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01c88a09cd
Instead of proxying through the magic getter of the RootConfig object. This should be more performant (and is more explicit).
262 lines
10 KiB
Python
262 lines
10 KiB
Python
# Copyright 2017 Vector Creations Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""The server side of the replication stream.
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"""
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import logging
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import random
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from prometheus_client import Counter
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from twisted.internet.protocol import Factory
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from synapse.metrics.background_process_metrics import run_as_background_process
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from synapse.replication.tcp.commands import PositionCommand
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from synapse.replication.tcp.protocol import ServerReplicationStreamProtocol
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from synapse.replication.tcp.streams import EventsStream
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from synapse.util.metrics import Measure
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stream_updates_counter = Counter(
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"synapse_replication_tcp_resource_stream_updates", "", ["stream_name"]
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)
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logger = logging.getLogger(__name__)
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class ReplicationStreamProtocolFactory(Factory):
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"""Factory for new replication connections."""
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def __init__(self, hs):
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self.command_handler = hs.get_tcp_replication()
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self.clock = hs.get_clock()
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self.server_name = hs.config.server.server_name
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# If we've created a `ReplicationStreamProtocolFactory` then we're
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# almost certainly registering a replication listener, so let's ensure
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# that we've started a `ReplicationStreamer` instance to actually push
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# data.
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#
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# (This is a bit of a weird place to do this, but the alternatives such
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# as putting this in `HomeServer.setup()`, requires either passing the
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# listener config again or always starting a `ReplicationStreamer`.)
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hs.get_replication_streamer()
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def buildProtocol(self, addr):
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return ServerReplicationStreamProtocol(
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self.server_name, self.clock, self.command_handler
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)
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class ReplicationStreamer:
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"""Handles replication connections.
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This needs to be poked when new replication data may be available. When new
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data is available it will propagate to all connected clients.
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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self.clock = hs.get_clock()
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self.notifier = hs.get_notifier()
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self._instance_name = hs.get_instance_name()
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self._replication_torture_level = hs.config.replication_torture_level
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self.notifier.add_replication_callback(self.on_notifier_poke)
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# Keeps track of whether we are currently checking for updates
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self.is_looping = False
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self.pending_updates = False
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self.command_handler = hs.get_tcp_replication()
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# Set of streams to replicate.
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self.streams = self.command_handler.get_streams_to_replicate()
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# If we have streams then we must have redis enabled or on master
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assert (
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not self.streams
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or hs.config.redis.redis_enabled
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or not hs.config.worker.worker_app
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)
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# If we are replicating an event stream we want to periodically check if
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# we should send updated POSITIONs. We do this as a looping call rather
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# explicitly poking when the position advances (without new data to
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# replicate) to reduce replication traffic (otherwise each writer would
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# likely send a POSITION for each new event received over replication).
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#
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# Note that if the position hasn't advanced then we won't send anything.
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if any(EventsStream.NAME == s.NAME for s in self.streams):
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self.clock.looping_call(self.on_notifier_poke, 1000)
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def on_notifier_poke(self):
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"""Checks if there is actually any new data and sends it to the
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connections if there are.
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This should get called each time new data is available, even if it
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is currently being executed, so that nothing gets missed
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"""
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if not self.command_handler.connected() or not self.streams:
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# Don't bother if nothing is listening. We still need to advance
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# the stream tokens otherwise they'll fall behind forever
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for stream in self.streams:
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stream.discard_updates_and_advance()
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return
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# We check up front to see if anything has actually changed, as we get
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# poked because of changes that happened on other instances.
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if all(
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stream.last_token == stream.current_token(self._instance_name)
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for stream in self.streams
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):
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return
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# If there are updates then we need to set this even if we're already
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# looping, as the loop needs to know that he might need to loop again.
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self.pending_updates = True
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if self.is_looping:
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logger.debug("Notifier poke loop already running")
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return
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run_as_background_process("replication_notifier", self._run_notifier_loop)
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async def _run_notifier_loop(self):
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self.is_looping = True
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try:
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# Keep looping while there have been pokes about potential updates.
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# This protects against the race where a stream we already checked
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# gets an update while we're handling other streams.
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while self.pending_updates:
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self.pending_updates = False
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with Measure(self.clock, "repl.stream.get_updates"):
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all_streams = self.streams
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if self._replication_torture_level is not None:
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# there is no guarantee about ordering between the streams,
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# so let's shuffle them around a bit when we are in torture mode.
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all_streams = list(all_streams)
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random.shuffle(all_streams)
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for stream in all_streams:
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if stream.last_token == stream.current_token(
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self._instance_name
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):
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continue
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if self._replication_torture_level:
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await self.clock.sleep(
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self._replication_torture_level / 1000.0
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)
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last_token = stream.last_token
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logger.debug(
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"Getting stream: %s: %s -> %s",
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stream.NAME,
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stream.last_token,
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stream.current_token(self._instance_name),
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)
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try:
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updates, current_token, limited = await stream.get_updates()
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self.pending_updates |= limited
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except Exception:
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logger.info("Failed to handle stream %s", stream.NAME)
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raise
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logger.debug(
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"Sending %d updates",
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len(updates),
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)
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if updates:
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logger.info(
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"Streaming: %s -> %s", stream.NAME, updates[-1][0]
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)
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stream_updates_counter.labels(stream.NAME).inc(len(updates))
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else:
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# The token has advanced but there is no data to
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# send, so we send a `POSITION` to inform other
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# workers of the updated position.
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if stream.NAME == EventsStream.NAME:
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# XXX: We only do this for the EventStream as it
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# turns out that e.g. account data streams share
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# their "current token" with each other, meaning
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# that it is *not* safe to send a POSITION.
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logger.info(
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"Sending position: %s -> %s",
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stream.NAME,
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current_token,
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)
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self.command_handler.send_command(
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PositionCommand(
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stream.NAME,
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self._instance_name,
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last_token,
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current_token,
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)
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)
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continue
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# Some streams return multiple rows with the same stream IDs,
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# we need to make sure they get sent out in batches. We do
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# this by setting the current token to all but the last of
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# a series of updates with the same token to have a None
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# token. See RdataCommand for more details.
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batched_updates = _batch_updates(updates)
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for token, row in batched_updates:
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try:
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self.command_handler.stream_update(
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stream.NAME, token, row
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)
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except Exception:
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logger.exception("Failed to replicate")
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logger.debug("No more pending updates, breaking poke loop")
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finally:
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self.pending_updates = False
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self.is_looping = False
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def _batch_updates(updates):
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"""Takes a list of updates of form [(token, row)] and sets the token to
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None for all rows where the next row has the same token. This is used to
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implement batching.
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For example:
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[(1, _), (1, _), (2, _), (3, _), (3, _)]
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becomes:
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[(None, _), (1, _), (2, _), (None, _), (3, _)]
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"""
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if not updates:
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return []
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new_updates = []
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for i, update in enumerate(updates[:-1]):
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if update[0] == updates[i + 1][0]:
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new_updates.append((None, update[1]))
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else:
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new_updates.append(update)
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new_updates.append(updates[-1])
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return new_updates
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