diff options
| -rw-r--r-- | changelog.d/8499.misc | 1 | ||||
| -rw-r--r-- | docs/tcp_replication.md | 13 | ||||
| -rw-r--r-- | synapse/replication/tcp/client.py | 4 | ||||
| -rw-r--r-- | synapse/replication/tcp/commands.py | 36 | ||||
| -rw-r--r-- | synapse/replication/tcp/handler.py | 24 | ||||
| -rw-r--r-- | synapse/replication/tcp/resource.py | 47 | ||||
| -rw-r--r-- | synapse/storage/util/id_generators.py | 10 | ||||
| -rw-r--r-- | synapse/storage/util/sequence.py | 2 | ||||
| -rw-r--r-- | tests/storage/test_id_generators.py | 25 |
9 files changed, 128 insertions, 34 deletions
diff --git a/changelog.d/8499.misc b/changelog.d/8499.misc new file mode 100644 index 0000000000..237cb3b311 --- /dev/null +++ b/changelog.d/8499.misc @@ -0,0 +1 @@ +Allow events to be sent to clients sooner when using sharded event persisters. diff --git a/docs/tcp_replication.md b/docs/tcp_replication.md index db318baa9d..ad145439b4 100644 --- a/docs/tcp_replication.md +++ b/docs/tcp_replication.md @@ -15,7 +15,7 @@ example flow would be (where '>' indicates master to worker and > SERVER example.com < REPLICATE - > POSITION events master 53 + > POSITION events master 53 53 > RDATA events master 54 ["$foo1:bar.com", ...] > RDATA events master 55 ["$foo4:bar.com", ...] @@ -138,9 +138,9 @@ the wire: < NAME synapse.app.appservice < PING 1490197665618 < REPLICATE - > POSITION events master 1 - > POSITION backfill master 1 - > POSITION caches master 1 + > POSITION events master 1 1 + > POSITION backfill master 1 1 + > POSITION caches master 1 1 > RDATA caches master 2 ["get_user_by_id",["@01register-user:localhost:8823"],1490197670513] > RDATA events master 14 ["$149019767112vOHxz:localhost:8823", "!AFDCvgApUmpdfVjIXm:localhost:8823","m.room.guest_access","",null] @@ -185,6 +185,11 @@ client (C): updates via HTTP API, rather than via the DB, then processes should make the request to the appropriate process. + Two positions are included, the "new" position and the last position sent respectively. + This allows servers to tell instances that the positions have advanced but no + data has been written, without clients needlessly checking to see if they + have missed any updates. + #### ERROR (S, C) There was an error diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py index e165429cad..e27ee216f0 100644 --- a/synapse/replication/tcp/client.py +++ b/synapse/replication/tcp/client.py @@ -191,6 +191,10 @@ class ReplicationDataHandler: async def on_position(self, stream_name: str, instance_name: str, token: int): self.store.process_replication_rows(stream_name, instance_name, token, []) + # We poke the generic "replication" notifier to wake anything up that + # may be streaming. + self.notifier.notify_replication() + def on_remote_server_up(self, server: str): """Called when get a new REMOTE_SERVER_UP command.""" diff --git a/synapse/replication/tcp/commands.py b/synapse/replication/tcp/commands.py index 8cd47770c1..ac532ed588 100644 --- a/synapse/replication/tcp/commands.py +++ b/synapse/replication/tcp/commands.py @@ -141,15 +141,23 @@ class RdataCommand(Command): class PositionCommand(Command): - """Sent by the server to tell the client the stream position without - needing to send an RDATA. + """Sent by an instance to tell others the stream position without needing to + send an RDATA. + + Two tokens are sent, the new position and the last position sent by the + instance (in an RDATA or other POSITION). The tokens are chosen so that *no* + rows were written by the instance between the `prev_token` and `new_token`. + (If an instance hasn't sent a position before then the new position can be + used for both.) Format:: - POSITION <stream_name> <instance_name> <token> + POSITION <stream_name> <instance_name> <prev_token> <new_token> - On receipt of a POSITION command clients should check if they have missed - any updates, and if so then fetch them out of band. + On receipt of a POSITION command instances should check if they have missed + any updates, and if so then fetch them out of band. Instances can check this + by comparing their view of the current token for the sending instance with + the included `prev_token`. The `<instance_name>` is the process that sent the command and is the source of the stream. @@ -157,18 +165,26 @@ class PositionCommand(Command): NAME = "POSITION" - def __init__(self, stream_name, instance_name, token): + def __init__(self, stream_name, instance_name, prev_token, new_token): self.stream_name = stream_name self.instance_name = instance_name - self.token = token + self.prev_token = prev_token + self.new_token = new_token @classmethod def from_line(cls, line): - stream_name, instance_name, token = line.split(" ", 2) - return cls(stream_name, instance_name, int(token)) + stream_name, instance_name, prev_token, new_token = line.split(" ", 3) + return cls(stream_name, instance_name, int(prev_token), int(new_token)) def to_line(self): - return " ".join((self.stream_name, self.instance_name, str(self.token))) + return " ".join( + ( + self.stream_name, + self.instance_name, + str(self.prev_token), + str(self.new_token), + ) + ) class ErrorCommand(_SimpleCommand): diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py index e92da7b263..95e5502bf2 100644 --- a/synapse/replication/tcp/handler.py +++ b/synapse/replication/tcp/handler.py @@ -101,8 +101,9 @@ class ReplicationCommandHandler: 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. + 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 @@ -313,11 +314,14 @@ class ReplicationCommandHandler: # 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, - stream.current_token(self._instance_name), + stream.NAME, self._instance_name, current_token, current_token, ) ) @@ -511,16 +515,16 @@ class ReplicationCommandHandler: # 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 + missing_updates = cmd.prev_token != current_token while missing_updates: logger.info( "Fetching replication rows for '%s' between %i and %i", stream_name, current_token, - cmd.token, + cmd.new_token, ) (updates, current_token, missing_updates) = await stream.get_updates_since( - cmd.instance_name, current_token, cmd.token + cmd.instance_name, current_token, cmd.new_token ) # TODO: add some tests for this @@ -536,11 +540,11 @@ class ReplicationCommandHandler: [stream.parse_row(row) for row in rows], ) - logger.info("Caught up with stream '%s' to %i", stream_name, cmd.token) + 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.token + cmd.stream_name, cmd.instance_name, cmd.new_token ) self._streams_by_connection.setdefault(conn, set()).add(stream_name) diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py index 687984e7a8..666c13fdb7 100644 --- a/synapse/replication/tcp/resource.py +++ b/synapse/replication/tcp/resource.py @@ -23,7 +23,9 @@ from prometheus_client import Counter from twisted.internet.protocol import Factory from synapse.metrics.background_process_metrics import run_as_background_process +from synapse.replication.tcp.commands import PositionCommand from synapse.replication.tcp.protocol import ServerReplicationStreamProtocol +from synapse.replication.tcp.streams import EventsStream from synapse.util.metrics import Measure stream_updates_counter = Counter( @@ -84,6 +86,23 @@ class ReplicationStreamer: # Set of streams to replicate. self.streams = self.command_handler.get_streams_to_replicate() + # If we have streams then we must have redis enabled or on master + assert ( + not self.streams + or hs.config.redis.redis_enabled + or not hs.config.worker.worker_app + ) + + # If we are replicating an event stream we want to periodically check if + # we should send updated POSITIONs. We do this as a looping call rather + # explicitly poking when the position advances (without new data to + # replicate) to reduce replication traffic (otherwise each writer would + # likely send a POSITION for each new event received over replication). + # + # Note that if the position hasn't advanced then we won't send anything. + if any(EventsStream.NAME == s.NAME for s in self.streams): + self.clock.looping_call(self.on_notifier_poke, 1000) + def on_notifier_poke(self): """Checks if there is actually any new data and sends it to the connections if there are. @@ -91,7 +110,7 @@ class ReplicationStreamer: This should get called each time new data is available, even if it is currently being executed, so that nothing gets missed """ - if not self.command_handler.connected(): + if not self.command_handler.connected() or not self.streams: # Don't bother if nothing is listening. We still need to advance # the stream tokens otherwise they'll fall behind forever for stream in self.streams: @@ -136,6 +155,8 @@ class ReplicationStreamer: self._replication_torture_level / 1000.0 ) + last_token = stream.last_token + logger.debug( "Getting stream: %s: %s -> %s", stream.NAME, @@ -159,6 +180,30 @@ class ReplicationStreamer: ) stream_updates_counter.labels(stream.NAME).inc(len(updates)) + else: + # The token has advanced but there is no data to + # send, so we send a `POSITION` to inform other + # workers of the updated position. + if stream.NAME == EventsStream.NAME: + # XXX: We only do this for the EventStream as it + # turns out that e.g. account data streams share + # their "current token" with each other, meaning + # that it is *not* safe to send a POSITION. + logger.info( + "Sending position: %s -> %s", + stream.NAME, + current_token, + ) + self.command_handler.send_command( + PositionCommand( + stream.NAME, + self._instance_name, + last_token, + current_token, + ) + ) + continue + # Some streams return multiple rows with the same stream IDs, # we need to make sure they get sent out in batches. We do # this by setting the current token to all but the last of diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py index d7e40aaa8b..3d8da48f2d 100644 --- a/synapse/storage/util/id_generators.py +++ b/synapse/storage/util/id_generators.py @@ -524,6 +524,16 @@ class MultiWriterIdGenerator: heapq.heappush(self._known_persisted_positions, new_id) + # If we're a writer and we don't have any active writes we update our + # current position to the latest position seen. This allows the instance + # to report a recent position when asked, rather than a potentially old + # one (if this instance hasn't written anything for a while). + our_current_position = self._current_positions.get(self._instance_name) + if our_current_position and not self._unfinished_ids: + self._current_positions[self._instance_name] = max( + our_current_position, new_id + ) + # We move the current min position up if the minimum current positions # of all instances is higher (since by definition all positions less # that that have been persisted). diff --git a/synapse/storage/util/sequence.py b/synapse/storage/util/sequence.py index ff2d038ad2..4386b6101e 100644 --- a/synapse/storage/util/sequence.py +++ b/synapse/storage/util/sequence.py @@ -126,6 +126,8 @@ class PostgresSequenceGenerator(SequenceGenerator): if max_stream_id > last_value: logger.warning( "Postgres sequence %s is behind table %s: %d < %d", + self._sequence_name, + table, last_value, max_stream_id, ) diff --git a/tests/storage/test_id_generators.py b/tests/storage/test_id_generators.py index 392b08832b..cc0612cf65 100644 --- a/tests/storage/test_id_generators.py +++ b/tests/storage/test_id_generators.py @@ -199,10 +199,17 @@ class MultiWriterIdGeneratorTestCase(HomeserverTestCase): first_id_gen = self._create_id_generator("first", writers=["first", "second"]) second_id_gen = self._create_id_generator("second", writers=["first", "second"]) - self.assertEqual(first_id_gen.get_positions(), {"first": 3, "second": 7}) - self.assertEqual(first_id_gen.get_current_token_for_writer("first"), 3) + # The first ID gen will notice that it can advance its token to 7 as it + # has no in progress writes... + self.assertEqual(first_id_gen.get_positions(), {"first": 7, "second": 7}) + self.assertEqual(first_id_gen.get_current_token_for_writer("first"), 7) self.assertEqual(first_id_gen.get_current_token_for_writer("second"), 7) + # ... but the second ID gen doesn't know that. + self.assertEqual(second_id_gen.get_positions(), {"first": 3, "second": 7}) + self.assertEqual(second_id_gen.get_current_token_for_writer("first"), 3) + self.assertEqual(second_id_gen.get_current_token_for_writer("second"), 7) + # Try allocating a new ID gen and check that we only see position # advanced after we leave the context manager. @@ -211,7 +218,7 @@ class MultiWriterIdGeneratorTestCase(HomeserverTestCase): self.assertEqual(stream_id, 8) self.assertEqual( - first_id_gen.get_positions(), {"first": 3, "second": 7} + first_id_gen.get_positions(), {"first": 7, "second": 7} ) self.get_success(_get_next_async()) @@ -279,7 +286,7 @@ class MultiWriterIdGeneratorTestCase(HomeserverTestCase): self._insert_row_with_id("first", 3) self._insert_row_with_id("second", 5) - id_gen = self._create_id_generator("first", writers=["first", "second"]) + id_gen = self._create_id_generator("worker", writers=["first", "second"]) self.assertEqual(id_gen.get_positions(), {"first": 3, "second": 5}) @@ -319,14 +326,14 @@ class MultiWriterIdGeneratorTestCase(HomeserverTestCase): id_gen = self._create_id_generator("first", writers=["first", "second"]) - self.assertEqual(id_gen.get_positions(), {"first": 3, "second": 5}) + self.assertEqual(id_gen.get_positions(), {"first": 5, "second": 5}) - self.assertEqual(id_gen.get_persisted_upto_position(), 3) + self.assertEqual(id_gen.get_persisted_upto_position(), 5) async def _get_next_async(): async with id_gen.get_next() as stream_id: self.assertEqual(stream_id, 6) - self.assertEqual(id_gen.get_persisted_upto_position(), 3) + self.assertEqual(id_gen.get_persisted_upto_position(), 5) self.get_success(_get_next_async()) @@ -388,7 +395,7 @@ class MultiWriterIdGeneratorTestCase(HomeserverTestCase): self._insert_row_with_id("second", 5) # Initial config has two writers - id_gen = self._create_id_generator("first", writers=["first", "second"]) + id_gen = self._create_id_generator("worker", writers=["first", "second"]) self.assertEqual(id_gen.get_persisted_upto_position(), 3) self.assertEqual(id_gen.get_current_token_for_writer("first"), 3) self.assertEqual(id_gen.get_current_token_for_writer("second"), 5) @@ -568,7 +575,7 @@ class BackwardsMultiWriterIdGeneratorTestCase(HomeserverTestCase): self.get_success(_get_next_async2()) - self.assertEqual(id_gen_1.get_positions(), {"first": -1, "second": -2}) + self.assertEqual(id_gen_1.get_positions(), {"first": -2, "second": -2}) self.assertEqual(id_gen_2.get_positions(), {"first": -1, "second": -2}) self.assertEqual(id_gen_1.get_persisted_upto_position(), -2) self.assertEqual(id_gen_2.get_persisted_upto_position(), -2) |