Imported Upstream version 0.33.0

author: Richard van der Hoff <richard@matrix.org> 2018-07-19 12:57:39 +0100
committer: Richard van der Hoff <richard@matrix.org> 2018-07-19 12:57:39 +0100
commit: ef2188c1bfd532ddc2e4c1acb533b422afde6c57 (patch)
tree: a9483e827cfabebcbb422c9a6426b53f928f3d31 /synapse
parent: d24e9b285fd8d602c3b12c6ba589da0dd2cddee3 (diff)
262 files changed, 1988 insertions, 1911 deletions
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 81a6e061..5c0f2f83 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -17,4 +17,4 @@
 """ This is a reference implementation of a Matrix home server.
 """
 
-__version__ = "0.32.1"
+__version__ = "0.33.0"
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 088b4e8b..bc629832 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -18,15 +18,16 @@ import logging
 from six import itervalues
 
 import pymacaroons
-from twisted.internet import defer
 from netaddr import IPAddress
 
+from twisted.internet import defer
+
 import synapse.types
 from synapse import event_auth
-from synapse.api.constants import EventTypes, Membership, JoinRules
+from synapse.api.constants import EventTypes, JoinRules, Membership
 from synapse.api.errors import AuthError, Codes
 from synapse.types import UserID
-from synapse.util.caches import register_cache, CACHE_SIZE_FACTOR
+from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.metrics import Measure
 
@@ -192,7 +193,7 @@ class Auth(object):
                     synapse.types.create_requester(user_id, app_service=app_service)
                 )
 
-            access_token = get_access_token_from_request(
+            access_token = self.get_access_token_from_request(
                 request, self.TOKEN_NOT_FOUND_HTTP_STATUS
             )
 
@@ -238,7 +239,7 @@ class Auth(object):
     @defer.inlineCallbacks
     def _get_appservice_user_id(self, request):
         app_service = self.store.get_app_service_by_token(
-            get_access_token_from_request(
+            self.get_access_token_from_request(
                 request, self.TOKEN_NOT_FOUND_HTTP_STATUS
             )
         )
@@ -512,7 +513,7 @@ class Auth(object):
 
     def get_appservice_by_req(self, request):
         try:
-            token = get_access_token_from_request(
+            token = self.get_access_token_from_request(
                 request, self.TOKEN_NOT_FOUND_HTTP_STATUS
             )
             service = self.store.get_app_service_by_token(token)
@@ -672,67 +673,67 @@ class Auth(object):
                 " edit its room list entry"
             )
 
+    @staticmethod
+    def has_access_token(request):
+        """Checks if the request has an access_token.
 
-def has_access_token(request):
-    """Checks if the request has an access_token.
+        Returns:
+            bool: False if no access_token was given, True otherwise.
+        """
+        query_params = request.args.get("access_token")
+        auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
+        return bool(query_params) or bool(auth_headers)
 
-    Returns:
-        bool: False if no access_token was given, True otherwise.
-    """
-    query_params = request.args.get("access_token")
-    auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
-    return bool(query_params) or bool(auth_headers)
-
-
-def get_access_token_from_request(request, token_not_found_http_status=401):
-    """Extracts the access_token from the request.
-
-    Args:
-        request: The http request.
-        token_not_found_http_status(int): The HTTP status code to set in the
-            AuthError if the token isn't found. This is used in some of the
-            legacy APIs to change the status code to 403 from the default of
-            401 since some of the old clients depended on auth errors returning
-            403.
-    Returns:
-        str: The access_token
-    Raises:
-        AuthError: If there isn't an access_token in the request.
-    """
+    @staticmethod
+    def get_access_token_from_request(request, token_not_found_http_status=401):
+        """Extracts the access_token from the request.
 
-    auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
-    query_params = request.args.get(b"access_token")
-    if auth_headers:
-        # Try the get the access_token from a "Authorization: Bearer"
-        # header
-        if query_params is not None:
-            raise AuthError(
-                token_not_found_http_status,
-                "Mixing Authorization headers and access_token query parameters.",
-                errcode=Codes.MISSING_TOKEN,
-            )
-        if len(auth_headers) > 1:
-            raise AuthError(
-                token_not_found_http_status,
-                "Too many Authorization headers.",
-                errcode=Codes.MISSING_TOKEN,
-            )
-        parts = auth_headers[0].split(" ")
-        if parts[0] == "Bearer" and len(parts) == 2:
-            return parts[1]
+        Args:
+            request: The http request.
+            token_not_found_http_status(int): The HTTP status code to set in the
+                AuthError if the token isn't found. This is used in some of the
+                legacy APIs to change the status code to 403 from the default of
+                401 since some of the old clients depended on auth errors returning
+                403.
+        Returns:
+            str: The access_token
+        Raises:
+            AuthError: If there isn't an access_token in the request.
+        """
+
+        auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
+        query_params = request.args.get(b"access_token")
+        if auth_headers:
+            # Try the get the access_token from a "Authorization: Bearer"
+            # header
+            if query_params is not None:
+                raise AuthError(
+                    token_not_found_http_status,
+                    "Mixing Authorization headers and access_token query parameters.",
+                    errcode=Codes.MISSING_TOKEN,
+                )
+            if len(auth_headers) > 1:
+                raise AuthError(
+                    token_not_found_http_status,
+                    "Too many Authorization headers.",
+                    errcode=Codes.MISSING_TOKEN,
+                )
+            parts = auth_headers[0].split(" ")
+            if parts[0] == "Bearer" and len(parts) == 2:
+                return parts[1]
+            else:
+                raise AuthError(
+                    token_not_found_http_status,
+                    "Invalid Authorization header.",
+                    errcode=Codes.MISSING_TOKEN,
+                )
         else:
-            raise AuthError(
-                token_not_found_http_status,
-                "Invalid Authorization header.",
-                errcode=Codes.MISSING_TOKEN,
-            )
-    else:
-        # Try to get the access_token from the query params.
-        if not query_params:
-            raise AuthError(
-                token_not_found_http_status,
-                "Missing access token.",
-                errcode=Codes.MISSING_TOKEN
-            )
+            # Try to get the access_token from the query params.
+            if not query_params:
+                raise AuthError(
+                    token_not_found_http_status,
+                    "Missing access token.",
+                    errcode=Codes.MISSING_TOKEN
+                )
 
-        return query_params[0]
+            return query_params[0]
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 227a0713..6074df29 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -17,11 +17,11 @@
 
 import logging
 
-from canonicaljson import json
-
 from six import iteritems
 from six.moves import http_client
 
+from canonicaljson import json
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index aae25e7a..25346baa 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -12,16 +12,16 @@
 # 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.api.errors import SynapseError
-from synapse.storage.presence import UserPresenceState
-from synapse.types import UserID, RoomID
-from twisted.internet import defer
-
-from canonicaljson import json
-
 import jsonschema
+from canonicaljson import json
 from jsonschema import FormatChecker
 
+from twisted.internet import defer
+
+from synapse.api.errors import SynapseError
+from synapse.storage.presence import UserPresenceState
+from synapse.types import RoomID, UserID
+
 FILTER_SCHEMA = {
     "additionalProperties": False,
     "type": "object",
diff --git a/synapse/api/urls.py b/synapse/api/urls.py
index bb46b5da..71347912 100644
--- a/synapse/api/urls.py
+++ b/synapse/api/urls.py
@@ -15,8 +15,8 @@
 # limitations under the License.
 
 """Contains the URL paths to prefix various aspects of the server with. """
-from hashlib import sha256
 import hmac
+from hashlib import sha256
 
 from six.moves.urllib.parse import urlencode
 
diff --git a/synapse/app/__init__.py b/synapse/app/__init__.py
index 9c2b6275..3b6b9368 100644
--- a/synapse/app/__init__.py
+++ b/synapse/app/__init__.py
@@ -14,9 +14,11 @@
 # limitations under the License.
 
 import sys
+
+from synapse import python_dependencies  # noqa: E402
+
 sys.dont_write_bytecode = True
 
-from synapse import python_dependencies   # noqa: E402
 
 try:
     python_dependencies.check_requirements()
diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index a6925ab1..391bd14c 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -17,15 +17,18 @@ import gc
 import logging
 import sys
 
+from daemonize import Daemonize
+
+from twisted.internet import error, reactor
+
+from synapse.util import PreserveLoggingContext
+from synapse.util.rlimit import change_resource_limit
+
 try:
     import affinity
 except Exception:
     affinity = None
 
-from daemonize import Daemonize
-from synapse.util import PreserveLoggingContext
-from synapse.util.rlimit import change_resource_limit
-from twisted.internet import error, reactor
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index 4319ddce..9a37384f 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -36,8 +39,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor, defer
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.appservice")
 
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index 654ddb84..b0ea26dc 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -44,8 +47,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.client_reader")
 
diff --git a/synapse/app/event_creator.py b/synapse/app/event_creator.py
index 44146709..374f1156 100644
--- a/synapse/app/event_creator.py
+++ b/synapse/app/event_creator.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -43,8 +46,10 @@ from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.slave.storage.transactions import TransactionStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.client.v1.room import (
-    RoomSendEventRestServlet, RoomMembershipRestServlet, RoomStateEventRestServlet,
     JoinRoomAliasServlet,
+    RoomMembershipRestServlet,
+    RoomSendEventRestServlet,
+    RoomStateEventRestServlet,
 )
 from synapse.server import HomeServer
 from synapse.storage.engines import create_engine
@@ -52,8 +57,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.event_creator")
 
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index b2415cc6..7af00b8b 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.api.urls import FEDERATION_PREFIX
@@ -41,8 +44,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.federation_reader")
 
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 13d2b700..18469013 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -42,8 +45,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.federation_sender")
 
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index d2bae4ad..b5f78f46 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.api.errors import SynapseError
@@ -25,9 +28,7 @@ from synapse.config.homeserver import HomeServerConfig
 from synapse.config.logger import setup_logging
 from synapse.crypto import context_factory
 from synapse.http.server import JsonResource
-from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request,
-)
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.http.site import SynapseSite
 from synapse.metrics import RegistryProxy
 from synapse.metrics.resource import METRICS_PREFIX, MetricsResource
@@ -44,8 +45,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.frontend_proxy")
 
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index ae5fc751..14e6dca5 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -18,27 +18,39 @@ import logging
 import os
 import sys
 
+from twisted.application import service
+from twisted.internet import defer, reactor
+from twisted.web.resource import EncodingResourceWrapper, NoResource
+from twisted.web.server import GzipEncoderFactory
+from twisted.web.static import File
+
 import synapse
 import synapse.config.logger
 from synapse import events
-from synapse.api.urls import CONTENT_REPO_PREFIX, FEDERATION_PREFIX, \
-    LEGACY_MEDIA_PREFIX, MEDIA_PREFIX, SERVER_KEY_PREFIX, SERVER_KEY_V2_PREFIX, \
-    STATIC_PREFIX, WEB_CLIENT_PREFIX
+from synapse.api.urls import (
+    CONTENT_REPO_PREFIX,
+    FEDERATION_PREFIX,
+    LEGACY_MEDIA_PREFIX,
+    MEDIA_PREFIX,
+    SERVER_KEY_PREFIX,
+    SERVER_KEY_V2_PREFIX,
+    STATIC_PREFIX,
+    WEB_CLIENT_PREFIX,
+)
 from synapse.app import _base
-from synapse.app._base import quit_with_error, listen_ssl, listen_tcp
+from synapse.app._base import listen_ssl, listen_tcp, quit_with_error
 from synapse.config._base import ConfigError
 from synapse.config.homeserver import HomeServerConfig
 from synapse.crypto import context_factory
 from synapse.federation.transport.server import TransportLayerServer
-from synapse.module_api import ModuleApi
 from synapse.http.additional_resource import AdditionalResource
 from synapse.http.server import RootRedirect
 from synapse.http.site import SynapseSite
 from synapse.metrics import RegistryProxy
 from synapse.metrics.resource import METRICS_PREFIX, MetricsResource
-from synapse.python_dependencies import CONDITIONAL_REQUIREMENTS, \
-    check_requirements
-from synapse.replication.http import ReplicationRestResource, REPLICATION_PREFIX
+from synapse.module_api import ModuleApi
+from synapse.python_dependencies import CONDITIONAL_REQUIREMENTS, check_requirements
+from synapse.replication.http import REPLICATION_PREFIX, ReplicationRestResource
 from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
 from synapse.rest import ClientRestResource
 from synapse.rest.key.v1.server_key_resource import LocalKey
@@ -55,11 +67,6 @@ from synapse.util.manhole import manhole
 from synapse.util.module_loader import load_module
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
-from twisted.application import service
-from twisted.internet import defer, reactor
-from twisted.web.resource import EncodingResourceWrapper, NoResource
-from twisted.web.server import GzipEncoderFactory
-from twisted.web.static import File
 
 logger = logging.getLogger("synapse.app.homeserver")
 
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index 19a682cc..749bbf37 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -16,11 +16,12 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
-from synapse.api.urls import (
-    CONTENT_REPO_PREFIX, LEGACY_MEDIA_PREFIX, MEDIA_PREFIX
-)
+from synapse.api.urls import CONTENT_REPO_PREFIX, LEGACY_MEDIA_PREFIX, MEDIA_PREFIX
 from synapse.app import _base
 from synapse.config._base import ConfigError
 from synapse.config.homeserver import HomeServerConfig
@@ -43,8 +44,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.media_repository")
 
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index 13cfbd08..9295a51d 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -37,8 +40,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.pusher")
 
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 82f06ea1..26b9ec85 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -17,6 +17,11 @@ import contextlib
 import logging
 import sys
 
+from six import iteritems
+
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse.api.constants import EventTypes
 from synapse.app import _base
@@ -36,12 +41,12 @@ from synapse.replication.slave.storage.deviceinbox import SlavedDeviceInboxStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.filtering import SlavedFilteringStore
+from synapse.replication.slave.storage.groups import SlavedGroupServerStore
 from synapse.replication.slave.storage.presence import SlavedPresenceStore
 from synapse.replication.slave.storage.push_rule import SlavedPushRuleStore
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.slave.storage.room import RoomStore
-from synapse.replication.slave.storage.groups import SlavedGroupServerStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.client.v1 import events
 from synapse.rest.client.v1.initial_sync import InitialSyncRestServlet
@@ -56,10 +61,6 @@ from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.stringutils import random_string
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
-
-from six import iteritems
 
 logger = logging.getLogger("synapse.app.synchrotron")
 
diff --git a/synapse/app/synctl.py b/synapse/app/synctl.py
index 56ae0861..68acc15a 100755
--- a/synapse/app/synctl.py
+++ b/synapse/app/synctl.py
@@ -16,16 +16,17 @@
 
 import argparse
 import collections
+import errno
 import glob
 import os
 import os.path
 import signal
 import subprocess
 import sys
-import yaml
-import errno
 import time
 
+import yaml
+
 SYNAPSE = [sys.executable, "-B", "-m", "synapse.app.homeserver"]
 
 GREEN = "\x1b[1;32m"
diff --git a/synapse/app/user_dir.py b/synapse/app/user_dir.py
index f5726e3d..637a8953 100644
--- a/synapse/app/user_dir.py
+++ b/synapse/app/user_dir.py
@@ -17,6 +17,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -43,8 +46,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor, defer
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.user_dir")
 
diff --git a/synapse/appservice/__init__.py b/synapse/appservice/__init__.py
index 328cbfa2..57ed8a3c 100644
--- a/synapse/appservice/__init__.py
+++ b/synapse/appservice/__init__.py
@@ -12,17 +12,17 @@
 # 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.api.constants import EventTypes
-from synapse.util.caches.descriptors import cachedInlineCallbacks
-from synapse.types import GroupID, get_domain_from_id
-
-from twisted.internet import defer
-
 import logging
 import re
 
 from six import string_types
 
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes
+from synapse.types import GroupID, get_domain_from_id
+from synapse.util.caches.descriptors import cachedInlineCallbacks
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/appservice/api.py b/synapse/appservice/api.py
index 47251fb6..6980e589 100644
--- a/synapse/appservice/api.py
+++ b/synapse/appservice/api.py
@@ -12,19 +12,19 @@
 # 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.
+import logging
+import urllib
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 
 from synapse.api.constants import ThirdPartyEntityKind
 from synapse.api.errors import CodeMessageException
-from synapse.http.client import SimpleHttpClient
 from synapse.events.utils import serialize_event
-from synapse.util.caches.response_cache import ResponseCache
+from synapse.http.client import SimpleHttpClient
 from synapse.types import ThirdPartyInstanceID
-
-import logging
-import urllib
-
-from prometheus_client import Counter
+from synapse.util.caches.response_cache import ResponseCache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/appservice/scheduler.py b/synapse/appservice/scheduler.py
index 6eddbc08..24308147 100644
--- a/synapse/appservice/scheduler.py
+++ b/synapse/appservice/scheduler.py
@@ -48,14 +48,14 @@ UP & quit           +---------- YES                       SUCCESS
 This is all tied together by the AppServiceScheduler which DIs the required
 components.
 """
+import logging
+
 from twisted.internet import defer
 
 from synapse.appservice import ApplicationServiceState
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import Measure
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/config/_base.py b/synapse/config/_base.py
index b748ed2b..3d2e90dd 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -16,11 +16,12 @@
 import argparse
 import errno
 import os
-import yaml
 from textwrap import dedent
 
 from six import integer_types
 
+import yaml
+
 
 class ConfigError(Exception):
     pass
diff --git a/synapse/config/api.py b/synapse/config/api.py
index 20ba3322..403d96ba 100644
--- a/synapse/config/api.py
+++ b/synapse/config/api.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
-
 from synapse.api.constants import EventTypes
 
+from ._base import Config
+
 
 class ApiConfig(Config):
 
diff --git a/synapse/config/appservice.py b/synapse/config/appservice.py
index 0c27bb2f..3b161d70 100644
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -12,18 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config, ConfigError
+import logging
 
-from synapse.appservice import ApplicationService
-from synapse.types import UserID
+from six import string_types
+from six.moves.urllib import parse as urlparse
 
+import yaml
 from netaddr import IPSet
 
-import yaml
-import logging
+from synapse.appservice import ApplicationService
+from synapse.types import UserID
 
-from six import string_types
-from six.moves.urllib import parse as urlparse
+from ._base import Config, ConfigError
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 1dea2ad0..2fd9c48a 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -13,32 +13,32 @@
 # 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 .tls import TlsConfig
-from .server import ServerConfig
-from .logger import LoggingConfig
-from .database import DatabaseConfig
-from .ratelimiting import RatelimitConfig
-from .repository import ContentRepositoryConfig
-from .captcha import CaptchaConfig
-from .voip import VoipConfig
-from .registration import RegistrationConfig
-from .metrics import MetricsConfig
 from .api import ApiConfig
 from .appservice import AppServiceConfig
-from .key import KeyConfig
-from .saml2 import SAML2Config
+from .captcha import CaptchaConfig
 from .cas import CasConfig
-from .password import PasswordConfig
+from .consent_config import ConsentConfig
+from .database import DatabaseConfig
+from .emailconfig import EmailConfig
+from .groups import GroupsConfig
 from .jwt import JWTConfig
+from .key import KeyConfig
+from .logger import LoggingConfig
+from .metrics import MetricsConfig
+from .password import PasswordConfig
 from .password_auth_providers import PasswordAuthProviderConfig
-from .emailconfig import EmailConfig
-from .workers import WorkerConfig
 from .push import PushConfig
+from .ratelimiting import RatelimitConfig
+from .registration import RegistrationConfig
+from .repository import ContentRepositoryConfig
+from .saml2 import SAML2Config
+from .server import ServerConfig
+from .server_notices_config import ServerNoticesConfig
 from .spam_checker import SpamCheckerConfig
-from .groups import GroupsConfig
+from .tls import TlsConfig
 from .user_directory import UserDirectoryConfig
-from .consent_config import ConsentConfig
-from .server_notices_config import ServerNoticesConfig
+from .voip import VoipConfig
+from .workers import WorkerConfig
 
 
 class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
diff --git a/synapse/config/jwt.py b/synapse/config/jwt.py
index 47f145c5..51e7f7e0 100644
--- a/synapse/config/jwt.py
+++ b/synapse/config/jwt.py
@@ -15,7 +15,6 @@
 
 from ._base import Config, ConfigError
 
-
 MISSING_JWT = (
     """Missing jwt library. This is required for jwt login.
 
diff --git a/synapse/config/key.py b/synapse/config/key.py
index d1382ad9..279c47bb 100644
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -13,21 +13,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config, ConfigError
+import hashlib
+import logging
+import os
 
-from synapse.util.stringutils import random_string
 from signedjson.key import (
-    generate_signing_key, is_signing_algorithm_supported,
-    decode_signing_key_base64, decode_verify_key_bytes,
-    read_signing_keys, write_signing_keys, NACL_ED25519
+    NACL_ED25519,
+    decode_signing_key_base64,
+    decode_verify_key_bytes,
+    generate_signing_key,
+    is_signing_algorithm_supported,
+    read_signing_keys,
+    write_signing_keys,
 )
 from unpaddedbase64 import decode_base64
-from synapse.util.stringutils import random_string_with_symbols
 
-import os
-import hashlib
-import logging
+from synapse.util.stringutils import random_string, random_string_with_symbols
 
+from ._base import Config, ConfigError
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/config/logger.py b/synapse/config/logger.py
index 557c270f..a87b11a1 100644
--- a/synapse/config/logger.py
+++ b/synapse/config/logger.py
@@ -16,15 +16,17 @@ import logging
 import logging.config
 import os
 import signal
-from string import Template
 import sys
+from string import Template
 
-from twisted.logger import STDLibLogObserver, globalLogBeginner
 import yaml
 
+from twisted.logger import STDLibLogObserver, globalLogBeginner
+
 import synapse
 from synapse.util.logcontext import LoggingContextFilter
 from synapse.util.versionstring import get_version_string
+
 from ._base import Config
 
 DEFAULT_LOG_CONFIG = Template("""
diff --git a/synapse/config/password_auth_providers.py b/synapse/config/password_auth_providers.py
index 6602c5b4..f4066abc 100644
--- a/synapse/config/password_auth_providers.py
+++ b/synapse/config/password_auth_providers.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
-
 from synapse.util.module_loader import load_module
 
+from ._base import Config
+
 LDAP_PROVIDER = 'ldap_auth_provider.LdapAuthProvider'
 
 
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index c5384b3a..0fb964eb 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
+from distutils.util import strtobool
 
 from synapse.util.stringutils import random_string_with_symbols
 
-from distutils.util import strtobool
+from ._base import Config
 
 
 class RegistrationConfig(Config):
diff --git a/synapse/config/repository.py b/synapse/config/repository.py
index 81ecf977..fc909c1f 100644
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config, ConfigError
 from collections import namedtuple
 
 from synapse.util.module_loader import load_module
 
+from ._base import Config, ConfigError
 
 MISSING_NETADDR = (
     "Missing netaddr library. This is required for URL preview API."
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 71fd51e4..18102656 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -17,6 +17,7 @@
 import logging
 
 from synapse.http.endpoint import parse_and_validate_server_name
+
 from ._base import Config, ConfigError
 
 logger = logging.Logger(__name__)
diff --git a/synapse/config/server_notices_config.py b/synapse/config/server_notices_config.py
index be1d1f76..3c39850a 100644
--- a/synapse/config/server_notices_config.py
+++ b/synapse/config/server_notices_config.py
@@ -12,9 +12,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from ._base import Config
 from synapse.types import UserID
 
+from ._base import Config
+
 DEFAULT_CONFIG = """\
 # Server Notices room configuration
 #
diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index b66154bc..fef1ea99 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -13,15 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
-
-from OpenSSL import crypto
-import subprocess
 import os
-
+import subprocess
 from hashlib import sha256
+
 from unpaddedbase64 import encode_base64
 
+from OpenSSL import crypto
+
+from ._base import Config
+
 GENERATE_DH_PARAMS = False
 
 
diff --git a/synapse/crypto/context_factory.py b/synapse/crypto/context_factory.py
index 0397f73a..a1e1d0d3 100644
--- a/synapse/crypto/context_factory.py
+++ b/synapse/crypto/context_factory.py
@@ -12,12 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import ssl
+import logging
+
 from OpenSSL import SSL, crypto
+from twisted.internet import ssl
 from twisted.internet._sslverify import _defaultCurveName
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py
index aaa3efac..8774b289 100644
--- a/synapse/crypto/event_signing.py
+++ b/synapse/crypto/event_signing.py
@@ -15,15 +15,15 @@
 # limitations under the License.
 
 
-from synapse.api.errors import SynapseError, Codes
-from synapse.events.utils import prune_event
+import hashlib
+import logging
 
 from canonicaljson import encode_canonical_json
-from unpaddedbase64 import encode_base64, decode_base64
 from signedjson.sign import sign_json
+from unpaddedbase64 import decode_base64, encode_base64
 
-import hashlib
-import logging
+from synapse.api.errors import Codes, SynapseError
+from synapse.events.utils import prune_event
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/crypto/keyclient.py b/synapse/crypto/keyclient.py
index 2a0eddbe..668b4f51 100644
--- a/synapse/crypto/keyclient.py
+++ b/synapse/crypto/keyclient.py
@@ -13,14 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util import logcontext
-from twisted.web.http import HTTPClient
-from twisted.internet.protocol import Factory
-from twisted.internet import defer, reactor
-from synapse.http.endpoint import matrix_federation_endpoint
-from canonicaljson import json
 import logging
 
+from canonicaljson import json
+
+from twisted.internet import defer, reactor
+from twisted.internet.protocol import Factory
+from twisted.web.http import HTTPClient
+
+from synapse.http.endpoint import matrix_federation_endpoint
+from synapse.util import logcontext
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py
index 9b17ef0a..e95b9fb4 100644
--- a/synapse/crypto/keyring.py
+++ b/synapse/crypto/keyring.py
@@ -14,35 +14,37 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.crypto.keyclient import fetch_server_key
-from synapse.api.errors import SynapseError, Codes
-from synapse.util import unwrapFirstError, logcontext
-from synapse.util.logcontext import (
-    PreserveLoggingContext,
-    preserve_fn,
-    run_in_background,
-)
-from synapse.util.metrics import Measure
-
-from twisted.internet import defer
+import hashlib
+import logging
+import urllib
+from collections import namedtuple
 
-from signedjson.sign import (
-    verify_signed_json, signature_ids, sign_json, encode_canonical_json,
-    SignatureVerifyException,
-)
 from signedjson.key import (
-    is_signing_algorithm_supported, decode_verify_key_bytes,
+    decode_verify_key_bytes,
     encode_verify_key_base64,
+    is_signing_algorithm_supported,
+)
+from signedjson.sign import (
+    SignatureVerifyException,
+    encode_canonical_json,
+    sign_json,
+    signature_ids,
+    verify_signed_json,
 )
 from unpaddedbase64 import decode_base64, encode_base64
 
 from OpenSSL import crypto
+from twisted.internet import defer
 
-from collections import namedtuple
-import urllib
-import hashlib
-import logging
-
+from synapse.api.errors import Codes, SynapseError
+from synapse.crypto.keyclient import fetch_server_key
+from synapse.util import logcontext, unwrapFirstError
+from synapse.util.logcontext import (
+    PreserveLoggingContext,
+    preserve_fn,
+    run_in_background,
+)
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index cdf99fd1..b32f64e7 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -17,11 +17,11 @@ import logging
 
 from canonicaljson import encode_canonical_json
 from signedjson.key import decode_verify_key_bytes
-from signedjson.sign import verify_signed_json, SignatureVerifyException
+from signedjson.sign import SignatureVerifyException, verify_signed_json
 from unpaddedbase64 import decode_base64
 
-from synapse.api.constants import EventTypes, Membership, JoinRules
-from synapse.api.errors import AuthError, SynapseError, EventSizeError
+from synapse.api.constants import EventTypes, JoinRules, Membership
+from synapse.api.errors import AuthError, EventSizeError, SynapseError
 from synapse.types import UserID, get_domain_from_id
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index cb08da49..51f9084b 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -13,9 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.frozenutils import freeze
 from synapse.util.caches import intern_dict
-
+from synapse.util.frozenutils import freeze
 
 # Whether we should use frozen_dict in FrozenEvent. Using frozen_dicts prevents
 # bugs where we accidentally share e.g. signature dicts. However, converting
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 13fbba68..e662eaef 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -13,13 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from . import EventBase, FrozenEvent, _event_dict_property
+import copy
 
 from synapse.types import EventID
-
 from synapse.util.stringutils import random_string
 
-import copy
+from . import EventBase, FrozenEvent, _event_dict_property
 
 
 class EventBuilder(EventBase):
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 8e684d91..bcd9bb59 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
 from frozendict import frozendict
 
+from twisted.internet import defer
+
 
 class EventContext(object):
     """
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 29ae0867..652941ca 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -13,14 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.api.constants import EventTypes
-from . import EventBase
+import re
+
+from six import string_types
 
 from frozendict import frozendict
 
-import re
+from synapse.api.constants import EventTypes
 
-from six import string_types
+from . import EventBase
 
 # Split strings on "." but not "\." This uses a negative lookbehind assertion for '\'
 # (?<!stuff) matches if the current position in the string is not preceded
diff --git a/synapse/events/validator.py b/synapse/events/validator.py
index e0e5bf81..cf184748 100644
--- a/synapse/events/validator.py
+++ b/synapse/events/validator.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.types import EventID, RoomID, UserID
-from synapse.api.errors import SynapseError
-from synapse.api.constants import EventTypes, Membership
-
 from six import string_types
 
+from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import SynapseError
+from synapse.types import EventID, RoomID, UserID
+
 
 class EventValidator(object):
 
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 4cc98a3f..c1179809 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -16,14 +16,15 @@ import logging
 
 import six
 
+from twisted.internet import defer
+
 from synapse.api.constants import MAX_DEPTH
-from synapse.api.errors import SynapseError, Codes
+from synapse.api.errors import Codes, SynapseError
 from synapse.crypto.event_signing import check_event_content_hash
 from synapse.events import FrozenEvent
 from synapse.events.utils import prune_event
-from synapse.http.servlet import assert_params_in_request
-from synapse.util import unwrapFirstError, logcontext
-from twisted.internet import defer
+from synapse.http.servlet import assert_params_in_dict
+from synapse.util import logcontext, unwrapFirstError
 
 logger = logging.getLogger(__name__)
 
@@ -198,7 +199,7 @@ def event_from_pdu_json(pdu_json, outlier=False):
     """
     # we could probably enforce a bunch of other fields here (room_id, sender,
     # origin, etc etc)
-    assert_params_in_request(pdu_json, ('event_id', 'type', 'depth'))
+    assert_params_in_dict(pdu_json, ('event_id', 'type', 'depth'))
 
     depth = pdu_json['depth']
     if not isinstance(depth, six.integer_types):
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 87a92f6e..62d7ed13 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -21,25 +21,25 @@ import random
 
 from six.moves import range
 
+from prometheus_client import Counter
+
 from twisted.internet import defer
 
 from synapse.api.constants import Membership
 from synapse.api.errors import (
-    CodeMessageException, HttpResponseException, SynapseError, FederationDeniedError
+    CodeMessageException,
+    FederationDeniedError,
+    HttpResponseException,
+    SynapseError,
 )
 from synapse.events import builder
-from synapse.federation.federation_base import (
-    FederationBase,
-    event_from_pdu_json,
-)
+from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.util import logcontext, unwrapFirstError
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.logutils import log_function
 from synapse.util.retryutils import NotRetryingDestination
 
-from prometheus_client import Counter
-
 logger = logging.getLogger(__name__)
 
 sent_queries_counter = Counter("synapse_federation_client_sent_queries", "", ["type"])
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 591d0026..48f26db6 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -16,19 +16,19 @@
 import logging
 import re
 
-from canonicaljson import json
 import six
+from six import iteritems
+
+from canonicaljson import json
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.internet.abstract import isIPAddress
 
 from synapse.api.constants import EventTypes
-from synapse.api.errors import AuthError, FederationError, SynapseError, NotFoundError
+from synapse.api.errors import AuthError, FederationError, NotFoundError, SynapseError
 from synapse.crypto.event_signing import compute_event_signature
-from synapse.federation.federation_base import (
-    FederationBase,
-    event_from_pdu_json,
-)
-
+from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
 from synapse.http.endpoint import parse_server_name
@@ -37,10 +37,6 @@ from synapse.util import async
 from synapse.util.caches.response_cache import ResponseCache
 from synapse.util.logutils import log_function
 
-from prometheus_client import Counter
-
-from six import iteritems
-
 # when processing incoming transactions, we try to handle multiple rooms in
 # parallel, up to this limit.
 TRANSACTION_CONCURRENCY_LIMIT = 10
diff --git a/synapse/federation/persistence.py b/synapse/federation/persistence.py
index 84dc6066..9146215c 100644
--- a/synapse/federation/persistence.py
+++ b/synapse/federation/persistence.py
@@ -19,13 +19,12 @@ package.
 These actions are mostly only used by the :py:mod:`.replication` module.
 """
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.util.logutils import log_function
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index 1d5c0f37..5157c386 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -29,18 +29,18 @@ dead worker doesn't cause the queues to grow limitlessly.
 Events are replicated via a separate events stream.
 """
 
-from .units import Edu
+import logging
+from collections import namedtuple
 
-from synapse.storage.presence import UserPresenceState
-from synapse.util.metrics import Measure
-from synapse.metrics import LaterGauge
+from six import iteritems, itervalues
 
 from sortedcontainers import SortedDict
-from collections import namedtuple
 
-import logging
+from synapse.metrics import LaterGauge
+from synapse.storage.presence import UserPresenceState
+from synapse.util.metrics import Measure
 
-from six import itervalues, iteritems
+from .units import Edu
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py
index d72b057e..5a956ecf 100644
--- a/synapse/federation/transaction_queue.py
+++ b/synapse/federation/transaction_queue.py
@@ -13,31 +13,29 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import datetime
+import logging
 
-from twisted.internet import defer
+from six import itervalues
 
-from .persistence import TransactionActions
-from .units import Transaction, Edu
+from prometheus_client import Counter
+
+from twisted.internet import defer
 
-from synapse.api.errors import HttpResponseException, FederationDeniedError
-from synapse.util import logcontext, PreserveLoggingContext
-from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter
-from synapse.util.metrics import measure_func
-from synapse.handlers.presence import format_user_presence_state, get_interested_remotes
 import synapse.metrics
-from synapse.metrics import LaterGauge
+from synapse.api.errors import FederationDeniedError, HttpResponseException
+from synapse.handlers.presence import format_user_presence_state, get_interested_remotes
 from synapse.metrics import (
+    LaterGauge,
+    events_processed_counter,
     sent_edus_counter,
     sent_transactions_counter,
-    events_processed_counter,
 )
+from synapse.util import PreserveLoggingContext, logcontext
+from synapse.util.metrics import measure_func
+from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter
 
-from prometheus_client import Counter
-
-from six import itervalues
-
-import logging
-
+from .persistence import TransactionActions
+from .units import Edu, Transaction
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 6db8efa6..4529d454 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -14,16 +14,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+import urllib
+
 from twisted.internet import defer
-from synapse.api.constants import Membership
 
+from synapse.api.constants import Membership
 from synapse.api.urls import FEDERATION_PREFIX as PREFIX
 from synapse.util.logutils import log_function
 
-import logging
-import urllib
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index c6d98d35..c9beca27 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -14,26 +14,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import functools
+import logging
+import re
+
 from twisted.internet import defer
 
+import synapse
+from synapse.api.errors import Codes, FederationDeniedError, SynapseError
 from synapse.api.urls import FEDERATION_PREFIX as PREFIX
-from synapse.api.errors import Codes, SynapseError, FederationDeniedError
 from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.http.server import JsonResource
 from synapse.http.servlet import (
-    parse_json_object_from_request, parse_integer_from_args, parse_string_from_args,
     parse_boolean_from_args,
+    parse_integer_from_args,
+    parse_json_object_from_request,
+    parse_string_from_args,
 )
+from synapse.types import ThirdPartyInstanceID, get_domain_from_id
+from synapse.util.logcontext import run_in_background
 from synapse.util.ratelimitutils import FederationRateLimiter
 from synapse.util.versionstring import get_version_string
-from synapse.util.logcontext import run_in_background
-from synapse.types import ThirdPartyInstanceID, get_domain_from_id
-
-import functools
-import logging
-import re
-import synapse
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/units.py b/synapse/federation/units.py
index 01c5b8fe..bb1b3b13 100644
--- a/synapse/federation/units.py
+++ b/synapse/federation/units.py
@@ -17,10 +17,9 @@
 server protocol.
 """
 
-from synapse.util.jsonobject import JsonEncodedObject
-
 import logging
 
+from synapse.util.jsonobject import JsonEncodedObject
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py
index 6f11fa37..47452700 100644
--- a/synapse/groups/attestations.py
+++ b/synapse/groups/attestations.py
@@ -23,9 +23,9 @@ If a user leaves (or gets kicked out of) a group, either side can still use
 their attestation to "prove" their membership, until the attestation expires.
 Therefore attestations shouldn't be relied on to prove membership in important
 cases, but can for less important situtations, e.g. showing a users membership
-of groups on their profile, showing flairs, etc.abs
+of groups on their profile, showing flairs, etc.
 
-An attestsation is a signed blob of json that looks like:
+An attestation is a signed blob of json that looks like:
 
     {
         "user_id": "@foo:a.example.com",
@@ -38,15 +38,14 @@ An attestsation is a signed blob of json that looks like:
 import logging
 import random
 
+from signedjson.sign import sign_json
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.types import get_domain_from_id
 from synapse.util.logcontext import run_in_background
 
-from signedjson.sign import sign_json
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
index 62d20ad1..633c865e 100644
--- a/synapse/groups/groups_server.py
+++ b/synapse/groups/groups_server.py
@@ -16,11 +16,12 @@
 
 import logging
 
-from synapse.api.errors import SynapseError
-from synapse.types import GroupID, RoomID, UserID, get_domain_from_id
+from six import string_types
+
 from twisted.internet import defer
 
-from six import string_types
+from synapse.api.errors import SynapseError
+from synapse.types import GroupID, RoomID, UserID, get_domain_from_id
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/__init__.py b/synapse/handlers/__init__.py
index d358842b..4b9923d8 100644
--- a/synapse/handlers/__init__.py
+++ b/synapse/handlers/__init__.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .register import RegistrationHandler
-from .room import RoomContextHandler
-from .message import MessageHandler
-from .federation import FederationHandler
-from .directory import DirectoryHandler
 from .admin import AdminHandler
+from .directory import DirectoryHandler
+from .federation import FederationHandler
 from .identity import IdentityHandler
+from .message import MessageHandler
+from .register import RegistrationHandler
+from .room import RoomContextHandler
 from .search import SearchHandler
 
 
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index 2d1db0c2..b6a8b3aa 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -18,11 +18,10 @@ import logging
 from twisted.internet import defer
 
 import synapse.types
-from synapse.api.constants import Membership, EventTypes
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import LimitExceededError
 from synapse.types import UserID
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/admin.py b/synapse/handlers/admin.py
index f36b358b..5d629126 100644
--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from ._base import BaseHandler
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index 1c29c43a..ec9fe01a 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -13,19 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
 from six import itervalues
 
+from prometheus_client import Counter
+
+from twisted.internet import defer
+
 import synapse
 from synapse.api.constants import EventTypes
+from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.metrics import Measure
-from synapse.util.logcontext import (
-    make_deferred_yieldable, run_in_background,
-)
-from prometheus_client import Counter
-
-import logging
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index cbef1f27..402e44cd 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -14,14 +14,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
+import logging
 
+import attr
+import bcrypt
+import pymacaroons
 from canonicaljson import json
 
-from ._base import BaseHandler
+from twisted.internet import defer, threads
+from twisted.web.client import PartialDownloadError
+
+import synapse.util.stringutils as stringutils
 from synapse.api.constants import LoginType
 from synapse.api.errors import (
-    AuthError, Codes, InteractiveAuthIncompleteError, LoginError, StoreError,
+    AuthError,
+    Codes,
+    InteractiveAuthIncompleteError,
+    LoginError,
+    StoreError,
     SynapseError,
 )
 from synapse.module_api import ModuleApi
@@ -29,15 +39,7 @@ from synapse.types import UserID
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logcontext import make_deferred_yieldable
 
-from twisted.web.client import PartialDownloadError
-
-import logging
-import bcrypt
-import pymacaroons
-import attr
-
-import synapse.util.stringutils as stringutils
-
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/deactivate_account.py b/synapse/handlers/deactivate_account.py
index a84b7b8b..b3c5a9ee 100644
--- a/synapse/handlers/deactivate_account.py
+++ b/synapse/handlers/deactivate_account.py
@@ -12,14 +12,15 @@
 # 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.
+import logging
+
 from twisted.internet import defer
 
-from ._base import BaseHandler
+from synapse.api.errors import SynapseError
 from synapse.types import UserID, create_requester
 from synapse.util.logcontext import run_in_background
-from synapse.api.errors import SynapseError
 
-import logging
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 11c6fb36..2d44f15d 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -12,21 +12,23 @@
 # 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.
+import logging
+
+from six import iteritems, itervalues
+
+from twisted.internet import defer
+
 from synapse.api import errors
 from synapse.api.constants import EventTypes
 from synapse.api.errors import FederationDeniedError
+from synapse.types import RoomStreamToken, get_domain_from_id
 from synapse.util import stringutils
 from synapse.util.async import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
-from synapse.util.retryutils import NotRetryingDestination
 from synapse.util.metrics import measure_func
-from synapse.types import get_domain_from_id, RoomStreamToken
-from twisted.internet import defer
-from ._base import BaseHandler
-
-import logging
+from synapse.util.retryutils import NotRetryingDestination
 
-from six import itervalues, iteritems
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
@@ -537,7 +539,7 @@ class DeviceListEduUpdater(object):
                 yield self.device_handler.notify_device_update(user_id, device_ids)
             else:
                 # Simply update the single device, since we know that is the only
-                # change (becuase of the single prev_id matching the current cache)
+                # change (because of the single prev_id matching the current cache)
                 for device_id, stream_id, prev_ids, content in pending_updates:
                     yield self.store.update_remote_device_list_cache_entry(
                         user_id, device_id, content, stream_id,
diff --git a/synapse/handlers/devicemessage.py b/synapse/handlers/devicemessage.py
index f147a20b..2e2e5261 100644
--- a/synapse/handlers/devicemessage.py
+++ b/synapse/handlers/devicemessage.py
@@ -18,10 +18,9 @@ import logging
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
-from synapse.types import get_domain_from_id, UserID
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.stringutils import random_string
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index c5b6e75e..ef866da1 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -14,15 +14,16 @@
 # limitations under the License.
 
 
+import logging
+import string
+
 from twisted.internet import defer
-from ._base import BaseHandler
 
-from synapse.api.errors import SynapseError, Codes, CodeMessageException, AuthError
 from synapse.api.constants import EventTypes
+from synapse.api.errors import AuthError, CodeMessageException, Codes, SynapseError
 from synapse.types import RoomAlias, UserID, get_domain_from_id
 
-import logging
-import string
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 62b4892a..5816bf8b 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -16,14 +16,14 @@
 
 import logging
 
+from six import iteritems
+
 from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
-from six import iteritems
 
-from synapse.api.errors import (
-    SynapseError, CodeMessageException, FederationDeniedError,
-)
-from synapse.types import get_domain_from_id, UserID
+from synapse.api.errors import CodeMessageException, FederationDeniedError, SynapseError
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.retryutils import NotRetryingDestination
 
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index 8bc64267..c3f2d7fe 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -13,20 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+import random
+
 from twisted.internet import defer
 
-from synapse.util.logutils import log_function
-from synapse.types import UserID
-from synapse.events.utils import serialize_event
-from synapse.api.constants import Membership, EventTypes
+from synapse.api.constants import EventTypes, Membership
 from synapse.events import EventBase
+from synapse.events.utils import serialize_event
+from synapse.types import UserID
+from synapse.util.logutils import log_function
 
 from ._base import BaseHandler
 
-import logging
-import random
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 13117d70..20fb46fc 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -20,38 +20,41 @@ import itertools
 import logging
 import sys
 
-from signedjson.key import decode_verify_key_bytes
-from signedjson.sign import verify_signed_json
 import six
-from six.moves import http_client
 from six import iteritems
-from twisted.internet import defer
+from six.moves import http_client
+
+from signedjson.key import decode_verify_key_bytes
+from signedjson.sign import verify_signed_json
 from unpaddedbase64 import decode_base64
 
-from ._base import BaseHandler
+from twisted.internet import defer
 
+from synapse.api.constants import EventTypes, Membership, RejectedReason
 from synapse.api.errors import (
-    AuthError, FederationError, StoreError, CodeMessageException, SynapseError,
+    AuthError,
+    CodeMessageException,
     FederationDeniedError,
+    FederationError,
+    StoreError,
+    SynapseError,
 )
-from synapse.api.constants import EventTypes, Membership, RejectedReason
-from synapse.events.validator import EventValidator
-from synapse.util import unwrapFirstError, logcontext
-from synapse.util.metrics import measure_func
-from synapse.util.logutils import log_function
-from synapse.util.async import Linearizer
-from synapse.util.frozenutils import unfreeze
 from synapse.crypto.event_signing import (
-    compute_event_signature, add_hashes_and_signatures,
+    add_hashes_and_signatures,
+    compute_event_signature,
 )
+from synapse.events.validator import EventValidator
 from synapse.state import resolve_events_with_factory
 from synapse.types import UserID, get_domain_from_id
-
-from synapse.events.utils import prune_event
-
+from synapse.util import logcontext, unwrapFirstError
+from synapse.util.async import Linearizer
+from synapse.util.distributor import user_joined_room
+from synapse.util.frozenutils import unfreeze
+from synapse.util.logutils import log_function
 from synapse.util.retryutils import NotRetryingDestination
+from synapse.visibility import filter_events_for_server
 
-from synapse.util.distributor import user_joined_room
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
@@ -497,137 +500,6 @@ class FederationHandler(BaseHandler):
                     user = UserID.from_string(event.state_key)
                     yield user_joined_room(self.distributor, user, event.room_id)
 
-    @measure_func("_filter_events_for_server")
-    @defer.inlineCallbacks
-    def _filter_events_for_server(self, server_name, room_id, events):
-        """Filter the given events for the given server, redacting those the
-        server can't see.
-
-        Assumes the server is currently in the room.
-
-        Returns
-            list[FrozenEvent]
-        """
-        # First lets check to see if all the events have a history visibility
-        # of "shared" or "world_readable". If thats the case then we don't
-        # need to check membership (as we know the server is in the room).
-        event_to_state_ids = yield self.store.get_state_ids_for_events(
-            frozenset(e.event_id for e in events),
-            types=(
-                (EventTypes.RoomHistoryVisibility, ""),
-            )
-        )
-
-        visibility_ids = set()
-        for sids in event_to_state_ids.itervalues():
-            hist = sids.get((EventTypes.RoomHistoryVisibility, ""))
-            if hist:
-                visibility_ids.add(hist)
-
-        # If we failed to find any history visibility events then the default
-        # is "shared" visiblity.
-        if not visibility_ids:
-            defer.returnValue(events)
-
-        event_map = yield self.store.get_events(visibility_ids)
-        all_open = all(
-            e.content.get("history_visibility") in (None, "shared", "world_readable")
-            for e in event_map.itervalues()
-        )
-
-        if all_open:
-            defer.returnValue(events)
-
-        # Ok, so we're dealing with events that have non-trivial visibility
-        # rules, so we need to also get the memberships of the room.
-
-        event_to_state_ids = yield self.store.get_state_ids_for_events(
-            frozenset(e.event_id for e in events),
-            types=(
-                (EventTypes.RoomHistoryVisibility, ""),
-                (EventTypes.Member, None),
-            )
-        )
-
-        # We only want to pull out member events that correspond to the
-        # server's domain.
-
-        def check_match(id):
-            try:
-                return server_name == get_domain_from_id(id)
-            except Exception:
-                return False
-
-        # Parses mapping `event_id -> (type, state_key) -> state event_id`
-        # to get all state ids that we're interested in.
-        event_map = yield self.store.get_events([
-            e_id
-            for key_to_eid in list(event_to_state_ids.values())
-            for key, e_id in key_to_eid.items()
-            if key[0] != EventTypes.Member or check_match(key[1])
-        ])
-
-        event_to_state = {
-            e_id: {
-                key: event_map[inner_e_id]
-                for key, inner_e_id in key_to_eid.iteritems()
-                if inner_e_id in event_map
-            }
-            for e_id, key_to_eid in event_to_state_ids.iteritems()
-        }
-
-        erased_senders = yield self.store.are_users_erased(
-            e.sender for e in events,
-        )
-
-        def redact_disallowed(event, state):
-            # if the sender has been gdpr17ed, always return a redacted
-            # copy of the event.
-            if erased_senders[event.sender]:
-                logger.info(
-                    "Sender of %s has been erased, redacting",
-                    event.event_id,
-                )
-                return prune_event(event)
-
-            if not state:
-                return event
-
-            history = state.get((EventTypes.RoomHistoryVisibility, ''), None)
-            if history:
-                visibility = history.content.get("history_visibility", "shared")
-                if visibility in ["invited", "joined"]:
-                    # We now loop through all state events looking for
-                    # membership states for the requesting server to determine
-                    # if the server is either in the room or has been invited
-                    # into the room.
-                    for ev in state.itervalues():
-                        if ev.type != EventTypes.Member:
-                            continue
-                        try:
-                            domain = get_domain_from_id(ev.state_key)
-                        except Exception:
-                            continue
-
-                        if domain != server_name:
-                            continue
-
-                        memtype = ev.membership
-                        if memtype == Membership.JOIN:
-                            return event
-                        elif memtype == Membership.INVITE:
-                            if visibility == "invited":
-                                return event
-                    else:
-                        return prune_event(event)
-
-            return event
-
-        defer.returnValue([
-            redact_disallowed(e, event_to_state[e.event_id])
-            for e in events
-        ])
-
     @log_function
     @defer.inlineCallbacks
     def backfill(self, dest, room_id, limit, extremities):
@@ -1554,7 +1426,7 @@ class FederationHandler(BaseHandler):
             limit
         )
 
-        events = yield self._filter_events_for_server(origin, room_id, events)
+        events = yield filter_events_for_server(self.store, origin, events)
 
         defer.returnValue(events)
 
@@ -1601,8 +1473,8 @@ class FederationHandler(BaseHandler):
             if not in_room:
                 raise AuthError(403, "Host not in room.")
 
-            events = yield self._filter_events_for_server(
-                origin, event.room_id, [event]
+            events = yield filter_events_for_server(
+                self.store, origin, [event],
             )
             event = events[0]
             defer.returnValue(event)
@@ -1892,8 +1764,8 @@ class FederationHandler(BaseHandler):
             min_depth=min_depth,
         )
 
-        missing_events = yield self._filter_events_for_server(
-            origin, room_id, missing_events,
+        missing_events = yield filter_events_for_server(
+            self.store, origin, missing_events,
         )
 
         defer.returnValue(missing_events)
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index dcae0837..53e5e264 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -14,14 +14,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+
 from six import iteritems
 
+from twisted.internet import defer
+
 from synapse.api.errors import SynapseError
 from synapse.types import get_domain_from_id
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 277c2b77..8c8aedb2 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -24,10 +24,13 @@ from canonicaljson import json
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    MatrixCodeMessageException, CodeMessageException
+    CodeMessageException,
+    Codes,
+    MatrixCodeMessageException,
+    SynapseError,
 )
+
 from ._base import BaseHandler
-from synapse.api.errors import SynapseError, Codes
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 71af86fe..fb11716e 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
@@ -21,9 +23,7 @@ from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
 from synapse.handlers.presence import format_user_presence_state
 from synapse.streams.config import PaginationConfig
-from synapse.types import (
-    UserID, StreamToken,
-)
+from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
 from synapse.util.async import concurrently_execute
 from synapse.util.caches.snapshot_cache import SnapshotCache
@@ -32,9 +32,6 @@ from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index cbadf3c8..a39b852c 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -16,32 +16,29 @@
 import logging
 import sys
 
-from canonicaljson import encode_canonical_json, json
 import six
-from six import string_types, itervalues, iteritems
+from six import iteritems, itervalues, string_types
+
+from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
 from twisted.internet.defer import succeed
 from twisted.python.failure import Failure
 
-from synapse.api.constants import EventTypes, Membership, MAX_DEPTH
-from synapse.api.errors import (
-    AuthError, Codes, SynapseError,
-    ConsentNotGivenError,
-)
+from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
+from synapse.api.errors import AuthError, Codes, ConsentNotGivenError, SynapseError
 from synapse.api.urls import ConsentURIBuilder
 from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
-from synapse.types import (
-    UserID, RoomAlias, RoomStreamToken,
-)
-from synapse.util.async import ReadWriteLock, Limiter
+from synapse.replication.http.send_event import send_event_to_master
+from synapse.types import RoomAlias, RoomStreamToken, UserID
+from synapse.util.async import Limiter, ReadWriteLock
+from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import measure_func
-from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.stringutils import random_string
 from synapse.visibility import filter_events_for_client
-from synapse.replication.http.send_event import send_event_to_master
 
 from ._base import BaseHandler
 
@@ -387,7 +384,7 @@ class MessageHandler(BaseHandler):
         users_with_profile = yield self.state.get_current_user_in_room(room_id)
 
         # If this is an AS, double check that they are allowed to see the members.
-        # This can either be because the AS user is in the room or becuase there
+        # This can either be because the AS user is in the room or because there
         # is a user in the room that the AS is "interested in"
         if requester.app_service and user_id not in users_with_profile:
             for uid in users_with_profile:
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 7db59fba..37328301 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -22,27 +22,26 @@ The methods that define policy are:
     - should_notify
 """
 
-from twisted.internet import defer
+import logging
 from contextlib import contextmanager
 
-from six import itervalues, iteritems
+from six import iteritems, itervalues
+
+from prometheus_client import Counter
+
+from twisted.internet import defer
 
-from synapse.api.errors import SynapseError
 from synapse.api.constants import PresenceState
+from synapse.api.errors import SynapseError
+from synapse.metrics import LaterGauge
 from synapse.storage.presence import UserPresenceState
-
-from synapse.util.caches.descriptors import cachedInlineCallbacks
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.async import Linearizer
+from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.logcontext import run_in_background
 from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
 from synapse.util.wheel_timer import WheelTimer
-from synapse.types import UserID, get_domain_from_id
-from synapse.metrics import LaterGauge
-
-import logging
-
-from prometheus_client import Counter
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 3465a787..859f6d2b 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -17,8 +17,9 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, AuthError, CodeMessageException
+from synapse.api.errors import AuthError, CodeMessageException, SynapseError
 from synapse.types import UserID, get_domain_from_id
+
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
index 5142ae15..995460f8 100644
--- a/synapse/handlers/read_marker.py
+++ b/synapse/handlers/read_marker.py
@@ -13,13 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseHandler
+import logging
 
 from twisted.internet import defer
 
 from synapse.util.async import Linearizer
 
-import logging
+from ._base import BaseHandler
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index 2e067216..cb905a39 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -12,17 +12,15 @@
 # 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 import logcontext
-
-from ._base import BaseHandler
+import logging
 
 from twisted.internet import defer
 
-from synapse.util.logcontext import PreserveLoggingContext
 from synapse.types import get_domain_from_id
+from synapse.util import logcontext
+from synapse.util.logcontext import PreserveLoggingContext
 
-import logging
-
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index e76ef542..7caff0cb 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -18,14 +18,19 @@ import logging
 
 from twisted.internet import defer
 
+from synapse import types
 from synapse.api.errors import (
-    AuthError, Codes, SynapseError, RegistrationError, InvalidCaptchaError
+    AuthError,
+    Codes,
+    InvalidCaptchaError,
+    RegistrationError,
+    SynapseError,
 )
 from synapse.http.client import CaptchaServerHttpClient
-from synapse import types
-from synapse.types import UserID, create_requester, RoomID, RoomAlias
+from synapse.types import RoomAlias, RoomID, UserID, create_requester
 from synapse.util.async import Linearizer
 from synapse.util.threepids import check_3pid_allowed
+
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index ab72963d..f6751207 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -15,23 +15,20 @@
 # limitations under the License.
 
 """Contains functions for performing events on rooms."""
-from twisted.internet import defer
+import logging
+import math
+import string
+from collections import OrderedDict
 
-from ._base import BaseHandler
+from twisted.internet import defer
 
-from synapse.types import UserID, RoomAlias, RoomID, RoomStreamToken
-from synapse.api.constants import (
-    EventTypes, JoinRules, RoomCreationPreset
-)
+from synapse.api.constants import EventTypes, JoinRules, RoomCreationPreset
 from synapse.api.errors import AuthError, Codes, StoreError, SynapseError
+from synapse.types import RoomAlias, RoomID, RoomStreamToken, UserID
 from synapse.util import stringutils
 from synapse.visibility import filter_events_for_client
 
-from collections import OrderedDict
-
-import logging
-import math
-import string
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index fc507cef..828229f5 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -13,26 +13,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+from collections import namedtuple
 
 from six import iteritems
 from six.moves import range
 
-from ._base import BaseHandler
+import msgpack
+from unpaddedbase64 import decode_base64, encode_base64
+
+from twisted.internet import defer
 
-from synapse.api.constants import (
-    EventTypes, JoinRules,
-)
+from synapse.api.constants import EventTypes, JoinRules
+from synapse.types import ThirdPartyInstanceID
 from synapse.util.async import concurrently_execute
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.caches.response_cache import ResponseCache
-from synapse.types import ThirdPartyInstanceID
-
-from collections import namedtuple
-from unpaddedbase64 import encode_base64, decode_base64
 
-import logging
-import msgpack
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
@@ -40,7 +38,7 @@ REMOTE_ROOM_LIST_POLL_INTERVAL = 60 * 1000
 
 
 # This is used to indicate we should only return rooms published to the main list.
-EMTPY_THIRD_PARTY_ID = ThirdPartyInstanceID(None, None)
+EMPTY_THIRD_PARTY_ID = ThirdPartyInstanceID(None, None)
 
 
 class RoomListHandler(BaseHandler):
@@ -52,7 +50,7 @@ class RoomListHandler(BaseHandler):
 
     def get_local_public_room_list(self, limit=None, since_token=None,
                                    search_filter=None,
-                                   network_tuple=EMTPY_THIRD_PARTY_ID,):
+                                   network_tuple=EMPTY_THIRD_PARTY_ID,):
         """Generate a local public room list.
 
         There are multiple different lists: the main one plus one per third
@@ -89,7 +87,7 @@ class RoomListHandler(BaseHandler):
     @defer.inlineCallbacks
     def _get_public_room_list(self, limit=None, since_token=None,
                               search_filter=None,
-                              network_tuple=EMTPY_THIRD_PARTY_ID,):
+                              network_tuple=EMPTY_THIRD_PARTY_ID,):
         if since_token and since_token != "END":
             since_token = RoomListNextBatch.from_token(since_token)
         else:
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index f930e939..00f2e279 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -21,19 +21,17 @@ from six.moves import http_client
 
 from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import verify_signed_json
-from twisted.internet import defer
 from unpaddedbase64 import decode_base64
 
+from twisted.internet import defer
+
 import synapse.server
 import synapse.types
-from synapse.api.constants import (
-    EventTypes, Membership,
-)
-from synapse.api.errors import AuthError, SynapseError, Codes
-from synapse.types import UserID, RoomID
+from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import AuthError, Codes, SynapseError
+from synapse.types import RoomID, UserID
 from synapse.util.async import Linearizer
-from synapse.util.distributor import user_left_room, user_joined_room
-
+from synapse.util.distributor import user_joined_room, user_left_room
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/room_member_worker.py b/synapse/handlers/room_member_worker.py
index 493aec1e..22d8b4b0 100644
--- a/synapse/handlers/room_member_worker.py
+++ b/synapse/handlers/room_member_worker.py
@@ -20,11 +20,12 @@ from twisted.internet import defer
 from synapse.api.errors import SynapseError
 from synapse.handlers.room_member import RoomMemberHandler
 from synapse.replication.http.membership import (
-    remote_join, remote_reject_invite, get_or_register_3pid_guest,
+    get_or_register_3pid_guest,
     notify_user_membership_change,
+    remote_join,
+    remote_reject_invite,
 )
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/search.py b/synapse/handlers/search.py
index 2e3a77ca..69ae9731 100644
--- a/synapse/handlers/search.py
+++ b/synapse/handlers/search.py
@@ -13,21 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import itertools
+import logging
 
-from ._base import BaseHandler
+from unpaddedbase64 import decode_base64, encode_base64
 
-from synapse.api.constants import Membership, EventTypes
-from synapse.api.filtering import Filter
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import SynapseError
+from synapse.api.filtering import Filter
 from synapse.events.utils import serialize_event
 from synapse.visibility import filter_events_for_client
 
-from unpaddedbase64 import decode_base64, encode_base64
-
-import itertools
-import logging
-
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/set_password.py b/synapse/handlers/set_password.py
index e057ae54..7ecdede4 100644
--- a/synapse/handlers/set_password.py
+++ b/synapse/handlers/set_password.py
@@ -17,6 +17,7 @@ import logging
 from twisted.internet import defer
 
 from synapse.api.errors import Codes, StoreError, SynapseError
+
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 7f486e48..c24e3536 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -13,22 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.api.constants import Membership, EventTypes
+import collections
+import itertools
+import logging
+
+from six import iteritems, itervalues
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
+from synapse.push.clientformat import format_push_rules_for_user
+from synapse.types import RoomStreamToken
 from synapse.util.async import concurrently_execute
+from synapse.util.caches.response_cache import ResponseCache
 from synapse.util.logcontext import LoggingContext
 from synapse.util.metrics import Measure, measure_func
-from synapse.util.caches.response_cache import ResponseCache
-from synapse.push.clientformat import format_push_rules_for_user
 from synapse.visibility import filter_events_for_client
-from synapse.types import RoomStreamToken
-
-from twisted.internet import defer
-
-import collections
-import logging
-import itertools
-
-from six import itervalues, iteritems
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index 5d9736e8..2d2d3d5a 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -13,17 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+from collections import namedtuple
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, AuthError
+from synapse.api.errors import AuthError, SynapseError
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import Measure
 from synapse.util.wheel_timer import WheelTimer
-from synapse.types import UserID, get_domain_from_id
-
-import logging
-
-from collections import namedtuple
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/user_directory.py b/synapse/handlers/user_directory.py
index 7e4a114d..37dda645 100644
--- a/synapse/handlers/user_directory.py
+++ b/synapse/handlers/user_directory.py
@@ -14,14 +14,15 @@
 # limitations under the License.
 
 import logging
+
+from six import iteritems
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, JoinRules, Membership
 from synapse.storage.roommember import ProfileInfo
-from synapse.util.metrics import Measure
 from synapse.types import get_localpart_from_id
-
-from six import iteritems
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/additional_resource.py b/synapse/http/additional_resource.py
index a797396a..0e10e3f8 100644
--- a/synapse/http/additional_resource.py
+++ b/synapse/http/additional_resource.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import wrap_json_request_handler
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
+from synapse.http.server import wrap_json_request_handler
+
 
 class AdditionalResource(Resource):
     """Resource wrapper for additional_resources
diff --git a/synapse/http/client.py b/synapse/http/client.py
index 5bdc484c..d6a0d75b 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -13,39 +13,41 @@
 # 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 OpenSSL import SSL
-from OpenSSL.SSL import VERIFY_NONE
+import logging
+import urllib
 
-from synapse.api.errors import (
-    CodeMessageException, MatrixCodeMessageException, SynapseError, Codes,
-)
-from synapse.http import cancelled_to_request_timed_out_error, redact_uri
-from synapse.util.async import add_timeout_to_deferred
-from synapse.util.caches import CACHE_SIZE_FACTOR
-from synapse.util.logcontext import make_deferred_yieldable
-from synapse.http.endpoint import SpiderEndpoint
+from six import StringIO
 
-from canonicaljson import encode_canonical_json
+from canonicaljson import encode_canonical_json, json
+from prometheus_client import Counter
 
-from twisted.internet import defer, reactor, ssl, protocol, task
+from OpenSSL import SSL
+from OpenSSL.SSL import VERIFY_NONE
+from twisted.internet import defer, protocol, reactor, ssl, task
 from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
+from twisted.web._newclient import ResponseDone
+from twisted.web.client import Agent, BrowserLikeRedirectAgent, ContentDecoderAgent
+from twisted.web.client import FileBodyProducer as TwistedFileBodyProducer
 from twisted.web.client import (
-    BrowserLikeRedirectAgent, ContentDecoderAgent, GzipDecoder, Agent,
-    readBody, PartialDownloadError,
+    GzipDecoder,
     HTTPConnectionPool,
+    PartialDownloadError,
+    readBody,
 )
-from twisted.web.client import FileBodyProducer as TwistedFileBodyProducer
 from twisted.web.http import PotentialDataLoss
 from twisted.web.http_headers import Headers
-from twisted.web._newclient import ResponseDone
-
-from six import StringIO
-
-from prometheus_client import Counter
-from canonicaljson import json
-import logging
-import urllib
 
+from synapse.api.errors import (
+    CodeMessageException,
+    Codes,
+    MatrixCodeMessageException,
+    SynapseError,
+)
+from synapse.http import cancelled_to_request_timed_out_error, redact_uri
+from synapse.http.endpoint import SpiderEndpoint
+from synapse.util.async import add_timeout_to_deferred
+from synapse.util.caches import CACHE_SIZE_FACTOR
+from synapse.util.logcontext import make_deferred_yieldable
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/endpoint.py b/synapse/http/endpoint.py
index 1b1123b2..d65daa72 100644
--- a/synapse/http/endpoint.py
+++ b/synapse/http/endpoint.py
@@ -12,20 +12,18 @@
 # 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.
+import collections
+import logging
+import random
 import re
+import time
 
-from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
 from twisted.internet import defer
+from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
 from twisted.internet.error import ConnectError
 from twisted.names import client, dns
 from twisted.names.error import DNSNameError, DomainError
 
-import collections
-import logging
-import random
-import time
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 2cb9e3e2..bf1aa295 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -13,38 +13,38 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from twisted.internet import defer, reactor, protocol
-from twisted.internet.error import DNSLookupError
-from twisted.web.client import readBody, HTTPConnectionPool, Agent
-from twisted.web.http_headers import Headers
-from twisted.web._newclient import ResponseDone
-
-from synapse.http import cancelled_to_request_timed_out_error
-from synapse.http.endpoint import matrix_federation_endpoint
-import synapse.metrics
-from synapse.util.async import add_timeout_to_deferred
-from synapse.util import logcontext
-from synapse.util.logcontext import make_deferred_yieldable
-import synapse.util.retryutils
-
-from canonicaljson import encode_canonical_json, json
-
-from synapse.api.errors import (
-    SynapseError, Codes, HttpResponseException, FederationDeniedError,
-)
-
-from signedjson.sign import sign_json
-
 import cgi
 import logging
 import random
 import sys
 import urllib
-from six.moves.urllib import parse as urlparse
-from six import string_types
 
+from six import string_types
+from six.moves.urllib import parse as urlparse
 
+from canonicaljson import encode_canonical_json, json
 from prometheus_client import Counter
+from signedjson.sign import sign_json
+
+from twisted.internet import defer, protocol, reactor
+from twisted.internet.error import DNSLookupError
+from twisted.web._newclient import ResponseDone
+from twisted.web.client import Agent, HTTPConnectionPool, readBody
+from twisted.web.http_headers import Headers
+
+import synapse.metrics
+import synapse.util.retryutils
+from synapse.api.errors import (
+    Codes,
+    FederationDeniedError,
+    HttpResponseException,
+    SynapseError,
+)
+from synapse.http import cancelled_to_request_timed_out_error
+from synapse.http.endpoint import matrix_federation_endpoint
+from synapse.util import logcontext
+from synapse.util.async import add_timeout_to_deferred
+from synapse.util.logcontext import make_deferred_yieldable
 
 logger = logging.getLogger(__name__)
 outbound_logger = logging.getLogger("synapse.http.outbound")
diff --git a/synapse/http/request_metrics.py b/synapse/http/request_metrics.py
index 1b711ca2..f24b4b94 100644
--- a/synapse/http/request_metrics.py
+++ b/synapse/http/request_metrics.py
@@ -17,8 +17,8 @@
 import logging
 
 from prometheus_client.core import Counter, Histogram
-from synapse.metrics import LaterGauge
 
+from synapse.metrics import LaterGauge
 from synapse.util.logcontext import LoggingContext
 
 logger = logging.getLogger(__name__)
@@ -149,7 +149,9 @@ class RequestMetrics(object):
         self.name = name
         self.method = method
 
-        self._request_stats = _RequestStats.from_context(self.start_context)
+        # _request_stats records resource usage that we have already added
+        # to the "in flight" metrics.
+        self._request_stats = self.start_context.get_resource_usage()
 
         _in_flight_requests.add(self)
 
@@ -177,18 +179,22 @@ class RequestMetrics(object):
             time_sec - self.start
         )
 
-        ru_utime, ru_stime = context.get_resource_usage()
+        resource_usage = context.get_resource_usage()
 
-        response_ru_utime.labels(request.method, self.name, tag).inc(ru_utime)
-        response_ru_stime.labels(request.method, self.name, tag).inc(ru_stime)
+        response_ru_utime.labels(request.method, self.name, tag).inc(
+            resource_usage.ru_utime,
+        )
+        response_ru_stime.labels(request.method, self.name, tag).inc(
+            resource_usage.ru_stime,
+        )
         response_db_txn_count.labels(request.method, self.name, tag).inc(
-            context.db_txn_count
+            resource_usage.db_txn_count
         )
         response_db_txn_duration.labels(request.method, self.name, tag).inc(
-            context.db_txn_duration_sec
+            resource_usage.db_txn_duration_sec
         )
         response_db_sched_duration.labels(request.method, self.name, tag).inc(
-            context.db_sched_duration_sec
+            resource_usage.db_sched_duration_sec
         )
 
         response_size.labels(request.method, self.name, tag).inc(request.sentLength)
@@ -201,7 +207,10 @@ class RequestMetrics(object):
     def update_metrics(self):
         """Updates the in flight metrics with values from this request.
         """
-        diff = self._request_stats.update(self.start_context)
+        new_stats = self.start_context.get_resource_usage()
+
+        diff = new_stats - self._request_stats
+        self._request_stats = new_stats
 
         in_flight_requests_ru_utime.labels(self.method, self.name).inc(diff.ru_utime)
         in_flight_requests_ru_stime.labels(self.method, self.name).inc(diff.ru_stime)
@@ -217,61 +226,3 @@ class RequestMetrics(object):
         in_flight_requests_db_sched_duration.labels(self.method, self.name).inc(
             diff.db_sched_duration_sec
         )
-
-
-class _RequestStats(object):
-    """Keeps tracks of various metrics for an in flight request.
-    """
-
-    __slots__ = [
-        "ru_utime",
-        "ru_stime",
-        "db_txn_count",
-        "db_txn_duration_sec",
-        "db_sched_duration_sec",
-    ]
-
-    def __init__(
-        self, ru_utime, ru_stime, db_txn_count, db_txn_duration_sec, db_sched_duration_sec
-    ):
-        self.ru_utime = ru_utime
-        self.ru_stime = ru_stime
-        self.db_txn_count = db_txn_count
-        self.db_txn_duration_sec = db_txn_duration_sec
-        self.db_sched_duration_sec = db_sched_duration_sec
-
-    @staticmethod
-    def from_context(context):
-        ru_utime, ru_stime = context.get_resource_usage()
-
-        return _RequestStats(
-            ru_utime, ru_stime,
-            context.db_txn_count,
-            context.db_txn_duration_sec,
-            context.db_sched_duration_sec,
-        )
-
-    def update(self, context):
-        """Updates the current values and returns the difference between the
-        old and new values.
-
-        Returns:
-            _RequestStats: The difference between the old and new values
-        """
-        new = _RequestStats.from_context(context)
-
-        diff = _RequestStats(
-            new.ru_utime - self.ru_utime,
-            new.ru_stime - self.ru_stime,
-            new.db_txn_count - self.db_txn_count,
-            new.db_txn_duration_sec - self.db_txn_duration_sec,
-            new.db_sched_duration_sec - self.db_sched_duration_sec,
-        )
-
-        self.ru_utime = new.ru_utime
-        self.ru_stime = new.ru_stime
-        self.db_txn_count = new.db_txn_count
-        self.db_txn_duration_sec = new.db_txn_duration_sec
-        self.db_sched_duration_sec = new.db_sched_duration_sec
-
-        return diff
diff --git a/synapse/http/server.py b/synapse/http/server.py
index 517aaf7b..c70fdbdf 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -14,33 +14,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import cgi
-from six.moves import http_client
+import collections
+import logging
+import urllib
 
-from synapse.api.errors import (
-    cs_exception, SynapseError, CodeMessageException, UnrecognizedRequestError, Codes
-)
-from synapse.http.request_metrics import (
-    requests_counter,
-)
-from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
-from synapse.util.caches import intern_dict
-from synapse.util.metrics import Measure
-import synapse.metrics
-import synapse.events
+from six.moves import http_client
 
-from canonicaljson import (
-    encode_canonical_json, encode_pretty_printed_json, json
-)
+from canonicaljson import encode_canonical_json, encode_pretty_printed_json, json
 
 from twisted.internet import defer
 from twisted.python import failure
-from twisted.web import server, resource
+from twisted.web import resource, server
 from twisted.web.server import NOT_DONE_YET
 from twisted.web.util import redirectTo
 
-import collections
-import logging
-import urllib
+import synapse.events
+import synapse.metrics
+from synapse.api.errors import (
+    CodeMessageException,
+    Codes,
+    SynapseError,
+    UnrecognizedRequestError,
+    cs_exception,
+)
+from synapse.http.request_metrics import requests_counter
+from synapse.util.caches import intern_dict
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index ef3a01dd..882816dc 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -15,12 +15,11 @@
 
 """ This module contains base REST classes for constructing REST servlets. """
 
-from synapse.api.errors import SynapseError, Codes
-
 import logging
 
 from canonicaljson import json
 
+from synapse.api.errors import Codes, SynapseError
 
 logger = logging.getLogger(__name__)
 
@@ -207,7 +206,7 @@ def parse_json_object_from_request(request, allow_empty_body=False):
     return content
 
 
-def assert_params_in_request(body, required):
+def assert_params_in_dict(body, required):
     absent = []
     for k in required:
         if k not in body:
diff --git a/synapse/http/site.py b/synapse/http/site.py
index fe93643b..5fd30a4c 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -16,11 +16,11 @@ import contextlib
 import logging
 import time
 
-from twisted.web.server import Site, Request
+from twisted.web.server import Request, Site
 
 from synapse.http import redact_uri
 from synapse.http.request_metrics import RequestMetrics
-from synapse.util.logcontext import LoggingContext
+from synapse.util.logcontext import ContextResourceUsage, LoggingContext
 
 logger = logging.getLogger(__name__)
 
@@ -42,9 +42,10 @@ class SynapseRequest(Request):
     which is handling the request, and returns a context manager.
 
     """
-    def __init__(self, site, *args, **kw):
-        Request.__init__(self, *args, **kw)
+    def __init__(self, site, channel, *args, **kw):
+        Request.__init__(self, channel, *args, **kw)
         self.site = site
+        self._channel = channel
         self.authenticated_entity = None
         self.start_time = 0
 
@@ -95,15 +96,9 @@ class SynapseRequest(Request):
     def _finished_processing(self):
         try:
             context = LoggingContext.current_context()
-            ru_utime, ru_stime = context.get_resource_usage()
-            db_txn_count = context.db_txn_count
-            db_txn_duration_sec = context.db_txn_duration_sec
-            db_sched_duration_sec = context.db_sched_duration_sec
-            evt_db_fetch_count = context.evt_db_fetch_count
+            usage = context.get_resource_usage()
         except Exception:
-            ru_utime, ru_stime = (0, 0)
-            db_txn_count, db_txn_duration_sec = (0, 0)
-            evt_db_fetch_count = 0
+            usage = ContextResourceUsage()
 
         end_time = time.time()
 
@@ -130,18 +125,18 @@ class SynapseRequest(Request):
             self.site.site_tag,
             authenticated_entity,
             end_time - self.start_time,
-            ru_utime,
-            ru_stime,
-            db_sched_duration_sec,
-            db_txn_duration_sec,
-            int(db_txn_count),
+            usage.ru_utime,
+            usage.ru_stime,
+            usage.db_sched_duration_sec,
+            usage.db_txn_duration_sec,
+            int(usage.db_txn_count),
             self.sentLength,
             self.code,
             self.method,
             self.get_redacted_uri(),
             self.clientproto,
             user_agent,
-            evt_db_fetch_count,
+            usage.evt_db_fetch_count,
         )
 
         try:
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index 2d2397ca..a9158fc0 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -13,20 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import logging
 import functools
-import time
 import gc
+import logging
 import os
 import platform
-import attr
+import time
 
-from prometheus_client import Gauge, Histogram, Counter
-from prometheus_client.core import GaugeMetricFamily, REGISTRY
+import attr
+from prometheus_client import Counter, Gauge, Histogram
+from prometheus_client.core import REGISTRY, GaugeMetricFamily
 
 from twisted.internet import reactor
 
-
 logger = logging.getLogger(__name__)
 
 running_on_pypy = platform.python_implementation() == "PyPy"
diff --git a/synapse/notifier.py b/synapse/notifier.py
index 3c0622a2..51cbd66f 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -13,28 +13,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+from collections import namedtuple
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import AuthError
 from synapse.handlers.presence import format_user_presence_state
-
-from synapse.util.logutils import log_function
+from synapse.metrics import LaterGauge
+from synapse.types import StreamToken
 from synapse.util.async import (
-    ObservableDeferred, add_timeout_to_deferred,
     DeferredTimeoutError,
+    ObservableDeferred,
+    add_timeout_to_deferred,
 )
 from synapse.util.logcontext import PreserveLoggingContext, run_in_background
+from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
-from synapse.types import StreamToken
 from synapse.visibility import filter_events_for_client
-from synapse.metrics import LaterGauge
-
-from collections import namedtuple
-from prometheus_client import Counter
-
-import logging
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/action_generator.py b/synapse/push/action_generator.py
index 8f619a7a..a5de75c4 100644
--- a/synapse/push/action_generator.py
+++ b/synapse/push/action_generator.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
-from .bulk_push_rule_evaluator import BulkPushRuleEvaluator
+from twisted.internet import defer
 
 from synapse.util.metrics import Measure
 
-import logging
+from .bulk_push_rule_evaluator import BulkPushRuleEvaluator
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/baserules.py b/synapse/push/baserules.py
index a8ae7bcd..8f0682c9 100644
--- a/synapse/push/baserules.py
+++ b/synapse/push/baserules.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.push.rulekinds import PRIORITY_CLASS_MAP, PRIORITY_CLASS_INVERSE_MAP
 import copy
 
+from synapse.push.rulekinds import PRIORITY_CLASS_INVERSE_MAP, PRIORITY_CLASS_MAP
+
 
 def list_with_base_rules(rawrules):
     """Combine the list of rules set by the user with the default push rules
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index a5cab1f0..bb181d94 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -15,21 +15,22 @@
 # limitations under the License.
 
 import logging
+from collections import namedtuple
 
-from twisted.internet import defer
+from six import iteritems, itervalues
 
-from .push_rule_evaluator import PushRuleEvaluatorForEvent
+from prometheus_client import Counter
+
+from twisted.internet import defer
 
-from synapse.event_auth import get_user_power_level
 from synapse.api.constants import EventTypes, Membership
+from synapse.event_auth import get_user_power_level
+from synapse.state import POWER_KEY
+from synapse.util.async import Linearizer
 from synapse.util.caches import register_cache
 from synapse.util.caches.descriptors import cached
-from synapse.util.async import Linearizer
-from synapse.state import POWER_KEY
 
-from collections import namedtuple
-from prometheus_client import Counter
-from six import itervalues, iteritems
+from .push_rule_evaluator import PushRuleEvaluatorForEvent
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/clientformat.py b/synapse/push/clientformat.py
index e0331b2d..ecbf364a 100644
--- a/synapse/push/clientformat.py
+++ b/synapse/push/clientformat.py
@@ -13,12 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.push.rulekinds import (
-    PRIORITY_CLASS_MAP, PRIORITY_CLASS_INVERSE_MAP
-)
-
 import copy
 
+from synapse.push.rulekinds import PRIORITY_CLASS_INVERSE_MAP, PRIORITY_CLASS_MAP
+
 
 def format_push_rules_for_user(user, ruleslist):
     """Converts a list of rawrules and a enabled map into nested dictionaries
diff --git a/synapse/push/emailpusher.py b/synapse/push/emailpusher.py
index 52d4f087..d7463714 100644
--- a/synapse/push/emailpusher.py
+++ b/synapse/push/emailpusher.py
@@ -13,14 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
-import logging
-
-from synapse.util.metrics import Measure
 from synapse.util.logcontext import LoggingContext
-
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/httppusher.py b/synapse/push/httppusher.py
index 7a481b5a..81e18bcf 100644
--- a/synapse/push/httppusher.py
+++ b/synapse/push/httppusher.py
@@ -15,16 +15,16 @@
 # limitations under the License.
 import logging
 
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
-from . import push_rule_evaluator
-from . import push_tools
 from synapse.push import PusherConfigException
 from synapse.util.logcontext import LoggingContext
 from synapse.util.metrics import Measure
 
-from prometheus_client import Counter
+from . import push_rule_evaluator, push_tools
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index d4be800e..9d601208 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -13,30 +13,31 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-from twisted.mail.smtp import sendmail
-
-import email.utils
 import email.mime.multipart
-from email.mime.text import MIMEText
+import email.utils
+import logging
+import time
+import urllib
 from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
 
-from synapse.util.async import concurrently_execute
+import bleach
+import jinja2
+
+from twisted.internet import defer
+from twisted.mail.smtp import sendmail
+
+from synapse.api.constants import EventTypes
+from synapse.api.errors import StoreError
 from synapse.push.presentable_names import (
-    calculate_room_name, name_from_member_event, descriptor_from_member_events
+    calculate_room_name,
+    descriptor_from_member_events,
+    name_from_member_event,
 )
 from synapse.types import UserID
-from synapse.api.errors import StoreError
-from synapse.api.constants import EventTypes
+from synapse.util.async import concurrently_execute
 from synapse.visibility import filter_events_for_client
 
-import jinja2
-import bleach
-
-import time
-import urllib
-
-import logging
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/push/presentable_names.py b/synapse/push/presentable_names.py
index 43f0c74f..eef6e18c 100644
--- a/synapse/push/presentable_names.py
+++ b/synapse/push/presentable_names.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-import re
 import logging
+import re
+
+from twisted.internet import defer
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py
index cf735f74..2bd321d5 100644
--- a/synapse/push/push_rule_evaluator.py
+++ b/synapse/push/push_rule_evaluator.py
@@ -17,12 +17,12 @@
 import logging
 import re
 
+from six import string_types
+
 from synapse.types import UserID
 from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
 from synapse.util.caches.lrucache import LruCache
 
-from six import string_types
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/push/push_tools.py b/synapse/push/push_tools.py
index 6835f54e..8049c298 100644
--- a/synapse/push/push_tools.py
+++ b/synapse/push/push_tools.py
@@ -14,9 +14,8 @@
 # limitations under the License.
 
 from twisted.internet import defer
-from synapse.push.presentable_names import (
-    calculate_room_name, name_from_member_event
-)
+
+from synapse.push.presentable_names import calculate_room_name, name_from_member_event
 
 
 @defer.inlineCallbacks
diff --git a/synapse/push/pusher.py b/synapse/push/pusher.py
index 5aa6667e..fcee6d9d 100644
--- a/synapse/push/pusher.py
+++ b/synapse/push/pusher.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from .httppusher import HttpPusher
 
-import logging
 logger = logging.getLogger(__name__)
 
 # We try importing this if we can (it will fail if we don't
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 7632dd50..987eec3e 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -57,7 +57,7 @@ REQUIREMENTS = {
     "phonenumbers>=8.2.0": ["phonenumbers"],
     "six": ["six"],
     "prometheus_client": ["prometheus_client"],
-    "attr": ["attr"],
+    "attrs": ["attr"],
     "netaddr>=0.7.18": ["netaddr"],
 }
 
diff --git a/synapse/replication/http/__init__.py b/synapse/replication/http/__init__.py
index 1d7a6075..589ee94c 100644
--- a/synapse/replication/http/__init__.py
+++ b/synapse/replication/http/__init__.py
@@ -16,7 +16,6 @@
 from synapse.http.server import JsonResource
 from synapse.replication.http import membership, send_event
 
-
 REPLICATION_PREFIX = "/_synapse/replication"
 
 
diff --git a/synapse/replication/http/membership.py b/synapse/replication/http/membership.py
index e66c4e88..6bfc8a5b 100644
--- a/synapse/replication/http/membership.py
+++ b/synapse/replication/http/membership.py
@@ -18,10 +18,10 @@ import re
 
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, MatrixCodeMessageException
+from synapse.api.errors import MatrixCodeMessageException, SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.types import Requester, UserID
-from synapse.util.distributor import user_left_room, user_joined_room
+from synapse.util.distributor import user_joined_room, user_left_room
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/replication/http/send_event.py b/synapse/replication/http/send_event.py
index f080f96c..2eede547 100644
--- a/synapse/replication/http/send_event.py
+++ b/synapse/replication/http/send_event.py
@@ -13,20 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+import re
+
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    SynapseError, MatrixCodeMessageException, CodeMessageException,
+    CodeMessageException,
+    MatrixCodeMessageException,
+    SynapseError,
 )
 from synapse.events import FrozenEvent
 from synapse.events.snapshot import EventContext
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.types import Requester, UserID
 from synapse.util.caches.response_cache import ResponseCache
 from synapse.util.metrics import Measure
-from synapse.types import Requester, UserID
-
-import logging
-import re
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/replication/slave/storage/_base.py b/synapse/replication/slave/storage/_base.py
index 61f5590c..3f7be74e 100644
--- a/synapse/replication/slave/storage/_base.py
+++ b/synapse/replication/slave/storage/_base.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.engines import PostgresEngine
 
 from ._slaved_id_tracker import SlavedIdTracker
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/replication/slave/storage/appservice.py b/synapse/replication/slave/storage/appservice.py
index 8cae3076..b53a4c6b 100644
--- a/synapse/replication/slave/storage/appservice.py
+++ b/synapse/replication/slave/storage/appservice.py
@@ -15,7 +15,8 @@
 # limitations under the License.
 
 from synapse.storage.appservice import (
-    ApplicationServiceWorkerStore, ApplicationServiceTransactionWorkerStore,
+    ApplicationServiceTransactionWorkerStore,
+    ApplicationServiceWorkerStore,
 )
 
 
diff --git a/synapse/replication/slave/storage/client_ips.py b/synapse/replication/slave/storage/client_ips.py
index 352c9a2a..60641f1a 100644
--- a/synapse/replication/slave/storage/client_ips.py
+++ b/synapse/replication/slave/storage/client_ips.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.client_ips import LAST_SEEN_GRANULARITY
 from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.caches.descriptors import Cache
 
+from ._base import BaseSlavedStore
+
 
 class SlavedClientIpStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/deviceinbox.py b/synapse/replication/slave/storage/deviceinbox.py
index 6f3fb647..87eaa530 100644
--- a/synapse/replication/slave/storage/deviceinbox.py
+++ b/synapse/replication/slave/storage/deviceinbox.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage import DataStore
-from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
 
 
 class SlavedDeviceInboxStore(BaseSlavedStore):
diff --git a/synapse/replication/slave/storage/devices.py b/synapse/replication/slave/storage/devices.py
index 7687867a..8206a988 100644
--- a/synapse/replication/slave/storage/devices.py
+++ b/synapse/replication/slave/storage/devices.py
@@ -13,12 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage import DataStore
 from synapse.storage.end_to_end_keys import EndToEndKeyStore
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
+
 
 class SlavedDeviceStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/directory.py b/synapse/replication/slave/storage/directory.py
index 6deecd39..1d1d4870 100644
--- a/synapse/replication/slave/storage/directory.py
+++ b/synapse/replication/slave/storage/directory.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.directory import DirectoryWorkerStore
 
+from ._base import BaseSlavedStore
+
 
 class DirectoryStore(DirectoryWorkerStore, BaseSlavedStore):
     pass
diff --git a/synapse/replication/slave/storage/events.py b/synapse/replication/slave/storage/events.py
index 97d31966..bdb5eee4 100644
--- a/synapse/replication/slave/storage/events.py
+++ b/synapse/replication/slave/storage/events.py
@@ -20,10 +20,11 @@ from synapse.storage.event_federation import EventFederationWorkerStore
 from synapse.storage.event_push_actions import EventPushActionsWorkerStore
 from synapse.storage.events_worker import EventsWorkerStore
 from synapse.storage.roommember import RoomMemberWorkerStore
+from synapse.storage.signatures import SignatureWorkerStore
 from synapse.storage.state import StateGroupWorkerStore
 from synapse.storage.stream import StreamWorkerStore
-from synapse.storage.signatures import SignatureWorkerStore
 from synapse.storage.user_erasure_store import UserErasureWorkerStore
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
diff --git a/synapse/replication/slave/storage/filtering.py b/synapse/replication/slave/storage/filtering.py
index 819ed628..456a14cd 100644
--- a/synapse/replication/slave/storage/filtering.py
+++ b/synapse/replication/slave/storage/filtering.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.filtering import FilteringStore
 
+from ._base import BaseSlavedStore
+
 
 class SlavedFilteringStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/groups.py b/synapse/replication/slave/storage/groups.py
index 0bc4bce5..5777f07c 100644
--- a/synapse/replication/slave/storage/groups.py
+++ b/synapse/replication/slave/storage/groups.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage import DataStore
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
+
 
 class SlavedGroupServerStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/keys.py b/synapse/replication/slave/storage/keys.py
index dd2ae49e..05ed1684 100644
--- a/synapse/replication/slave/storage/keys.py
+++ b/synapse/replication/slave/storage/keys.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage import DataStore
 from synapse.storage.keys import KeyStore
 
+from ._base import BaseSlavedStore
+
 
 class SlavedKeyStore(BaseSlavedStore):
     _get_server_verify_key = KeyStore.__dict__[
diff --git a/synapse/replication/slave/storage/presence.py b/synapse/replication/slave/storage/presence.py
index cfb92801..80b74408 100644
--- a/synapse/replication/slave/storage/presence.py
+++ b/synapse/replication/slave/storage/presence.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
-
-from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.storage import DataStore
 from synapse.storage.presence import PresenceStore
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
 
 
 class SlavedPresenceStore(BaseSlavedStore):
diff --git a/synapse/replication/slave/storage/push_rule.py b/synapse/replication/slave/storage/push_rule.py
index bb2c40b6..f0200c1e 100644
--- a/synapse/replication/slave/storage/push_rule.py
+++ b/synapse/replication/slave/storage/push_rule.py
@@ -14,10 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .events import SlavedEventStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage.push_rule import PushRulesWorkerStore
 
+from ._slaved_id_tracker import SlavedIdTracker
+from .events import SlavedEventStore
+
 
 class SlavedPushRuleStore(PushRulesWorkerStore, SlavedEventStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/pushers.py b/synapse/replication/slave/storage/pushers.py
index a7cd5a72..3b2213c0 100644
--- a/synapse/replication/slave/storage/pushers.py
+++ b/synapse/replication/slave/storage/pushers.py
@@ -14,11 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from synapse.storage.pusher import PusherWorkerStore
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
-from synapse.storage.pusher import PusherWorkerStore
-
 
 class SlavedPusherStore(PusherWorkerStore, BaseSlavedStore):
 
diff --git a/synapse/replication/slave/storage/receipts.py b/synapse/replication/slave/storage/receipts.py
index 1647072f..ed12342f 100644
--- a/synapse/replication/slave/storage/receipts.py
+++ b/synapse/replication/slave/storage/receipts.py
@@ -14,11 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from synapse.storage.receipts import ReceiptsWorkerStore
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
-from synapse.storage.receipts import ReceiptsWorkerStore
-
 # So, um, we want to borrow a load of functions intended for reading from
 # a DataStore, but we don't want to take functions that either write to the
 # DataStore or are cached and don't have cache invalidation logic.
@@ -49,7 +49,7 @@ class SlavedReceiptsStore(ReceiptsWorkerStore, BaseSlavedStore):
 
     def invalidate_caches_for_receipt(self, room_id, receipt_type, user_id):
         self.get_receipts_for_user.invalidate((user_id, receipt_type))
-        self.get_linearized_receipts_for_room.invalidate_many((room_id,))
+        self._get_linearized_receipts_for_room.invalidate_many((room_id,))
         self.get_last_receipt_event_id_for_user.invalidate(
             (user_id, room_id, receipt_type)
         )
diff --git a/synapse/replication/slave/storage/registration.py b/synapse/replication/slave/storage/registration.py
index 7323bf0f..408d91df 100644
--- a/synapse/replication/slave/storage/registration.py
+++ b/synapse/replication/slave/storage/registration.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.registration import RegistrationWorkerStore
 
+from ._base import BaseSlavedStore
+
 
 class SlavedRegistrationStore(RegistrationWorkerStore, BaseSlavedStore):
     pass
diff --git a/synapse/replication/slave/storage/room.py b/synapse/replication/slave/storage/room.py
index 5ae16701..0cb47492 100644
--- a/synapse/replication/slave/storage/room.py
+++ b/synapse/replication/slave/storage/room.py
@@ -13,8 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.room import RoomWorkerStore
+
+from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
 
diff --git a/synapse/replication/slave/storage/transactions.py b/synapse/replication/slave/storage/transactions.py
index fbb58f35..9c9a5ead 100644
--- a/synapse/replication/slave/storage/transactions.py
+++ b/synapse/replication/slave/storage/transactions.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage import DataStore
 from synapse.storage.transactions import TransactionStore
 
+from ._base import BaseSlavedStore
+
 
 class TransactionStore(BaseSlavedStore):
     get_destination_retry_timings = TransactionStore.__dict__[
diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
index bb852b00..e592ab57 100644
--- a/synapse/replication/tcp/client.py
+++ b/synapse/replication/tcp/client.py
@@ -15,17 +15,20 @@
 """A replication client for use by synapse workers.
 """
 
+import logging
+
 from twisted.internet import defer
 from twisted.internet.protocol import ReconnectingClientFactory
 
 from .commands import (
-    FederationAckCommand, UserSyncCommand, RemovePusherCommand, InvalidateCacheCommand,
+    FederationAckCommand,
+    InvalidateCacheCommand,
+    RemovePusherCommand,
     UserIpCommand,
+    UserSyncCommand,
 )
 from .protocol import ClientReplicationStreamProtocol
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index 171a698e..dec5ac09 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -49,29 +49,37 @@ indicate which side is sending, these are *not* included on the wire::
     * connection closed by server *
 """
 
+import fcntl
+import logging
+import struct
+from collections import defaultdict
+
+from six import iteritems, iterkeys
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.protocols.basic import LineOnlyReceiver
 from twisted.python.failure import Failure
 
-from .commands import (
-    COMMAND_MAP, VALID_CLIENT_COMMANDS, VALID_SERVER_COMMANDS,
-    ErrorCommand, ServerCommand, RdataCommand, PositionCommand, PingCommand,
-    NameCommand, ReplicateCommand, UserSyncCommand, SyncCommand,
-)
-from .streams import STREAMS_MAP
-
 from synapse.metrics import LaterGauge
 from synapse.util.stringutils import random_string
 
-from prometheus_client import Counter
-
-from collections import defaultdict
-
-from six import iterkeys, iteritems
-
-import logging
-import struct
-import fcntl
+from .commands import (
+    COMMAND_MAP,
+    VALID_CLIENT_COMMANDS,
+    VALID_SERVER_COMMANDS,
+    ErrorCommand,
+    NameCommand,
+    PingCommand,
+    PositionCommand,
+    RdataCommand,
+    ReplicateCommand,
+    ServerCommand,
+    SyncCommand,
+    UserSyncCommand,
+)
+from .streams import STREAMS_MAP
 
 connection_close_counter = Counter(
     "synapse_replication_tcp_protocol_close_reason", "", ["reason_type"])
diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py
index 95ad8c1b..611fb66e 100644
--- a/synapse/replication/tcp/resource.py
+++ b/synapse/replication/tcp/resource.py
@@ -15,19 +15,20 @@
 """The server side of the replication stream.
 """
 
+import logging
+
+from six import itervalues
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.internet.protocol import Factory
 
-from .streams import STREAMS_MAP, FederationStream
-from .protocol import ServerReplicationStreamProtocol
-
-from synapse.util.metrics import Measure, measure_func
 from synapse.metrics import LaterGauge
+from synapse.util.metrics import Measure, measure_func
 
-import logging
-
-from prometheus_client import Counter
-from six import itervalues
+from .protocol import ServerReplicationStreamProtocol
+from .streams import STREAMS_MAP, FederationStream
 
 stream_updates_counter = Counter("synapse_replication_tcp_resource_stream_updates",
                                  "", ["stream_name"])
diff --git a/synapse/replication/tcp/streams.py b/synapse/replication/tcp/streams.py
index 4c60bf79..55fe701c 100644
--- a/synapse/replication/tcp/streams.py
+++ b/synapse/replication/tcp/streams.py
@@ -24,11 +24,10 @@ Each stream is defined by the following information:
     update_function:    The function that returns a list of updates between two tokens
 """
 
-from twisted.internet import defer
-from collections import namedtuple
-
 import logging
+from collections import namedtuple
 
+from twisted.internet import defer
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 16f5a73b..75c2a4ec 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -13,50 +13,35 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.rest.client import (
-    versions,
-)
-
-from synapse.rest.client.v1 import (
-    room,
-    events,
-    profile,
-    presence,
-    initial_sync,
-    directory,
-    voip,
-    admin,
-    pusher,
-    push_rule,
-    register as v1_register,
-    login as v1_login,
-    logout,
-)
-
+from synapse.http.server import JsonResource
+from synapse.rest.client import versions
+from synapse.rest.client.v1 import admin, directory, events, initial_sync
+from synapse.rest.client.v1 import login as v1_login
+from synapse.rest.client.v1 import logout, presence, profile, push_rule, pusher
+from synapse.rest.client.v1 import register as v1_register
+from synapse.rest.client.v1 import room, voip
 from synapse.rest.client.v2_alpha import (
-    sync,
-    filter,
     account,
-    register,
+    account_data,
     auth,
-    receipts,
-    read_marker,
+    devices,
+    filter,
+    groups,
     keys,
-    tokenrefresh,
-    tags,
-    account_data,
-    report_event,
-    openid,
     notifications,
-    devices,
-    thirdparty,
+    openid,
+    read_marker,
+    receipts,
+    register,
+    report_event,
     sendtodevice,
+    sync,
+    tags,
+    thirdparty,
+    tokenrefresh,
     user_directory,
-    groups,
 )
 
-from synapse.http.server import JsonResource
-
 
 class ClientRestResource(JsonResource):
     """A resource for version 1 of the matrix client API."""
diff --git a/synapse/rest/client/transactions.py b/synapse/rest/client/transactions.py
index 7c01b438..00b1b306 100644
--- a/synapse/rest/client/transactions.py
+++ b/synapse/rest/client/transactions.py
@@ -17,38 +17,20 @@
 to ensure idempotency when performing PUTs using the REST API."""
 import logging
 
-from synapse.api.auth import get_access_token_from_request
 from synapse.util.async import ObservableDeferred
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 
 logger = logging.getLogger(__name__)
 
-
-def get_transaction_key(request):
-    """A helper function which returns a transaction key that can be used
-    with TransactionCache for idempotent requests.
-
-    Idempotency is based on the returned key being the same for separate
-    requests to the same endpoint. The key is formed from the HTTP request
-    path and the access_token for the requesting user.
-
-    Args:
-        request (twisted.web.http.Request): The incoming request. Must
-        contain an access_token.
-    Returns:
-        str: A transaction key
-    """
-    token = get_access_token_from_request(request)
-    return request.path + "/" + token
-
-
 CLEANUP_PERIOD_MS = 1000 * 60 * 30  # 30 mins
 
 
 class HttpTransactionCache(object):
 
-    def __init__(self, clock):
-        self.clock = clock
+    def __init__(self, hs):
+        self.hs = hs
+        self.auth = self.hs.get_auth()
+        self.clock = self.hs.get_clock()
         self.transactions = {
             # $txn_key: (ObservableDeferred<(res_code, res_json_body)>, timestamp)
         }
@@ -56,6 +38,23 @@ class HttpTransactionCache(object):
         # for at *LEAST* 30 mins, and at *MOST* 60 mins.
         self.cleaner = self.clock.looping_call(self._cleanup, CLEANUP_PERIOD_MS)
 
+    def _get_transaction_key(self, request):
+        """A helper function which returns a transaction key that can be used
+        with TransactionCache for idempotent requests.
+
+        Idempotency is based on the returned key being the same for separate
+        requests to the same endpoint. The key is formed from the HTTP request
+        path and the access_token for the requesting user.
+
+        Args:
+            request (twisted.web.http.Request): The incoming request. Must
+            contain an access_token.
+        Returns:
+            str: A transaction key
+        """
+        token = self.auth.get_access_token_from_request(request)
+        return request.path + "/" + token
+
     def fetch_or_execute_request(self, request, fn, *args, **kwargs):
         """A helper function for fetch_or_execute which extracts
         a transaction key from the given request.
@@ -64,7 +63,7 @@ class HttpTransactionCache(object):
             fetch_or_execute
         """
         return self.fetch_or_execute(
-            get_transaction_key(request), fn, *args, **kwargs
+            self._get_transaction_key(request), fn, *args, **kwargs
         )
 
     def fetch_or_execute(self, txn_key, fn, *args, **kwargs):
diff --git a/synapse/rest/client/v1/admin.py b/synapse/rest/client/v1/admin.py
index 8fb08dc5..2dc50e58 100644
--- a/synapse/rest/client/v1/admin.py
+++ b/synapse/rest/client/v1/admin.py
@@ -14,19 +14,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
 from six.moves import http_client
 
+from twisted.internet import defer
+
 from synapse.api.constants import Membership
-from synapse.api.errors import AuthError, SynapseError, Codes, NotFoundError
+from synapse.api.errors import AuthError, Codes, NotFoundError, SynapseError
+from synapse.http.servlet import (
+    assert_params_in_dict,
+    parse_integer,
+    parse_json_object_from_request,
+    parse_string,
+)
 from synapse.types import UserID, create_requester
-from synapse.http.servlet import parse_json_object_from_request
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
@@ -98,16 +103,8 @@ class PurgeMediaCacheRestServlet(ClientV1RestServlet):
         if not is_admin:
             raise AuthError(403, "You are not a server admin")
 
-        before_ts = request.args.get("before_ts", None)
-        if not before_ts:
-            raise SynapseError(400, "Missing 'before_ts' arg")
-
-        logger.info("before_ts: %r", before_ts[0])
-
-        try:
-            before_ts = int(before_ts[0])
-        except Exception:
-            raise SynapseError(400, "Invalid 'before_ts' arg")
+        before_ts = parse_integer(request, "before_ts", required=True)
+        logger.info("before_ts: %r", before_ts)
 
         ret = yield self.media_repository.delete_old_remote_media(before_ts)
 
@@ -300,10 +297,8 @@ class ShutdownRoomRestServlet(ClientV1RestServlet):
             raise AuthError(403, "You are not a server admin")
 
         content = parse_json_object_from_request(request)
-
-        new_room_user_id = content.get("new_room_user_id")
-        if not new_room_user_id:
-            raise SynapseError(400, "Please provide field `new_room_user_id`")
+        assert_params_in_dict(content, ["new_room_user_id"])
+        new_room_user_id = content["new_room_user_id"]
 
         room_creator_requester = create_requester(new_room_user_id)
 
@@ -464,9 +459,8 @@ class ResetPasswordRestServlet(ClientV1RestServlet):
             raise AuthError(403, "You are not a server admin")
 
         params = parse_json_object_from_request(request)
+        assert_params_in_dict(params, ["new_password"])
         new_password = params['new_password']
-        if not new_password:
-            raise SynapseError(400, "Missing 'new_password' arg")
 
         logger.info("new_password: %r", new_password)
 
@@ -514,12 +508,9 @@ class GetUsersPaginatedRestServlet(ClientV1RestServlet):
             raise SynapseError(400, "Can only users a local user")
 
         order = "name"  # order by name in user table
-        start = request.args.get("start")[0]
-        limit = request.args.get("limit")[0]
-        if not limit:
-            raise SynapseError(400, "Missing 'limit' arg")
-        if not start:
-            raise SynapseError(400, "Missing 'start' arg")
+        start = parse_integer(request, "start", required=True)
+        limit = parse_integer(request, "limit", required=True)
+
         logger.info("limit: %s, start: %s", limit, start)
 
         ret = yield self.handlers.admin_handler.get_users_paginate(
@@ -551,12 +542,9 @@ class GetUsersPaginatedRestServlet(ClientV1RestServlet):
 
         order = "name"  # order by name in user table
         params = parse_json_object_from_request(request)
+        assert_params_in_dict(params, ["limit", "start"])
         limit = params['limit']
         start = params['start']
-        if not limit:
-            raise SynapseError(400, "Missing 'limit' arg")
-        if not start:
-            raise SynapseError(400, "Missing 'start' arg")
         logger.info("limit: %s, start: %s", limit, start)
 
         ret = yield self.handlers.admin_handler.get_users_paginate(
@@ -604,10 +592,7 @@ class SearchUsersRestServlet(ClientV1RestServlet):
         if not self.hs.is_mine(target_user):
             raise SynapseError(400, "Can only users a local user")
 
-        term = request.args.get("term")[0]
-        if not term:
-            raise SynapseError(400, "Missing 'term' arg")
-
+        term = parse_string(request, "term", required=True)
         logger.info("term: %s ", term)
 
         ret = yield self.handlers.admin_handler.search_users(
diff --git a/synapse/rest/client/v1/base.py b/synapse/rest/client/v1/base.py
index 197335d7..c77d7aba 100644
--- a/synapse/rest/client/v1/base.py
+++ b/synapse/rest/client/v1/base.py
@@ -16,14 +16,12 @@
 """This module contains base REST classes for constructing client v1 servlets.
 """
 
-from synapse.http.servlet import RestServlet
-from synapse.api.urls import CLIENT_PREFIX
-from synapse.rest.client.transactions import HttpTransactionCache
-
-import re
-
 import logging
+import re
 
+from synapse.api.urls import CLIENT_PREFIX
+from synapse.http.servlet import RestServlet
+from synapse.rest.client.transactions import HttpTransactionCache
 
 logger = logging.getLogger(__name__)
 
@@ -64,4 +62,4 @@ class ClientV1RestServlet(RestServlet):
         self.hs = hs
         self.builder_factory = hs.get_event_builder_factory()
         self.auth = hs.get_auth()
-        self.txns = HttpTransactionCache(hs.get_clock())
+        self.txns = HttpTransactionCache(hs)
diff --git a/synapse/rest/client/v1/directory.py b/synapse/rest/client/v1/directory.py
index 1c393338..69dcd618 100644
--- a/synapse/rest/client/v1/directory.py
+++ b/synapse/rest/client/v1/directory.py
@@ -14,17 +14,16 @@
 # limitations under the License.
 
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.api.errors import AuthError, SynapseError, Codes
-from synapse.types import RoomAlias
+from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import RoomAlias
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
@@ -53,15 +52,14 @@ class ClientDirectoryServer(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def on_PUT(self, request, room_alias):
+        room_alias = RoomAlias.from_string(room_alias)
+
         content = parse_json_object_from_request(request)
         if "room_id" not in content:
-            raise SynapseError(400, "Missing room_id key",
+            raise SynapseError(400, 'Missing params: ["room_id"]',
                                errcode=Codes.BAD_JSON)
 
         logger.debug("Got content: %s", content)
-
-        room_alias = RoomAlias.from_string(room_alias)
-
         logger.debug("Got room name: %s", room_alias.to_string())
 
         room_id = content["room_id"]
diff --git a/synapse/rest/client/v1/events.py b/synapse/rest/client/v1/events.py
index 701b6f54..b70c9c28 100644
--- a/synapse/rest/client/v1/events.py
+++ b/synapse/rest/client/v1/events.py
@@ -14,15 +14,15 @@
 # limitations under the License.
 
 """This module contains REST servlets to do with event streaming, /events."""
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
-from synapse.streams.config import PaginationConfig
-from .base import ClientV1RestServlet, client_path_patterns
 from synapse.events.utils import serialize_event
+from synapse.streams.config import PaginationConfig
 
-import logging
-
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/initial_sync.py b/synapse/rest/client/v1/initial_sync.py
index 478e21ee..fd5f85b5 100644
--- a/synapse/rest/client/v1/initial_sync.py
+++ b/synapse/rest/client/v1/initial_sync.py
@@ -15,7 +15,9 @@
 
 from twisted.internet import defer
 
+from synapse.http.servlet import parse_boolean
 from synapse.streams.config import PaginationConfig
+
 from .base import ClientV1RestServlet, client_path_patterns
 
 
@@ -32,7 +34,7 @@ class InitialSyncRestServlet(ClientV1RestServlet):
         requester = yield self.auth.get_user_by_req(request)
         as_client_event = "raw" not in request.args
         pagination_config = PaginationConfig.from_request(request)
-        include_archived = request.args.get("archived", None) == ["true"]
+        include_archived = parse_boolean(request, "archived", default=False)
         content = yield self.initial_sync_handler.snapshot_all_rooms(
             user_id=requester.user.to_string(),
             pagin_config=pagination_config,
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index 88ca5184..cb85fa14 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -13,30 +13,26 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from synapse.api.errors import SynapseError, LoginError, Codes
-from synapse.types import UserID
-from synapse.http.server import finish_request
-from synapse.http.servlet import parse_json_object_from_request
-from synapse.util.msisdn import phone_number_to_msisdn
-
-from .base import ClientV1RestServlet, client_path_patterns
-
-from canonicaljson import json
-
+import logging
 import urllib
+import xml.etree.ElementTree as ET
+
 from six.moves.urllib import parse as urlparse
 
-import logging
-from saml2 import BINDING_HTTP_POST
-from saml2 import config
+from canonicaljson import json
+from saml2 import BINDING_HTTP_POST, config
 from saml2.client import Saml2Client
 
-import xml.etree.ElementTree as ET
-
+from twisted.internet import defer
 from twisted.web.client import PartialDownloadError
 
+from synapse.api.errors import Codes, LoginError, SynapseError
+from synapse.http.server import finish_request
+from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import UserID
+from synapse.util.msisdn import phone_number_to_msisdn
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/logout.py b/synapse/rest/client/v1/logout.py
index e092158c..430c6923 100644
--- a/synapse/rest/client/v1/logout.py
+++ b/synapse/rest/client/v1/logout.py
@@ -13,16 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.api.auth import get_access_token_from_request
 from synapse.api.errors import AuthError
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
@@ -52,7 +50,7 @@ class LogoutRestServlet(ClientV1RestServlet):
             if requester.device_id is None:
                 # the acccess token wasn't associated with a device.
                 # Just delete the access token
-                access_token = get_access_token_from_request(request)
+                access_token = self._auth.get_access_token_from_request(request)
                 yield self._auth_handler.delete_access_token(access_token)
             else:
                 yield self._device_handler.delete_device(
diff --git a/synapse/rest/client/v1/presence.py b/synapse/rest/client/v1/presence.py
index 647994bd..a14f0c80 100644
--- a/synapse/rest/client/v1/presence.py
+++ b/synapse/rest/client/v1/presence.py
@@ -15,17 +15,18 @@
 
 """ This module contains REST servlets to do with presence: /presence/<paths>
 """
+import logging
+
+from six import string_types
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, AuthError
-from synapse.types import UserID
+from synapse.api.errors import AuthError, SynapseError
 from synapse.handlers.presence import format_user_presence_state
 from synapse.http.servlet import parse_json_object_from_request
-from .base import ClientV1RestServlet, client_path_patterns
-
-from six import string_types
+from synapse.types import UserID
 
-import logging
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/profile.py b/synapse/rest/client/v1/profile.py
index e4e3611a..a23edd8f 100644
--- a/synapse/rest/client/v1/profile.py
+++ b/synapse/rest/client/v1/profile.py
@@ -16,9 +16,10 @@
 """ This module contains REST servlets to do with profile: /profile/<paths> """
 from twisted.internet import defer
 
-from .base import ClientV1RestServlet, client_path_patterns
-from synapse.types import UserID
 from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import UserID
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 
 class ProfileDisplaynameRestServlet(ClientV1RestServlet):
diff --git a/synapse/rest/client/v1/push_rule.py b/synapse/rest/client/v1/push_rule.py
index 6bb4821e..6e95d9be 100644
--- a/synapse/rest/client/v1/push_rule.py
+++ b/synapse/rest/client/v1/push_rule.py
@@ -16,16 +16,18 @@
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    SynapseError, UnrecognizedRequestError, NotFoundError, StoreError
+    NotFoundError,
+    StoreError,
+    SynapseError,
+    UnrecognizedRequestError,
 )
-from .base import ClientV1RestServlet, client_path_patterns
-from synapse.storage.push_rule import (
-    InconsistentRuleException, RuleNotFoundException
-)
-from synapse.push.clientformat import format_push_rules_for_user
+from synapse.http.servlet import parse_json_value_from_request, parse_string
 from synapse.push.baserules import BASE_RULE_IDS
+from synapse.push.clientformat import format_push_rules_for_user
 from synapse.push.rulekinds import PRIORITY_CLASS_MAP
-from synapse.http.servlet import parse_json_value_from_request
+from synapse.storage.push_rule import InconsistentRuleException, RuleNotFoundException
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 
 class PushRuleRestServlet(ClientV1RestServlet):
@@ -73,13 +75,13 @@ class PushRuleRestServlet(ClientV1RestServlet):
         except InvalidRuleException as e:
             raise SynapseError(400, e.message)
 
-        before = request.args.get("before", None)
+        before = parse_string(request, "before")
         if before:
-            before = _namespaced_rule_id(spec, before[0])
+            before = _namespaced_rule_id(spec, before)
 
-        after = request.args.get("after", None)
+        after = parse_string(request, "after")
         if after:
-            after = _namespaced_rule_id(spec, after[0])
+            after = _namespaced_rule_id(spec, after)
 
         try:
             yield self.store.add_push_rule(
diff --git a/synapse/rest/client/v1/pusher.py b/synapse/rest/client/v1/pusher.py
index 40e523cc..182a68b1 100644
--- a/synapse/rest/client/v1/pusher.py
+++ b/synapse/rest/client/v1/pusher.py
@@ -13,20 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, Codes
-from synapse.push import PusherConfigException
+from synapse.api.errors import Codes, StoreError, SynapseError
+from synapse.http.server import finish_request
 from synapse.http.servlet import (
-    parse_json_object_from_request, parse_string, RestServlet
+    RestServlet,
+    assert_params_in_dict,
+    parse_json_object_from_request,
+    parse_string,
 )
-from synapse.http.server import finish_request
-from synapse.api.errors import StoreError
+from synapse.push import PusherConfigException
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
@@ -90,15 +92,11 @@ class PushersSetRestServlet(ClientV1RestServlet):
             )
             defer.returnValue((200, {}))
 
-        reqd = ['kind', 'app_id', 'app_display_name',
-                'device_display_name', 'pushkey', 'lang', 'data']
-        missing = []
-        for i in reqd:
-            if i not in content:
-                missing.append(i)
-        if len(missing):
-            raise SynapseError(400, "Missing parameters: " + ','.join(missing),
-                               errcode=Codes.MISSING_PARAM)
+        assert_params_in_dict(
+            content,
+            ['kind', 'app_id', 'app_display_name',
+             'device_display_name', 'pushkey', 'lang', 'data']
+        )
 
         logger.debug("set pushkey %s to kind %s", content['pushkey'], content['kind'])
         logger.debug("Got pushers request with body: %r", content)
@@ -147,7 +145,7 @@ class PushersRemoveRestServlet(RestServlet):
     SUCCESS_HTML = "<html><body>You have been unsubscribed</body><html>"
 
     def __init__(self, hs):
-        super(RestServlet, self).__init__()
+        super(PushersRemoveRestServlet, self).__init__()
         self.hs = hs
         self.notifier = hs.get_notifier()
         self.auth = hs.get_auth()
diff --git a/synapse/rest/client/v1/register.py b/synapse/rest/client/v1/register.py
index c10320de..25a143af 100644
--- a/synapse/rest/client/v1/register.py
+++ b/synapse/rest/client/v1/register.py
@@ -14,21 +14,19 @@
 # limitations under the License.
 
 """This module contains REST servlets to do with registration: /register"""
+import hmac
+import logging
+from hashlib import sha1
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, Codes
-from synapse.api.constants import LoginType
-from synapse.api.auth import get_access_token_from_request
-from .base import ClientV1RestServlet, client_path_patterns
 import synapse.util.stringutils as stringutils
-from synapse.http.servlet import parse_json_object_from_request
+from synapse.api.constants import LoginType
+from synapse.api.errors import Codes, SynapseError
+from synapse.http.servlet import assert_params_in_dict, parse_json_object_from_request
 from synapse.types import create_requester
 
-from hashlib import sha1
-import hmac
-import logging
-
-from six import string_types
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
@@ -66,6 +64,7 @@ class RegisterRestServlet(ClientV1RestServlet):
         # TODO: persistent storage
         self.sessions = {}
         self.enable_registration = hs.config.enable_registration
+        self.auth = hs.get_auth()
         self.auth_handler = hs.get_auth_handler()
         self.handlers = hs.get_handlers()
 
@@ -123,8 +122,7 @@ class RegisterRestServlet(ClientV1RestServlet):
         session = (register_json["session"]
                    if "session" in register_json else None)
         login_type = None
-        if "type" not in register_json:
-            raise SynapseError(400, "Missing 'type' key.")
+        assert_params_in_dict(register_json, ["type"])
 
         try:
             login_type = register_json["type"]
@@ -309,11 +307,9 @@ class RegisterRestServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def _do_app_service(self, request, register_json, session):
-        as_token = get_access_token_from_request(request)
-
-        if "user" not in register_json:
-            raise SynapseError(400, "Expected 'user' key.")
+        as_token = self.auth.get_access_token_from_request(request)
 
+        assert_params_in_dict(register_json, ["user"])
         user_localpart = register_json["user"].encode("utf-8")
 
         handler = self.handlers.registration_handler
@@ -330,12 +326,7 @@ class RegisterRestServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def _do_shared_secret(self, request, register_json, session):
-        if not isinstance(register_json.get("mac", None), string_types):
-            raise SynapseError(400, "Expected mac.")
-        if not isinstance(register_json.get("user", None), string_types):
-            raise SynapseError(400, "Expected 'user' key.")
-        if not isinstance(register_json.get("password", None), string_types):
-            raise SynapseError(400, "Expected 'password' key.")
+        assert_params_in_dict(register_json, ["mac", "user", "password"])
 
         if not self.hs.config.registration_shared_secret:
             raise SynapseError(400, "Shared secret registration is not enabled")
@@ -399,7 +390,7 @@ class CreateUserRestServlet(ClientV1RestServlet):
     def on_POST(self, request):
         user_json = parse_json_object_from_request(request)
 
-        access_token = get_access_token_from_request(request)
+        access_token = self.auth.get_access_token_from_request(request)
         app_service = self.store.get_app_service_by_token(
             access_token
         )
@@ -418,11 +409,7 @@ class CreateUserRestServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def _do_create(self, requester, user_json):
-        if "localpart" not in user_json:
-            raise SynapseError(400, "Expected 'localpart' key.")
-
-        if "displayname" not in user_json:
-            raise SynapseError(400, "Expected 'displayname' key.")
+        assert_params_in_dict(user_json, ["localpart", "displayname"])
 
         localpart = user_json["localpart"].encode("utf-8")
         displayname = user_json["displayname"].encode("utf-8")
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index e6ae5db7..3d624478 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -15,23 +15,28 @@
 # limitations under the License.
 
 """ This module contains REST servlets to do with rooms: /rooms/<paths> """
+import logging
+
+from six.moves.urllib import parse as urlparse
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
-from .base import ClientV1RestServlet, client_path_patterns
-from synapse.api.errors import SynapseError, Codes, AuthError
-from synapse.streams.config import PaginationConfig
 from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.api.filtering import Filter
-from synapse.types import UserID, RoomID, RoomAlias, ThirdPartyInstanceID
-from synapse.events.utils import serialize_event, format_event_for_client_v2
+from synapse.events.utils import format_event_for_client_v2, serialize_event
 from synapse.http.servlet import (
-    parse_json_object_from_request, parse_string, parse_integer
+    assert_params_in_dict,
+    parse_integer,
+    parse_json_object_from_request,
+    parse_string,
 )
+from synapse.streams.config import PaginationConfig
+from synapse.types import RoomAlias, RoomID, ThirdPartyInstanceID, UserID
 
-from six.moves.urllib import parse as urlparse
-
-import logging
-from canonicaljson import json
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
@@ -431,9 +436,9 @@ class RoomMessageListRestServlet(ClientV1RestServlet):
             request, default_limit=10,
         )
         as_client_event = "raw" not in request.args
-        filter_bytes = request.args.get("filter", None)
+        filter_bytes = parse_string(request, "filter")
         if filter_bytes:
-            filter_json = urlparse.unquote(filter_bytes[-1]).decode("UTF-8")
+            filter_json = urlparse.unquote(filter_bytes).decode("UTF-8")
             event_filter = Filter(json.loads(filter_json))
         else:
             event_filter = None
@@ -526,7 +531,7 @@ class RoomEventContextServlet(ClientV1RestServlet):
     def on_GET(self, request, room_id, event_id):
         requester = yield self.auth.get_user_by_req(request, allow_guest=True)
 
-        limit = int(request.args.get("limit", [10])[0])
+        limit = parse_integer(request, "limit", default=10)
 
         results = yield self.handlers.room_context_handler.get_event_context(
             requester.user,
@@ -632,8 +637,7 @@ class RoomMembershipRestServlet(ClientV1RestServlet):
 
         target = requester.user
         if membership_action in ["invite", "ban", "unban", "kick"]:
-            if "user_id" not in content:
-                raise SynapseError(400, "Missing user_id key.")
+            assert_params_in_dict(content, ["user_id"])
             target = UserID.from_string(content["user_id"])
 
         event_content = None
@@ -760,7 +764,7 @@ class SearchRestServlet(ClientV1RestServlet):
 
         content = parse_json_object_from_request(request)
 
-        batch = request.args.get("next_batch", [None])[0]
+        batch = parse_string(request, "next_batch")
         results = yield self.handlers.search_handler.search(
             requester.user,
             content,
diff --git a/synapse/rest/client/v1/voip.py b/synapse/rest/client/v1/voip.py
index c43b30b7..62f4c3d9 100644
--- a/synapse/rest/client/v1/voip.py
+++ b/synapse/rest/client/v1/voip.py
@@ -13,16 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import base64
+import hashlib
+import hmac
+
 from twisted.internet import defer
 
 from .base import ClientV1RestServlet, client_path_patterns
 
 
-import hmac
-import hashlib
-import base64
-
-
 class VoipRestServlet(ClientV1RestServlet):
     PATTERNS = client_path_patterns("/voip/turnServer$")
 
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 80dbc3c9..eeae466d 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -17,17 +17,19 @@
 import logging
 
 from six.moves import http_client
+
 from twisted.internet import defer
 
-from synapse.api.auth import has_access_token
 from synapse.api.constants import LoginType
 from synapse.api.errors import Codes, SynapseError
 from synapse.http.servlet import (
-    RestServlet, assert_params_in_request,
+    RestServlet,
+    assert_params_in_dict,
     parse_json_object_from_request,
 )
 from synapse.util.msisdn import phone_number_to_msisdn
 from synapse.util.threepids import check_3pid_allowed
+
 from ._base import client_v2_patterns, interactive_auth_handler
 
 logger = logging.getLogger(__name__)
@@ -45,7 +47,7 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
 
-        assert_params_in_request(body, [
+        assert_params_in_dict(body, [
             'id_server', 'client_secret', 'email', 'send_attempt'
         ])
 
@@ -78,7 +80,7 @@ class MsisdnPasswordRequestTokenRestServlet(RestServlet):
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
 
-        assert_params_in_request(body, [
+        assert_params_in_dict(body, [
             'id_server', 'client_secret',
             'country', 'phone_number', 'send_attempt',
         ])
@@ -127,7 +129,7 @@ class PasswordRestServlet(RestServlet):
         #
         # In the second case, we require a password to confirm their identity.
 
-        if has_access_token(request):
+        if self.auth.has_access_token(request):
             requester = yield self.auth.get_user_by_req(request)
             params = yield self.auth_handler.validate_user_via_ui_auth(
                 requester, body, self.hs.get_ip_from_request(request),
@@ -157,11 +159,10 @@ class PasswordRestServlet(RestServlet):
                     raise SynapseError(404, "Email address not found", Codes.NOT_FOUND)
                 user_id = threepid_user_id
             else:
-                logger.error("Auth succeeded but no known type!", result.keys())
+                logger.error("Auth succeeded but no known type! %r", result.keys())
                 raise SynapseError(500, "", Codes.UNKNOWN)
 
-        if 'new_password' not in params:
-            raise SynapseError(400, "", Codes.MISSING_PARAM)
+        assert_params_in_dict(params, ["new_password"])
         new_password = params['new_password']
 
         yield self._set_password_handler.set_password(
@@ -226,15 +227,10 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
     @defer.inlineCallbacks
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
-
-        required = ['id_server', 'client_secret', 'email', 'send_attempt']
-        absent = []
-        for k in required:
-            if k not in body:
-                absent.append(k)
-
-        if absent:
-            raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
+        assert_params_in_dict(
+            body,
+            ['id_server', 'client_secret', 'email', 'send_attempt'],
+        )
 
         if not check_3pid_allowed(self.hs, "email", body['email']):
             raise SynapseError(
@@ -264,18 +260,10 @@ class MsisdnThreepidRequestTokenRestServlet(RestServlet):
     @defer.inlineCallbacks
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
-
-        required = [
+        assert_params_in_dict(body, [
             'id_server', 'client_secret',
             'country', 'phone_number', 'send_attempt',
-        ]
-        absent = []
-        for k in required:
-            if k not in body:
-                absent.append(k)
-
-        if absent:
-            raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
+        ])
 
         msisdn = phone_number_to_msisdn(body['country'], body['phone_number'])
 
@@ -370,15 +358,7 @@ class ThreepidDeleteRestServlet(RestServlet):
     @defer.inlineCallbacks
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
-
-        required = ['medium', 'address']
-        absent = []
-        for k in required:
-            if k not in body:
-                absent.append(k)
-
-        if absent:
-            raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
+        assert_params_in_dict(body, ['medium', 'address'])
 
         requester = yield self.auth.get_user_by_req(request)
         user_id = requester.user.to_string()
diff --git a/synapse/rest/client/v2_alpha/account_data.py b/synapse/rest/client/v2_alpha/account_data.py
index 0e0a187e..371e9aa3 100644
--- a/synapse/rest/client/v2_alpha/account_data.py
+++ b/synapse/rest/client/v2_alpha/account_data.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import client_v2_patterns
-
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.api.errors import AuthError, SynapseError
+import logging
 
 from twisted.internet import defer
 
-import logging
+from synapse.api.errors import AuthError, SynapseError
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/auth.py b/synapse/rest/client/v2_alpha/auth.py
index d6f3a196..bd8b5f4a 100644
--- a/synapse/rest/client/v2_alpha/auth.py
+++ b/synapse/rest/client/v2_alpha/auth.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.constants import LoginType
@@ -23,9 +25,6 @@ from synapse.http.servlet import RestServlet
 
 from ._base import client_v2_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 RECAPTCHA_TEMPLATE = """
diff --git a/synapse/rest/client/v2_alpha/devices.py b/synapse/rest/client/v2_alpha/devices.py
index 35d58b36..9b75bb13 100644
--- a/synapse/rest/client/v2_alpha/devices.py
+++ b/synapse/rest/client/v2_alpha/devices.py
@@ -18,13 +18,18 @@ import logging
 from twisted.internet import defer
 
 from synapse.api import errors
-from synapse.http import servlet
+from synapse.http.servlet import (
+    RestServlet,
+    assert_params_in_dict,
+    parse_json_object_from_request,
+)
+
 from ._base import client_v2_patterns, interactive_auth_handler
 
 logger = logging.getLogger(__name__)
 
 
-class DevicesRestServlet(servlet.RestServlet):
+class DevicesRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/devices$", v2_alpha=False)
 
     def __init__(self, hs):
@@ -46,7 +51,7 @@ class DevicesRestServlet(servlet.RestServlet):
         defer.returnValue((200, {"devices": devices}))
 
 
-class DeleteDevicesRestServlet(servlet.RestServlet):
+class DeleteDevicesRestServlet(RestServlet):
     """
     API for bulk deletion of devices. Accepts a JSON object with a devices
     key which lists the device_ids to delete. Requires user interactive auth.
@@ -66,19 +71,17 @@ class DeleteDevicesRestServlet(servlet.RestServlet):
         requester = yield self.auth.get_user_by_req(request)
 
         try:
-            body = servlet.parse_json_object_from_request(request)
+            body = parse_json_object_from_request(request)
         except errors.SynapseError as e:
             if e.errcode == errors.Codes.NOT_JSON:
-                # deal with older clients which didn't pass a J*DELETESON dict
+                # DELETE
+                # deal with older clients which didn't pass a JSON dict
                 # the same as those that pass an empty dict
                 body = {}
             else:
                 raise e
 
-        if 'devices' not in body:
-            raise errors.SynapseError(
-                400, "No devices supplied", errcode=errors.Codes.MISSING_PARAM
-            )
+        assert_params_in_dict(body, ["devices"])
 
         yield self.auth_handler.validate_user_via_ui_auth(
             requester, body, self.hs.get_ip_from_request(request),
@@ -91,7 +94,7 @@ class DeleteDevicesRestServlet(servlet.RestServlet):
         defer.returnValue((200, {}))
 
 
-class DeviceRestServlet(servlet.RestServlet):
+class DeviceRestServlet(RestServlet):
     PATTERNS = client_v2_patterns("/devices/(?P<device_id>[^/]*)$", v2_alpha=False)
 
     def __init__(self, hs):
@@ -120,7 +123,7 @@ class DeviceRestServlet(servlet.RestServlet):
         requester = yield self.auth.get_user_by_req(request)
 
         try:
-            body = servlet.parse_json_object_from_request(request)
+            body = parse_json_object_from_request(request)
 
         except errors.SynapseError as e:
             if e.errcode == errors.Codes.NOT_JSON:
@@ -143,7 +146,7 @@ class DeviceRestServlet(servlet.RestServlet):
     def on_PUT(self, request, device_id):
         requester = yield self.auth.get_user_by_req(request, allow_guest=True)
 
-        body = servlet.parse_json_object_from_request(request)
+        body = parse_json_object_from_request(request)
         yield self.device_handler.update_device(
             requester.user.to_string(),
             device_id,
diff --git a/synapse/rest/client/v2_alpha/filter.py b/synapse/rest/client/v2_alpha/filter.py
index 1b9dc452..ae867288 100644
--- a/synapse/rest/client/v2_alpha/filter.py
+++ b/synapse/rest/client/v2_alpha/filter.py
@@ -13,17 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.api.errors import AuthError, SynapseError, StoreError, Codes
+from synapse.api.errors import AuthError, Codes, StoreError, SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.types import UserID
 
-from ._base import client_v2_patterns
-from ._base import set_timeline_upper_limit
-
-import logging
-
+from ._base import client_v2_patterns, set_timeline_upper_limit
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/groups.py b/synapse/rest/client/v2_alpha/groups.py
index 3bb1ec2a..21e02c07 100644
--- a/synapse/rest/client/v2_alpha/groups.py
+++ b/synapse/rest/client/v2_alpha/groups.py
@@ -14,6 +14,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
@@ -21,8 +23,6 @@ from synapse.types import GroupID
 
 from ._base import client_v2_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/keys.py b/synapse/rest/client/v2_alpha/keys.py
index 3cc87ea6..8486086b 100644
--- a/synapse/rest/client/v2_alpha/keys.py
+++ b/synapse/rest/client/v2_alpha/keys.py
@@ -19,10 +19,13 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request, parse_integer
+    RestServlet,
+    parse_integer,
+    parse_json_object_from_request,
+    parse_string,
 )
-from synapse.http.servlet import parse_string
 from synapse.types import StreamToken
+
 from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/v2_alpha/notifications.py b/synapse/rest/client/v2_alpha/notifications.py
index 66583d67..2a6ea3df 100644
--- a/synapse/rest/client/v2_alpha/notifications.py
+++ b/synapse/rest/client/v2_alpha/notifications.py
@@ -13,19 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.http.servlet import (
-    RestServlet, parse_string, parse_integer
-)
 from synapse.events.utils import (
-    serialize_event, format_event_for_client_v2_without_room_id,
+    format_event_for_client_v2_without_room_id,
+    serialize_event,
 )
+from synapse.http.servlet import RestServlet, parse_integer, parse_string
 
 from ._base import client_v2_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/openid.py b/synapse/rest/client/v2_alpha/openid.py
index aa1cae8e..01c90aa2 100644
--- a/synapse/rest/client/v2_alpha/openid.py
+++ b/synapse/rest/client/v2_alpha/openid.py
@@ -14,15 +14,15 @@
 # limitations under the License.
 
 
-from ._base import client_v2_patterns
+import logging
+
+from twisted.internet import defer
 
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.api.errors import AuthError
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.util.stringutils import random_string
 
-from twisted.internet import defer
-
-import logging
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/read_marker.py b/synapse/rest/client/v2_alpha/read_marker.py
index 2f8784fe..a6e582a5 100644
--- a/synapse/rest/client/v2_alpha/read_marker.py
+++ b/synapse/rest/client/v2_alpha/read_marker.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from ._base import client_v2_patterns
-
-import logging
 
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/receipts.py b/synapse/rest/client/v2_alpha/receipts.py
index 1fbff2ed..de370cac 100644
--- a/synapse/rest/client/v2_alpha/receipts.py
+++ b/synapse/rest/client/v2_alpha/receipts.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.http.servlet import RestServlet
-from ._base import client_v2_patterns
-
-import logging
 
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index 97e7c0f7..d6cf915d 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -14,29 +14,30 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import hmac
+import logging
+from hashlib import sha1
+
+from six import string_types
+
 from twisted.internet import defer
 
 import synapse
 import synapse.types
-from synapse.api.auth import get_access_token_from_request, has_access_token
 from synapse.api.constants import LoginType
-from synapse.api.errors import SynapseError, Codes, UnrecognizedRequestError
+from synapse.api.errors import Codes, SynapseError, UnrecognizedRequestError
 from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request, assert_params_in_request, parse_string
+    RestServlet,
+    assert_params_in_dict,
+    parse_json_object_from_request,
+    parse_string,
 )
 from synapse.util.msisdn import phone_number_to_msisdn
+from synapse.util.ratelimitutils import FederationRateLimiter
 from synapse.util.threepids import check_3pid_allowed
 
 from ._base import client_v2_patterns, interactive_auth_handler
 
-import logging
-import hmac
-from hashlib import sha1
-from synapse.util.ratelimitutils import FederationRateLimiter
-
-from six import string_types
-
-
 # We ought to be using hmac.compare_digest() but on older pythons it doesn't
 # exist. It's a _really minor_ security flaw to use plain string comparison
 # because the timing attack is so obscured by all the other code here it's
@@ -67,7 +68,7 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
 
-        assert_params_in_request(body, [
+        assert_params_in_dict(body, [
             'id_server', 'client_secret', 'email', 'send_attempt'
         ])
 
@@ -103,7 +104,7 @@ class MsisdnRegisterRequestTokenRestServlet(RestServlet):
     def on_POST(self, request):
         body = parse_json_object_from_request(request)
 
-        assert_params_in_request(body, [
+        assert_params_in_dict(body, [
             'id_server', 'client_secret',
             'country', 'phone_number',
             'send_attempt',
@@ -222,7 +223,7 @@ class RegisterRestServlet(RestServlet):
             desired_username = body['username']
 
         appservice = None
-        if has_access_token(request):
+        if self.auth.has_access_token(request):
             appservice = yield self.auth.get_appservice_by_req(request)
 
         # fork off as soon as possible for ASes and shared secret auth which
@@ -240,7 +241,7 @@ class RegisterRestServlet(RestServlet):
             # because the IRC bridges rely on being able to register stupid
             # IDs.
 
-            access_token = get_access_token_from_request(request)
+            access_token = self.auth.get_access_token_from_request(request)
 
             if isinstance(desired_username, string_types):
                 result = yield self._do_appservice_registration(
@@ -385,9 +386,7 @@ class RegisterRestServlet(RestServlet):
             add_msisdn = False
         else:
             # NB: This may be from the auth handler and NOT from the POST
-            if 'password' not in params:
-                raise SynapseError(400, "Missing password.",
-                                   Codes.MISSING_PARAM)
+            assert_params_in_dict(params, ["password"])
 
             desired_username = params.get("username", None)
             new_password = params.get("password", None)
@@ -564,11 +563,14 @@ class RegisterRestServlet(RestServlet):
         Returns:
             defer.Deferred:
         """
-        reqd = ('medium', 'address', 'validated_at')
-        if any(x not in threepid for x in reqd):
-            # This will only happen if the ID server returns a malformed response
-            logger.info("Can't add incomplete 3pid")
-            defer.returnValue()
+        try:
+            assert_params_in_dict(threepid, ['medium', 'address', 'validated_at'])
+        except SynapseError as ex:
+            if ex.errcode == Codes.MISSING_PARAM:
+                # This will only happen if the ID server returns a malformed response
+                logger.info("Can't add incomplete 3pid")
+                defer.returnValue(None)
+            raise
 
         yield self.auth_handler.add_threepid(
             user_id,
@@ -641,7 +643,7 @@ class RegisterRestServlet(RestServlet):
     @defer.inlineCallbacks
     def _do_guest_registration(self, params):
         if not self.hs.config.allow_guest_access:
-            defer.returnValue((403, "Guest access is disabled"))
+            raise SynapseError(403, "Guest access is disabled")
         user_id, _ = yield self.registration_handler.register(
             generate_token=False,
             make_guest=True
diff --git a/synapse/rest/client/v2_alpha/report_event.py b/synapse/rest/client/v2_alpha/report_event.py
index 8903e124..95d2a71e 100644
--- a/synapse/rest/client/v2_alpha/report_event.py
+++ b/synapse/rest/client/v2_alpha/report_event.py
@@ -13,13 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from ._base import client_v2_patterns
+from six import string_types
+from six.moves import http_client
 
-import logging
+from twisted.internet import defer
+
+from synapse.api.errors import Codes, SynapseError
+from synapse.http.servlet import (
+    RestServlet,
+    assert_params_in_dict,
+    parse_json_object_from_request,
+)
 
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
@@ -42,12 +50,26 @@ class ReportEventRestServlet(RestServlet):
         user_id = requester.user.to_string()
 
         body = parse_json_object_from_request(request)
+        assert_params_in_dict(body, ("reason", "score"))
+
+        if not isinstance(body["reason"], string_types):
+            raise SynapseError(
+                http_client.BAD_REQUEST,
+                "Param 'reason' must be a string",
+                Codes.BAD_JSON,
+            )
+        if not isinstance(body["score"], int):
+            raise SynapseError(
+                http_client.BAD_REQUEST,
+                "Param 'score' must be an integer",
+                Codes.BAD_JSON,
+            )
 
         yield self.store.add_event_report(
             room_id=room_id,
             event_id=event_id,
             user_id=user_id,
-            reason=body.get("reason"),
+            reason=body["reason"],
             content=body,
             received_ts=self.clock.time_msec(),
         )
diff --git a/synapse/rest/client/v2_alpha/sendtodevice.py b/synapse/rest/client/v2_alpha/sendtodevice.py
index 90bdb1db..a9e9a47a 100644
--- a/synapse/rest/client/v2_alpha/sendtodevice.py
+++ b/synapse/rest/client/v2_alpha/sendtodevice.py
@@ -40,7 +40,7 @@ class SendToDeviceRestServlet(servlet.RestServlet):
         super(SendToDeviceRestServlet, self).__init__()
         self.hs = hs
         self.auth = hs.get_auth()
-        self.txns = HttpTransactionCache(hs.get_clock())
+        self.txns = HttpTransactionCache(hs)
         self.device_message_handler = hs.get_device_message_handler()
 
     def on_PUT(self, request, message_type, txn_id):
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index d2aa47b3..8aa06faf 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -13,27 +13,26 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import itertools
+import logging
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
-from synapse.http.servlet import (
-    RestServlet, parse_string, parse_integer, parse_boolean
+from synapse.api.constants import PresenceState
+from synapse.api.errors import SynapseError
+from synapse.api.filtering import DEFAULT_FILTER_COLLECTION, FilterCollection
+from synapse.events.utils import (
+    format_event_for_client_v2_without_room_id,
+    serialize_event,
 )
 from synapse.handlers.presence import format_user_presence_state
 from synapse.handlers.sync import SyncConfig
+from synapse.http.servlet import RestServlet, parse_boolean, parse_integer, parse_string
 from synapse.types import StreamToken
-from synapse.events.utils import (
-    serialize_event, format_event_for_client_v2_without_room_id,
-)
-from synapse.api.filtering import FilterCollection, DEFAULT_FILTER_COLLECTION
-from synapse.api.errors import SynapseError
-from synapse.api.constants import PresenceState
-from ._base import client_v2_patterns
-from ._base import set_timeline_upper_limit
 
-import itertools
-import logging
-
-from canonicaljson import json
+from ._base import client_v2_patterns, set_timeline_upper_limit
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/tags.py b/synapse/rest/client/v2_alpha/tags.py
index dac8603b..4fea614e 100644
--- a/synapse/rest/client/v2_alpha/tags.py
+++ b/synapse/rest/client/v2_alpha/tags.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import client_v2_patterns
-
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.api.errors import AuthError
+import logging
 
 from twisted.internet import defer
 
-import logging
+from synapse.api.errors import AuthError
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
index 6773b9ba..d9d37918 100644
--- a/synapse/rest/client/v2_alpha/thirdparty.py
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -20,6 +20,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import ThirdPartyEntityKind
 from synapse.http.servlet import RestServlet
+
 from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/v2_alpha/user_directory.py b/synapse/rest/client/v2_alpha/user_directory.py
index 2d4a43c3..cac0624b 100644
--- a/synapse/rest/client/v2_alpha/user_directory.py
+++ b/synapse/rest/client/v2_alpha/user_directory.py
@@ -19,6 +19,7 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
 from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 2ecb15de..6ac2987b 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.servlet import RestServlet
-
 import logging
 import re
 
+from synapse.http.servlet import RestServlet
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py
index 724911d1..147ff7d7 100644
--- a/synapse/rest/consent/consent_resource.py
+++ b/synapse/rest/consent/consent_resource.py
@@ -13,28 +13,26 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from hashlib import sha256
 import hmac
 import logging
+from hashlib import sha256
 from os import path
+
 from six.moves import http_client
 
 import jinja2
 from jinja2 import TemplateNotFound
+
 from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.api.errors import NotFoundError, SynapseError, StoreError
+from synapse.api.errors import NotFoundError, StoreError, SynapseError
 from synapse.config import ConfigError
-from synapse.http.server import (
-    finish_request,
-    wrap_html_request_handler,
-)
+from synapse.http.server import finish_request, wrap_html_request_handler
 from synapse.http.servlet import parse_string
 from synapse.types import UserID
 
-
 # language to use for the templates. TODO: figure this out from Accept-Language
 TEMPLATE_LANGUAGE = "en"
 
diff --git a/synapse/rest/key/v1/server_key_resource.py b/synapse/rest/key/v1/server_key_resource.py
index 1498d188..b9ee6e1c 100644
--- a/synapse/rest/key/v1/server_key_resource.py
+++ b/synapse/rest/key/v1/server_key_resource.py
@@ -14,14 +14,16 @@
 # limitations under the License.
 
 
-from twisted.web.resource import Resource
-from synapse.http.server import respond_with_json_bytes
+import logging
+
+from canonicaljson import encode_canonical_json
 from signedjson.sign import sign_json
 from unpaddedbase64 import encode_base64
-from canonicaljson import encode_canonical_json
+
 from OpenSSL import crypto
-import logging
+from twisted.web.resource import Resource
 
+from synapse.http.server import respond_with_json_bytes
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/key/v2/__init__.py b/synapse/rest/key/v2/__init__.py
index a0722414..3491fd21 100644
--- a/synapse/rest/key/v2/__init__.py
+++ b/synapse/rest/key/v2/__init__.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 from twisted.web.resource import Resource
+
 from .local_key_resource import LocalKey
 from .remote_key_resource import RemoteKey
 
diff --git a/synapse/rest/key/v2/local_key_resource.py b/synapse/rest/key/v2/local_key_resource.py
index 04775b3c..ec0ec7b4 100644
--- a/synapse/rest/key/v2/local_key_resource.py
+++ b/synapse/rest/key/v2/local_key_resource.py
@@ -14,13 +14,15 @@
 # limitations under the License.
 
 
-from twisted.web.resource import Resource
-from synapse.http.server import respond_with_json_bytes
+import logging
+
+from canonicaljson import encode_canonical_json
 from signedjson.sign import sign_json
 from unpaddedbase64 import encode_base64
-from canonicaljson import encode_canonical_json
-import logging
 
+from twisted.web.resource import Resource
+
+from synapse.http.server import respond_with_json_bytes
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index 21b4c117..7d67e4b0 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -12,20 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import (
-    respond_with_json_bytes, wrap_json_request_handler,
-)
-from synapse.http.servlet import parse_integer, parse_json_object_from_request
-from synapse.api.errors import SynapseError, Codes
-from synapse.crypto.keyring import KeyLookupError
+import logging
+from io import BytesIO
 
+from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
-from twisted.internet import defer
 
+from synapse.api.errors import Codes, SynapseError
+from synapse.crypto.keyring import KeyLookupError
+from synapse.http.server import respond_with_json_bytes, wrap_json_request_handler
+from synapse.http.servlet import parse_integer, parse_json_object_from_request
 
-from io import BytesIO
-import logging
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/media/v0/content_repository.py b/synapse/rest/media/v0/content_repository.py
index e44d4276..f255f288 100644
--- a/synapse/rest/media/v0/content_repository.py
+++ b/synapse/rest/media/v0/content_repository.py
@@ -13,22 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import respond_with_json_bytes, finish_request
-
-from synapse.api.errors import (
-    Codes, cs_error
-)
-
-from twisted.protocols.basic import FileSender
-from twisted.web import server, resource
-
-from canonicaljson import json
-
 import base64
 import logging
 import os
 import re
 
+from canonicaljson import json
+
+from twisted.protocols.basic import FileSender
+from twisted.web import resource, server
+
+from synapse.api.errors import Codes, cs_error
+from synapse.http.server import finish_request, respond_with_json_bytes
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/media/v1/_base.py b/synapse/rest/media/v1/_base.py
index c0d2f068..65f4bd29 100644
--- a/synapse/rest/media/v1/_base.py
+++ b/synapse/rest/media/v1/_base.py
@@ -13,23 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import respond_with_json, finish_request
-from synapse.api.errors import (
-    cs_error, Codes, SynapseError
-)
-from synapse.util import logcontext
+import logging
+import os
+import urllib
+
+from six.moves.urllib import parse as urlparse
 
 from twisted.internet import defer
 from twisted.protocols.basic import FileSender
 
+from synapse.api.errors import Codes, SynapseError, cs_error
+from synapse.http.server import finish_request, respond_with_json
+from synapse.util import logcontext
 from synapse.util.stringutils import is_ascii
 
-import os
-
-import logging
-import urllib
-from six.moves.urllib import parse as urlparse
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/media/v1/download_resource.py b/synapse/rest/media/v1/download_resource.py
index 8cf8820c..fbfa85f7 100644
--- a/synapse/rest/media/v1/download_resource.py
+++ b/synapse/rest/media/v1/download_resource.py
@@ -18,11 +18,9 @@ from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import (
-    set_cors_headers,
-    wrap_json_request_handler,
-)
 import synapse.http.servlet
+from synapse.http.server import set_cors_headers, wrap_json_request_handler
+
 from ._base import parse_media_id, respond_404
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/media/v1/filepath.py b/synapse/rest/media/v1/filepath.py
index d5164e47..c8586fa2 100644
--- a/synapse/rest/media/v1/filepath.py
+++ b/synapse/rest/media/v1/filepath.py
@@ -13,9 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import functools
 import os
 import re
-import functools
 
 NEW_FORMAT_ID_RE = re.compile(r"^\d\d\d\d-\d\d-\d\d")
 
diff --git a/synapse/rest/media/v1/identicon_resource.py b/synapse/rest/media/v1/identicon_resource.py
index 66f2b6bd..bdbd8d50 100644
--- a/synapse/rest/media/v1/identicon_resource.py
+++ b/synapse/rest/media/v1/identicon_resource.py
@@ -13,8 +13,11 @@
 # limitations under the License.
 
 from pydenticon import Generator
+
 from twisted.web.resource import Resource
 
+from synapse.http.servlet import parse_integer
+
 FOREGROUND = [
     "rgb(45,79,255)",
     "rgb(254,180,44)",
@@ -55,8 +58,8 @@ class IdenticonResource(Resource):
 
     def render_GET(self, request):
         name = "/".join(request.postpath)
-        width = int(request.args.get("width", [96])[0])
-        height = int(request.args.get("height", [96])[0])
+        width = parse_integer(request, "width", default=96)
+        height = parse_integer(request, "height", default=96)
         identicon_bytes = self.generate_identicon(name, width, height)
         request.setHeader(b"Content-Type", b"image/png")
         request.setHeader(
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 218ba7a0..30242c52 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -14,41 +14,42 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
+import cgi
+import errno
+import logging
+import os
+import shutil
+
+from six import iteritems
+from six.moves.urllib import parse as urlparse
+
 import twisted.internet.error
 import twisted.web.http
+from twisted.internet import defer, threads
 from twisted.web.resource import Resource
 
-from ._base import respond_404, FileInfo, respond_with_responder
-from .upload_resource import UploadResource
-from .download_resource import DownloadResource
-from .thumbnail_resource import ThumbnailResource
-from .identicon_resource import IdenticonResource
-from .preview_url_resource import PreviewUrlResource
-from .filepath import MediaFilePaths
-from .thumbnailer import Thumbnailer
-from .storage_provider import StorageProviderWrapper
-from .media_storage import MediaStorage
-
-from synapse.http.matrixfederationclient import MatrixFederationHttpClient
-from synapse.util.stringutils import random_string
 from synapse.api.errors import (
-    SynapseError, HttpResponseException, NotFoundError, FederationDeniedError,
+    FederationDeniedError,
+    HttpResponseException,
+    NotFoundError,
+    SynapseError,
 )
-
+from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.util.async import Linearizer
-from synapse.util.stringutils import is_ascii
 from synapse.util.logcontext import make_deferred_yieldable
 from synapse.util.retryutils import NotRetryingDestination
+from synapse.util.stringutils import is_ascii, random_string
 
-import os
-import errno
-import shutil
-
-import cgi
-import logging
-from six.moves.urllib import parse as urlparse
-from six import iteritems
+from ._base import FileInfo, respond_404, respond_with_responder
+from .download_resource import DownloadResource
+from .filepath import MediaFilePaths
+from .identicon_resource import IdenticonResource
+from .media_storage import MediaStorage
+from .preview_url_resource import PreviewUrlResource
+from .storage_provider import StorageProviderWrapper
+from .thumbnail_resource import ThumbnailResource
+from .thumbnailer import Thumbnailer
+from .upload_resource import UploadResource
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/media_storage.py b/synapse/rest/media/v1/media_storage.py
index d6b8ebbe..b25993fc 100644
--- a/synapse/rest/media/v1/media_storage.py
+++ b/synapse/rest/media/v1/media_storage.py
@@ -13,22 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
-from twisted.protocols.basic import FileSender
+import contextlib
+import logging
+import os
+import shutil
+import sys
 
 import six
 
-from ._base import Responder
+from twisted.internet import defer, threads
+from twisted.protocols.basic import FileSender
 
 from synapse.util.file_consumer import BackgroundFileConsumer
 from synapse.util.logcontext import make_deferred_yieldable
 
-import contextlib
-import os
-import logging
-import shutil
-import sys
-
+from ._base import Responder
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index adca4906..b70b15c4 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -24,31 +24,29 @@ import shutil
 import sys
 import traceback
 
-from canonicaljson import json
-
-from six.moves import urllib_parse as urlparse
 from six import string_types
+from six.moves import urllib_parse as urlparse
+
+from canonicaljson import json
 
-from twisted.web.server import NOT_DONE_YET
 from twisted.internet import defer
 from twisted.web.resource import Resource
+from twisted.web.server import NOT_DONE_YET
 
-from ._base import FileInfo
-
-from synapse.api.errors import (
-    SynapseError, Codes,
-)
-from synapse.util.logcontext import make_deferred_yieldable, run_in_background
-from synapse.util.stringutils import random_string
-from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.api.errors import Codes, SynapseError
 from synapse.http.client import SpiderHttpClient
 from synapse.http.server import (
-    respond_with_json_bytes,
     respond_with_json,
+    respond_with_json_bytes,
     wrap_json_request_handler,
 )
+from synapse.http.servlet import parse_integer, parse_string
 from synapse.util.async import ObservableDeferred
-from synapse.util.stringutils import is_ascii
+from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.logcontext import make_deferred_yieldable, run_in_background
+from synapse.util.stringutils import is_ascii, random_string
+
+from ._base import FileInfo
 
 logger = logging.getLogger(__name__)
 
@@ -99,9 +97,9 @@ class PreviewUrlResource(Resource):
 
         # XXX: if get_user_by_req fails, what should we do in an async render?
         requester = yield self.auth.get_user_by_req(request)
-        url = request.args.get("url")[0]
+        url = parse_string(request, "url")
         if "ts" in request.args:
-            ts = int(request.args.get("ts")[0])
+            ts = parse_integer(request, "ts")
         else:
             ts = self.clock.time_msec()
 
diff --git a/synapse/rest/media/v1/storage_provider.py b/synapse/rest/media/v1/storage_provider.py
index 0252afd9..7b9f8b4d 100644
--- a/synapse/rest/media/v1/storage_provider.py
+++ b/synapse/rest/media/v1/storage_provider.py
@@ -13,17 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
+import logging
+import os
+import shutil
 
-from .media_storage import FileResponder
+from twisted.internet import defer, threads
 
 from synapse.config._base import Config
 from synapse.util.logcontext import run_in_background
 
-import logging
-import os
-import shutil
-
+from .media_storage import FileResponder
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/thumbnail_resource.py b/synapse/rest/media/v1/thumbnail_resource.py
index aae6e464..5305e917 100644
--- a/synapse/rest/media/v1/thumbnail_resource.py
+++ b/synapse/rest/media/v1/thumbnail_resource.py
@@ -20,13 +20,14 @@ from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import (
-    set_cors_headers,
-    wrap_json_request_handler,
-)
+from synapse.http.server import set_cors_headers, wrap_json_request_handler
 from synapse.http.servlet import parse_integer, parse_string
+
 from ._base import (
-    FileInfo, parse_media_id, respond_404, respond_with_file,
+    FileInfo,
+    parse_media_id,
+    respond_404,
+    respond_with_file,
     respond_with_responder,
 )
 
diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py
index e1ee535b..a4b26c25 100644
--- a/synapse/rest/media/v1/thumbnailer.py
+++ b/synapse/rest/media/v1/thumbnailer.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import PIL.Image as Image
+import logging
 from io import BytesIO
 
-import logging
+import PIL.Image as Image
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
index 7567476f..9b22d204 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -20,10 +20,8 @@ from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import SynapseError
-from synapse.http.server import (
-    respond_with_json,
-    wrap_json_request_handler,
-)
+from synapse.http.server import respond_with_json, wrap_json_request_handler
+from synapse.http.servlet import parse_string
 
 logger = logging.getLogger(__name__)
 
@@ -68,10 +66,10 @@ class UploadResource(Resource):
                 code=413,
             )
 
-        upload_name = request.args.get("filename", None)
+        upload_name = parse_string(request, "filename")
         if upload_name:
             try:
-                upload_name = upload_name[0].decode('UTF-8')
+                upload_name = upload_name.decode('UTF-8')
             except UnicodeDecodeError:
                 raise SynapseError(
                     msg="Invalid UTF-8 filename parameter: %r" % (upload_name),
diff --git a/synapse/server.py b/synapse/server.py
index c29c1928..92bea96c 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -33,19 +33,30 @@ from synapse.crypto.keyring import Keyring
 from synapse.events.builder import EventBuilderFactory
 from synapse.events.spamcheck import SpamChecker
 from synapse.federation.federation_client import FederationClient
-from synapse.federation.federation_server import FederationServer
+from synapse.federation.federation_server import (
+    FederationHandlerRegistry,
+    FederationServer,
+)
 from synapse.federation.send_queue import FederationRemoteSendQueue
-from synapse.federation.federation_server import FederationHandlerRegistry
-from synapse.federation.transport.client import TransportLayerClient
 from synapse.federation.transaction_queue import TransactionQueue
+from synapse.federation.transport.client import TransportLayerClient
+from synapse.groups.attestations import GroupAttestationSigning, GroupAttestionRenewer
+from synapse.groups.groups_server import GroupsServerHandler
 from synapse.handlers import Handlers
 from synapse.handlers.appservice import ApplicationServicesHandler
 from synapse.handlers.auth import AuthHandler, MacaroonGenerator
 from synapse.handlers.deactivate_account import DeactivateAccountHandler
-from synapse.handlers.devicemessage import DeviceMessageHandler
 from synapse.handlers.device import DeviceHandler
+from synapse.handlers.devicemessage import DeviceMessageHandler
 from synapse.handlers.e2e_keys import E2eKeysHandler
+from synapse.handlers.events import EventHandler, EventStreamHandler
+from synapse.handlers.groups_local import GroupsLocalHandler
+from synapse.handlers.initial_sync import InitialSyncHandler
+from synapse.handlers.message import EventCreationHandler
 from synapse.handlers.presence import PresenceHandler
+from synapse.handlers.profile import ProfileHandler
+from synapse.handlers.read_marker import ReadMarkerHandler
+from synapse.handlers.receipts import ReceiptsHandler
 from synapse.handlers.room import RoomCreationHandler
 from synapse.handlers.room_list import RoomListHandler
 from synapse.handlers.room_member import RoomMemberMasterHandler
@@ -53,17 +64,8 @@ from synapse.handlers.room_member_worker import RoomMemberWorkerHandler
 from synapse.handlers.set_password import SetPasswordHandler
 from synapse.handlers.sync import SyncHandler
 from synapse.handlers.typing import TypingHandler
-from synapse.handlers.events import EventHandler, EventStreamHandler
-from synapse.handlers.initial_sync import InitialSyncHandler
-from synapse.handlers.receipts import ReceiptsHandler
-from synapse.handlers.read_marker import ReadMarkerHandler
 from synapse.handlers.user_directory import UserDirectoryHandler
-from synapse.handlers.groups_local import GroupsLocalHandler
-from synapse.handlers.profile import ProfileHandler
-from synapse.handlers.message import EventCreationHandler
-from synapse.groups.groups_server import GroupsServerHandler
-from synapse.groups.attestations import GroupAttestionRenewer, GroupAttestationSigning
-from synapse.http.client import SimpleHttpClient, InsecureInterceptableContextFactory
+from synapse.http.client import InsecureInterceptableContextFactory, SimpleHttpClient
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.notifier import Notifier
 from synapse.push.action_generator import ActionGenerator
@@ -74,9 +76,7 @@ from synapse.rest.media.v1.media_repository import (
 )
 from synapse.server_notices.server_notices_manager import ServerNoticesManager
 from synapse.server_notices.server_notices_sender import ServerNoticesSender
-from synapse.server_notices.worker_server_notices_sender import (
-    WorkerServerNoticesSender,
-)
+from synapse.server_notices.worker_server_notices_sender import WorkerServerNoticesSender
 from synapse.state import StateHandler, StateResolutionHandler
 from synapse.storage import DataStore
 from synapse.streams.events import EventSources
diff --git a/synapse/server_notices/consent_server_notices.py b/synapse/server_notices/consent_server_notices.py
index bb74af1a..5e3044d1 100644
--- a/synapse/server_notices/consent_server_notices.py
+++ b/synapse/server_notices/consent_server_notices.py
@@ -14,7 +14,8 @@
 # limitations under the License.
 import logging
 
-from six import (iteritems, string_types)
+from six import iteritems, string_types
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
diff --git a/synapse/state.py b/synapse/state.py
index 8098db94..15a593d4 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -14,25 +14,25 @@
 # limitations under the License.
 
 
+import hashlib
+import logging
+from collections import namedtuple
+
+from six import iteritems, itervalues
+
+from frozendict import frozendict
+
 from twisted.internet import defer
 
 from synapse import event_auth
-from synapse.util.logutils import log_function
-from synapse.util.caches.expiringcache import ExpiringCache
-from synapse.util.metrics import Measure
 from synapse.api.constants import EventTypes
 from synapse.api.errors import AuthError
 from synapse.events.snapshot import EventContext
 from synapse.util.async import Linearizer
 from synapse.util.caches import CACHE_SIZE_FACTOR
-
-from collections import namedtuple
-from frozendict import frozendict
-
-import logging
-import hashlib
-
-from six import iteritems, itervalues
+from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.logutils import log_function
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index e843b702..ba88a549 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -15,51 +15,48 @@
 # limitations under the License.
 
 import datetime
-from dateutil import tz
-import time
 import logging
+import time
 
+from dateutil import tz
+
+from synapse.api.constants import PresenceState
 from synapse.storage.devices import DeviceStore
 from synapse.storage.user_erasure_store import UserErasureStore
-from .appservice import (
-    ApplicationServiceStore, ApplicationServiceTransactionStore
-)
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+from .account_data import AccountDataStore
+from .appservice import ApplicationServiceStore, ApplicationServiceTransactionStore
+from .client_ips import ClientIpStore
+from .deviceinbox import DeviceInboxStore
 from .directory import DirectoryStore
+from .end_to_end_keys import EndToEndKeyStore
+from .engines import PostgresEngine
+from .event_federation import EventFederationStore
+from .event_push_actions import EventPushActionsStore
 from .events import EventsStore
+from .filtering import FilteringStore
+from .group_server import GroupServerStore
+from .keys import KeyStore
+from .media_repository import MediaRepositoryStore
+from .openid import OpenIdStore
 from .presence import PresenceStore, UserPresenceState
 from .profile import ProfileStore
+from .push_rule import PushRuleStore
+from .pusher import PusherStore
+from .receipts import ReceiptsStore
 from .registration import RegistrationStore
+from .rejections import RejectionsStore
 from .room import RoomStore
 from .roommember import RoomMemberStore
-from .stream import StreamStore
-from .transactions import TransactionStore
-from .keys import KeyStore
-from .event_federation import EventFederationStore
-from .pusher import PusherStore
-from .push_rule import PushRuleStore
-from .media_repository import MediaRepositoryStore
-from .rejections import RejectionsStore
-from .event_push_actions import EventPushActionsStore
-from .deviceinbox import DeviceInboxStore
-from .group_server import GroupServerStore
-from .state import StateStore
-from .signatures import SignatureStore
-from .filtering import FilteringStore
-from .end_to_end_keys import EndToEndKeyStore
-
-from .receipts import ReceiptsStore
 from .search import SearchStore
+from .signatures import SignatureStore
+from .state import StateStore
+from .stream import StreamStore
 from .tags import TagsStore
-from .account_data import AccountDataStore
-from .openid import OpenIdStore
-from .client_ips import ClientIpStore
+from .transactions import TransactionStore
 from .user_directory import UserDirectoryStore
-
-from .util.id_generators import IdGenerator, StreamIdGenerator, ChainedIdGenerator
-from .engines import PostgresEngine
-
-from synapse.api.constants import PresenceState
-from synapse.util.caches.stream_change_cache import StreamChangeCache
+from .util.id_generators import ChainedIdGenerator, IdGenerator, StreamIdGenerator
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 22d6257a..a6a0e6ec 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -13,22 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import sys
+import threading
+import time
 
-from synapse.api.errors import StoreError
-from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
-from synapse.util.caches.descriptors import Cache
-from synapse.storage.engines import PostgresEngine
+from six import iteritems, iterkeys, itervalues
+from six.moves import intern, range
 
 from prometheus_client import Histogram
 
 from twisted.internet import defer
 
-import sys
-import time
-import threading
-
-from six import itervalues, iterkeys, iteritems
-from six.moves import intern, range
+from synapse.api.errors import StoreError
+from synapse.storage.engines import PostgresEngine
+from synapse.util.caches.descriptors import Cache
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 
 logger = logging.getLogger(__name__)
 
@@ -221,7 +220,7 @@ class SQLBaseStore(object):
         self._clock.looping_call(loop, 10000)
 
     def _new_transaction(self, conn, desc, after_callbacks, exception_callbacks,
-                         logging_context, func, *args, **kwargs):
+                         func, *args, **kwargs):
         start = time.time()
         txn_id = self._TXN_ID
 
@@ -285,8 +284,7 @@ class SQLBaseStore(object):
             end = time.time()
             duration = end - start
 
-            if logging_context is not None:
-                logging_context.add_database_transaction(duration)
+            LoggingContext.current_context().add_database_transaction(duration)
 
             transaction_logger.debug("[TXN END] {%s} %f sec", name, duration)
 
@@ -310,19 +308,15 @@ class SQLBaseStore(object):
         Returns:
             Deferred: The result of func
         """
-        current_context = LoggingContext.current_context()
-
         after_callbacks = []
         exception_callbacks = []
 
-        def inner_func(conn, *args, **kwargs):
-            return self._new_transaction(
-                conn, desc, after_callbacks, exception_callbacks, current_context,
-                func, *args, **kwargs
-            )
-
         try:
-            result = yield self.runWithConnection(inner_func, *args, **kwargs)
+            result = yield self.runWithConnection(
+                self._new_transaction,
+                desc, after_callbacks, exception_callbacks, func,
+                *args, **kwargs
+            )
 
             for after_callback, after_args, after_kwargs in after_callbacks:
                 after_callback(*after_args, **after_kwargs)
@@ -347,22 +341,26 @@ class SQLBaseStore(object):
         Returns:
             Deferred: The result of func
         """
-        current_context = LoggingContext.current_context()
+        parent_context = LoggingContext.current_context()
+        if parent_context == LoggingContext.sentinel:
+            # warning disabled for 0.33.0 release; proper fixes will land imminently.
+            # logger.warn(
+            #    "Running db txn from sentinel context: metrics will be lost",
+            # )
+            parent_context = None
 
         start_time = time.time()
 
         def inner_func(conn, *args, **kwargs):
-            with LoggingContext("runWithConnection") as context:
+            with LoggingContext("runWithConnection", parent_context) as context:
                 sched_duration_sec = time.time() - start_time
                 sql_scheduling_timer.observe(sched_duration_sec)
-                current_context.add_database_scheduled(sched_duration_sec)
+                context.add_database_scheduled(sched_duration_sec)
 
                 if self.database_engine.is_connection_closed(conn):
                     logger.debug("Reconnecting closed database connection")
                     conn.reconnect()
 
-                current_context.copy_to(context)
-
                 return func(conn, *args, **kwargs)
 
         with PreserveLoggingContext():
diff --git a/synapse/storage/account_data.py b/synapse/storage/account_data.py
index 7034a613..bbc3355c 100644
--- a/synapse/storage/account_data.py
+++ b/synapse/storage/account_data.py
@@ -14,18 +14,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import abc
+import logging
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.util.id_generators import StreamIdGenerator
-
-from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
-
-from canonicaljson import json
-
-import abc
-import logging
+from synapse.util.caches.stream_change_cache import StreamChangeCache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 4d32d0bd..9f12b360 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -15,14 +15,16 @@
 # limitations under the License.
 import logging
 import re
-from twisted.internet import defer
+
 from canonicaljson import json
 
+from twisted.internet import defer
+
 from synapse.appservice import AppServiceTransaction
 from synapse.config.appservice import load_appservices
 from synapse.storage.events import EventsWorkerStore
-from ._base import SQLBaseStore
 
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index af189645..dc9eca7d 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from . import engines
-
-from twisted.internet import defer
+import logging
 
 from canonicaljson import json
 
-import logging
+from twisted.internet import defer
+
+from . import engines
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py
index 968d2fed..b78eda34 100644
--- a/synapse/storage/client_ips.py
+++ b/synapse/storage/client_ips.py
@@ -15,15 +15,14 @@
 
 import logging
 
-from twisted.internet import defer
+from six import iteritems
 
-from ._base import Cache
-from . import background_updates
+from twisted.internet import defer
 
 from synapse.util.caches import CACHE_SIZE_FACTOR
 
-from six import iteritems
-
+from . import background_updates
+from ._base import Cache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index 38addbf9..73646da0 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -19,10 +19,9 @@ from canonicaljson import json
 
 from twisted.internet import defer
 
-from .background_updates import BackgroundUpdateStore
-
 from synapse.util.caches.expiringcache import ExpiringCache
 
+from .background_updates import BackgroundUpdateStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index 2ed9ada7..ec68e39f 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -14,15 +14,16 @@
 # limitations under the License.
 import logging
 
+from six import iteritems, itervalues
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
-from ._base import SQLBaseStore, Cache
-from synapse.util.caches.descriptors import cached, cachedList, cachedInlineCallbacks
-
-from canonicaljson import json
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
 
-from six import itervalues, iteritems
+from ._base import Cache, SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/directory.py b/synapse/storage/directory.py
index d0c00597..80819423 100644
--- a/synapse/storage/directory.py
+++ b/synapse/storage/directory.py
@@ -13,15 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cached
-
-from synapse.api.errors import SynapseError
+from collections import namedtuple
 
 from twisted.internet import defer
 
-from collections import namedtuple
+from synapse.api.errors import SynapseError
+from synapse.util.caches.descriptors import cached
 
+from ._base import SQLBaseStore
 
 RoomAliasMapping = namedtuple(
     "RoomAliasMapping",
diff --git a/synapse/storage/end_to_end_keys.py b/synapse/storage/end_to_end_keys.py
index 181047c8..7ae5c654 100644
--- a/synapse/storage/end_to_end_keys.py
+++ b/synapse/storage/end_to_end_keys.py
@@ -12,16 +12,16 @@
 # 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 six import iteritems
+
+from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
 
 from synapse.util.caches.descriptors import cached
 
-from canonicaljson import encode_canonical_json, json
-
 from ._base import SQLBaseStore
 
-from six import iteritems
-
 
 class EndToEndKeyStore(SQLBaseStore):
     def set_e2e_device_keys(self, user_id, device_id, time_now, device_keys):
diff --git a/synapse/storage/engines/__init__.py b/synapse/storage/engines/__init__.py
index 8c868ece..e2f9de84 100644
--- a/synapse/storage/engines/__init__.py
+++ b/synapse/storage/engines/__init__.py
@@ -13,13 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import IncorrectDatabaseSetup
-from .postgres import PostgresEngine
-from .sqlite3 import Sqlite3Engine
-
 import importlib
 import platform
 
+from ._base import IncorrectDatabaseSetup
+from .postgres import PostgresEngine
+from .sqlite3 import Sqlite3Engine
 
 SUPPORTED_MODULE = {
     "sqlite3": Sqlite3Engine,
diff --git a/synapse/storage/engines/sqlite3.py b/synapse/storage/engines/sqlite3.py
index 60f0fa7f..19949fc4 100644
--- a/synapse/storage/engines/sqlite3.py
+++ b/synapse/storage/engines/sqlite3.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import prepare_database
-
 import struct
 import threading
 
+from synapse.storage.prepare_database import prepare_database
+
 
 class Sqlite3Engine(object):
     single_threaded = True
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
index 8fbf7ffb..8d366d1b 100644
--- a/synapse/storage/event_federation.py
+++ b/synapse/storage/event_federation.py
@@ -12,23 +12,21 @@
 # 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.
+import logging
 import random
 
+from six.moves import range
+from six.moves.queue import Empty, PriorityQueue
+
+from unpaddedbase64 import encode_base64
+
 from twisted.internet import defer
 
+from synapse.api.errors import StoreError
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.events import EventsWorkerStore
 from synapse.storage.signatures import SignatureWorkerStore
-
-from synapse.api.errors import StoreError
 from synapse.util.caches.descriptors import cached
-from unpaddedbase64 import encode_base64
-
-import logging
-from six.moves.queue import PriorityQueue, Empty
-
-from six.moves import range
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/event_push_actions.py b/synapse/storage/event_push_actions.py
index 05cb3f61..29b511ae 100644
--- a/synapse/storage/event_push_actions.py
+++ b/synapse/storage/event_push_actions.py
@@ -14,15 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage._base import SQLBaseStore, LoggingTransaction
-from twisted.internet import defer
-from synapse.util.caches.descriptors import cachedInlineCallbacks
-
 import logging
 
+from six import iteritems
+
 from canonicaljson import json
 
-from six import iteritems
+from twisted.internet import defer
+
+from synapse.storage._base import LoggingTransaction, SQLBaseStore
+from synapse.util.caches.descriptors import cachedInlineCallbacks
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index a54abb9e..2aaab0d0 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -14,37 +14,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import OrderedDict, deque, namedtuple
-from functools import wraps
 import itertools
 import logging
+from collections import OrderedDict, deque, namedtuple
+from functools import wraps
+
+from six import iteritems, itervalues
+from six.moves import range
 
 from canonicaljson import json
+from prometheus_client import Counter
 
 from twisted.internet import defer
 
+import synapse.metrics
+from synapse.api.constants import EventTypes
+from synapse.api.errors import SynapseError
+# these are only included to make the type annotations work
+from synapse.events import EventBase  # noqa: F401
+from synapse.events.snapshot import EventContext  # noqa: F401
 from synapse.storage.events_worker import EventsWorkerStore
+from synapse.types import RoomStreamToken, get_domain_from_id
 from synapse.util.async import ObservableDeferred
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 from synapse.util.frozenutils import frozendict_json_encoder
-from synapse.util.logcontext import (
-    PreserveLoggingContext, make_deferred_yieldable,
-)
+from synapse.util.logcontext import PreserveLoggingContext, make_deferred_yieldable
 from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
-from synapse.api.constants import EventTypes
-from synapse.api.errors import SynapseError
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
-from synapse.types import get_domain_from_id, RoomStreamToken
-import synapse.metrics
-
-# these are only included to make the type annotations work
-from synapse.events import EventBase    # noqa: F401
-from synapse.events.snapshot import EventContext   # noqa: F401
-
-from six.moves import range
-from six import itervalues, iteritems
-
-from prometheus_client import Counter
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py
index 896225aa..67433606 100644
--- a/synapse/storage/events_worker.py
+++ b/synapse/storage/events_worker.py
@@ -12,29 +12,28 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from ._base import SQLBaseStore
+import logging
+from collections import namedtuple
+
+from canonicaljson import json
 
 from twisted.internet import defer
 
+from synapse.api.errors import SynapseError
+# these are only included to make the type annotations work
+from synapse.events import EventBase  # noqa: F401
 from synapse.events import FrozenEvent
+from synapse.events.snapshot import EventContext  # noqa: F401
 from synapse.events.utils import prune_event
-
 from synapse.util.logcontext import (
-    PreserveLoggingContext, make_deferred_yieldable, run_in_background,
     LoggingContext,
+    PreserveLoggingContext,
+    make_deferred_yieldable,
+    run_in_background,
 )
 from synapse.util.metrics import Measure
-from synapse.api.errors import SynapseError
-
-from collections import namedtuple
-
-import logging
-
-from canonicaljson import json
 
-# these are only included to make the type annotations work
-from synapse.events import EventBase    # noqa: F401
-from synapse.events.snapshot import EventContext   # noqa: F401
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
@@ -223,32 +222,47 @@ class EventsWorkerStore(SQLBaseStore):
         """Takes a database connection and waits for requests for events from
         the _event_fetch_list queue.
         """
-        event_list = []
         i = 0
         while True:
-            try:
-                with self._event_fetch_lock:
-                    event_list = self._event_fetch_list
-                    self._event_fetch_list = []
-
-                    if not event_list:
-                        single_threaded = self.database_engine.single_threaded
-                        if single_threaded or i > EVENT_QUEUE_ITERATIONS:
-                            self._event_fetch_ongoing -= 1
-                            return
-                        else:
-                            self._event_fetch_lock.wait(EVENT_QUEUE_TIMEOUT_S)
-                            i += 1
-                            continue
-                    i = 0
+            with self._event_fetch_lock:
+                event_list = self._event_fetch_list
+                self._event_fetch_list = []
+
+                if not event_list:
+                    single_threaded = self.database_engine.single_threaded
+                    if single_threaded or i > EVENT_QUEUE_ITERATIONS:
+                        self._event_fetch_ongoing -= 1
+                        return
+                    else:
+                        self._event_fetch_lock.wait(EVENT_QUEUE_TIMEOUT_S)
+                        i += 1
+                        continue
+                i = 0
+
+            self._fetch_event_list(conn, event_list)
+
+    def _fetch_event_list(self, conn, event_list):
+        """Handle a load of requests from the _event_fetch_list queue
 
+        Args:
+            conn (twisted.enterprise.adbapi.Connection): database connection
+
+            event_list (list[Tuple[list[str], Deferred]]):
+                The fetch requests. Each entry consists of a list of event
+                ids to be fetched, and a deferred to be completed once the
+                events have been fetched.
+
+        """
+        with Measure(self._clock, "_fetch_event_list"):
+            try:
                 event_id_lists = zip(*event_list)[0]
                 event_ids = [
                     item for sublist in event_id_lists for item in sublist
                 ]
 
                 rows = self._new_transaction(
-                    conn, "do_fetch", [], [], None, self._fetch_event_rows, event_ids
+                    conn, "do_fetch", [], [],
+                    self._fetch_event_rows, event_ids,
                 )
 
                 row_dict = {
@@ -281,9 +295,8 @@ class EventsWorkerStore(SQLBaseStore):
                             with PreserveLoggingContext():
                                 d.errback(e)
 
-                if event_list:
-                    with PreserveLoggingContext():
-                        self.hs.get_reactor().callFromThread(fire, event_list)
+                with PreserveLoggingContext():
+                    self.hs.get_reactor().callFromThread(fire, event_list)
 
     @defer.inlineCallbacks
     def _enqueue_events(self, events, check_redacted=True, allow_rejected=False):
diff --git a/synapse/storage/filtering.py b/synapse/storage/filtering.py
index eae6027c..2d5896c5 100644
--- a/synapse/storage/filtering.py
+++ b/synapse/storage/filtering.py
@@ -13,13 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
 
-from ._base import SQLBaseStore
-from synapse.api.errors import SynapseError, Codes
+from synapse.api.errors import Codes, SynapseError
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 
-from canonicaljson import encode_canonical_json, json
+from ._base import SQLBaseStore
 
 
 class FilteringStore(SQLBaseStore):
diff --git a/synapse/storage/group_server.py b/synapse/storage/group_server.py
index b77402d2..592d1b4c 100644
--- a/synapse/storage/group_server.py
+++ b/synapse/storage/group_server.py
@@ -14,15 +14,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 
 from ._base import SQLBaseStore
 
-from canonicaljson import json
-
-
 # The category ID for the "default" category. We don't store as null in the
 # database to avoid the fun of null != null
 _DEFAULT_CATEGORY_ID = ""
diff --git a/synapse/storage/keys.py b/synapse/storage/keys.py
index 0f13b61d..f5479776 100644
--- a/synapse/storage/keys.py
+++ b/synapse/storage/keys.py
@@ -13,17 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cachedInlineCallbacks
+import hashlib
+import logging
 
-from twisted.internet import defer
 import six
 
-import OpenSSL
 from signedjson.key import decode_verify_key_bytes
-import hashlib
 
-import logging
+import OpenSSL
+from twisted.internet import defer
+
+from synapse.util.caches.descriptors import cachedInlineCallbacks
+
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index cf2aae04..b290f834 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -20,7 +20,6 @@ import logging
 import os
 import re
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/presence.py b/synapse/storage/presence.py
index f05d91cc..a0c7a0dc 100644
--- a/synapse/storage/presence.py
+++ b/synapse/storage/presence.py
@@ -13,13 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
+from collections import namedtuple
+
+from twisted.internet import defer
+
 from synapse.api.constants import PresenceState
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
 from synapse.util import batch_iter
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
 
-from collections import namedtuple
-from twisted.internet import defer
+from ._base import SQLBaseStore
 
 
 class UserPresenceState(namedtuple("UserPresenceState",
diff --git a/synapse/storage/profile.py b/synapse/storage/profile.py
index 8612bd5e..60295da2 100644
--- a/synapse/storage/profile.py
+++ b/synapse/storage/profile.py
@@ -15,8 +15,8 @@
 
 from twisted.internet import defer
 
-from synapse.storage.roommember import ProfileInfo
 from synapse.api.errors import StoreError
+from synapse.storage.roommember import ProfileInfo
 
 from ._base import SQLBaseStore
 
diff --git a/synapse/storage/push_rule.py b/synapse/storage/push_rule.py
index 9e52e992..be655d28 100644
--- a/synapse/storage/push_rule.py
+++ b/synapse/storage/push_rule.py
@@ -14,21 +14,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
+import abc
+import logging
+
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes
+from synapse.push.baserules import list_with_base_rules
 from synapse.storage.appservice import ApplicationServiceWorkerStore
 from synapse.storage.pusher import PusherWorkerStore
 from synapse.storage.receipts import ReceiptsWorkerStore
 from synapse.storage.roommember import RoomMemberWorkerStore
 from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList
 from synapse.util.caches.stream_change_cache import StreamChangeCache
-from synapse.push.baserules import list_with_base_rules
-from synapse.api.constants import EventTypes
-from twisted.internet import defer
 
-from canonicaljson import json
-
-import abc
-import logging
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/pusher.py b/synapse/storage/pusher.py
index c6def861..cc273a57 100644
--- a/synapse/storage/pusher.py
+++ b/synapse/storage/pusher.py
@@ -14,15 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from twisted.internet import defer
+import logging
+import types
 
 from canonicaljson import encode_canonical_json, json
 
+from twisted.internet import defer
+
 from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList
 
-import logging
-import types
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/receipts.py b/synapse/storage/receipts.py
index f230a3ba..0ac665e9 100644
--- a/synapse/storage/receipts.py
+++ b/synapse/storage/receipts.py
@@ -14,18 +14,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from .util.id_generators import StreamIdGenerator
-from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList, cached
-from synapse.util.caches.stream_change_cache import StreamChangeCache
-
-from twisted.internet import defer
+import abc
+import logging
 
 from canonicaljson import json
 
-import abc
-import logging
+from twisted.internet import defer
 
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+from ._base import SQLBaseStore
+from .util.id_generators import StreamIdGenerator
 
 logger = logging.getLogger(__name__)
 
@@ -140,7 +140,9 @@ class ReceiptsWorkerStore(SQLBaseStore):
         """
         room_ids = set(room_ids)
 
-        if from_key:
+        if from_key is not None:
+            # Only ask the database about rooms where there have been new
+            # receipts added since `from_key`
             room_ids = yield self._receipts_stream_cache.get_entities_changed(
                 room_ids, from_key
             )
@@ -151,7 +153,6 @@ class ReceiptsWorkerStore(SQLBaseStore):
 
         defer.returnValue([ev for res in results.values() for ev in res])
 
-    @cachedInlineCallbacks(num_args=3, tree=True)
     def get_linearized_receipts_for_room(self, room_id, to_key, from_key=None):
         """Get receipts for a single room for sending to clients.
 
@@ -162,7 +163,19 @@ class ReceiptsWorkerStore(SQLBaseStore):
                 from the start.
 
         Returns:
-            list: A list of receipts.
+            Deferred[list]: A list of receipts.
+        """
+        if from_key is not None:
+            # Check the cache first to see if any new receipts have been added
+            # since`from_key`. If not we can no-op.
+            if not self._receipts_stream_cache.has_entity_changed(room_id, from_key):
+                defer.succeed([])
+
+        return self._get_linearized_receipts_for_room(room_id, to_key, from_key)
+
+    @cachedInlineCallbacks(num_args=3, tree=True)
+    def _get_linearized_receipts_for_room(self, room_id, to_key, from_key=None):
+        """See get_linearized_receipts_for_room
         """
         def f(txn):
             if from_key:
@@ -211,7 +224,7 @@ class ReceiptsWorkerStore(SQLBaseStore):
             "content": content,
         }])
 
-    @cachedList(cached_method_name="get_linearized_receipts_for_room",
+    @cachedList(cached_method_name="_get_linearized_receipts_for_room",
                 list_name="room_ids", num_args=3, inlineCallbacks=True)
     def _get_linearized_receipts_for_rooms(self, room_ids, to_key, from_key=None):
         if not room_ids:
@@ -373,7 +386,7 @@ class ReceiptsStore(ReceiptsWorkerStore):
             self.get_receipts_for_user.invalidate, (user_id, receipt_type)
         )
         # FIXME: This shouldn't invalidate the whole cache
-        txn.call_after(self.get_linearized_receipts_for_room.invalidate_many, (room_id,))
+        txn.call_after(self._get_linearized_receipts_for_room.invalidate_many, (room_id,))
 
         txn.call_after(
             self._receipts_stream_cache.entity_has_changed,
@@ -493,7 +506,7 @@ class ReceiptsStore(ReceiptsWorkerStore):
             self.get_receipts_for_user.invalidate, (user_id, receipt_type)
         )
         # FIXME: This shouldn't invalidate the whole cache
-        txn.call_after(self.get_linearized_receipts_for_room.invalidate_many, (room_id,))
+        txn.call_after(self._get_linearized_receipts_for_room.invalidate_many, (room_id,))
 
         self._simple_delete_txn(
             txn,
diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index 0d18f6d8..07333f77 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -15,15 +15,15 @@
 
 import re
 
+from six.moves import range
+
 from twisted.internet import defer
 
-from synapse.api.errors import StoreError, Codes
+from synapse.api.errors import Codes, StoreError
 from synapse.storage import background_updates
 from synapse.storage._base import SQLBaseStore
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
-from six.moves import range
-
 
 class RegistrationWorkerStore(SQLBaseStore):
     @cached()
diff --git a/synapse/storage/rejections.py b/synapse/storage/rejections.py
index 40acb5c4..880f047a 100644
--- a/synapse/storage/rejections.py
+++ b/synapse/storage/rejections.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-
 import logging
 
+from ._base import SQLBaseStore
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index ca0eb187..3147fb68 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -13,6 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import collections
+import logging
+import re
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
@@ -20,12 +26,6 @@ from synapse.storage._base import SQLBaseStore
 from synapse.storage.search import SearchStore
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
-from canonicaljson import json
-
-import collections
-import logging
-import re
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 8fc9549a..02a802be 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -14,24 +14,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
+import logging
 from collections import namedtuple
 
+from six import iteritems, itervalues
+
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
 from synapse.storage.events import EventsWorkerStore
+from synapse.types import get_domain_from_id
 from synapse.util.async import Linearizer
 from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 from synapse.util.stringutils import to_ascii
 
-from synapse.api.constants import Membership, EventTypes
-from synapse.types import get_domain_from_id
-
-import logging
-from canonicaljson import json
-
-from six import itervalues, iteritems
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/25/fts.py b/synapse/storage/schema/delta/25/fts.py
index e7351c3a..4b2ffd35 100644
--- a/synapse/storage/schema/delta/25/fts.py
+++ b/synapse/storage/schema/delta/25/fts.py
@@ -14,11 +14,11 @@
 
 import logging
 
-from synapse.storage.prepare_database import get_statements
-from synapse.storage.engines import PostgresEngine, Sqlite3Engine
-
 import simplejson
 
+from synapse.storage.engines import PostgresEngine, Sqlite3Engine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/27/ts.py b/synapse/storage/schema/delta/27/ts.py
index 6df57b52..414f9f5a 100644
--- a/synapse/storage/schema/delta/27/ts.py
+++ b/synapse/storage/schema/delta/27/ts.py
@@ -14,10 +14,10 @@
 
 import logging
 
-from synapse.storage.prepare_database import get_statements
-
 import simplejson
 
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/30/as_users.py b/synapse/storage/schema/delta/30/as_users.py
index 85bd1a20..ef7ec343 100644
--- a/synapse/storage/schema/delta/30/as_users.py
+++ b/synapse/storage/schema/delta/30/as_users.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from synapse.config.appservice import load_appservices
 
 from six.moves import range
 
+from synapse.config.appservice import load_appservices
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/schema/delta/31/search_update.py b/synapse/storage/schema/delta/31/search_update.py
index fe6b7d19..7d8ca5f9 100644
--- a/synapse/storage/schema/delta/31/search_update.py
+++ b/synapse/storage/schema/delta/31/search_update.py
@@ -12,12 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.engines import PostgresEngine
-from synapse.storage.prepare_database import get_statements
-
 import logging
+
 import simplejson
 
+from synapse.storage.engines import PostgresEngine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/33/event_fields.py b/synapse/storage/schema/delta/33/event_fields.py
index 1e002f9d..bff1256a 100644
--- a/synapse/storage/schema/delta/33/event_fields.py
+++ b/synapse/storage/schema/delta/33/event_fields.py
@@ -12,11 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import get_statements
-
 import logging
+
 import simplejson
 
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/33/remote_media_ts.py b/synapse/storage/schema/delta/33/remote_media_ts.py
index 55ae43f3..9754d3cc 100644
--- a/synapse/storage/schema/delta/33/remote_media_ts.py
+++ b/synapse/storage/schema/delta/33/remote_media_ts.py
@@ -14,7 +14,6 @@
 
 import time
 
-
 ALTER_TABLE = "ALTER TABLE remote_media_cache ADD COLUMN last_access_ts BIGINT"
 
 
diff --git a/synapse/storage/schema/delta/34/cache_stream.py b/synapse/storage/schema/delta/34/cache_stream.py
index 3b63a156..cf09e43e 100644
--- a/synapse/storage/schema/delta/34/cache_stream.py
+++ b/synapse/storage/schema/delta/34/cache_stream.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import get_statements
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/34/received_txn_purge.py b/synapse/storage/schema/delta/34/received_txn_purge.py
index 03314434..67d505e6 100644
--- a/synapse/storage/schema/delta/34/received_txn_purge.py
+++ b/synapse/storage/schema/delta/34/received_txn_purge.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/34/sent_txn_purge.py b/synapse/storage/schema/delta/34/sent_txn_purge.py
index 81948e34..0ffab10b 100644
--- a/synapse/storage/schema/delta/34/sent_txn_purge.py
+++ b/synapse/storage/schema/delta/34/sent_txn_purge.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/37/remove_auth_idx.py b/synapse/storage/schema/delta/37/remove_auth_idx.py
index 20ad8bd5..a3778841 100644
--- a/synapse/storage/schema/delta/37/remove_auth_idx.py
+++ b/synapse/storage/schema/delta/37/remove_auth_idx.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import get_statements
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 DROP_INDICES = """
diff --git a/synapse/storage/schema/delta/42/user_dir.py b/synapse/storage/schema/delta/42/user_dir.py
index ea6a1819..506f326f 100644
--- a/synapse/storage/schema/delta/42/user_dir.py
+++ b/synapse/storage/schema/delta/42/user_dir.py
@@ -14,8 +14,8 @@
 
 import logging
 
-from synapse.storage.prepare_database import get_statements
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
+from synapse.storage.prepare_database import get_statements
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/search.py b/synapse/storage/search.py
index 9b77c453..d5b5df93 100644
--- a/synapse/storage/search.py
+++ b/synapse/storage/search.py
@@ -13,19 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import namedtuple
 import logging
 import re
-from canonicaljson import json
+from collections import namedtuple
 
 from six import string_types
 
+from canonicaljson import json
+
 from twisted.internet import defer
 
-from .background_updates import BackgroundUpdateStore
 from synapse.api.errors import SynapseError
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 
+from .background_updates import BackgroundUpdateStore
+
 logger = logging.getLogger(__name__)
 
 SearchEntry = namedtuple('SearchEntry', [
diff --git a/synapse/storage/signatures.py b/synapse/storage/signatures.py
index 25922e5a..470212aa 100644
--- a/synapse/storage/signatures.py
+++ b/synapse/storage/signatures.py
@@ -13,15 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
 import six
 
-from ._base import SQLBaseStore
-
 from unpaddedbase64 import encode_base64
+
+from twisted.internet import defer
+
 from synapse.crypto.event_signing import compute_event_reference_hash
 from synapse.util.caches.descriptors import cached, cachedList
 
+from ._base import SQLBaseStore
+
 # py2 sqlite has buffer hardcoded as only binary type, so we must use it,
 # despite being deprecated and removed in favor of memoryview
 if six.PY2:
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index cd9821c2..89a05c46 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -13,8 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import namedtuple
 import logging
+from collections import namedtuple
 
 from six import iteritems, itervalues
 from six.moves import range
@@ -23,10 +23,11 @@ from twisted.internet import defer
 
 from synapse.storage.background_updates import BackgroundUpdateStore
 from synapse.storage.engines import PostgresEngine
-from synapse.util.caches import intern_string, get_cache_factor_for
+from synapse.util.caches import get_cache_factor_for, intern_string
 from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches.dictionary_cache import DictionaryCache
 from synapse.util.stringutils import to_ascii
+
 from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index fb463c52..66856342 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -33,22 +33,20 @@ what sort order was used:
       and stream ordering columns respectively.
 """
 
+import abc
+import logging
+from collections import namedtuple
+
+from six.moves import range
+
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
+from synapse.storage.engines import PostgresEngine
 from synapse.storage.events import EventsWorkerStore
-
 from synapse.types import RoomStreamToken
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
-from synapse.storage.engines import PostgresEngine
-
-import abc
-import logging
-
-from six.moves import range
-from collections import namedtuple
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/tags.py b/synapse/storage/tags.py
index 04d123ed..0f657b2b 100644
--- a/synapse/storage/tags.py
+++ b/synapse/storage/tags.py
@@ -14,16 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.account_data import AccountDataWorkerStore
+import logging
 
-from synapse.util.caches.descriptors import cached
-from twisted.internet import defer
+from six.moves import range
 
 from canonicaljson import json
 
-import logging
+from twisted.internet import defer
 
-from six.moves import range
+from synapse.storage.account_data import AccountDataWorkerStore
+from synapse.util.caches.descriptors import cached
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index acbc0344..c3bc94f5 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -13,17 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cached
+import logging
+from collections import namedtuple
 
-from twisted.internet import defer
 import six
 
 from canonicaljson import encode_canonical_json, json
 
-from collections import namedtuple
+from twisted.internet import defer
 
-import logging
+from synapse.util.caches.descriptors import cached
+
+from ._base import SQLBaseStore
 
 # py2 sqlite has buffer hardcoded as only binary type, so we must use it,
 # despite being deprecated and removed in favor of memoryview
diff --git a/synapse/storage/user_directory.py b/synapse/storage/user_directory.py
index 275c2999..a8781b0e 100644
--- a/synapse/storage/user_directory.py
+++ b/synapse/storage/user_directory.py
@@ -13,19 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+import re
 
-from ._base import SQLBaseStore
+from six import iteritems
+
+from twisted.internet import defer
 
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 from synapse.api.constants import EventTypes, JoinRules
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 from synapse.types import get_domain_from_id, get_localpart_from_id
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
-from six import iteritems
-
-import re
-import logging
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
@@ -265,7 +265,7 @@ class UserDirectoryStore(SQLBaseStore):
         self.get_user_in_public_room.invalidate((user_id,))
 
     def get_users_in_public_due_to_room(self, room_id):
-        """Get all user_ids that are in the room directory becuase they're
+        """Get all user_ids that are in the room directory because they're
         in the given room_id
         """
         return self._simple_select_onecol(
@@ -277,7 +277,7 @@ class UserDirectoryStore(SQLBaseStore):
 
     @defer.inlineCallbacks
     def get_users_in_dir_due_to_room(self, room_id):
-        """Get all user_ids that are in the room directory becuase they're
+        """Get all user_ids that are in the room directory because they're
         in the given room_id
         """
         user_ids_dir = yield self._simple_select_onecol(
diff --git a/synapse/storage/user_erasure_store.py b/synapse/storage/user_erasure_store.py
index 47bfc01e..be013f44 100644
--- a/synapse/storage/user_erasure_store.py
+++ b/synapse/storage/user_erasure_store.py
@@ -17,7 +17,7 @@ import operator
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
-from synapse.util.caches.descriptors import cachedList, cached
+from synapse.util.caches.descriptors import cached, cachedList
 
 
 class UserErasureWorkerStore(SQLBaseStore):
diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index 95031dc9..d6160d5e 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -13,9 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import deque
 import contextlib
 import threading
+from collections import deque
 
 
 class IdGenerator(object):
diff --git a/synapse/streams/config.py b/synapse/streams/config.py
index ca78e551..451e4fa4 100644
--- a/synapse/streams/config.py
+++ b/synapse/streams/config.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.api.errors import SynapseError
-from synapse.types import StreamToken
-
 import logging
 
+from synapse.api.errors import SynapseError
+from synapse.http.servlet import parse_integer, parse_string
+from synapse.types import StreamToken
 
 logger = logging.getLogger(__name__)
 
@@ -57,23 +57,10 @@ class PaginationConfig(object):
     @classmethod
     def from_request(cls, request, raise_invalid_params=True,
                      default_limit=None):
-        def get_param(name, default=None):
-            lst = request.args.get(name, [])
-            if len(lst) > 1:
-                raise SynapseError(
-                    400, "%s must be specified only once" % (name,)
-                )
-            elif len(lst) == 1:
-                return lst[0]
-            else:
-                return default
-
-        direction = get_param("dir", 'f')
-        if direction not in ['f', 'b']:
-            raise SynapseError(400, "'dir' parameter is invalid.")
-
-        from_tok = get_param("from")
-        to_tok = get_param("to")
+        direction = parse_string(request, "dir", default='f', allowed_values=['f', 'b'])
+
+        from_tok = parse_string(request, "from")
+        to_tok = parse_string(request, "to")
 
         try:
             if from_tok == "END":
@@ -89,12 +76,10 @@ class PaginationConfig(object):
         except Exception:
             raise SynapseError(400, "'to' paramater is invalid")
 
-        limit = get_param("limit", None)
-        if limit is not None and not limit.isdigit():
-            raise SynapseError(400, "'limit' parameter must be an integer.")
+        limit = parse_integer(request, "limit", default=default_limit)
 
-        if limit is None:
-            limit = default_limit
+        if limit and limit < 0:
+            raise SynapseError(400, "Limit must be 0 or above")
 
         try:
             return PaginationConfig(from_tok, to_tok, direction, limit)
diff --git a/synapse/streams/events.py b/synapse/streams/events.py
index f03ad991..e5220132 100644
--- a/synapse/streams/events.py
+++ b/synapse/streams/events.py
@@ -15,13 +15,12 @@
 
 from twisted.internet import defer
 
-from synapse.types import StreamToken
-
+from synapse.handlers.account_data import AccountDataEventSource
 from synapse.handlers.presence import PresenceEventSource
+from synapse.handlers.receipts import ReceiptEventSource
 from synapse.handlers.room import RoomEventSource
 from synapse.handlers.typing import TypingNotificationEventSource
-from synapse.handlers.receipts import ReceiptEventSource
-from synapse.handlers.account_data import AccountDataEventSource
+from synapse.types import StreamToken
 
 
 class EventSources(object):
diff --git a/synapse/types.py b/synapse/types.py
index cc7c182a..08f058f7 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import string
+from collections import namedtuple
 
 from synapse.api.errors import SynapseError
 
-from collections import namedtuple
-
 
 class Requester(namedtuple("Requester", [
     "user", "access_token_id", "is_guest", "device_id", "app_service",
diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py
index e9886ef2..680ea928 100644
--- a/synapse/util/__init__.py
+++ b/synapse/util/__init__.py
@@ -17,6 +17,7 @@ import logging
 from itertools import islice
 
 import attr
+
 from twisted.internet import defer, task
 
 from synapse.util.logcontext import PreserveLoggingContext
diff --git a/synapse/util/async.py b/synapse/util/async.py
index 1668df4c..5d0fb391 100644
--- a/synapse/util/async.py
+++ b/synapse/util/async.py
@@ -13,20 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+from contextlib import contextmanager
+
+from six.moves import range
+
 from twisted.internet import defer
 from twisted.internet.defer import CancelledError
 from twisted.python import failure
 
+from synapse.util import Clock, logcontext, unwrapFirstError
+
 from .logcontext import (
-    PreserveLoggingContext, make_deferred_yieldable, run_in_background
+    PreserveLoggingContext,
+    make_deferred_yieldable,
+    run_in_background,
 )
-from synapse.util import logcontext, unwrapFirstError, Clock
-
-from contextlib import contextmanager
-
-import logging
-
-from six.moves import range
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 900575eb..7b065b19 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from prometheus_client.core import Gauge, REGISTRY, GaugeMetricFamily
-
 import os
 
-from six.moves import intern
 import six
+from six.moves import intern
+
+from prometheus_client.core import REGISTRY, Gauge, GaugeMetricFamily
 
 CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.5))
 
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 65a1042d..f8a07df6 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -13,10 +13,19 @@
 # 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.
+import functools
+import inspect
 import logging
+import threading
+from collections import namedtuple
 
+import six
+from six import itervalues, string_types
+
+from twisted.internet import defer
+
+from synapse.util import logcontext, unwrapFirstError
 from synapse.util.async import ObservableDeferred
-from synapse.util import unwrapFirstError, logcontext
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
@@ -24,17 +33,6 @@ from synapse.util.stringutils import to_ascii
 
 from . import register_cache
 
-from twisted.internet import defer
-from collections import namedtuple
-
-import functools
-import inspect
-import threading
-
-from six import string_types, itervalues
-import six
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/util/caches/dictionary_cache.py b/synapse/util/caches/dictionary_cache.py
index 95793d46..6c0b5a40 100644
--- a/synapse/util/caches/dictionary_cache.py
+++ b/synapse/util/caches/dictionary_cache.py
@@ -13,12 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.caches.lrucache import LruCache
-from collections import namedtuple
-from . import register_cache
-import threading
 import logging
+import threading
+from collections import namedtuple
+
+from synapse.util.caches.lrucache import LruCache
 
+from . import register_cache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index ff04c919..4abca91f 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.caches import register_cache
-
-from collections import OrderedDict
 import logging
+from collections import OrderedDict
 
+from synapse.util.caches import register_cache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index 1c5a9820..b684f24e 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -14,8 +14,8 @@
 # limitations under the License.
 
 
-from functools import wraps
 import threading
+from functools import wraps
 
 from synapse.util.caches.treecache import TreeCache
 
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index 0fb86200..f2bde74d 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -13,12 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util import caches
-
+import logging
 
 from sortedcontainers import SortedDict
-import logging
 
+from synapse.util import caches
 
 logger = logging.getLogger(__name__)
 
@@ -75,14 +74,13 @@ class StreamChangeCache(object):
         assert type(stream_pos) is int
 
         if stream_pos >= self._earliest_known_stream_pos:
-            not_known_entities = set(entities) - set(self._entity_to_key)
-
-            result = (
-                {self._cache[k] for k in self._cache.islice(
-                    start=self._cache.bisect_right(stream_pos))}
-                .intersection(entities)
-                .union(not_known_entities)
-            )
+            changed_entities = {
+                self._cache[k] for k in self._cache.islice(
+                    start=self._cache.bisect_right(stream_pos),
+                )
+            }
+
+            result = changed_entities.intersection(entities)
 
             self.metrics.inc_hits()
         else:
diff --git a/synapse/util/file_consumer.py b/synapse/util/file_consumer.py
index c7880101..629ed441 100644
--- a/synapse/util/file_consumer.py
+++ b/synapse/util/file_consumer.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from six.moves import queue
+
 from twisted.internet import threads
 
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 
-from six.moves import queue
-
 
 class BackgroundFileConsumer(object):
     """A consumer that writes to a file like object. Supports both push
diff --git a/synapse/util/frozenutils.py b/synapse/util/frozenutils.py
index 535e7d0e..581c6052 100644
--- a/synapse/util/frozenutils.py
+++ b/synapse/util/frozenutils.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from frozendict import frozendict
-from canonicaljson import json
-
 from six import string_types
 
+from canonicaljson import json
+from frozendict import frozendict
+
 
 def freeze(o):
     if isinstance(o, dict):
diff --git a/synapse/util/httpresourcetree.py b/synapse/util/httpresourcetree.py
index e9f0f292..2d7ddc1c 100644
--- a/synapse/util/httpresourcetree.py
+++ b/synapse/util/httpresourcetree.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.web.resource import NoResource
-
 import logging
 
+from twisted.web.resource import NoResource
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py
index df2b71b7..f6c7175f 100644
--- a/synapse/util/logcontext.py
+++ b/synapse/util/logcontext.py
@@ -22,10 +22,10 @@ them.
 See doc/log_contexts.rst for details on how this works.
 """
 
-from twisted.internet import defer
-
-import threading
 import logging
+import threading
+
+from twisted.internet import defer
 
 logger = logging.getLogger(__name__)
 
@@ -49,18 +49,107 @@ except Exception:
         return None
 
 
+class ContextResourceUsage(object):
+    """Object for tracking the resources used by a log context
+
+    Attributes:
+        ru_utime (float): user CPU time (in seconds)
+        ru_stime (float): system CPU time (in seconds)
+        db_txn_count (int): number of database transactions done
+        db_sched_duration_sec (float): amount of time spent waiting for a
+            database connection
+        db_txn_duration_sec (float): amount of time spent doing database
+            transactions (excluding scheduling time)
+        evt_db_fetch_count (int): number of events requested from the database
+    """
+
+    __slots__ = [
+        "ru_stime", "ru_utime",
+        "db_txn_count", "db_txn_duration_sec", "db_sched_duration_sec",
+        "evt_db_fetch_count",
+    ]
+
+    def __init__(self, copy_from=None):
+        """Create a new ContextResourceUsage
+
+        Args:
+            copy_from (ContextResourceUsage|None): if not None, an object to
+                copy stats from
+        """
+        if copy_from is None:
+            self.reset()
+        else:
+            self.ru_utime = copy_from.ru_utime
+            self.ru_stime = copy_from.ru_stime
+            self.db_txn_count = copy_from.db_txn_count
+
+            self.db_txn_duration_sec = copy_from.db_txn_duration_sec
+            self.db_sched_duration_sec = copy_from.db_sched_duration_sec
+            self.evt_db_fetch_count = copy_from.evt_db_fetch_count
+
+    def copy(self):
+        return ContextResourceUsage(copy_from=self)
+
+    def reset(self):
+        self.ru_stime = 0.
+        self.ru_utime = 0.
+        self.db_txn_count = 0
+
+        self.db_txn_duration_sec = 0
+        self.db_sched_duration_sec = 0
+        self.evt_db_fetch_count = 0
+
+    def __iadd__(self, other):
+        """Add another ContextResourceUsage's stats to this one's.
+
+        Args:
+            other (ContextResourceUsage): the other resource usage object
+        """
+        self.ru_utime += other.ru_utime
+        self.ru_stime += other.ru_stime
+        self.db_txn_count += other.db_txn_count
+        self.db_txn_duration_sec += other.db_txn_duration_sec
+        self.db_sched_duration_sec += other.db_sched_duration_sec
+        self.evt_db_fetch_count += other.evt_db_fetch_count
+        return self
+
+    def __isub__(self, other):
+        self.ru_utime -= other.ru_utime
+        self.ru_stime -= other.ru_stime
+        self.db_txn_count -= other.db_txn_count
+        self.db_txn_duration_sec -= other.db_txn_duration_sec
+        self.db_sched_duration_sec -= other.db_sched_duration_sec
+        self.evt_db_fetch_count -= other.evt_db_fetch_count
+        return self
+
+    def __add__(self, other):
+        res = ContextResourceUsage(copy_from=self)
+        res += other
+        return res
+
+    def __sub__(self, other):
+        res = ContextResourceUsage(copy_from=self)
+        res -= other
+        return res
+
+
 class LoggingContext(object):
     """Additional context for log formatting. Contexts are scoped within a
     "with" block.
 
+    If a parent is given when creating a new context, then:
+        - logging fields are copied from the parent to the new context on entry
+        - when the new context exits, the cpu usage stats are copied from the
+          child to the parent
+
     Args:
         name (str): Name for the context for debugging.
+        parent_context (LoggingContext|None): The parent of the new context
     """
 
     __slots__ = [
-        "previous_context", "name", "ru_stime", "ru_utime",
-        "db_txn_count", "db_txn_duration_sec", "db_sched_duration_sec",
-        "evt_db_fetch_count",
+        "previous_context", "name", "parent_context",
+        "_resource_usage",
         "usage_start",
         "main_thread", "alive",
         "request", "tag",
@@ -100,21 +189,12 @@ class LoggingContext(object):
 
     sentinel = Sentinel()
 
-    def __init__(self, name=None):
+    def __init__(self, name=None, parent_context=None):
         self.previous_context = LoggingContext.current_context()
         self.name = name
-        self.ru_stime = 0.
-        self.ru_utime = 0.
-        self.db_txn_count = 0
-
-        # sec spent waiting for db txns, excluding scheduling time
-        self.db_txn_duration_sec = 0
-
-        # sec spent waiting for db txns to be scheduled
-        self.db_sched_duration_sec = 0
 
-        # number of events this thread has fetched from the db
-        self.evt_db_fetch_count = 0
+        # track the resources used by this context so far
+        self._resource_usage = ContextResourceUsage()
 
         # If alive has the thread resource usage when the logcontext last
         # became active.
@@ -125,6 +205,8 @@ class LoggingContext(object):
         self.tag = ""
         self.alive = True
 
+        self.parent_context = parent_context
+
     def __str__(self):
         return "%s@%x" % (self.name, id(self))
 
@@ -162,6 +244,10 @@ class LoggingContext(object):
                 self.previous_context, old_context
             )
         self.alive = True
+
+        if self.parent_context is not None:
+            self.parent_context.copy_to(self)
+
         return self
 
     def __exit__(self, type, value, traceback):
@@ -183,6 +269,13 @@ class LoggingContext(object):
         self.previous_context = None
         self.alive = False
 
+        # if we have a parent, pass our CPU usage stats on
+        if self.parent_context is not None:
+            self.parent_context._resource_usage += self._resource_usage
+
+            # reset them in case we get entered again
+            self._resource_usage.reset()
+
     def copy_to(self, record):
         """Copy logging fields from this context to a log record or
         another LoggingContext
@@ -207,39 +300,43 @@ class LoggingContext(object):
             logger.warning("Stopped logcontext %s on different thread", self)
             return
 
-        # When we stop, let's record the resource used since we started
-        if self.usage_start:
-            usage_end = get_thread_resource_usage()
+        # When we stop, let's record the cpu used since we started
+        if not self.usage_start:
+            logger.warning(
+                "Called stop on logcontext %s without calling start", self,
+            )
+            return
+
+        usage_end = get_thread_resource_usage()
 
-            self.ru_utime += usage_end.ru_utime - self.usage_start.ru_utime
-            self.ru_stime += usage_end.ru_stime - self.usage_start.ru_stime
+        self._resource_usage.ru_utime += usage_end.ru_utime - self.usage_start.ru_utime
+        self._resource_usage.ru_stime += usage_end.ru_stime - self.usage_start.ru_stime
 
-            self.usage_start = None
-        else:
-            logger.warning("Called stop on logcontext %s without calling start", self)
+        self.usage_start = None
 
     def get_resource_usage(self):
-        """Get CPU time used by this logcontext so far.
+        """Get resources used by this logcontext so far.
 
         Returns:
-            tuple[float, float]: The user and system CPU usage in seconds
+            ContextResourceUsage: a *copy* of the object tracking resource
+                usage so far
         """
-        ru_utime = self.ru_utime
-        ru_stime = self.ru_stime
+        # we always return a copy, for consistency
+        res = self._resource_usage.copy()
 
         # If we are on the correct thread and we're currently running then we
         # can include resource usage so far.
         is_main_thread = threading.current_thread() is self.main_thread
         if self.alive and self.usage_start and is_main_thread:
             current = get_thread_resource_usage()
-            ru_utime += current.ru_utime - self.usage_start.ru_utime
-            ru_stime += current.ru_stime - self.usage_start.ru_stime
+            res.ru_utime += current.ru_utime - self.usage_start.ru_utime
+            res.ru_stime += current.ru_stime - self.usage_start.ru_stime
 
-        return ru_utime, ru_stime
+        return res
 
     def add_database_transaction(self, duration_sec):
-        self.db_txn_count += 1
-        self.db_txn_duration_sec += duration_sec
+        self._resource_usage.db_txn_count += 1
+        self._resource_usage.db_txn_duration_sec += duration_sec
 
     def add_database_scheduled(self, sched_sec):
         """Record a use of the database pool
@@ -248,7 +345,7 @@ class LoggingContext(object):
             sched_sec (float): number of seconds it took us to get a
                 connection
         """
-        self.db_sched_duration_sec += sched_sec
+        self._resource_usage.db_sched_duration_sec += sched_sec
 
     def record_event_fetch(self, event_count):
         """Record a number of events being fetched from the db
@@ -256,7 +353,7 @@ class LoggingContext(object):
         Args:
             event_count (int): number of events being fetched
         """
-        self.evt_db_fetch_count += event_count
+        self._resource_usage.evt_db_fetch_count += event_count
 
 
 class LoggingContextFilter(logging.Filter):
diff --git a/synapse/util/logformatter.py b/synapse/util/logformatter.py
index 3e42868e..a46bc47c 100644
--- a/synapse/util/logformatter.py
+++ b/synapse/util/logformatter.py
@@ -14,10 +14,11 @@
 # limitations under the License.
 
 
-from six import StringIO
 import logging
 import traceback
 
+from six import StringIO
+
 
 class LogFormatter(logging.Formatter):
     """Log formatter which gives more detail for exceptions
diff --git a/synapse/util/logutils.py b/synapse/util/logutils.py
index 03249c5d..62a00189 100644
--- a/synapse/util/logutils.py
+++ b/synapse/util/logutils.py
@@ -14,13 +14,11 @@
 # limitations under the License.
 
 
-from inspect import getcallargs
-from functools import wraps
-
-import logging
 import inspect
+import logging
 import time
-
+from functools import wraps
+from inspect import getcallargs
 
 _TIME_FUNC_ID = 0
 
diff --git a/synapse/util/manhole.py b/synapse/util/manhole.py
index 97e0f00b..14be3c73 100644
--- a/synapse/util/manhole.py
+++ b/synapse/util/manhole.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.conch.manhole import ColoredManhole
-from twisted.conch.insults import insults
 from twisted.conch import manhole_ssh
-from twisted.cred import checkers, portal
+from twisted.conch.insults import insults
+from twisted.conch.manhole import ColoredManhole
 from twisted.conch.ssh.keys import Key
+from twisted.cred import checkers, portal
 
 PUBLIC_KEY = (
     "ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAGEArzJx8OYOnJmzf4tfBEvLi8DVPrJ3/c9k2I/Az"
diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py
index 1ba7d65c..6ba71078 100644
--- a/synapse/util/metrics.py
+++ b/synapse/util/metrics.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+from functools import wraps
 
 from prometheus_client import Counter
-from synapse.util.logcontext import LoggingContext
 
-from functools import wraps
-import logging
+from twisted.internet import defer
 
+from synapse.util.logcontext import LoggingContext
 
 logger = logging.getLogger(__name__)
 
@@ -60,10 +60,9 @@ def measure_func(name):
 
 class Measure(object):
     __slots__ = [
-        "clock", "name", "start_context", "start", "new_context", "ru_utime",
-        "ru_stime",
-        "db_txn_count", "db_txn_duration_sec", "db_sched_duration_sec",
+        "clock", "name", "start_context", "start",
         "created_context",
+        "start_usage",
     ]
 
     def __init__(self, clock, name):
@@ -81,10 +80,7 @@ class Measure(object):
             self.start_context.__enter__()
             self.created_context = True
 
-        self.ru_utime, self.ru_stime = self.start_context.get_resource_usage()
-        self.db_txn_count = self.start_context.db_txn_count
-        self.db_txn_duration_sec = self.start_context.db_txn_duration_sec
-        self.db_sched_duration_sec = self.start_context.db_sched_duration_sec
+        self.start_usage = self.start_context.get_resource_usage()
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         if isinstance(exc_type, Exception) or not self.start_context:
@@ -108,15 +104,12 @@ class Measure(object):
             logger.warn("Expected context. (%r)", self.name)
             return
 
-        ru_utime, ru_stime = context.get_resource_usage()
-
-        block_ru_utime.labels(self.name).inc(ru_utime - self.ru_utime)
-        block_ru_stime.labels(self.name).inc(ru_stime - self.ru_stime)
-        block_db_txn_count.labels(self.name).inc(context.db_txn_count - self.db_txn_count)
-        block_db_txn_duration.labels(self.name).inc(
-            context.db_txn_duration_sec - self.db_txn_duration_sec)
-        block_db_sched_duration.labels(self.name).inc(
-            context.db_sched_duration_sec - self.db_sched_duration_sec)
+        usage = context.get_resource_usage() - self.start_usage
+        block_ru_utime.labels(self.name).inc(usage.ru_utime)
+        block_ru_stime.labels(self.name).inc(usage.ru_stime)
+        block_db_txn_count.labels(self.name).inc(usage.db_txn_count)
+        block_db_txn_duration.labels(self.name).inc(usage.db_txn_duration_sec)
+        block_db_sched_duration.labels(self.name).inc(usage.db_sched_duration_sec)
 
         if self.created_context:
             self.start_context.__exit__(exc_type, exc_val, exc_tb)
diff --git a/synapse/util/msisdn.py b/synapse/util/msisdn.py
index 607161e7..a6c30e52 100644
--- a/synapse/util/msisdn.py
+++ b/synapse/util/msisdn.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import phonenumbers
+
 from synapse.api.errors import SynapseError
 
 
diff --git a/synapse/util/ratelimitutils.py b/synapse/util/ratelimitutils.py
index c5a45cef..7deb38f2 100644
--- a/synapse/util/ratelimitutils.py
+++ b/synapse/util/ratelimitutils.py
@@ -13,20 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import collections
+import contextlib
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.errors import LimitExceededError
-
 from synapse.util.logcontext import (
-    run_in_background, make_deferred_yieldable,
     PreserveLoggingContext,
+    make_deferred_yieldable,
+    run_in_background,
 )
 
-import collections
-import contextlib
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
@@ -93,13 +92,22 @@ class _PerHostRatelimiter(object):
 
         self.window_size = window_size
         self.sleep_limit = sleep_limit
-        self.sleep_msec = sleep_msec
+        self.sleep_sec = sleep_msec / 1000.0
         self.reject_limit = reject_limit
         self.concurrent_requests = concurrent_requests
 
+        # request_id objects for requests which have been slept
         self.sleeping_requests = set()
+
+        # map from request_id object to Deferred for requests which are ready
+        # for processing but have been queued
         self.ready_request_queue = collections.OrderedDict()
+
+        # request id objects for requests which are in progress
         self.current_processing = set()
+
+        # times at which we have recently (within the last window_size ms)
+        # received requests.
         self.request_times = []
 
     @contextlib.contextmanager
@@ -118,11 +126,15 @@ class _PerHostRatelimiter(object):
 
     def _on_enter(self, request_id):
         time_now = self.clock.time_msec()
+
+        # remove any entries from request_times which aren't within the window
         self.request_times[:] = [
             r for r in self.request_times
             if time_now - r < self.window_size
         ]
 
+        # reject the request if we already have too many queued up (either
+        # sleeping or in the ready queue).
         queue_size = len(self.ready_request_queue) + len(self.sleeping_requests)
         if queue_size > self.reject_limit:
             raise LimitExceededError(
@@ -135,9 +147,13 @@ class _PerHostRatelimiter(object):
 
         def queue_request():
             if len(self.current_processing) > self.concurrent_requests:
-                logger.debug("Ratelimit [%s]: Queue req", id(request_id))
                 queue_defer = defer.Deferred()
                 self.ready_request_queue[request_id] = queue_defer
+                logger.info(
+                    "Ratelimiter: queueing request (queue now %i items)",
+                    len(self.ready_request_queue),
+                )
+
                 return queue_defer
             else:
                 return defer.succeed(None)
@@ -149,10 +165,9 @@ class _PerHostRatelimiter(object):
 
         if len(self.request_times) > self.sleep_limit:
             logger.debug(
-                "Ratelimit [%s]: sleeping req",
-                id(request_id),
+                "Ratelimiter: sleeping request for %f sec", self.sleep_sec,
             )
-            ret_defer = run_in_background(self.clock.sleep, self.sleep_msec / 1000.0)
+            ret_defer = run_in_background(self.clock.sleep, self.sleep_sec)
 
             self.sleeping_requests.add(request_id)
 
@@ -201,11 +216,8 @@ class _PerHostRatelimiter(object):
         )
         self.current_processing.discard(request_id)
         try:
-            request_id, deferred = self.ready_request_queue.popitem()
-
-            # XXX: why do we do the following? the on_start callback above will
-            # do it for us.
-            self.current_processing.add(request_id)
+            # start processing the next item on the queue.
+            _, deferred = self.ready_request_queue.popitem(last=False)
 
             with PreserveLoggingContext():
                 deferred.callback(None)
diff --git a/synapse/util/retryutils.py b/synapse/util/retryutils.py
index 4e93f69d..8a3a06fd 100644
--- a/synapse/util/retryutils.py
+++ b/synapse/util/retryutils.py
@@ -12,14 +12,13 @@
 # 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.
-import synapse.util.logcontext
-from twisted.internet import defer
-
-from synapse.api.errors import CodeMessageException
-
 import logging
 import random
 
+from twisted.internet import defer
+
+import synapse.util.logcontext
+from synapse.api.errors import CodeMessageException
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/rlimit.py b/synapse/util/rlimit.py
index f4a9abf8..6c0f2bb0 100644
--- a/synapse/util/rlimit.py
+++ b/synapse/util/rlimit.py
@@ -13,9 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import resource
 import logging
-
+import resource
 
 logger = logging.getLogger("synapse.app.homeserver")
 
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index b98b9dc6..43d9db67 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -15,6 +15,7 @@
 
 import random
 import string
+
 from six.moves import range
 
 _string_with_symbols = (
diff --git a/synapse/util/versionstring.py b/synapse/util/versionstring.py
index 52086df4..1fbcd411 100644
--- a/synapse/util/versionstring.py
+++ b/synapse/util/versionstring.py
@@ -14,9 +14,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import subprocess
-import os
 import logging
+import os
+import subprocess
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/visibility.py b/synapse/visibility.py
index 65d79cf0..9b97ea2b 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -16,13 +16,14 @@ import itertools
 import logging
 import operator
 
+import six
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.events.utils import prune_event
-from synapse.util.logcontext import (
-    make_deferred_yieldable, preserve_fn,
-)
+from synapse.types import get_domain_from_id
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 
 logger = logging.getLogger(__name__)
 
@@ -227,3 +228,154 @@ def filter_events_for_client(store, user_id, events, is_peeking=False,
 
     # we turn it into a list before returning it.
     defer.returnValue(list(filtered_events))
+
+
+@defer.inlineCallbacks
+def filter_events_for_server(store, server_name, events):
+    # Whatever else we do, we need to check for senders which have requested
+    # erasure of their data.
+    erased_senders = yield store.are_users_erased(
+        e.sender for e in events,
+    )
+
+    def redact_disallowed(event, state):
+        # if the sender has been gdpr17ed, always return a redacted
+        # copy of the event.
+        if erased_senders[event.sender]:
+            logger.info(
+                "Sender of %s has been erased, redacting",
+                event.event_id,
+            )
+            return prune_event(event)
+
+        # state will be None if we decided we didn't need to filter by
+        # room membership.
+        if not state:
+            return event
+
+        history = state.get((EventTypes.RoomHistoryVisibility, ''), None)
+        if history:
+            visibility = history.content.get("history_visibility", "shared")
+            if visibility in ["invited", "joined"]:
+                # We now loop through all state events looking for
+                # membership states for the requesting server to determine
+                # if the server is either in the room or has been invited
+                # into the room.
+                for ev in state.itervalues():
+                    if ev.type != EventTypes.Member:
+                        continue
+                    try:
+                        domain = get_domain_from_id(ev.state_key)
+                    except Exception:
+                        continue
+
+                    if domain != server_name:
+                        continue
+
+                    memtype = ev.membership
+                    if memtype == Membership.JOIN:
+                        return event
+                    elif memtype == Membership.INVITE:
+                        if visibility == "invited":
+                            return event
+                else:
+                    # server has no users in the room: redact
+                    return prune_event(event)
+
+        return event
+
+    # Next lets check to see if all the events have a history visibility
+    # of "shared" or "world_readable". If thats the case then we don't
+    # need to check membership (as we know the server is in the room).
+    event_to_state_ids = yield store.get_state_ids_for_events(
+        frozenset(e.event_id for e in events),
+        types=(
+            (EventTypes.RoomHistoryVisibility, ""),
+        )
+    )
+
+    visibility_ids = set()
+    for sids in event_to_state_ids.itervalues():
+        hist = sids.get((EventTypes.RoomHistoryVisibility, ""))
+        if hist:
+            visibility_ids.add(hist)
+
+    # If we failed to find any history visibility events then the default
+    # is "shared" visiblity.
+    if not visibility_ids:
+        all_open = True
+    else:
+        event_map = yield store.get_events(visibility_ids)
+        all_open = all(
+            e.content.get("history_visibility") in (None, "shared", "world_readable")
+            for e in event_map.itervalues()
+        )
+
+    if all_open:
+        # all the history_visibility state affecting these events is open, so
+        # we don't need to filter by membership state. We *do* need to check
+        # for user erasure, though.
+        if erased_senders:
+            events = [
+                redact_disallowed(e, None)
+                for e in events
+            ]
+
+        defer.returnValue(events)
+
+    # Ok, so we're dealing with events that have non-trivial visibility
+    # rules, so we need to also get the memberships of the room.
+
+    # first, for each event we're wanting to return, get the event_ids
+    # of the history vis and membership state at those events.
+    event_to_state_ids = yield store.get_state_ids_for_events(
+        frozenset(e.event_id for e in events),
+        types=(
+            (EventTypes.RoomHistoryVisibility, ""),
+            (EventTypes.Member, None),
+        )
+    )
+
+    # We only want to pull out member events that correspond to the
+    # server's domain.
+    #
+    # event_to_state_ids contains lots of duplicates, so it turns out to be
+    # cheaper to build a complete set of unique
+    # ((type, state_key), event_id) tuples, and then filter out the ones we
+    # don't want.
+    #
+    state_key_to_event_id_set = {
+        e
+        for key_to_eid in six.itervalues(event_to_state_ids)
+        for e in key_to_eid.items()
+    }
+
+    def include(typ, state_key):
+        if typ != EventTypes.Member:
+            return True
+
+        # we avoid using get_domain_from_id here for efficiency.
+        idx = state_key.find(":")
+        if idx == -1:
+            return False
+        return state_key[idx + 1:] == server_name
+
+    event_map = yield store.get_events([
+        e_id
+        for key, e_id in state_key_to_event_id_set
+        if include(key[0], key[1])
+    ])
+
+    event_to_state = {
+        e_id: {
+            key: event_map[inner_e_id]
+            for key, inner_e_id in key_to_eid.iteritems()
+            if inner_e_id in event_map
+        }
+        for e_id, key_to_eid in event_to_state_ids.iteritems()
+    }
+
+    defer.returnValue([
+        redact_disallowed(e, event_to_state[e.event_id])
+        for e in events
+    ])
author	Richard van der Hoff <richard@matrix.org>	2018-07-19 12:57:39 +0100
committer	Richard van der Hoff <richard@matrix.org>	2018-07-19 12:57:39 +0100
commit	ef2188c1bfd532ddc2e4c1acb533b422afde6c57 (patch)
tree	a9483e827cfabebcbb422c9a6426b53f928f3d31 /synapse
parent	d24e9b285fd8d602c3b12c6ba589da0dd2cddee3 (diff)