diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py
new file mode 100644
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--- /dev/null
+++ b/synapse/replication/tcp/handler.py
@@ -0,0 +1,596 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 Vector Creations Ltd
+# Copyright 2020 The Matrix.org Foundation C.I.C.
+#
+# 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 typing import Any, Dict, Iterable, Iterator, List, Optional, Set, Tuple, TypeVar
+
+from prometheus_client import Counter
+
+from twisted.internet.protocol import ReconnectingClientFactory
+
+from synapse.metrics import LaterGauge
+from synapse.replication.tcp.client import DirectTcpReplicationClientFactory
+from synapse.replication.tcp.commands import (
+ ClearUserSyncsCommand,
+ Command,
+ FederationAckCommand,
+ PositionCommand,
+ RdataCommand,
+ RemoteServerUpCommand,
+ RemovePusherCommand,
+ ReplicateCommand,
+ UserIpCommand,
+ UserSyncCommand,
+)
+from synapse.replication.tcp.protocol import AbstractConnection
+from synapse.replication.tcp.streams import (
+ STREAMS_MAP,
+ BackfillStream,
+ CachesStream,
+ EventsStream,
+ FederationStream,
+ Stream,
+)
+from synapse.util.async_helpers import Linearizer
+
+logger = logging.getLogger(__name__)
+
+
+# number of updates received for each RDATA stream
+inbound_rdata_count = Counter(
+ "synapse_replication_tcp_protocol_inbound_rdata_count", "", ["stream_name"]
+)
+user_sync_counter = Counter("synapse_replication_tcp_resource_user_sync", "")
+federation_ack_counter = Counter("synapse_replication_tcp_resource_federation_ack", "")
+remove_pusher_counter = Counter("synapse_replication_tcp_resource_remove_pusher", "")
+invalidate_cache_counter = Counter(
+ "synapse_replication_tcp_resource_invalidate_cache", ""
+)
+user_ip_cache_counter = Counter("synapse_replication_tcp_resource_user_ip_cache", "")
+
+
+class ReplicationCommandHandler:
+ """Handles incoming commands from replication as well as sending commands
+ back out to connections.
+ """
+
+ def __init__(self, hs):
+ self._replication_data_handler = hs.get_replication_data_handler()
+ self._presence_handler = hs.get_presence_handler()
+ self._store = hs.get_datastore()
+ self._notifier = hs.get_notifier()
+ self._clock = hs.get_clock()
+ self._instance_id = hs.get_instance_id()
+ self._instance_name = hs.get_instance_name()
+
+ self._streams = {
+ stream.NAME: stream(hs) for stream in STREAMS_MAP.values()
+ } # type: Dict[str, Stream]
+
+ # List of streams that this instance is the source of
+ self._streams_to_replicate = [] # type: List[Stream]
+
+ for stream in self._streams.values():
+ if stream.NAME == CachesStream.NAME:
+ # All workers can write to the cache invalidation stream.
+ self._streams_to_replicate.append(stream)
+ continue
+
+ if isinstance(stream, (EventsStream, BackfillStream)):
+ # Only add EventStream and BackfillStream as a source on the
+ # instance in charge of event persistence.
+ if hs.config.worker.writers.events == hs.get_instance_name():
+ self._streams_to_replicate.append(stream)
+
+ continue
+
+ # Only add any other streams if we're on master.
+ if hs.config.worker_app is not None:
+ continue
+
+ if stream.NAME == FederationStream.NAME and hs.config.send_federation:
+ # We only support federation stream if federation sending
+ # has been disabled on the master.
+ continue
+
+ self._streams_to_replicate.append(stream)
+
+ self._position_linearizer = Linearizer(
+ "replication_position", clock=self._clock
+ )
+
+ # Map of stream to batched updates. See RdataCommand for info on how
+ # batching works.
+ self._pending_batches = {} # type: Dict[str, List[Any]]
+
+ # The factory used to create connections.
+ self._factory = None # type: Optional[ReconnectingClientFactory]
+
+ # The currently connected connections. (The list of places we need to send
+ # outgoing replication commands to.)
+ self._connections = [] # type: List[AbstractConnection]
+
+ # For each connection, the incoming streams that are coming from that connection
+ self._streams_by_connection = {} # type: Dict[AbstractConnection, Set[str]]
+
+ LaterGauge(
+ "synapse_replication_tcp_resource_total_connections",
+ "",
+ [],
+ lambda: len(self._connections),
+ )
+
+ self._is_master = hs.config.worker_app is None
+
+ self._federation_sender = None
+ if self._is_master and not hs.config.send_federation:
+ self._federation_sender = hs.get_federation_sender()
+
+ self._server_notices_sender = None
+ if self._is_master:
+ self._server_notices_sender = hs.get_server_notices_sender()
+
+ def start_replication(self, hs):
+ """Helper method to start a replication connection to the remote server
+ using TCP.
+ """
+ if hs.config.redis.redis_enabled:
+ from synapse.replication.tcp.redis import (
+ RedisDirectTcpReplicationClientFactory,
+ )
+ import txredisapi
+
+ logger.info(
+ "Connecting to redis (host=%r port=%r)",
+ hs.config.redis_host,
+ hs.config.redis_port,
+ )
+
+ # First let's ensure that we have a ReplicationStreamer started.
+ hs.get_replication_streamer()
+
+ # We need two connections to redis, one for the subscription stream and
+ # one to send commands to (as you can't send further redis commands to a
+ # connection after SUBSCRIBE is called).
+
+ # First create the connection for sending commands.
+ outbound_redis_connection = txredisapi.lazyConnection(
+ host=hs.config.redis_host,
+ port=hs.config.redis_port,
+ password=hs.config.redis.redis_password,
+ reconnect=True,
+ )
+
+ # Now create the factory/connection for the subscription stream.
+ self._factory = RedisDirectTcpReplicationClientFactory(
+ hs, outbound_redis_connection
+ )
+ hs.get_reactor().connectTCP(
+ hs.config.redis.redis_host, hs.config.redis.redis_port, self._factory,
+ )
+ else:
+ client_name = hs.get_instance_name()
+ self._factory = DirectTcpReplicationClientFactory(hs, client_name, self)
+ host = hs.config.worker_replication_host
+ port = hs.config.worker_replication_port
+ hs.get_reactor().connectTCP(host, port, self._factory)
+
+ def get_streams(self) -> Dict[str, Stream]:
+ """Get a map from stream name to all streams.
+ """
+ return self._streams
+
+ def get_streams_to_replicate(self) -> List[Stream]:
+ """Get a list of streams that this instances replicates.
+ """
+ return self._streams_to_replicate
+
+ async def on_REPLICATE(self, conn: AbstractConnection, cmd: ReplicateCommand):
+ self.send_positions_to_connection(conn)
+
+ def send_positions_to_connection(self, conn: AbstractConnection):
+ """Send current position of all streams this process is source of to
+ the connection.
+ """
+
+ # We respond with current position of all streams this instance
+ # replicates.
+ for stream in self.get_streams_to_replicate():
+ self.send_command(
+ PositionCommand(
+ stream.NAME,
+ self._instance_name,
+ stream.current_token(self._instance_name),
+ )
+ )
+
+ async def on_USER_SYNC(self, conn: AbstractConnection, cmd: UserSyncCommand):
+ user_sync_counter.inc()
+
+ if self._is_master:
+ await self._presence_handler.update_external_syncs_row(
+ cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
+ )
+
+ async def on_CLEAR_USER_SYNC(
+ self, conn: AbstractConnection, cmd: ClearUserSyncsCommand
+ ):
+ if self._is_master:
+ await self._presence_handler.update_external_syncs_clear(cmd.instance_id)
+
+ async def on_FEDERATION_ACK(
+ self, conn: AbstractConnection, cmd: FederationAckCommand
+ ):
+ federation_ack_counter.inc()
+
+ if self._federation_sender:
+ self._federation_sender.federation_ack(cmd.token)
+
+ async def on_REMOVE_PUSHER(
+ self, conn: AbstractConnection, cmd: RemovePusherCommand
+ ):
+ remove_pusher_counter.inc()
+
+ if self._is_master:
+ await self._store.delete_pusher_by_app_id_pushkey_user_id(
+ app_id=cmd.app_id, pushkey=cmd.push_key, user_id=cmd.user_id
+ )
+
+ self._notifier.on_new_replication_data()
+
+ async def on_USER_IP(self, conn: AbstractConnection, cmd: UserIpCommand):
+ user_ip_cache_counter.inc()
+
+ if self._is_master:
+ await self._store.insert_client_ip(
+ cmd.user_id,
+ cmd.access_token,
+ cmd.ip,
+ cmd.user_agent,
+ cmd.device_id,
+ cmd.last_seen,
+ )
+
+ if self._server_notices_sender:
+ await self._server_notices_sender.on_user_ip(cmd.user_id)
+
+ async def on_RDATA(self, conn: AbstractConnection, cmd: RdataCommand):
+ if cmd.instance_name == self._instance_name:
+ # Ignore RDATA that are just our own echoes
+ return
+
+ stream_name = cmd.stream_name
+ inbound_rdata_count.labels(stream_name).inc()
+
+ try:
+ row = STREAMS_MAP[stream_name].parse_row(cmd.row)
+ except Exception:
+ logger.exception("Failed to parse RDATA: %r %r", stream_name, cmd.row)
+ raise
+
+ # We linearize here for two reasons:
+ # 1. so we don't try and concurrently handle multiple rows for the
+ # same stream, and
+ # 2. so we don't race with getting a POSITION command and fetching
+ # missing RDATA.
+ with await self._position_linearizer.queue(cmd.stream_name):
+ # make sure that we've processed a POSITION for this stream *on this
+ # connection*. (A POSITION on another connection is no good, as there
+ # is no guarantee that we have seen all the intermediate updates.)
+ sbc = self._streams_by_connection.get(conn)
+ if not sbc or stream_name not in sbc:
+ # Let's drop the row for now, on the assumption we'll receive a
+ # `POSITION` soon and we'll catch up correctly then.
+ logger.debug(
+ "Discarding RDATA for unconnected stream %s -> %s",
+ stream_name,
+ cmd.token,
+ )
+ return
+
+ if cmd.token is None:
+ # I.e. this is part of a batch of updates for this stream (in
+ # which case batch until we get an update for the stream with a non
+ # None token).
+ self._pending_batches.setdefault(stream_name, []).append(row)
+ else:
+ # Check if this is the last of a batch of updates
+ rows = self._pending_batches.pop(stream_name, [])
+ rows.append(row)
+ await self.on_rdata(stream_name, cmd.instance_name, cmd.token, rows)
+
+ async def on_rdata(
+ self, stream_name: str, instance_name: str, token: int, rows: list
+ ):
+ """Called to handle a batch of replication data with a given stream token.
+
+ Args:
+ stream_name: name of the replication stream for this batch of rows
+ instance_name: the instance that wrote the rows.
+ token: stream token for this batch of rows
+ rows: a list of Stream.ROW_TYPE objects as returned by
+ Stream.parse_row.
+ """
+ logger.debug("Received rdata %s (%s) -> %s", stream_name, instance_name, token)
+ await self._replication_data_handler.on_rdata(
+ stream_name, instance_name, token, rows
+ )
+
+ async def on_POSITION(self, conn: AbstractConnection, cmd: PositionCommand):
+ if cmd.instance_name == self._instance_name:
+ # Ignore POSITION that are just our own echoes
+ return
+
+ logger.info("Handling '%s %s'", cmd.NAME, cmd.to_line())
+
+ stream_name = cmd.stream_name
+ stream = self._streams.get(stream_name)
+ if not stream:
+ logger.error("Got POSITION for unknown stream: %s", stream_name)
+ return
+
+ # We protect catching up with a linearizer in case the replication
+ # connection reconnects under us.
+ with await self._position_linearizer.queue(stream_name):
+ # We're about to go and catch up with the stream, so remove from set
+ # of connected streams.
+ for streams in self._streams_by_connection.values():
+ streams.discard(stream_name)
+
+ # We clear the pending batches for the stream as the fetching of the
+ # missing updates below will fetch all rows in the batch.
+ self._pending_batches.pop(stream_name, [])
+
+ # Find where we previously streamed up to.
+ current_token = stream.current_token(cmd.instance_name)
+
+ # If the position token matches our current token then we're up to
+ # date and there's nothing to do. Otherwise, fetch all updates
+ # between then and now.
+ missing_updates = cmd.token != current_token
+ while missing_updates:
+ logger.info(
+ "Fetching replication rows for '%s' between %i and %i",
+ stream_name,
+ current_token,
+ cmd.token,
+ )
+ (
+ updates,
+ current_token,
+ missing_updates,
+ ) = await stream.get_updates_since(
+ cmd.instance_name, current_token, cmd.token
+ )
+
+ # TODO: add some tests for this
+
+ # Some streams return multiple rows with the same stream IDs,
+ # which need to be processed in batches.
+
+ for token, rows in _batch_updates(updates):
+ await self.on_rdata(
+ stream_name,
+ cmd.instance_name,
+ token,
+ [stream.parse_row(row) for row in rows],
+ )
+
+ logger.info("Caught up with stream '%s' to %i", stream_name, cmd.token)
+
+ # We've now caught up to position sent to us, notify handler.
+ await self._replication_data_handler.on_position(
+ cmd.stream_name, cmd.instance_name, cmd.token
+ )
+
+ self._streams_by_connection.setdefault(conn, set()).add(stream_name)
+
+ async def on_REMOTE_SERVER_UP(
+ self, conn: AbstractConnection, cmd: RemoteServerUpCommand
+ ):
+ """"Called when get a new REMOTE_SERVER_UP command."""
+ self._replication_data_handler.on_remote_server_up(cmd.data)
+
+ self._notifier.notify_remote_server_up(cmd.data)
+
+ # We relay to all other connections to ensure every instance gets the
+ # notification.
+ #
+ # When configured to use redis we'll always only have one connection and
+ # so this is a no-op (all instances will have already received the same
+ # REMOTE_SERVER_UP command).
+ #
+ # For direct TCP connections this will relay to all other connections
+ # connected to us. When on master this will correctly fan out to all
+ # other direct TCP clients and on workers there'll only be the one
+ # connection to master.
+ #
+ # (The logic here should also be sound if we have a mix of Redis and
+ # direct TCP connections so long as there is only one traffic route
+ # between two instances, but that is not currently supported).
+ self.send_command(cmd, ignore_conn=conn)
+
+ def new_connection(self, connection: AbstractConnection):
+ """Called when we have a new connection.
+ """
+ self._connections.append(connection)
+
+ # If we are connected to replication as a client (rather than a server)
+ # we need to reset the reconnection delay on the client factory (which
+ # is used to do exponential back off when the connection drops).
+ #
+ # Ideally we would reset the delay when we've "fully established" the
+ # connection (for some definition thereof) to stop us from tightlooping
+ # on reconnection if something fails after this point and we drop the
+ # connection. Unfortunately, we don't really have a better definition of
+ # "fully established" than the connection being established.
+ if self._factory:
+ self._factory.resetDelay()
+
+ # Tell the other end if we have any users currently syncing.
+ currently_syncing = (
+ self._presence_handler.get_currently_syncing_users_for_replication()
+ )
+
+ now = self._clock.time_msec()
+ for user_id in currently_syncing:
+ connection.send_command(
+ UserSyncCommand(self._instance_id, user_id, True, now)
+ )
+
+ def lost_connection(self, connection: AbstractConnection):
+ """Called when a connection is closed/lost.
+ """
+ # we no longer need _streams_by_connection for this connection.
+ streams = self._streams_by_connection.pop(connection, None)
+ if streams:
+ logger.info(
+ "Lost replication connection; streams now disconnected: %s", streams
+ )
+ try:
+ self._connections.remove(connection)
+ except ValueError:
+ pass
+
+ def connected(self) -> bool:
+ """Do we have any replication connections open?
+
+ Is used by e.g. `ReplicationStreamer` to no-op if nothing is connected.
+ """
+ return bool(self._connections)
+
+ def send_command(
+ self, cmd: Command, ignore_conn: Optional[AbstractConnection] = None
+ ):
+ """Send a command to all connected connections.
+
+ Args:
+ cmd
+ ignore_conn: If set don't send command to the given connection.
+ Used when relaying commands from one connection to all others.
+ """
+ if self._connections:
+ for connection in self._connections:
+ if connection == ignore_conn:
+ continue
+
+ try:
+ connection.send_command(cmd)
+ except Exception:
+ # We probably want to catch some types of exceptions here
+ # and log them as warnings (e.g. connection gone), but I
+ # can't find what those exception types they would be.
+ logger.exception(
+ "Failed to write command %s to connection %s",
+ cmd.NAME,
+ connection,
+ )
+ else:
+ logger.warning("Dropping command as not connected: %r", cmd.NAME)
+
+ def send_federation_ack(self, token: int):
+ """Ack data for the federation stream. This allows the master to drop
+ data stored purely in memory.
+ """
+ self.send_command(FederationAckCommand(token))
+
+ def send_user_sync(
+ self, instance_id: str, user_id: str, is_syncing: bool, last_sync_ms: int
+ ):
+ """Poke the master that a user has started/stopped syncing.
+ """
+ self.send_command(
+ UserSyncCommand(instance_id, user_id, is_syncing, last_sync_ms)
+ )
+
+ def send_remove_pusher(self, app_id: str, push_key: str, user_id: str):
+ """Poke the master to remove a pusher for a user
+ """
+ cmd = RemovePusherCommand(app_id, push_key, user_id)
+ self.send_command(cmd)
+
+ def send_user_ip(
+ self,
+ user_id: str,
+ access_token: str,
+ ip: str,
+ user_agent: str,
+ device_id: str,
+ last_seen: int,
+ ):
+ """Tell the master that the user made a request.
+ """
+ cmd = UserIpCommand(user_id, access_token, ip, user_agent, device_id, last_seen)
+ self.send_command(cmd)
+
+ def send_remote_server_up(self, server: str):
+ self.send_command(RemoteServerUpCommand(server))
+
+ def stream_update(self, stream_name: str, token: str, data: Any):
+ """Called when a new update is available to stream to clients.
+
+ We need to check if the client is interested in the stream or not
+ """
+ self.send_command(RdataCommand(stream_name, self._instance_name, token, data))
+
+
+UpdateToken = TypeVar("UpdateToken")
+UpdateRow = TypeVar("UpdateRow")
+
+
+def _batch_updates(
+ updates: Iterable[Tuple[UpdateToken, UpdateRow]]
+) -> Iterator[Tuple[UpdateToken, List[UpdateRow]]]:
+ """Collect stream updates with the same token together
+
+ Given a series of updates returned by Stream.get_updates_since(), collects
+ the updates which share the same stream_id together.
+
+ For example:
+
+ [(1, a), (1, b), (2, c), (3, d), (3, e)]
+
+ becomes:
+
+ [
+ (1, [a, b]),
+ (2, [c]),
+ (3, [d, e]),
+ ]
+ """
+
+ update_iter = iter(updates)
+
+ first_update = next(update_iter, None)
+ if first_update is None:
+ # empty input
+ return
+
+ current_batch_token = first_update[0]
+ current_batch = [first_update[1]]
+
+ for token, row in update_iter:
+ if token != current_batch_token:
+ # different token to the previous row: flush the previous
+ # batch and start anew
+ yield current_batch_token, current_batch
+ current_batch_token = token
+ current_batch = []
+
+ current_batch.append(row)
+
+ # flush the final batch
+ yield current_batch_token, current_batch
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