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- # Copyright 2017 Vector Creations Ltd
- # Copyright 2020, 2022 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 (
- TYPE_CHECKING,
- Any,
- Awaitable,
- Dict,
- Iterable,
- Iterator,
- List,
- Optional,
- Set,
- Tuple,
- TypeVar,
- Union,
- )
- from prometheus_client import Counter
- from typing_extensions import Deque
- from twisted.internet.protocol import ReconnectingClientFactory
- from synapse.metrics import LaterGauge
- from synapse.metrics.background_process_metrics import run_as_background_process
- from synapse.replication.tcp.commands import (
- ClearUserSyncsCommand,
- Command,
- FederationAckCommand,
- PositionCommand,
- RdataCommand,
- RemoteServerUpCommand,
- ReplicateCommand,
- UserIpCommand,
- UserSyncCommand,
- )
- from synapse.replication.tcp.context import ClientContextFactory
- from synapse.replication.tcp.protocol import IReplicationConnection
- from synapse.replication.tcp.streams import (
- STREAMS_MAP,
- AccountDataStream,
- BackfillStream,
- CachesStream,
- EventsStream,
- FederationStream,
- PresenceFederationStream,
- PresenceStream,
- ReceiptsStream,
- Stream,
- ToDeviceStream,
- TypingStream,
- )
- if TYPE_CHECKING:
- from synapse.server import HomeServer
- 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", "")
- user_ip_cache_counter = Counter("synapse_replication_tcp_resource_user_ip_cache", "")
- # the type of the entries in _command_queues_by_stream
- _StreamCommandQueue = Deque[
- Tuple[Union[RdataCommand, PositionCommand], IReplicationConnection]
- ]
- class ReplicationCommandHandler:
- """Handles incoming commands from replication as well as sending commands
- back out to connections.
- """
- def __init__(self, hs: "HomeServer"):
- self._replication_data_handler = hs.get_replication_data_handler()
- self._presence_handler = hs.get_presence_handler()
- self._store = hs.get_datastores().main
- self._notifier = hs.get_notifier()
- self._clock = hs.get_clock()
- self._instance_id = hs.get_instance_id()
- self._instance_name = hs.get_instance_name()
- # Additional Redis channel suffixes to subscribe to.
- self._channels_to_subscribe_to: List[str] = []
- self._is_presence_writer = (
- hs.get_instance_name() in hs.config.worker.writers.presence
- )
- self._streams: Dict[str, Stream] = {
- stream.NAME: stream(hs) for stream in STREAMS_MAP.values()
- }
- # List of streams that this instance is the source of
- self._streams_to_replicate: List[Stream] = []
- for stream in self._streams.values():
- if hs.config.redis.redis_enabled and stream.NAME == CachesStream.NAME:
- # All workers can write to the cache invalidation stream when
- # using redis.
- 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.get_instance_name() in hs.config.worker.writers.events:
- self._streams_to_replicate.append(stream)
- continue
- if isinstance(stream, ToDeviceStream):
- # Only add ToDeviceStream as a source on instances in charge of
- # sending to device messages.
- if hs.get_instance_name() in hs.config.worker.writers.to_device:
- self._streams_to_replicate.append(stream)
- continue
- if isinstance(stream, TypingStream):
- # Only add TypingStream as a source on the instance in charge of
- # typing.
- if hs.get_instance_name() in hs.config.worker.writers.typing:
- self._streams_to_replicate.append(stream)
- continue
- if isinstance(stream, AccountDataStream):
- # Only add AccountDataStream and TagAccountDataStream as a source on the
- # instance in charge of account_data persistence.
- if hs.get_instance_name() in hs.config.worker.writers.account_data:
- self._streams_to_replicate.append(stream)
- continue
- if isinstance(stream, ReceiptsStream):
- # Only add ReceiptsStream as a source on the instance in charge of
- # receipts.
- if hs.get_instance_name() in hs.config.worker.writers.receipts:
- self._streams_to_replicate.append(stream)
- continue
- if isinstance(stream, (PresenceStream, PresenceFederationStream)):
- # Only add PresenceStream as a source on the instance in charge
- # of presence.
- if self._is_presence_writer:
- self._streams_to_replicate.append(stream)
- continue
- # Only add any other streams if we're on master.
- if hs.config.worker.worker_app is not None:
- continue
- if (
- stream.NAME == FederationStream.NAME
- and hs.config.worker.send_federation
- ):
- # We only support federation stream if federation sending
- # has been disabled on the master.
- continue
- self._streams_to_replicate.append(stream)
- # Map of stream name to batched updates. See RdataCommand for info on
- # how batching works.
- self._pending_batches: Dict[str, List[Any]] = {}
- # The factory used to create connections.
- self._factory: Optional[ReconnectingClientFactory] = None
- # The currently connected connections. (The list of places we need to send
- # outgoing replication commands to.)
- self._connections: List[IReplicationConnection] = []
- LaterGauge(
- "synapse_replication_tcp_resource_total_connections",
- "",
- [],
- lambda: len(self._connections),
- )
- # When POSITION or RDATA commands arrive, we stick them in a queue and process
- # them in order in a separate background process.
- # the streams which are currently being processed by _unsafe_process_queue
- self._processing_streams: Set[str] = set()
- # for each stream, a queue of commands that are awaiting processing, and the
- # connection that they arrived on.
- self._command_queues_by_stream = {
- stream_name: _StreamCommandQueue() for stream_name in self._streams
- }
- # For each connection, the incoming stream names that have received a POSITION
- # from that connection.
- self._streams_by_connection: Dict[IReplicationConnection, Set[str]] = {}
- LaterGauge(
- "synapse_replication_tcp_command_queue",
- "Number of inbound RDATA/POSITION commands queued for processing",
- ["stream_name"],
- lambda: {
- (stream_name,): len(queue)
- for stream_name, queue in self._command_queues_by_stream.items()
- },
- )
- self._is_master = hs.config.worker.worker_app is None
- self._federation_sender = None
- if self._is_master and not hs.config.worker.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()
- if hs.config.redis.redis_enabled:
- # If we're using Redis, it's the background worker that should
- # receive USER_IP commands and store the relevant client IPs.
- self._should_insert_client_ips = hs.config.worker.run_background_tasks
- else:
- # If we're NOT using Redis, this must be handled by the master
- self._should_insert_client_ips = hs.get_instance_name() == "master"
- if self._is_master or self._should_insert_client_ips:
- self.subscribe_to_channel("USER_IP")
- def subscribe_to_channel(self, channel_name: str) -> None:
- """
- Indicates that we wish to subscribe to a Redis channel by name.
- (The name will later be prefixed with the server name; i.e. subscribing
- to the 'ABC' channel actually subscribes to 'example.com/ABC' Redis-side.)
- Raises:
- - If replication has already started, then it's too late to subscribe
- to new channels.
- """
- if self._factory is not None:
- # We don't allow subscribing after the fact to avoid the chance
- # of missing an important message because we didn't subscribe in time.
- raise RuntimeError(
- "Cannot subscribe to more channels after replication started."
- )
- if channel_name not in self._channels_to_subscribe_to:
- self._channels_to_subscribe_to.append(channel_name)
- def _add_command_to_stream_queue(
- self, conn: IReplicationConnection, cmd: Union[RdataCommand, PositionCommand]
- ) -> None:
- """Queue the given received command for processing
- Adds the given command to the per-stream queue, and processes the queue if
- necessary
- """
- stream_name = cmd.stream_name
- queue = self._command_queues_by_stream.get(stream_name)
- if queue is None:
- logger.error("Got %s for unknown stream: %s", cmd.NAME, stream_name)
- return
- queue.append((cmd, conn))
- # if we're already processing this stream, there's nothing more to do:
- # the new entry on the queue will get picked up in due course
- if stream_name in self._processing_streams:
- return
- # fire off a background process to start processing the queue.
- run_as_background_process(
- "process-replication-data", self._unsafe_process_queue, stream_name
- )
- async def _unsafe_process_queue(self, stream_name: str) -> None:
- """Processes the command queue for the given stream, until it is empty
- Does not check if there is already a thread processing the queue, hence "unsafe"
- """
- assert stream_name not in self._processing_streams
- self._processing_streams.add(stream_name)
- try:
- queue = self._command_queues_by_stream.get(stream_name)
- while queue:
- cmd, conn = queue.popleft()
- try:
- await self._process_command(cmd, conn, stream_name)
- except Exception:
- logger.exception("Failed to handle command %s", cmd)
- finally:
- self._processing_streams.discard(stream_name)
- async def _process_command(
- self,
- cmd: Union[PositionCommand, RdataCommand],
- conn: IReplicationConnection,
- stream_name: str,
- ) -> None:
- if isinstance(cmd, PositionCommand):
- await self._process_position(stream_name, conn, cmd)
- elif isinstance(cmd, RdataCommand):
- await self._process_rdata(stream_name, conn, cmd)
- else:
- # This shouldn't be possible
- raise Exception("Unrecognised command %s in stream queue", cmd.NAME)
- def start_replication(self, hs: "HomeServer") -> None:
- """Helper method to start replication."""
- from synapse.replication.tcp.redis import RedisDirectTcpReplicationClientFactory
- # 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 = hs.get_outbound_redis_connection()
- # Now create the factory/connection for the subscription stream.
- self._factory = RedisDirectTcpReplicationClientFactory(
- hs,
- outbound_redis_connection,
- channel_names=self._channels_to_subscribe_to,
- )
- reactor = hs.get_reactor()
- redis_config = hs.config.redis
- if hs.config.redis.redis_use_tls:
- ssl_context_factory = ClientContextFactory(hs.config.redis)
- reactor.connectSSL(
- redis_config.redis_host,
- redis_config.redis_port,
- self._factory,
- ssl_context_factory,
- timeout=30,
- bindAddress=None,
- )
- else:
- reactor.connectTCP(
- redis_config.redis_host,
- redis_config.redis_port,
- self._factory,
- timeout=30,
- bindAddress=None,
- )
- 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
- def on_REPLICATE(self, conn: IReplicationConnection, cmd: ReplicateCommand) -> None:
- self.send_positions_to_connection(conn)
- def send_positions_to_connection(self, conn: IReplicationConnection) -> None:
- """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():
- # Note that we use the current token as the prev token here (rather
- # than stream.last_token), as we can't be sure that there have been
- # no rows written between last token and the current token (since we
- # might be racing with the replication sending bg process).
- current_token = stream.current_token(self._instance_name)
- self.send_command(
- PositionCommand(
- stream.NAME,
- self._instance_name,
- current_token,
- current_token,
- )
- )
- def on_USER_SYNC(
- self, conn: IReplicationConnection, cmd: UserSyncCommand
- ) -> Optional[Awaitable[None]]:
- user_sync_counter.inc()
- if self._is_presence_writer:
- return self._presence_handler.update_external_syncs_row(
- cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
- )
- else:
- return None
- def on_CLEAR_USER_SYNC(
- self, conn: IReplicationConnection, cmd: ClearUserSyncsCommand
- ) -> Optional[Awaitable[None]]:
- if self._is_presence_writer:
- return self._presence_handler.update_external_syncs_clear(cmd.instance_id)
- else:
- return None
- def on_FEDERATION_ACK(
- self, conn: IReplicationConnection, cmd: FederationAckCommand
- ) -> None:
- federation_ack_counter.inc()
- if self._federation_sender:
- self._federation_sender.federation_ack(cmd.instance_name, cmd.token)
- def on_USER_IP(
- self, conn: IReplicationConnection, cmd: UserIpCommand
- ) -> Optional[Awaitable[None]]:
- user_ip_cache_counter.inc()
- if self._is_master or self._should_insert_client_ips:
- # We make a point of only returning an awaitable if there's actually
- # something to do; on_USER_IP is not an async function, but
- # _handle_user_ip is.
- # If on_USER_IP returns an awaitable, it gets scheduled as a
- # background process (see `BaseReplicationStreamProtocol.handle_command`).
- return self._handle_user_ip(cmd)
- else:
- # Returning None when this process definitely has nothing to do
- # reduces the overhead of handling the USER_IP command, which is
- # currently broadcast to all workers regardless of utility.
- return None
- async def _handle_user_ip(self, cmd: UserIpCommand) -> None:
- """
- Handles a User IP, branching depending on whether we are the main process
- and/or the background worker.
- """
- if self._is_master:
- assert self._server_notices_sender is not None
- await self._server_notices_sender.on_user_ip(cmd.user_id)
- if self._should_insert_client_ips:
- await self._store.insert_client_ip(
- cmd.user_id,
- cmd.access_token,
- cmd.ip,
- cmd.user_agent,
- cmd.device_id,
- cmd.last_seen,
- )
- def on_RDATA(self, conn: IReplicationConnection, cmd: RdataCommand) -> None:
- 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()
- # We put the received command into a queue 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.
- self._add_command_to_stream_queue(conn, cmd)
- async def _process_rdata(
- self, stream_name: str, conn: IReplicationConnection, cmd: RdataCommand
- ) -> None:
- """Process an RDATA command
- Called after the command has been popped off the queue of inbound commands
- """
- try:
- row = STREAMS_MAP[stream_name].parse_row(cmd.row)
- except Exception as e:
- raise Exception(
- "Failed to parse RDATA: %r %r" % (stream_name, cmd.row)
- ) from e
- # 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)
- return
- # Check if this is the last of a batch of updates
- rows = self._pending_batches.pop(stream_name, [])
- rows.append(row)
- stream = self._streams[stream_name]
- # Find where we previously streamed up to.
- current_token = stream.current_token(cmd.instance_name)
- # Discard this data if this token is earlier than the current
- # position. Note that streams can be reset (in which case you
- # expect an earlier token), but that must be preceded by a
- # POSITION command.
- if cmd.token <= current_token:
- logger.debug(
- "Discarding RDATA from stream %s at position %s before previous position %s",
- stream_name,
- cmd.token,
- current_token,
- )
- else:
- 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
- ) -> None:
- """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
- )
- def on_POSITION(self, conn: IReplicationConnection, cmd: PositionCommand) -> None:
- if cmd.instance_name == self._instance_name:
- # Ignore POSITION that are just our own echoes
- return
- logger.debug("Handling '%s %s'", cmd.NAME, cmd.to_line())
- self._add_command_to_stream_queue(conn, cmd)
- async def _process_position(
- self, stream_name: str, conn: IReplicationConnection, cmd: PositionCommand
- ) -> None:
- """Process a POSITION command
- Called after the command has been popped off the queue of inbound commands
- """
- stream = self._streams[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.prev_token != current_token
- while missing_updates:
- # Note: There may very well not be any new updates, but we check to
- # make sure. This can particularly happen for the event stream where
- # event persisters continuously send `POSITION`. See `resource.py`
- # for why this can happen.
- logger.info(
- "Fetching replication rows for '%s' between %i and %i",
- stream_name,
- current_token,
- cmd.new_token,
- )
- (updates, current_token, missing_updates) = await stream.get_updates_since(
- cmd.instance_name, current_token, cmd.new_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.new_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.new_token
- )
- self._streams_by_connection.setdefault(conn, set()).add(stream_name)
- def on_REMOTE_SERVER_UP(
- self, conn: IReplicationConnection, cmd: RemoteServerUpCommand
- ) -> None:
- """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)
- def new_connection(self, connection: IReplicationConnection) -> None:
- """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: IReplicationConnection) -> None:
- """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) -> None:
- """Send a command to all connected connections.
- Args:
- cmd
- """
- if self._connections:
- for connection in self._connections:
- 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) -> None:
- """Ack data for the federation stream. This allows the master to drop
- data stored purely in memory.
- """
- self.send_command(FederationAckCommand(self._instance_name, token))
- def send_user_sync(
- self, instance_id: str, user_id: str, is_syncing: bool, last_sync_ms: int
- ) -> None:
- """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_user_ip(
- self,
- user_id: str,
- access_token: str,
- ip: str,
- user_agent: str,
- device_id: Optional[str],
- last_seen: int,
- ) -> None:
- """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) -> None:
- self.send_command(RemoteServerUpCommand(server))
- def stream_update(self, stream_name: str, token: Optional[int], data: Any) -> None:
- """Called when a new update is available to stream to Redis subscribers.
- 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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