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-rw-r--r--synapse/app/federation_sender.py2
-rw-r--r--synapse/appservice/api.py2
-rw-r--r--synapse/config/appservice.py2
-rw-r--r--synapse/config/room_directory.py2
-rw-r--r--synapse/config/server.py6
-rw-r--r--synapse/federation/persistence.py4
-rw-r--r--synapse/federation/sender/__init__.py2
-rw-r--r--synapse/federation/sender/transaction_manager.py4
-rw-r--r--synapse/handlers/directory.py2
-rw-r--r--synapse/handlers/e2e_keys.py19
-rw-r--r--synapse/http/servlet.py2
-rw-r--r--synapse/logging/_structured.py14
-rw-r--r--synapse/logging/_terse_json.py106
-rw-r--r--synapse/push/httppusher.py5
-rw-r--r--synapse/push/mailer.py4
-rw-r--r--synapse/replication/http/__init__.py10
-rw-r--r--synapse/replication/http/devices.py73
-rw-r--r--synapse/replication/tcp/streams/_base.py7
-rw-r--r--synapse/rest/media/v1/preview_url_resource.py2
-rw-r--r--synapse/server_notices/consent_server_notices.py2
-rw-r--r--synapse/storage/_base.py53
-rw-r--r--synapse/storage/data_stores/main/account_data.py6
-rw-r--r--synapse/storage/data_stores/main/deviceinbox.py2
-rw-r--r--synapse/storage/data_stores/main/end_to_end_keys.py6
-rw-r--r--synapse/storage/data_stores/main/events.py8
-rw-r--r--synapse/storage/data_stores/main/filtering.py2
-rw-r--r--synapse/storage/data_stores/main/media_repository.py6
-rw-r--r--synapse/storage/data_stores/main/receipts.py2
-rw-r--r--synapse/storage/data_stores/main/registration.py4
-rw-r--r--synapse/storage/data_stores/main/stream.py2
-rw-r--r--synapse/storage/data_stores/main/tags.py4
-rw-r--r--synapse/storage/prepare_database.py2
-rw-r--r--synapse/streams/config.py9
33 files changed, 279 insertions, 97 deletions
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 139221ad34..448e45e00f 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -69,7 +69,7 @@ class FederationSenderSlaveStore(
         self.federation_out_pos_startup = self._get_federation_out_pos(db_conn)
 
     def _get_federation_out_pos(self, db_conn):
-        sql = "SELECT stream_id FROM federation_stream_position" " WHERE type = ?"
+        sql = "SELECT stream_id FROM federation_stream_position WHERE type = ?"
         sql = self.database_engine.convert_param_style(sql)
 
         txn = db_conn.cursor()
diff --git a/synapse/appservice/api.py b/synapse/appservice/api.py
index 3e25bf5747..57174da021 100644
--- a/synapse/appservice/api.py
+++ b/synapse/appservice/api.py
@@ -185,7 +185,7 @@ class ApplicationServiceApi(SimpleHttpClient):
 
                 if not _is_valid_3pe_metadata(info):
                     logger.warning(
-                        "query_3pe_protocol to %s did not return a" " valid result", uri
+                        "query_3pe_protocol to %s did not return a valid result", uri
                     )
                     return None
 
diff --git a/synapse/config/appservice.py b/synapse/config/appservice.py
index e77d3387ff..ca43e96bd1 100644
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -134,7 +134,7 @@ def _load_appservice(hostname, as_info, config_filename):
             for regex_obj in as_info["namespaces"][ns]:
                 if not isinstance(regex_obj, dict):
                     raise ValueError(
-                        "Expected namespace entry in %s to be an object," " but got %s",
+                        "Expected namespace entry in %s to be an object, but got %s",
                         ns,
                         regex_obj,
                     )
diff --git a/synapse/config/room_directory.py b/synapse/config/room_directory.py
index 7c9f05bde4..7ac7699676 100644
--- a/synapse/config/room_directory.py
+++ b/synapse/config/room_directory.py
@@ -170,7 +170,7 @@ class _RoomDirectoryRule(object):
             self.action = action
         else:
             raise ConfigError(
-                "%s rules can only have action of 'allow'" " or 'deny'" % (option_name,)
+                "%s rules can only have action of 'allow' or 'deny'" % (option_name,)
             )
 
         self._alias_matches_all = alias == "*"
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 00d01c43af..11336d7549 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -223,7 +223,7 @@ class ServerConfig(Config):
             self.federation_ip_range_blacklist.update(["0.0.0.0", "::"])
         except Exception as e:
             raise ConfigError(
-                "Invalid range(s) provided in " "federation_ip_range_blacklist: %s" % e
+                "Invalid range(s) provided in federation_ip_range_blacklist: %s" % e
             )
 
         if self.public_baseurl is not None:
@@ -787,14 +787,14 @@ class ServerConfig(Config):
             "--print-pidfile",
             action="store_true",
             default=None,
-            help="Print the path to the pidfile just" " before daemonizing",
+            help="Print the path to the pidfile just before daemonizing",
         )
         server_group.add_argument(
             "--manhole",
             metavar="PORT",
             dest="manhole",
             type=int,
-            help="Turn on the twisted telnet manhole" " service on the given port.",
+            help="Turn on the twisted telnet manhole service on the given port.",
         )
 
 
diff --git a/synapse/federation/persistence.py b/synapse/federation/persistence.py
index 44edcabed4..d68b4bd670 100644
--- a/synapse/federation/persistence.py
+++ b/synapse/federation/persistence.py
@@ -44,7 +44,7 @@ class TransactionActions(object):
             response code and response body.
         """
         if not transaction.transaction_id:
-            raise RuntimeError("Cannot persist a transaction with no " "transaction_id")
+            raise RuntimeError("Cannot persist a transaction with no transaction_id")
 
         return self.store.get_received_txn_response(transaction.transaction_id, origin)
 
@@ -56,7 +56,7 @@ class TransactionActions(object):
             Deferred
         """
         if not transaction.transaction_id:
-            raise RuntimeError("Cannot persist a transaction with no " "transaction_id")
+            raise RuntimeError("Cannot persist a transaction with no transaction_id")
 
         return self.store.set_received_txn_response(
             transaction.transaction_id, origin, code, response
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index 2b2ee8612a..4ebb0e8bc0 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -49,7 +49,7 @@ sent_pdus_destination_dist_count = Counter(
 
 sent_pdus_destination_dist_total = Counter(
     "synapse_federation_client_sent_pdu_destinations:total",
-    "" "Total number of PDUs queued for sending across all destinations",
+    "Total number of PDUs queued for sending across all destinations",
 )
 
 
diff --git a/synapse/federation/sender/transaction_manager.py b/synapse/federation/sender/transaction_manager.py
index 67b3e1ab6e..5fed626d5b 100644
--- a/synapse/federation/sender/transaction_manager.py
+++ b/synapse/federation/sender/transaction_manager.py
@@ -84,7 +84,7 @@ class TransactionManager(object):
             txn_id = str(self._next_txn_id)
 
             logger.debug(
-                "TX [%s] {%s} Attempting new transaction" " (pdus: %d, edus: %d)",
+                "TX [%s] {%s} Attempting new transaction (pdus: %d, edus: %d)",
                 destination,
                 txn_id,
                 len(pdus),
@@ -103,7 +103,7 @@ class TransactionManager(object):
             self._next_txn_id += 1
 
             logger.info(
-                "TX [%s] {%s} Sending transaction [%s]," " (PDUs: %d, EDUs: %d)",
+                "TX [%s] {%s} Sending transaction [%s], (PDUs: %d, EDUs: %d)",
                 destination,
                 txn_id,
                 transaction.transaction_id,
diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index 69051101a6..a07d2f1a17 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -119,7 +119,7 @@ class DirectoryHandler(BaseHandler):
             if not service.is_interested_in_alias(room_alias.to_string()):
                 raise SynapseError(
                     400,
-                    "This application service has not reserved" " this kind of alias.",
+                    "This application service has not reserved this kind of alias.",
                     errcode=Codes.EXCLUSIVE,
                 )
         else:
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index f09a0b73c8..28c12753c1 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -30,6 +30,7 @@ from twisted.internet import defer
 from synapse.api.errors import CodeMessageException, Codes, NotFoundError, SynapseError
 from synapse.logging.context import make_deferred_yieldable, run_in_background
 from synapse.logging.opentracing import log_kv, set_tag, tag_args, trace
+from synapse.replication.http.devices import ReplicationUserDevicesResyncRestServlet
 from synapse.types import (
     UserID,
     get_domain_from_id,
@@ -53,6 +54,12 @@ class E2eKeysHandler(object):
 
         self._edu_updater = SigningKeyEduUpdater(hs, self)
 
+        self._is_master = hs.config.worker_app is None
+        if not self._is_master:
+            self._user_device_resync_client = ReplicationUserDevicesResyncRestServlet.make_client(
+                hs
+            )
+
         federation_registry = hs.get_federation_registry()
 
         # FIXME: switch to m.signing_key_update when MSC1756 is merged into the spec
@@ -191,9 +198,15 @@ class E2eKeysHandler(object):
                 # probably be tracking their device lists. However, we haven't
                 # done an initial sync on the device list so we do it now.
                 try:
-                    user_devices = yield self.device_handler.device_list_updater.user_device_resync(
-                        user_id
-                    )
+                    if self._is_master:
+                        user_devices = yield self.device_handler.device_list_updater.user_device_resync(
+                            user_id
+                        )
+                    else:
+                        user_devices = yield self._user_device_resync_client(
+                            user_id=user_id
+                        )
+
                     user_devices = user_devices["devices"]
                     for device in user_devices:
                         results[user_id] = {device["device_id"]: device["keys"]}
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index e9a5e46ced..13fcb408a6 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -96,7 +96,7 @@ def parse_boolean_from_args(args, name, default=None, required=False):
             return {b"true": True, b"false": False}[args[name][0]]
         except Exception:
             message = (
-                "Boolean query parameter %r must be one of" " ['true', 'false']"
+                "Boolean query parameter %r must be one of ['true', 'false']"
             ) % (name,)
             raise SynapseError(400, message)
     else:
diff --git a/synapse/logging/_structured.py b/synapse/logging/_structured.py
index 334ddaf39a..ffa7b20ca8 100644
--- a/synapse/logging/_structured.py
+++ b/synapse/logging/_structured.py
@@ -261,6 +261,18 @@ def parse_drain_configs(
             )
 
 
+class StoppableLogPublisher(LogPublisher):
+    """
+    A log publisher that can tell its observers to shut down any external
+    communications.
+    """
+
+    def stop(self):
+        for obs in self._observers:
+            if hasattr(obs, "stop"):
+                obs.stop()
+
+
 def setup_structured_logging(
     hs,
     config,
@@ -336,7 +348,7 @@ def setup_structured_logging(
             # We should never get here, but, just in case, throw an error.
             raise ConfigError("%s drain type cannot be configured" % (observer.type,))
 
-    publisher = LogPublisher(*observers)
+    publisher = StoppableLogPublisher(*observers)
     log_filter = LogLevelFilterPredicate()
 
     for namespace, namespace_config in log_config.get(
diff --git a/synapse/logging/_terse_json.py b/synapse/logging/_terse_json.py
index 76ce7d8808..05fc64f409 100644
--- a/synapse/logging/_terse_json.py
+++ b/synapse/logging/_terse_json.py
@@ -17,25 +17,29 @@
 Log formatters that output terse JSON.
 """
 
+import json
 import sys
+import traceback
 from collections import deque
 from ipaddress import IPv4Address, IPv6Address, ip_address
 from math import floor
-from typing import IO
+from typing import IO, Optional
 
 import attr
-from simplejson import dumps
 from zope.interface import implementer
 
 from twisted.application.internet import ClientService
+from twisted.internet.defer import Deferred
 from twisted.internet.endpoints import (
     HostnameEndpoint,
     TCP4ClientEndpoint,
     TCP6ClientEndpoint,
 )
+from twisted.internet.interfaces import IPushProducer, ITransport
 from twisted.internet.protocol import Factory, Protocol
 from twisted.logger import FileLogObserver, ILogObserver, Logger
-from twisted.python.failure import Failure
+
+_encoder = json.JSONEncoder(ensure_ascii=False, separators=(",", ":"))
 
 
 def flatten_event(event: dict, metadata: dict, include_time: bool = False):
@@ -141,12 +145,50 @@ def TerseJSONToConsoleLogObserver(outFile: IO[str], metadata: dict) -> FileLogOb
 
     def formatEvent(_event: dict) -> str:
         flattened = flatten_event(_event, metadata)
-        return dumps(flattened, ensure_ascii=False, separators=(",", ":")) + "\n"
+        return _encoder.encode(flattened) + "\n"
 
     return FileLogObserver(outFile, formatEvent)
 
 
 @attr.s
+@implementer(IPushProducer)
+class LogProducer(object):
+    """
+    An IPushProducer that writes logs from its buffer to its transport when it
+    is resumed.
+
+    Args:
+        buffer: Log buffer to read logs from.
+        transport: Transport to write to.
+    """
+
+    transport = attr.ib(type=ITransport)
+    _buffer = attr.ib(type=deque)
+    _paused = attr.ib(default=False, type=bool, init=False)
+
+    def pauseProducing(self):
+        self._paused = True
+
+    def stopProducing(self):
+        self._paused = True
+        self._buffer = None
+
+    def resumeProducing(self):
+        self._paused = False
+
+        while self._paused is False and (self._buffer and self.transport.connected):
+            try:
+                event = self._buffer.popleft()
+                self.transport.write(_encoder.encode(event).encode("utf8"))
+                self.transport.write(b"\n")
+            except Exception:
+                # Something has gone wrong writing to the transport -- log it
+                # and break out of the while.
+                traceback.print_exc(file=sys.__stderr__)
+                break
+
+
+@attr.s
 @implementer(ILogObserver)
 class TerseJSONToTCPLogObserver(object):
     """
@@ -165,8 +207,9 @@ class TerseJSONToTCPLogObserver(object):
     metadata = attr.ib(type=dict)
     maximum_buffer = attr.ib(type=int)
     _buffer = attr.ib(default=attr.Factory(deque), type=deque)
-    _writer = attr.ib(default=None)
+    _connection_waiter = attr.ib(default=None, type=Optional[Deferred])
     _logger = attr.ib(default=attr.Factory(Logger))
+    _producer = attr.ib(default=None, type=Optional[LogProducer])
 
     def start(self) -> None:
 
@@ -187,38 +230,43 @@ class TerseJSONToTCPLogObserver(object):
         factory = Factory.forProtocol(Protocol)
         self._service = ClientService(endpoint, factory, clock=self.hs.get_reactor())
         self._service.startService()
+        self._connect()
 
-    def _write_loop(self) -> None:
+    def stop(self):
+        self._service.stopService()
+
+    def _connect(self) -> None:
         """
-        Implement the write loop.
+        Triggers an attempt to connect then write to the remote if not already writing.
         """
-        if self._writer:
+        if self._connection_waiter:
             return
 
-        self._writer = self._service.whenConnected()
+        self._connection_waiter = self._service.whenConnected(failAfterFailures=1)
+
+        @self._connection_waiter.addErrback
+        def fail(r):
+            r.printTraceback(file=sys.__stderr__)
+            self._connection_waiter = None
+            self._connect()
 
-        @self._writer.addBoth
+        @self._connection_waiter.addCallback
         def writer(r):
-            if isinstance(r, Failure):
-                r.printTraceback(file=sys.__stderr__)
-                self._writer = None
-                self.hs.get_reactor().callLater(1, self._write_loop)
+            # We have a connection. If we already have a producer, and its
+            # transport is the same, just trigger a resumeProducing.
+            if self._producer and r.transport is self._producer.transport:
+                self._producer.resumeProducing()
                 return
 
-            try:
-                for event in self._buffer:
-                    r.transport.write(
-                        dumps(event, ensure_ascii=False, separators=(",", ":")).encode(
-                            "utf8"
-                        )
-                    )
-                    r.transport.write(b"\n")
-                self._buffer.clear()
-            except Exception as e:
-                sys.__stderr__.write("Failed writing out logs with %s\n" % (str(e),))
-
-            self._writer = False
-            self.hs.get_reactor().callLater(1, self._write_loop)
+            # If the producer is still producing, stop it.
+            if self._producer:
+                self._producer.stopProducing()
+
+            # Make a new producer and start it.
+            self._producer = LogProducer(buffer=self._buffer, transport=r.transport)
+            r.transport.registerProducer(self._producer, True)
+            self._producer.resumeProducing()
+            self._connection_waiter = None
 
     def _handle_pressure(self) -> None:
         """
@@ -277,4 +325,4 @@ class TerseJSONToTCPLogObserver(object):
             self._logger.failure("Failed clearing backpressure")
 
         # Try and write immediately.
-        self._write_loop()
+        self._connect()
diff --git a/synapse/push/httppusher.py b/synapse/push/httppusher.py
index e994037be6..d0879b0490 100644
--- a/synapse/push/httppusher.py
+++ b/synapse/push/httppusher.py
@@ -246,7 +246,7 @@ class HttpPusher(object):
                     # fixed, we don't suddenly deliver a load
                     # of old notifications.
                     logger.warning(
-                        "Giving up on a notification to user %s, " "pushkey %s",
+                        "Giving up on a notification to user %s, pushkey %s",
                         self.user_id,
                         self.pushkey,
                     )
@@ -299,8 +299,7 @@ class HttpPusher(object):
                     # for sanity, we only remove the pushkey if it
                     # was the one we actually sent...
                     logger.warning(
-                        ("Ignoring rejected pushkey %s because we" " didn't send it"),
-                        pk,
+                        ("Ignoring rejected pushkey %s because we didn't send it"), pk,
                     )
                 else:
                     logger.info("Pushkey %s was rejected: removing", pk)
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index 1d15a06a58..b13b646bfd 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -43,7 +43,7 @@ logger = logging.getLogger(__name__)
 
 
 MESSAGE_FROM_PERSON_IN_ROOM = (
-    "You have a message on %(app)s from %(person)s " "in the %(room)s room..."
+    "You have a message on %(app)s from %(person)s in the %(room)s room..."
 )
 MESSAGE_FROM_PERSON = "You have a message on %(app)s from %(person)s..."
 MESSAGES_FROM_PERSON = "You have messages on %(app)s from %(person)s..."
@@ -55,7 +55,7 @@ MESSAGES_FROM_PERSON_AND_OTHERS = (
     "You have messages on %(app)s from %(person)s and others..."
 )
 INVITE_FROM_PERSON_TO_ROOM = (
-    "%(person)s has invited you to join the " "%(room)s room on %(app)s..."
+    "%(person)s has invited you to join the %(room)s room on %(app)s..."
 )
 INVITE_FROM_PERSON = "%(person)s has invited you to chat on %(app)s..."
 
diff --git a/synapse/replication/http/__init__.py b/synapse/replication/http/__init__.py
index 81b85352b1..28dbc6fcba 100644
--- a/synapse/replication/http/__init__.py
+++ b/synapse/replication/http/__init__.py
@@ -14,7 +14,14 @@
 # limitations under the License.
 
 from synapse.http.server import JsonResource
-from synapse.replication.http import federation, login, membership, register, send_event
+from synapse.replication.http import (
+    devices,
+    federation,
+    login,
+    membership,
+    register,
+    send_event,
+)
 
 REPLICATION_PREFIX = "/_synapse/replication"
 
@@ -30,3 +37,4 @@ class ReplicationRestResource(JsonResource):
         federation.register_servlets(hs, self)
         login.register_servlets(hs, self)
         register.register_servlets(hs, self)
+        devices.register_servlets(hs, self)
diff --git a/synapse/replication/http/devices.py b/synapse/replication/http/devices.py
new file mode 100644
index 0000000000..e32aac0a25
--- /dev/null
+++ b/synapse/replication/http/devices.py
@@ -0,0 +1,73 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from synapse.replication.http._base import ReplicationEndpoint
+
+logger = logging.getLogger(__name__)
+
+
+class ReplicationUserDevicesResyncRestServlet(ReplicationEndpoint):
+    """Ask master to resync the device list for a user by contacting their
+    server.
+
+    This must happen on master so that the results can be correctly cached in
+    the database and streamed to workers.
+
+    Request format:
+
+        POST /_synapse/replication/user_device_resync/:user_id
+
+        {}
+
+    Response is equivalent to ` /_matrix/federation/v1/user/devices/:user_id`
+    response, e.g.:
+
+        {
+            "user_id": "@alice:example.org",
+            "devices": [
+                {
+                    "device_id": "JLAFKJWSCS",
+                    "keys": { ... },
+                    "device_display_name": "Alice's Mobile Phone"
+                }
+            ]
+        }
+    """
+
+    NAME = "user_device_resync"
+    PATH_ARGS = ("user_id",)
+    CACHE = False
+
+    def __init__(self, hs):
+        super(ReplicationUserDevicesResyncRestServlet, self).__init__(hs)
+
+        self.device_list_updater = hs.get_device_handler().device_list_updater
+        self.store = hs.get_datastore()
+        self.clock = hs.get_clock()
+
+    @staticmethod
+    def _serialize_payload(user_id):
+        return {}
+
+    async def _handle_request(self, request, user_id):
+        user_devices = await self.device_list_updater.user_device_resync(user_id)
+
+        return 200, user_devices
+
+
+def register_servlets(hs, http_server):
+    ReplicationUserDevicesResyncRestServlet(hs).register(http_server)
diff --git a/synapse/replication/tcp/streams/_base.py b/synapse/replication/tcp/streams/_base.py
index 9e45429d49..8512923eae 100644
--- a/synapse/replication/tcp/streams/_base.py
+++ b/synapse/replication/tcp/streams/_base.py
@@ -88,8 +88,7 @@ TagAccountDataStreamRow = namedtuple(
     "TagAccountDataStreamRow", ("user_id", "room_id", "data")  # str  # str  # dict
 )
 AccountDataStreamRow = namedtuple(
-    "AccountDataStream",
-    ("user_id", "room_id", "data_type", "data"),  # str  # str  # str  # dict
+    "AccountDataStream", ("user_id", "room_id", "data_type")  # str  # str  # str
 )
 GroupsStreamRow = namedtuple(
     "GroupsStreamRow",
@@ -421,8 +420,8 @@ class AccountDataStream(Stream):
 
         results = list(room_results)
         results.extend(
-            (stream_id, user_id, None, account_data_type, content)
-            for stream_id, user_id, account_data_type, content in global_results
+            (stream_id, user_id, None, account_data_type)
+            for stream_id, user_id, account_data_type in global_results
         )
 
         return results
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index 15c15a12f5..a23d6f5c75 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -122,7 +122,7 @@ class PreviewUrlResource(DirectServeResource):
                 pattern = entry[attrib]
                 value = getattr(url_tuple, attrib)
                 logger.debug(
-                    "Matching attrib '%s' with value '%s' against" " pattern '%s'",
+                    "Matching attrib '%s' with value '%s' against pattern '%s'",
                     attrib,
                     value,
                     pattern,
diff --git a/synapse/server_notices/consent_server_notices.py b/synapse/server_notices/consent_server_notices.py
index 415e9c17d8..5736c56032 100644
--- a/synapse/server_notices/consent_server_notices.py
+++ b/synapse/server_notices/consent_server_notices.py
@@ -54,7 +54,7 @@ class ConsentServerNotices(object):
                 )
             if "body" not in self._server_notice_content:
                 raise ConfigError(
-                    "user_consent server_notice_consent must contain a 'body' " "key."
+                    "user_consent server_notice_consent must contain a 'body' key."
                 )
 
             self._consent_uri_builder = ConsentURIBuilder(hs.config)
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index ab596fa68d..459901ac60 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -409,16 +409,15 @@ class SQLBaseStore(object):
             i = 0
             N = 5
             while True:
+                cursor = LoggingTransaction(
+                    conn.cursor(),
+                    name,
+                    self.database_engine,
+                    after_callbacks,
+                    exception_callbacks,
+                )
                 try:
-                    txn = conn.cursor()
-                    txn = LoggingTransaction(
-                        txn,
-                        name,
-                        self.database_engine,
-                        after_callbacks,
-                        exception_callbacks,
-                    )
-                    r = func(txn, *args, **kwargs)
+                    r = func(cursor, *args, **kwargs)
                     conn.commit()
                     return r
                 except self.database_engine.module.OperationalError as e:
@@ -456,6 +455,40 @@ class SQLBaseStore(object):
                                 )
                             continue
                     raise
+                finally:
+                    # we're either about to retry with a new cursor, or we're about to
+                    # release the connection. Once we release the connection, it could
+                    # get used for another query, which might do a conn.rollback().
+                    #
+                    # In the latter case, even though that probably wouldn't affect the
+                    # results of this transaction, python's sqlite will reset all
+                    # statements on the connection [1], which will make our cursor
+                    # invalid [2].
+                    #
+                    # In any case, continuing to read rows after commit()ing seems
+                    # dubious from the PoV of ACID transactional semantics
+                    # (sqlite explicitly says that once you commit, you may see rows
+                    # from subsequent updates.)
+                    #
+                    # In psycopg2, cursors are essentially a client-side fabrication -
+                    # all the data is transferred to the client side when the statement
+                    # finishes executing - so in theory we could go on streaming results
+                    # from the cursor, but attempting to do so would make us
+                    # incompatible with sqlite, so let's make sure we're not doing that
+                    # by closing the cursor.
+                    #
+                    # (*named* cursors in psycopg2 are different and are proper server-
+                    # side things, but (a) we don't use them and (b) they are implicitly
+                    # closed by ending the transaction anyway.)
+                    #
+                    # In short, if we haven't finished with the cursor yet, that's a
+                    # problem waiting to bite us.
+                    #
+                    # TL;DR: we're done with the cursor, so we can close it.
+                    #
+                    # [1]: https://github.com/python/cpython/blob/v3.8.0/Modules/_sqlite/connection.c#L465
+                    # [2]: https://github.com/python/cpython/blob/v3.8.0/Modules/_sqlite/cursor.c#L236
+                    cursor.close()
         except Exception as e:
             logger.debug("[TXN FAIL] {%s} %s", name, e)
             raise
@@ -851,7 +884,7 @@ class SQLBaseStore(object):
             allvalues.update(values)
             latter = "UPDATE SET " + ", ".join(k + "=EXCLUDED." + k for k in values)
 
-        sql = ("INSERT INTO %s (%s) VALUES (%s) " "ON CONFLICT (%s) DO %s") % (
+        sql = ("INSERT INTO %s (%s) VALUES (%s) ON CONFLICT (%s) DO %s") % (
             table,
             ", ".join(k for k in allvalues),
             ", ".join("?" for _ in allvalues),
diff --git a/synapse/storage/data_stores/main/account_data.py b/synapse/storage/data_stores/main/account_data.py
index 6afbfc0d74..22093484ed 100644
--- a/synapse/storage/data_stores/main/account_data.py
+++ b/synapse/storage/data_stores/main/account_data.py
@@ -184,14 +184,14 @@ class AccountDataWorkerStore(SQLBaseStore):
             current_id(int): The position to fetch up to.
         Returns:
             A deferred pair of lists of tuples of stream_id int, user_id string,
-            room_id string, type string, and content string.
+            room_id string, and type string.
         """
         if last_room_id == current_id and last_global_id == current_id:
             return defer.succeed(([], []))
 
         def get_updated_account_data_txn(txn):
             sql = (
-                "SELECT stream_id, user_id, account_data_type, content"
+                "SELECT stream_id, user_id, account_data_type"
                 " FROM account_data WHERE ? < stream_id AND stream_id <= ?"
                 " ORDER BY stream_id ASC LIMIT ?"
             )
@@ -199,7 +199,7 @@ class AccountDataWorkerStore(SQLBaseStore):
             global_results = txn.fetchall()
 
             sql = (
-                "SELECT stream_id, user_id, room_id, account_data_type, content"
+                "SELECT stream_id, user_id, room_id, account_data_type"
                 " FROM room_account_data WHERE ? < stream_id AND stream_id <= ?"
                 " ORDER BY stream_id ASC LIMIT ?"
             )
diff --git a/synapse/storage/data_stores/main/deviceinbox.py b/synapse/storage/data_stores/main/deviceinbox.py
index 96cd0fb77a..a23744f11c 100644
--- a/synapse/storage/data_stores/main/deviceinbox.py
+++ b/synapse/storage/data_stores/main/deviceinbox.py
@@ -380,7 +380,7 @@ class DeviceInboxStore(DeviceInboxWorkerStore, DeviceInboxBackgroundUpdateStore)
             devices = list(messages_by_device.keys())
             if len(devices) == 1 and devices[0] == "*":
                 # Handle wildcard device_ids.
-                sql = "SELECT device_id FROM devices" " WHERE user_id = ?"
+                sql = "SELECT device_id FROM devices WHERE user_id = ?"
                 txn.execute(sql, (user_id,))
                 message_json = json.dumps(messages_by_device["*"])
                 for row in txn:
diff --git a/synapse/storage/data_stores/main/end_to_end_keys.py b/synapse/storage/data_stores/main/end_to_end_keys.py
index 073412a78d..d8ad59ad93 100644
--- a/synapse/storage/data_stores/main/end_to_end_keys.py
+++ b/synapse/storage/data_stores/main/end_to_end_keys.py
@@ -138,9 +138,9 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
                 result.setdefault(user_id, {})[device_id] = None
 
         # get signatures on the device
-        signature_sql = (
-            "SELECT * " "  FROM e2e_cross_signing_signatures " " WHERE %s"
-        ) % (" OR ".join("(" + q + ")" for q in signature_query_clauses))
+        signature_sql = ("SELECT *  FROM e2e_cross_signing_signatures WHERE %s") % (
+            " OR ".join("(" + q + ")" for q in signature_query_clauses)
+        )
 
         txn.execute(signature_sql, signature_query_params)
         rows = self.cursor_to_dict(txn)
diff --git a/synapse/storage/data_stores/main/events.py b/synapse/storage/data_stores/main/events.py
index 878f7568a6..627c0b67f1 100644
--- a/synapse/storage/data_stores/main/events.py
+++ b/synapse/storage/data_stores/main/events.py
@@ -713,9 +713,7 @@ class EventsStore(
 
                 metadata_json = encode_json(event.internal_metadata.get_dict())
 
-                sql = (
-                    "UPDATE event_json SET internal_metadata = ?" " WHERE event_id = ?"
-                )
+                sql = "UPDATE event_json SET internal_metadata = ? WHERE event_id = ?"
                 txn.execute(sql, (metadata_json, event.event_id))
 
                 # Add an entry to the ex_outlier_stream table to replicate the
@@ -732,7 +730,7 @@ class EventsStore(
                     },
                 )
 
-                sql = "UPDATE events SET outlier = ?" " WHERE event_id = ?"
+                sql = "UPDATE events SET outlier = ? WHERE event_id = ?"
                 txn.execute(sql, (False, event.event_id))
 
                 # Update the event_backward_extremities table now that this
@@ -1479,7 +1477,7 @@ class EventsStore(
 
         # We do joins against events_to_purge for e.g. calculating state
         # groups to purge, etc., so lets make an index.
-        txn.execute("CREATE INDEX events_to_purge_id" " ON events_to_purge(event_id)")
+        txn.execute("CREATE INDEX events_to_purge_id ON events_to_purge(event_id)")
 
         txn.execute("SELECT event_id, should_delete FROM events_to_purge")
         event_rows = txn.fetchall()
diff --git a/synapse/storage/data_stores/main/filtering.py b/synapse/storage/data_stores/main/filtering.py
index a2a2a67927..f05ace299a 100644
--- a/synapse/storage/data_stores/main/filtering.py
+++ b/synapse/storage/data_stores/main/filtering.py
@@ -55,7 +55,7 @@ class FilteringStore(SQLBaseStore):
             if filter_id_response is not None:
                 return filter_id_response[0]
 
-            sql = "SELECT MAX(filter_id) FROM user_filters " "WHERE user_id = ?"
+            sql = "SELECT MAX(filter_id) FROM user_filters WHERE user_id = ?"
             txn.execute(sql, (user_localpart,))
             max_id = txn.fetchone()[0]
             if max_id is None:
diff --git a/synapse/storage/data_stores/main/media_repository.py b/synapse/storage/data_stores/main/media_repository.py
index 84b5f3ad5e..0f2887bdce 100644
--- a/synapse/storage/data_stores/main/media_repository.py
+++ b/synapse/storage/data_stores/main/media_repository.py
@@ -337,7 +337,7 @@ class MediaRepositoryStore(MediaRepositoryBackgroundUpdateStore):
         if len(media_ids) == 0:
             return
 
-        sql = "DELETE FROM local_media_repository_url_cache" " WHERE media_id = ?"
+        sql = "DELETE FROM local_media_repository_url_cache WHERE media_id = ?"
 
         def _delete_url_cache_txn(txn):
             txn.executemany(sql, [(media_id,) for media_id in media_ids])
@@ -365,11 +365,11 @@ class MediaRepositoryStore(MediaRepositoryBackgroundUpdateStore):
             return
 
         def _delete_url_cache_media_txn(txn):
-            sql = "DELETE FROM local_media_repository" " WHERE media_id = ?"
+            sql = "DELETE FROM local_media_repository WHERE media_id = ?"
 
             txn.executemany(sql, [(media_id,) for media_id in media_ids])
 
-            sql = "DELETE FROM local_media_repository_thumbnails" " WHERE media_id = ?"
+            sql = "DELETE FROM local_media_repository_thumbnails WHERE media_id = ?"
 
             txn.executemany(sql, [(media_id,) for media_id in media_ids])
 
diff --git a/synapse/storage/data_stores/main/receipts.py b/synapse/storage/data_stores/main/receipts.py
index 0c24430f28..8b17334ff4 100644
--- a/synapse/storage/data_stores/main/receipts.py
+++ b/synapse/storage/data_stores/main/receipts.py
@@ -280,7 +280,7 @@ class ReceiptsWorkerStore(SQLBaseStore):
                 args.append(limit)
             txn.execute(sql, args)
 
-            return (r[0:5] + (json.loads(r[5]),) for r in txn)
+            return list(r[0:5] + (json.loads(r[5]),) for r in txn)
 
         return self.runInteraction(
             "get_all_updated_receipts", get_all_updated_receipts_txn
diff --git a/synapse/storage/data_stores/main/registration.py b/synapse/storage/data_stores/main/registration.py
index ee1b2b2bbf..6a594c160c 100644
--- a/synapse/storage/data_stores/main/registration.py
+++ b/synapse/storage/data_stores/main/registration.py
@@ -377,9 +377,7 @@ class RegistrationWorkerStore(SQLBaseStore):
         """
 
         def f(txn):
-            sql = (
-                "SELECT name, password_hash FROM users" " WHERE lower(name) = lower(?)"
-            )
+            sql = "SELECT name, password_hash FROM users WHERE lower(name) = lower(?)"
             txn.execute(sql, (user_id,))
             return dict(txn)
 
diff --git a/synapse/storage/data_stores/main/stream.py b/synapse/storage/data_stores/main/stream.py
index 8780fdd989..9ae4a913a1 100644
--- a/synapse/storage/data_stores/main/stream.py
+++ b/synapse/storage/data_stores/main/stream.py
@@ -616,7 +616,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
 
     def _get_max_topological_txn(self, txn, room_id):
         txn.execute(
-            "SELECT MAX(topological_ordering) FROM events" " WHERE room_id = ?",
+            "SELECT MAX(topological_ordering) FROM events WHERE room_id = ?",
             (room_id,),
         )
 
diff --git a/synapse/storage/data_stores/main/tags.py b/synapse/storage/data_stores/main/tags.py
index 10d1887f75..aa24339717 100644
--- a/synapse/storage/data_stores/main/tags.py
+++ b/synapse/storage/data_stores/main/tags.py
@@ -83,9 +83,7 @@ class TagsWorkerStore(AccountDataWorkerStore):
         )
 
         def get_tag_content(txn, tag_ids):
-            sql = (
-                "SELECT tag, content" " FROM room_tags" " WHERE user_id=? AND room_id=?"
-            )
+            sql = "SELECT tag, content FROM room_tags WHERE user_id=? AND room_id=?"
             results = []
             for stream_id, user_id, room_id in tag_ids:
                 txn.execute(sql, (user_id, room_id))
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index 2e7753820e..731e1c9d9c 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -447,7 +447,7 @@ def _apply_module_schema_files(cur, database_engine, modname, names_and_streams)
         # Mark as done.
         cur.execute(
             database_engine.convert_param_style(
-                "INSERT INTO applied_module_schemas (module_name, file)" " VALUES (?,?)"
+                "INSERT INTO applied_module_schemas (module_name, file) VALUES (?,?)"
             ),
             (modname, name),
         )
diff --git a/synapse/streams/config.py b/synapse/streams/config.py
index 02994ab2a5..cd56cd91ed 100644
--- a/synapse/streams/config.py
+++ b/synapse/streams/config.py
@@ -88,9 +88,12 @@ class PaginationConfig(object):
             raise SynapseError(400, "Invalid request.")
 
     def __repr__(self):
-        return (
-            "PaginationConfig(from_tok=%r, to_tok=%r," " direction=%r, limit=%r)"
-        ) % (self.from_token, self.to_token, self.direction, self.limit)
+        return ("PaginationConfig(from_tok=%r, to_tok=%r, direction=%r, limit=%r)") % (
+            self.from_token,
+            self.to_token,
+            self.direction,
+            self.limit,
+        )
 
     def get_source_config(self, source_name):
         keyname = "%s_key" % source_name