventValidator
 from synapse.logging.context import run_in_background
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.storage.state import StateFilter
 from synapse.types import RoomAlias, UserID, create_requester
 from synapse.util.async_helpers import Linearizer
@@ -875,7 +876,7 @@ class EventCreationHandler(object):
             if event.type == EventTypes.Redaction:
                 original_event = yield self.store.get_event(
                     event.redacts,
-                    check_redacted=False,
+                    redact_behaviour=EventRedactBehaviour.AS_IS,
                     get_prev_content=False,
                     allow_rejected=False,
                     allow_none=True,
@@ -952,7 +953,7 @@ class EventCreationHandler(object):
         if event.type == EventTypes.Redaction:
             original_event = yield self.store.get_event(
                 event.redacts,
-                check_redacted=False,
+                redact_behaviour=EventRedactBehaviour.AS_IS,
                 get_prev_content=False,
                 allow_rejected=False,
                 allow_none=True,
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 8514ddc600..00a6afc963 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -280,8 +280,7 @@ class PaginationHandler(object):
 
             await self.storage.purge_events.purge_room(room_id)
 
-    @defer.inlineCallbacks
-    def get_messages(
+    async def get_messages(
         self,
         requester,
         room_id=None,
@@ -307,7 +306,7 @@ class PaginationHandler(object):
             room_token = pagin_config.from_token.room_key
         else:
             pagin_config.from_token = (
-                yield self.hs.get_event_sources().get_current_token_for_pagination()
+                await self.hs.get_event_sources().get_current_token_for_pagination()
             )
             room_token = pagin_config.from_token.room_key
 
@@ -319,11 +318,11 @@ class PaginationHandler(object):
 
         source_config = pagin_config.get_source_config("room")
 
-        with (yield self.pagination_lock.read(room_id)):
+        with (await self.pagination_lock.read(room_id)):
             (
                 membership,
                 member_event_id,
-            ) = yield self.auth.check_in_room_or_world_readable(room_id, user_id)
+            ) = await self.auth.check_in_room_or_world_readable(room_id, user_id)
 
             if source_config.direction == "b":
                 # if we're going backwards, we might need to backfill. This
@@ -331,7 +330,7 @@ class PaginationHandler(object):
                 if room_token.topological:
                     max_topo = room_token.topological
                 else:
-                    max_topo = yield self.store.get_max_topological_token(
+                    max_topo = await self.store.get_max_topological_token(
                         room_id, room_token.stream
                     )
 
@@ -339,18 +338,18 @@ class PaginationHandler(object):
                     # If they have left the room then clamp the token to be before
                     # they left the room, to save the effort of loading from the
                     # database.
-                    leave_token = yield self.store.get_topological_token_for_event(
+                    leave_token = await self.store.get_topological_token_for_event(
                         member_event_id
                     )
                     leave_token = RoomStreamToken.parse(leave_token)
                     if leave_token.topological < max_topo:
                         source_config.from_key = str(leave_token)
 
-                yield self.hs.get_handlers().federation_handler.maybe_backfill(
+                await self.hs.get_handlers().federation_handler.maybe_backfill(
                     room_id, max_topo
                 )
 
-            events, next_key = yield self.store.paginate_room_events(
+            events, next_key = await self.store.paginate_room_events(
                 room_id=room_id,
                 from_key=source_config.from_key,
                 to_key=source_config.to_key,
@@ -365,7 +364,7 @@ class PaginationHandler(object):
             if event_filter:
                 events = event_filter.filter(events)
 
-            events = yield filter_events_for_client(
+            events = await filter_events_for_client(
                 self.storage, user_id, events, is_peeking=(member_event_id is None)
             )
 
@@ -385,19 +384,19 @@ class PaginationHandler(object):
                 (EventTypes.Member, event.sender) for event in events
             )
 
-            state_ids = yield self.state_store.get_state_ids_for_event(
+            state_ids = await self.state_store.get_state_ids_for_event(
                 events[0].event_id, state_filter=state_filter
             )
 
             if state_ids:
-                state = yield self.store.get_events(list(state_ids.values()))
+                state = await self.store.get_events(list(state_ids.values()))
                 state = state.values()
 
         time_now = self.clock.time_msec()
 
         chunk = {
             "chunk": (
-                yield self._event_serializer.serialize_events(
+                await self._event_serializer.serialize_events(
                     events, time_now, as_client_event=as_client_event
                 )
             ),
@@ -406,7 +405,7 @@ class PaginationHandler(object):
         }
 
         if state:
-            chunk["state"] = yield self._event_serializer.serialize_events(
+            chunk["state"] = await self._event_serializer.serialize_events(
                 state, time_now, as_client_event=as_client_event
             )
 
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 1e5a4613c9..f9579d69ee 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -295,12 +295,16 @@ class BaseProfileHandler(BaseHandler):
                 be found to be in any room the server is in, and therefore the query
                 is denied.
         """
+
         # Implementation of MSC1301: don't allow looking up profiles if the
         # requester isn't in the same room as the target. We expect requester to
         # be None when this function is called outside of a profile query, e.g.
         # when building a membership event. In this case, we must allow the
         # lookup.
-        if not self.hs.config.require_auth_for_profile_requests or not requester:
+        if (
+            not self.hs.config.limit_profile_requests_to_users_who_share_rooms
+            or not requester
+        ):
             return
 
         # Always allow the user to query their own profile.
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 60b8bbc7a5..d3a1a7b4a6 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -1011,15 +1011,3 @@ class RoomEventSource(object):
 
     def get_current_key_for_room(self, room_id):
         return self.store.get_room_events_max_id(room_id)
-
-    @defer.inlineCallbacks
-    def get_pagination_rows(self, user, config, key):
-        events, next_key = yield self.store.paginate_room_events(
-            room_id=key,
-            from_key=config.from_key,
-            to_key=config.to_key,
-            direction=config.direction,
-            limit=config.limit,
-        )
-
-        return (events, next_key)
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index cc9e6b9bd0..0082f85c26 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -13,20 +13,36 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import re
+from typing import Tuple
 
 import attr
 import saml2
+import saml2.response
 from saml2.client import Saml2Client
 
 from synapse.api.errors import SynapseError
+from synapse.config import ConfigError
 from synapse.http.servlet import parse_string
 from synapse.rest.client.v1.login import SSOAuthHandler
-from synapse.types import UserID, map_username_to_mxid_localpart
+from synapse.types import (
+    UserID,
+    map_username_to_mxid_localpart,
+    mxid_localpart_allowed_characters,
+)
 from synapse.util.async_helpers import Linearizer
 
 logger = logging.getLogger(__name__)
 
 
+@attr.s
+class Saml2SessionData:
+    """Data we track about SAML2 sessions"""
+
+    # time the session was created, in milliseconds
+    creation_time = attr.ib()
+
+
 class SamlHandler:
     def __init__(self, hs):
         self._saml_client = Saml2Client(hs.config.saml2_sp_config)
@@ -37,11 +53,14 @@ class SamlHandler:
         self._datastore = hs.get_datastore()
         self._hostname = hs.hostname
         self._saml2_session_lifetime = hs.config.saml2_session_lifetime
-        self._mxid_source_attribute = hs.config.saml2_mxid_source_attribute
         self._grandfathered_mxid_source_attribute = (
             hs.config.saml2_grandfathered_mxid_source_attribute
         )
-        self._mxid_mapper = hs.config.saml2_mxid_mapper
+
+        # plugin to do custom mapping from saml response to mxid
+        self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
+            hs.config.saml2_user_mapping_provider_config
+        )
 
         # identifier for the external_ids table
         self._auth_provider_id = "saml"
@@ -118,22 +137,10 @@ class SamlHandler:
             remote_user_id = saml2_auth.ava["uid"][0]
         except KeyError:
             logger.warning("SAML2 response lacks a 'uid' attestation")
-            raise SynapseError(400, "uid not in SAML2 response")
-
-        try:
-            mxid_source = saml2_auth.ava[self._mxid_source_attribute][0]
-        except KeyError:
-            logger.warning(
-                "SAML2 response lacks a '%s' attestation", self._mxid_source_attribute
-            )
-            raise SynapseError(
-                400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
-            )
+            raise SynapseError(400, "'uid' not in SAML2 response")
 
         self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
 
-        displayName = saml2_auth.ava.get("displayName", [None])[0]
-
         with (await self._mapping_lock.queue(self._auth_provider_id)):
             # first of all, check if we already have a mapping for this user
             logger.info(
@@ -173,22 +180,46 @@ class SamlHandler:
                     )
                     return registered_user_id
 
-            # figure out a new mxid for this user
-            base_mxid_localpart = self._mxid_mapper(mxid_source)
+            # Map saml response to user attributes using the configured mapping provider
+            for i in range(1000):
+                attribute_dict = self._user_mapping_provider.saml_response_to_user_attributes(
+                    saml2_auth, i
+                )
+
+                logger.debug(
+                    "Retrieved SAML attributes from user mapping provider: %s "
+                    "(attempt %d)",
+                    attribute_dict,
+                    i,
+                )
+
+                localpart = attribute_dict.get("mxid_localpart")
+                if not localpart:
+                    logger.error(
+                        "SAML mapping provider plugin did not return a "
+                        "mxid_localpart object"
+                    )
+                    raise SynapseError(500, "Error parsing SAML2 response")
 
-            suffix = 0
-            while True:
-                localpart = base_mxid_localpart + (str(suffix) if suffix else "")
+                displayname = attribute_dict.get("displayname")
+
+                # Check if this mxid already exists
                 if not await self._datastore.get_users_by_id_case_insensitive(
                     UserID(localpart, self._hostname).to_string()
                 ):
+                    # This mxid is free
                     break
-                suffix += 1
-            logger.info("Allocating mxid for new user with localpart %s", localpart)
+            else:
+                # Unable to generate a username in 1000 iterations
+                # Break and return error to the user
+                raise SynapseError(
+                    500, "Unable to generate a Matrix ID from the SAML response"
+                )
 
             registered_user_id = await self._registration_handler.register_user(
-                localpart=localpart, default_display_name=displayName
+                localpart=localpart, default_display_name=displayname
             )
+
             await self._datastore.record_user_external_id(
                 self._auth_provider_id, remote_user_id, registered_user_id
             )
@@ -205,9 +236,120 @@ class SamlHandler:
             del self._outstanding_requests_dict[reqid]
 
 
+DOT_REPLACE_PATTERN = re.compile(
+    ("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
+)
+
+
+def dot_replace_for_mxid(username: str) -> str:
+    username = username.lower()
+    username = DOT_REPLACE_PATTERN.sub(".", username)
+
+    # regular mxids aren't allowed to start with an underscore either
+    username = re.sub("^_", "", username)
+    return username
+
+
+MXID_MAPPER_MAP = {
+    "hexencode": map_username_to_mxid_localpart,
+    "dotreplace": dot_replace_for_mxid,
+}
+
+
 @attr.s
-class Saml2SessionData:
-    """Data we track about SAML2 sessions"""
+class SamlConfig(object):
+    mxid_source_attribute = attr.ib()
+    mxid_mapper = attr.ib()
 
-    # time the session was created, in milliseconds
-    creation_time = attr.ib()
+
+class DefaultSamlMappingProvider(object):
+    __version__ = "0.0.1"
+
+    def __init__(self, parsed_config: SamlConfig):
+        """The default SAML user mapping provider
+
+        Args:
+            parsed_config: Module configuration
+        """
+        self._mxid_source_attribute = parsed_config.mxid_source_attribute
+        self._mxid_mapper = parsed_config.mxid_mapper
+
+    def saml_response_to_user_attributes(
+        self, saml_response: saml2.response.AuthnResponse, failures: int = 0,
+    ) -> dict:
+        """Maps some text from a SAML response to attributes of a new user
+
+        Args:
+            saml_response: A SAML auth response object
+
+            failures: How many times a call to this function with this
+                saml_response has resulted in a failure
+
+        Returns:
+            dict: A dict containing new user attributes. Possible keys:
+                * mxid_localpart (str): Required. The localpart of the user's mxid
+                * displayname (str): The displayname of the user
+        """
+        try:
+            mxid_source = saml_response.ava[self._mxid_source_attribute][0]
+        except KeyError:
+            logger.warning(
+                "SAML2 response lacks a '%s' attestation", self._mxid_source_attribute,
+            )
+            raise SynapseError(
+                400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
+            )
+
+        # Use the configured mapper for this mxid_source
+        base_mxid_localpart = self._mxid_mapper(mxid_source)
+
+        # Append suffix integer if last call to this function failed to produce
+        # a usable mxid
+        localpart = base_mxid_localpart + (str(failures) if failures else "")
+
+        # Retrieve the display name from the saml response
+        # If displayname is None, the mxid_localpart will be used instead
+        displayname = saml_response.ava.get("displayName", [None])[0]
+
+        return {
+            "mxid_localpart": localpart,
+            "displayname": displayname,
+        }
+
+    @staticmethod
+    def parse_config(config: dict) -> SamlConfig:
+        """Parse the dict provided by the homeserver's config
+        Args:
+            config: A dictionary containing configuration options for this provider
+        Returns:
+            SamlConfig: A custom config object for this module
+        """
+        # Parse config options and use defaults where necessary
+        mxid_source_attribute = config.get("mxid_source_attribute", "uid")
+        mapping_type = config.get("mxid_mapping", "hexencode")
+
+        # Retrieve the associating mapping function
+        try:
+            mxid_mapper = MXID_MAPPER_MAP[mapping_type]
+        except KeyError:
+            raise ConfigError(
+                "saml2_config.user_mapping_provider.config: '%s' is not a valid "
+                "mxid_mapping value" % (mapping_type,)
+            )
+
+        return SamlConfig(mxid_source_attribute, mxid_mapper)
+
+    @staticmethod
+    def get_saml_attributes(config: SamlConfig) -> Tuple[set, set]:
+        """Returns the required attributes of a SAML
+
+        Args:
+            config: A SamlConfig object containing configuration params for this provider
+
+        Returns:
+            tuple[set,set]: The first set equates to the saml auth response
+                attributes that are required for the module to function, whereas the
+                second set consists of those attributes which can be used if
+                available, but are not necessary
+        """
+        return {"uid", config.mxid_source_attribute}, {"displayName"}
diff --git a/synapse/handlers/search.py b/synapse/handlers/search.py
index 56ed262a1f..ef750d1497 100644
--- a/synapse/handlers/search.py
+++ b/synapse/handlers/search.py
@@ -21,7 +21,7 @@ from unpaddedbase64 import decode_base64, encode_base64
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import SynapseError
+from synapse.api.errors import NotFoundError, SynapseError
 from synapse.api.filtering import Filter
 from synapse.storage.state import StateFilter
 from synapse.visibility import filter_events_for_client
@@ -37,6 +37,7 @@ class SearchHandler(BaseHandler):
         self._event_serializer = hs.get_event_client_serializer()
         self.storage = hs.get_storage()
         self.state_store = self.storage.state
+        self.auth = hs.get_auth()
 
     @defer.inlineCallbacks
     def get_old_rooms_from_upgraded_room(self, room_id):
@@ -53,23 +54,38 @@ class SearchHandler(BaseHandler):
             room_id (str): id of the room to search through.
 
         Returns:
-            Deferred[iterable[unicode]]: predecessor room ids
+            Deferred[iterable[str]]: predecessor room ids
         """
 
         historical_room_ids = []
 
-        while True:
-            predecessor = yield self.store.get_room_predecessor(room_id)
+        # The initial room must have been known for us to get this far
+        predecessor = yield self.store.get_room_predecessor(room_id)
 
-            # If no predecessor, assume we've hit a dead end
+        while True:
             if not predecessor:
+                # We have reached the end of the chain of predecessors
+                break
+
+            if not isinstance(predecessor.get("room_id"), str):
+                # This predecessor object is malformed. Exit here
+                break
+
+            predecessor_room_id = predecessor["room_id"]
+
+            # Don't add it to the list until we have checked that we are in the room
+            try:
+                next_predecessor_room = yield self.store.get_room_predecessor(
+                    predecessor_room_id
+                )
+            except NotFoundError:
+                # The predecessor is not a known room, so we are done here
                 break
 
-            # Add predecessor's room ID
-            historical_room_ids.append(predecessor["room_id"])
+            historical_room_ids.append(predecessor_room_id)
 
-            # Scan through the old room for further predecessors
-            room_id = predecessor["room_id"]
+            # And repeat
+            predecessor = next_predecessor_room
 
         return historical_room_ids
 
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index 6f78454322..b635c339ed 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -317,6 +317,3 @@ class TypingNotificationEventSource(object):
 
     def get_current_key(self):
         return self.get_typing_handler()._latest_room_serial
-
-    def get_pagination_rows(self, user, pagination_config, key):
-        return [], pagination_config.from_key
diff --git a/synapse/logging/_terse_json.py b/synapse/logging/_terse_json.py
index 03934956f4..c0b9384189 100644
--- a/synapse/logging/_terse_json.py
+++ b/synapse/logging/_terse_json.py
@@ -171,7 +171,7 @@ class LogProducer(object):
 
     def stopProducing(self):
         self._paused = True
-        self._buffer = None
+        self._buffer = deque()
 
     def resumeProducing(self):
         self._paused = False
diff --git a/synapse/logging/context.py b/synapse/logging/context.py
index 2c1fb9ddac..33b322209d 100644
--- a/synapse/logging/context.py
+++ b/synapse/logging/context.py
@@ -23,6 +23,7 @@ them.
 See doc/log_contexts.rst for details on how this works.
 """
 
+import inspect
 import logging
 import threading
 import types
@@ -404,6 +405,9 @@ class LoggingContext(object):
         """
         current = get_thread_resource_usage()
 
+        # Indicate to mypy that we know that self.usage_start is None.
+        assert self.usage_start is not None
+
         utime_delta = current.ru_utime - self.usage_start.ru_utime
         stime_delta = current.ru_stime - self.usage_start.ru_stime
 
@@ -612,7 +616,8 @@ def run_in_background(f, *args, **kwargs):
 
 
 def make_deferred_yieldable(deferred):
-    """Given a deferred, make it follow the Synapse logcontext rules:
+    """Given a deferred (or coroutine), make it follow the Synapse logcontext
+    rules:
 
     If the deferred has completed (or is not actually a Deferred), essentially
     does nothing (just returns another completed deferred with the
@@ -624,6 +629,13 @@ def make_deferred_yieldable(deferred):
 
     (This is more-or-less the opposite operation to run_in_background.)
     """
+    if inspect.isawaitable(deferred):
+        # If we're given a coroutine we convert it to a deferred so that we
+        # run it and find out if it immediately finishes, it it does then we
+        # don't need to fiddle with log contexts at all and can return
+        # immediately.
+        deferred = defer.ensureDeferred(deferred)
+
     if not isinstance(deferred, defer.Deferred):
         return deferred
 
diff --git a/synapse/server.py b/synapse/server.py
index 2db3dab221..5021068ce0 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -34,6 +34,7 @@ from synapse.api.filtering import Filtering
 from synapse.api.ratelimiting import Ratelimiter
 from synapse.appservice.api import ApplicationServiceApi
 from synapse.appservice.scheduler import ApplicationServiceScheduler
+from synapse.config.homeserver import HomeServerConfig
 from synapse.crypto import context_factory
 from synapse.crypto.keyring import Keyring
 from synapse.events.builder import EventBuilderFactory
@@ -97,6 +98,7 @@ from synapse.server_notices.worker_server_notices_sender import (
 )
 from synapse.state import StateHandler, StateResolutionHandler
 from synapse.storage import DataStores, Storage
+from synapse.storage.engines import create_engine
 from synapse.streams.events import EventSources
 from synapse.util import Clock
 from synapse.util.distributor import Distributor
@@ -209,16 +211,18 @@ class HomeServer(object):
     # instantiated during setup() for future return by get_datastore()
     DATASTORE_CLASS = abc.abstractproperty()
 
-    def __init__(self, hostname, reactor=None, **kwargs):
+    def __init__(self, hostname: str, config: HomeServerConfig, reactor=None, **kwargs):
         """
         Args:
             hostname : The hostname for the server.
+            config: The full config for the homeserver.
         """
         if not reactor:
             from twisted.internet import reactor
 
         self._reactor = reactor
         self.hostname = hostname
+        self.config = config
         self._building = {}
         self._listening_services = []
         self.start_time = None
@@ -229,6 +233,12 @@ class HomeServer(object):
         self.admin_redaction_ratelimiter = Ratelimiter()
         self.registration_ratelimiter = Ratelimiter()
 
+        self.database_engine = create_engine(config.database_config)
+        config.database_config.setdefault("args", {})[
+            "cp_openfun"
+        ] = self.database_engine.on_new_connection
+        self.db_config = config.database_config
+
         self.datastores = None
 
         # Other kwargs are explicit dependencies
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index 0e75e94c6f..5accc071ab 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -32,6 +32,7 @@ from synapse.events import EventBase
 from synapse.events.snapshot import EventContext
 from synapse.logging.utils import log_function
 from synapse.state import v1, v2
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -655,7 +656,7 @@ class StateResolutionStore(object):
 
         return self.store.get_events(
             event_ids,
-            check_redacted=False,
+            redact_behaviour=EventRedactBehaviour.AS_IS,
             get_prev_content=False,
             allow_rejected=allow_rejected,
         )
diff --git a/synapse/storage/data_stores/main/client_ips.py b/synapse/storage/data_stores/main/client_ips.py
index 320c5b0f07..add3037b69 100644
--- a/synapse/storage/data_stores/main/client_ips.py
+++ b/synapse/storage/data_stores/main/client_ips.py
@@ -451,16 +451,18 @@ class ClientIpStore(ClientIpBackgroundUpdateStore):
                 # Technically an access token might not be associated with
                 # a device so we need to check.
                 if device_id:
-                    self.db.simple_upsert_txn(
+                    # this is always an update rather than an upsert: the row should
+                    # already exist, and if it doesn't, that may be because it has been
+                    # deleted, and we don't want to re-create it.
+                    self.db.simple_update_txn(
                         txn,
                         table="devices",
                         keyvalues={"user_id": user_id, "device_id": device_id},
-                        values={
+                        updatevalues={
                             "user_agent": user_agent,
                             "last_seen": last_seen,
                             "ip": ip,
                         },
-                        lock=False,
                     )
             except Exception as e:
                 # Failed to upsert, log and continue
diff --git a/synapse/storage/data_stores/main/end_to_end_keys.py b/synapse/storage/data_stores/main/end_to_end_keys.py
index 38cd0ca9b8..e551606f9d 100644
--- a/synapse/storage/data_stores/main/end_to_end_keys.py
+++ b/synapse/storage/data_stores/main/end_to_end_keys.py
@@ -14,15 +14,18 @@
 # 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 typing import Dict, List
+
 from six import iteritems
 
 from canonicaljson import encode_canonical_json, json
 
+from twisted.enterprise.adbapi import Connection
 from twisted.internet import defer
 
 from synapse.logging.opentracing import log_kv, set_tag, trace
 from synapse.storage._base import SQLBaseStore, db_to_json
-from synapse.util.caches.descriptors import cached
+from synapse.util.caches.descriptors import cached, cachedList
 
 
 class EndToEndKeyWorkerStore(SQLBaseStore):
@@ -271,7 +274,7 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
         Args:
             txn (twisted.enterprise.adbapi.Connection): db connection
             user_id (str): the user whose key is being requested
-            key_type (str): the type of key that is being set: either 'master'
+            key_type (str): the type of key that is being requested: either 'master'
                 for a master key, 'self_signing' for a self-signing key, or
                 'user_signing' for a user-signing key
             from_user_id (str): if specified, signatures made by this user on
@@ -316,8 +319,10 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
         """Returns a user's cross-signing key.
 
         Args:
-            user_id (str): the user whose self-signing key is being requested
-            key_type (str): the type of cross-signing key to get
+            user_id (str): the user whose key is being requested
+            key_type (str): the type of key that is being requested: either 'master'
+                for a master key, 'self_signing' for a self-signing key, or
+                'user_signing' for a user-signing key
             from_user_id (str): if specified, signatures made by this user on
                 the self-signing key will be included in the result
 
@@ -332,6 +337,206 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             from_user_id,
         )
 
+    @cached(num_args=1)
+    def _get_bare_e2e_cross_signing_keys(self, user_id):
+        """Dummy function.  Only used to make a cache for
+        _get_bare_e2e_cross_signing_keys_bulk.
+        """
+        raise NotImplementedError()
+
+    @cachedList(
+        cached_method_name="_get_bare_e2e_cross_signing_keys",
+        list_name="user_ids",
+        num_args=1,
+    )
+    def _get_bare_e2e_cross_signing_keys_bulk(
+        self, user_ids: List[str]
+    ) -> Dict[str, Dict[str, dict]]:
+        """Returns the cross-signing keys for a set of users.  The output of this
+        function should be passed to _get_e2e_cross_signing_signatures_txn if
+        the signatures for the calling user need to be fetched.
+
+        Args:
+            user_ids (list[str]): the users whose keys are being requested
+
+        Returns:
+            dict[str, dict[str, dict]]: mapping from user ID to key type to key
+                data.  If a user's cross-signing keys were not found, either
+                their user ID will not be in the dict, or their user ID will map
+                to None.
+
+        """
+        return self.db.runInteraction(
+            "get_bare_e2e_cross_signing_keys_bulk",
+            self._get_bare_e2e_cross_signing_keys_bulk_txn,
+            user_ids,
+        )
+
+    def _get_bare_e2e_cross_signing_keys_bulk_txn(
+        self, txn: Connection, user_ids: List[str],
+    ) -> Dict[str, Dict[str, dict]]:
+        """Returns the cross-signing keys for a set of users.  The output of this
+        function should be passed to _get_e2e_cross_signing_signatures_txn if
+        the signatures for the calling user need to be fetched.
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            user_ids (list[str]): the users whose keys are being requested
+
+        Returns:
+            dict[str, dict[str, dict]]: mapping from user ID to key type to key
+                data.  If a user's cross-signing keys were not found, their user
+                ID will not be in the dict.
+
+        """
+        result = {}
+
+        batch_size = 100
+        chunks = [
+            user_ids[i : i + batch_size] for i in range(0, len(user_ids), batch_size)
+        ]
+        for user_chunk in chunks:
+            sql = """
+                SELECT k.user_id, k.keytype, k.keydata, k.stream_id
+                  FROM e2e_cross_signing_keys k
+                  INNER JOIN (SELECT user_id, keytype, MAX(stream_id) AS stream_id
+                                FROM e2e_cross_signing_keys
+                               GROUP BY user_id, keytype) s
+                 USING (user_id, stream_id, keytype)
+                 WHERE k.user_id IN (%s)
+            """ % (
+                ",".join("?" for u in user_chunk),
+            )
+            query_params = []
+            query_params.extend(user_chunk)
+
+            txn.execute(sql, query_params)
+            rows = self.db.cursor_to_dict(txn)
+
+            for row in rows:
+                user_id = row["user_id"]
+                key_type = row["keytype"]
+                key = json.loads(row["keydata"])
+                user_info = result.setdefault(user_id, {})
+                user_info[key_type] = key
+
+        return result
+
+    def _get_e2e_cross_signing_signatures_txn(
+        self, txn: Connection, keys: Dict[str, Dict[str, dict]], from_user_id: str,
+    ) -> Dict[str, Dict[str, dict]]:
+        """Returns the cross-signing signatures made by a user on a set of keys.
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            keys (dict[str, dict[str, dict]]): a map of user ID to key type to
+                key data.  This dict will be modified to add signatures.
+            from_user_id (str): fetch the signatures made by this user
+
+        Returns:
+            dict[str, dict[str, dict]]: mapping from user ID to key type to key
+                data.  The return value will be the same as the keys argument,
+                with the modifications included.
+        """
+
+        # find out what cross-signing keys (a.k.a. devices) we need to get
+        # signatures for.  This is a map of (user_id, device_id) to key type
+        # (device_id is the key's public part).
+        devices = {}
+
+        for user_id, user_info in keys.items():
+            if user_info is None:
+                continue
+            for key_type, key in user_info.items():
+                device_id = None
+                for k in key["keys"].values():
+                    device_id = k
+                devices[(user_id, device_id)] = key_type
+
+        device_list = list(devices)
+
+        # split into batches
+        batch_size = 100
+        chunks = [
+            device_list[i : i + batch_size]
+            for i in range(0, len(device_list), batch_size)
+        ]
+        for user_chunk in chunks:
+            sql = """
+                SELECT target_user_id, target_device_id, key_id, signature
+                  FROM e2e_cross_signing_signatures
+                 WHERE user_id = ?
+                   AND (%s)
+            """ % (
+                " OR ".join(
+                    "(target_user_id = ? AND target_device_id = ?)" for d in devices
+                )
+            )
+            query_params = [from_user_id]
+            for item in devices:
+                # item is a (user_id, device_id) tuple
+                query_params.extend(item)
+
+            txn.execute(sql, query_params)
+            rows = self.db.cursor_to_dict(txn)
+
+            # and add the signatures to the appropriate keys
+            for row in rows:
+                key_id = row["key_id"]
+                target_user_id = row["target_user_id"]
+                target_device_id = row["target_device_id"]
+                key_type = devices[(target_user_id, target_device_id)]
+                # We need to copy everything, because the result may have come
+                # from the cache.  dict.copy only does a shallow copy, so we
+                # need to recursively copy the dicts that will be modified.
+                user_info = keys[target_user_id] = keys[target_user_id].copy()
+                target_user_key = user_info[key_type] = user_info[key_type].copy()
+                if "signatures" in target_user_key:
+                    signatures = target_user_key["signatures"] = target_user_key[
+                        "signatures"
+                    ].copy()
+                    if from_user_id in signatures:
+                        user_sigs = signatures[from_user_id] = signatures[from_user_id]
+                        user_sigs[key_id] = row["signature"]
+                    else:
+                        signatures[from_user_id] = {key_id: row["signature"]}
+                else:
+                    target_user_key["signatures"] = {
+                        from_user_id: {key_id: row["signature"]}
+                    }
+
+        return keys
+
+    @defer.inlineCallbacks
+    def get_e2e_cross_signing_keys_bulk(
+        self, user_ids: List[str], from_user_id: str = None
+    ) -> defer.Deferred:
+        """Returns the cross-signing keys for a set of users.
+
+        Args:
+            user_ids (list[str]): the users whose keys are being requested
+            from_user_id (str): if specified, signatures made by this user on
+                the self-signing keys will be included in the result
+
+        Returns:
+            Deferred[dict[str, dict[str, dict]]]: map of user ID to key type to
+                key data.  If a user's cross-signing keys were not found, either
+                their user ID will not be in the dict, or their user ID will map
+                to None.
+        """
+
+        result = yield self._get_bare_e2e_cross_signing_keys_bulk(user_ids)
+
+        if from_user_id:
+            result = yield self.db.runInteraction(
+                "get_e2e_cross_signing_signatures",
+                self._get_e2e_cross_signing_signatures_txn,
+                result,
+                from_user_id,
+            )
+
+        return result
+
     def get_all_user_signature_changes_for_remotes(self, from_key, to_key):
         """Return a list of changes from the user signature stream to notify remotes.
         Note that the user signature stream represents when a user signs their
@@ -520,6 +725,10 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
                 },
             )
 
+        self._invalidate_cache_and_stream(
+            txn, self._get_bare_e2e_cross_signing_keys, (user_id,)
+        )
+
     def set_e2e_cross_signing_key(self, user_id, key_type, key):
         """Set a user's cross-signing key.
 
diff --git a/synapse/storage/data_stores/main/events_worker.py b/synapse/storage/data_stores/main/events_worker.py
index 9ee117ce0f..2c9142814c 100644
--- a/synapse/storage/data_stores/main/events_worker.py
+++ b/synapse/storage/data_stores/main/events_worker.py
@@ -19,8 +19,10 @@ import itertools
 import logging
 import threading
 from collections import namedtuple
+from typing import List, Optional
 
 from canonicaljson import json
+from constantly import NamedConstant, Names
 
 from twisted.internet import defer
 
@@ -55,6 +57,16 @@ EVENT_QUEUE_TIMEOUT_S = 0.1  # Timeout when waiting for requests for events
 _EventCacheEntry = namedtuple("_EventCacheEntry", ("event", "redacted_event"))
 
 
+class EventRedactBehaviour(Names):
+    """
+    What to do when retrieving a redacted event from the database.
+    """
+
+    AS_IS = NamedConstant()
+    REDACT = NamedConstant()
+    BLOCK = NamedConstant()
+
+
 class EventsWorkerStore(SQLBaseStore):
     def __init__(self, database: Database, db_conn, hs):
         super(EventsWorkerStore, self).__init__(database, db_conn, hs)
@@ -125,25 +137,27 @@ class EventsWorkerStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_event(
         self,
-        event_id,
-        check_redacted=True,
-        get_prev_content=False,
-        allow_rejected=False,
-        allow_none=False,
-        check_room_id=None,
+        event_id: List[str],
+        redact_behaviour: EventRedactBehaviour = EventRedactBehaviour.REDACT,
+        get_prev_content: bool = False,
+        allow_rejected: bool = False,
+        allow_none: bool = False,
+        check_room_id: Optional[str] = None,
     ):
         """Get an event from the database by event_id.
 
         Args:
-            event_id (str): The event_id of the event to fetch
-            check_redacted (bool): If True, check if event has been redacted
-                and redact it.
-            get_prev_content (bool): If True and event is a state event,
+            event_id: The event_id of the event to fetch
+            redact_behaviour: Determine what to do with a redacted event. Possible values:
+                * AS_IS - Return the full event body with no redacted content
+                * REDACT - Return the event but with a redacted body
+                * DISALLOW - Do not return redacted events
+            get_prev_content: If True and event is a state event,
                 include the previous states content in the unsigned field.
-            allow_rejected (bool): If True return rejected events.
-            allow_none (bool): If True, return None if no event found, if
+            allow_rejected: If True return rejected events.
+            allow_none: If True, return None if no event found, if
                 False throw a NotFoundError
-            check_room_id (str|None): if not None, check the room of the found event.
+            check_room_id: if not None, check the room of the found event.
                 If there is a mismatch, behave as per allow_none.
 
         Returns:
@@ -154,7 +168,7 @@ class EventsWorkerStore(SQLBaseStore):
 
         events = yield self.get_events_as_list(
             [event_id],
-            check_redacted=check_redacted,
+            redact_behaviour=redact_behaviour,
             get_prev_content=get_prev_content,
             allow_rejected=allow_rejected,
         )
@@ -173,27 +187,30 @@ class EventsWorkerStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_events(
         self,
-        event_ids,
-        check_redacted=True,
-        get_prev_content=False,
-        allow_rejected=False,
+        event_ids: List[str],
+        redact_behaviour: EventRedactBehaviour = EventRedactBehaviour.REDACT,
+        get_prev_content: bool = False,
+        allow_rejected: bool = False,
     ):
         """Get events from the database
 
         Args:
-            event_ids (list): The event_ids of the events to fetch
-            check_redacted (bool): If True, check if event has been redacted
-                and redact it.
-            get_prev_content (bool): If True and event is a state event,
+            event_ids: The event_ids of the events to fetch
+            redact_behaviour: Determine what to do with a redacted event. Possible
+                values:
+                * AS_IS - Return the full event body with no redacted content
+                * REDACT - Return the event but with a redacted body
+                * DISALLOW - Do not return redacted events
+            get_prev_content: If True and event is a state event,
                 include the previous states content in the unsigned field.
-            allow_rejected (bool): If True return rejected events.
+            allow_rejected: If True return rejected events.
 
         Returns:
             Deferred : Dict from event_id to event.
         """
         events = yield self.get_events_as_list(
             event_ids,
-            check_redacted=check_redacted,
+            redact_behaviour=redact_behaviour,
             get_prev_content=get_prev_content,
             allow_rejected=allow_rejected,
         )
@@ -203,21 +220,23 @@ class EventsWorkerStore(SQLBaseStore):
     @defer.inlineCallbacks
     def get_events_as_list(
         self,
-        event_ids,
-        check_redacted=True,
-        get_prev_content=False,
-        allow_rejected=False,
+        event_ids: List[str],
+        redact_behaviour: EventRedactBehaviour = EventRedactBehaviour.REDACT,
+        get_prev_content: bool = False,
+        allow_rejected: bool = False,
     ):
         """Get events from the database and return in a list in the same order
         as given by `event_ids` arg.
 
         Args:
-            event_ids (list): The event_ids of the events to fetch
-            check_redacted (bool): If True, check if event has been redacted
-                and redact it.
-            get_prev_content (bool): If True and event is a state event,
+            event_ids: The event_ids of the events to fetch
+            redact_behaviour: Determine what to do with a redacted event. Possible values:
+                * AS_IS - Return the full event body with no redacted content
+                * REDACT - Return the event but with a redacted body
+                * DISALLOW - Do not return redacted events
+            get_prev_content: If True and event is a state event,
                 include the previous states content in the unsigned field.
-            allow_rejected (bool): If True return rejected events.
+            allow_rejected: If True, return rejected events.
 
         Returns:
             Deferred[list[EventBase]]: List of events fetched from the database. The
@@ -319,10 +338,14 @@ class EventsWorkerStore(SQLBaseStore):
                     # Update the cache to save doing the checks again.
                     entry.event.internal_metadata.recheck_redaction = False
 
-            if check_redacted and entry.redacted_event:
-                event = entry.redacted_event
-            else:
-                event = entry.event
+            event = entry.event
+
+            if entry.redacted_event:
+                if redact_behaviour == EventRedactBehaviour.BLOCK:
+                    # Skip this event
+                    continue
+                elif redact_behaviour == EventRedactBehaviour.REDACT:
+                    event = entry.redacted_event
 
             events.append(event)
 
diff --git a/synapse/storage/data_stores/main/schema/delta/56/nuke_empty_communities_from_db.sql b/synapse/storage/data_stores/main/schema/delta/56/nuke_empty_communities_from_db.sql
new file mode 100644
index 0000000000..4f24c1405d
--- /dev/null
+++ b/synapse/storage/data_stores/main/schema/delta/56/nuke_empty_communities_from_db.sql
@@ -0,0 +1,29 @@
+/* Copyright 2019 Werner Sembach
+ *
+ * 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.
+ */
+
+-- Groups/communities now get deleted when the last member leaves. This is a one time cleanup to remove old groups/communities that were already empty before that change was made.
+DELETE FROM group_attestations_remote WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_attestations_renewals WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_invites WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_roles WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_room_categories WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_rooms WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_summary_roles WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_summary_room_categories WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_summary_rooms WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM group_summary_users WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM local_group_membership WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM local_group_updates WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
+DELETE FROM groups WHERE group_id IN (SELECT group_id FROM groups WHERE NOT EXISTS (SELECT group_id FROM group_users WHERE group_id = groups.group_id));
diff --git a/synapse/storage/data_stores/main/schema/full_schemas/README.md b/synapse/storage/data_stores/main/schema/full_schemas/README.md
new file mode 100644
index 0000000000..bbd3f18604
--- /dev/null
+++ b/synapse/storage/data_stores/main/schema/full_schemas/README.md
@@ -0,0 +1,13 @@
+# Building full schema dumps
+
+These schemas need to be made from a database that has had all background updates run.
+
+To do so, use `scripts-dev/make_full_schema.sh`. This will produce
+`full.sql.postgres ` and `full.sql.sqlite` files.
+
+Ensure postgres is installed and your user has the ability to run bash commands
+such as `createdb`.
+
+```
+./scripts-dev/make_full_schema.sh -p postgres_username -o output_dir/
+```
diff --git a/synapse/storage/data_stores/main/schema/full_schemas/README.txt b/synapse/storage/data_stores/main/schema/full_schemas/README.txt
deleted file mode 100644
index d3f6401344..0000000000
--- a/synapse/storage/data_stores/main/schema/full_schemas/README.txt
+++ /dev/null
@@ -1,19 +0,0 @@
-Building full schema dumps
-==========================
-
-These schemas need to be made from a database that has had all background updates run.
-
-Postgres
---------
-
-$ pg_dump --format=plain --schema-only --no-tablespaces --no-acl --no-owner $DATABASE_NAME| sed -e '/^--/d' -e 's/public\.//g' -e '/^SET /d' -e '/^SELECT /d' > full.sql.postgres
-
-SQLite
-------
-
-$ sqlite3 $DATABASE_FILE ".schema" > full.sql.sqlite
-
-After
------
-
-Delete the CREATE statements for "sqlite_stat1", "schema_version", "applied_schema_deltas", and "applied_module_schemas".
\ No newline at end of file
diff --git a/synapse/storage/data_stores/main/search.py b/synapse/storage/data_stores/main/search.py
index 4eec2fae5e..47ebb8a214 100644
--- a/synapse/storage/data_stores/main/search.py
+++ b/synapse/storage/data_stores/main/search.py
@@ -25,6 +25,7 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.storage._base import SQLBaseStore, make_in_list_sql_clause
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.storage.database import Database
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 
@@ -384,7 +385,7 @@ class SearchStore(SearchBackgroundUpdateStore):
         """
         clauses = []
 
-        search_query = search_query = _parse_query(self.database_engine, search_term)
+        search_query = _parse_query(self.database_engine, search_term)
 
         args = []
 
@@ -453,7 +454,12 @@ class SearchStore(SearchBackgroundUpdateStore):
 
         results = list(filter(lambda row: row["room_id"] in room_ids, results))
 
-        events = yield self.get_events_as_list([r["event_id"] for r in results])
+        # We set redact_behaviour to BLOCK here to prevent redacted events being returned in
+        # search results (which is a data leak)
+        events = yield self.get_events_as_list(
+            [r["event_id"] for r in results],
+            redact_behaviour=EventRedactBehaviour.BLOCK,
+        )
 
         event_map = {ev.event_id: ev for ev in events}
 
@@ -495,7 +501,7 @@ class SearchStore(SearchBackgroundUpdateStore):
         """
         clauses = []
 
-        search_query = search_query = _parse_query(self.database_engine, search_term)
+        search_query = _parse_query(self.database_engine, search_term)
 
         args = []
 
@@ -600,7 +606,12 @@ class SearchStore(SearchBackgroundUpdateStore):
 
         results = list(filter(lambda row: row["room_id"] in room_ids, results))
 
-        events = yield self.get_events_as_list([r["event_id"] for r in results])
+        # We set redact_behaviour to BLOCK here to prevent redacted events being returned in
+        # search results (which is a data leak)
+        events = yield self.get_events_as_list(
+            [r["event_id"] for r in results],
+            redact_behaviour=EventRedactBehaviour.BLOCK,
+        )
 
         event_map = {ev.event_id: ev for ev in events}
 
diff --git a/synapse/storage/data_stores/main/state.py b/synapse/storage/data_stores/main/state.py
index 9ef7b48c74..dcc6b43cdf 100644
--- a/synapse/storage/data_stores/main/state.py
+++ b/synapse/storage/data_stores/main/state.py
@@ -278,7 +278,7 @@ class StateGroupWorkerStore(
 
     @defer.inlineCallbacks
     def get_room_predecessor(self, room_id):
-        """Get the predecessor room of an upgraded room if one exists.
+        """Get the predecessor of an upgraded room if it exists.
         Otherwise return None.
 
         Args:
@@ -291,14 +291,22 @@ class StateGroupWorkerStore(
                     * room_id (str): The room ID of the predecessor room
                     * event_id (str): The ID of the tombstone event in the predecessor room
 
+                None if a predecessor key is not found, or is not a dictionary.
+
         Raises:
-            NotFoundError if the room is unknown
+            NotFoundError if the given room is unknown
         """
         # Retrieve the room's create event
         create_event = yield self.get_create_event_for_room(room_id)
 
-        # Return predecessor if present
-        return create_event.content.get("predecessor", None)
+        # Retrieve the predecessor key of the create event
+        predecessor = create_event.content.get("predecessor", None)
+
+        # Ensure the key is a dictionary
+        if not isinstance(predecessor, dict):
+            return None
+
+        return predecessor
 
     @defer.inlineCallbacks
     def get_create_event_for_room(self, room_id):
@@ -318,7 +326,7 @@ class StateGroupWorkerStore(
 
         # If we can't find the create event, assume we've hit a dead end
         if not create_id:
-            raise NotFoundError("Unknown room %s" % (room_id))
+            raise NotFoundError("Unknown room %s" % (room_id,))
 
         # Retrieve the room's create event and return
         create_event = yield self.get_event(create_id)
diff --git a/synapse/streams/events.py b/synapse/streams/events.py
index b91fb2db7b..fcd2aaa9c9 100644
--- a/synapse/streams/events.py
+++ b/synapse/streams/events.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import Any, Dict
+
 from twisted.internet import defer
 
 from synapse.handlers.account_data import AccountDataEventSource
@@ -35,7 +37,7 @@ class EventSources(object):
     def __init__(self, hs):
         self.sources = {
             name: cls(hs) for name, cls in EventSources.SOURCE_TYPES.items()
-        }
+        }  # type: Dict[str, Any]
         self.store = hs.get_datastore()
 
     @defer.inlineCallbacks
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 84f5ae22c3..2e8f6543e5 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -271,7 +271,7 @@ class _CacheDescriptorBase(object):
         else:
             self.function_to_call = orig
 
-        arg_spec = inspect.getargspec(orig)
+        arg_spec = inspect.getfullargspec(orig)
         all_args = arg_spec.args
 
         if "cache_context" in all_args:
diff --git a/synapse/util/caches/snapshot_cache.py b/synapse/util/caches/snapshot_cache.py
deleted file mode 100644
index 8318db8d2c..0000000000
--- a/synapse/util/caches/snapshot_cache.py
+++ /dev/null
@@ -1,94 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015, 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.util.async_helpers import ObservableDeferred
-
-
-class SnapshotCache(object):
-    """Cache for snapshots like the response of /initialSync.
-    The response of initialSync only has to be a recent snapshot of the
-    server state. It shouldn't matter to clients if it is a few minutes out
-    of date.
-
-    This caches a deferred response. Until the deferred completes it will be
-    returned from the cache. This means that if the client retries the request
-    while the response is still being computed, that original response will be
-    used rather than trying to compute a new response.
-
-    Once the deferred completes it will removed from the cache after 5 minutes.
-    We delay removing it from the cache because a client retrying its request
-    could race with us finishing computing the response.
-
-    Rather than tracking precisely how long something has been in the cache we
-    keep two generations of completed responses. Every 5 minutes discard the
-    old generation, move the new generation to the old generation, and set the
-    new generation to be empty. This means that a result will be in the cache
-    somewhere between 5 and 10 minutes.
-    """
-
-    DURATION_MS = 5 * 60 * 1000  # Cache results for 5 minutes.
-
-    def __init__(self):
-        self.pending_result_cache = {}  # Request that haven't finished yet.
-        self.prev_result_cache = {}  # The older requests that have finished.
-        self.next_result_cache = {}  # The newer requests that have finished.
-        self.time_last_rotated_ms = 0
-
-    def rotate(self, time_now_ms):
-        # Rotate once if the cache duration has passed since the last rotation.
-        if time_now_ms - self.time_last_rotated_ms >= self.DURATION_MS:
-            self.prev_result_cache = self.next_result_cache
-            self.next_result_cache = {}
-            self.time_last_rotated_ms += self.DURATION_MS
-
-        # Rotate again if the cache duration has passed twice since the last
-        # rotation.
-        if time_now_ms - self.time_last_rotated_ms >= self.DURATION_MS:
-            self.prev_result_cache = self.next_result_cache
-            self.next_result_cache = {}
-            self.time_last_rotated_ms = time_now_ms
-
-    def get(self, time_now_ms, key):
-        self.rotate(time_now_ms)
-        # This cache is intended to deduplicate requests, so we expect it to be
-        # missed most of the time. So we just lookup the key in all of the
-        # dictionaries rather than trying to short circuit the lookup if the
-        # key is found.
-        result = self.prev_result_cache.get(key)
-        result = self.next_result_cache.get(key, result)
-        result = self.pending_result_cache.get(key, result)
-        if result is not None:
-            return result.observe()
-        else:
-            return None
-
-    def set(self, time_now_ms, key, deferred):
-        self.rotate(time_now_ms)
-
-        result = ObservableDeferred(deferred)
-
-        self.pending_result_cache[key] = result
-
-        def shuffle_along(r):
-            # When the deferred completes we shuffle it along to the first
-            # generation of the result cache. So that it will eventually
-            # expire from the rotation of that cache.
-            self.next_result_cache[key] = result
-            self.pending_result_cache.pop(key, None)
-            return r
-
-        result.addBoth(shuffle_along)
-
-        return result.observe()