diff options
Diffstat (limited to 'synapse/replication/tcp/handler.py')
| -rw-r--r-- | synapse/replication/tcp/handler.py | 73 |
1 files changed, 45 insertions, 28 deletions
diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py index 8ec0119697..dd71d1bc34 100644 --- a/synapse/replication/tcp/handler.py +++ b/synapse/replication/tcp/handler.py @@ -189,16 +189,34 @@ class ReplicationCommandHandler: logger.exception("Failed to parse RDATA: %r %r", stream_name, cmd.row) raise - if cmd.token is None or stream_name not in self._streams_connected: - # I.e. either 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) or we're currently connecting so we queue up rows. - 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.token, rows) + # 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): + if stream_name not in self._streams_connected: + # If the stream isn't marked as connected then we haven't seen a + # `POSITION` command yet, and so we may have missed some rows. + # Let's drop the row for now, on the assumption we'll receive a + # `POSITION` soon and we'll catch up correctly then. + logger.warning( + "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.token, rows) async def on_rdata(self, stream_name: str, token: int, rows: list): """Called to handle a batch of replication data with a given stream token. @@ -221,12 +239,13 @@ class ReplicationCommandHandler: # We protect catching up with a linearizer in case the replication # connection reconnects under us. with await self._position_linearizer.queue(cmd.stream_name): - # We're about to go and catch up with the stream, so mark as connecting - # to stop RDATA being handled at the same time by removing stream from - # list of connected streams. We also clear any batched up RDATA from - # before we got the POSITION. + # We're about to go and catch up with the stream, so remove from set + # of connected streams. self._streams_connected.discard(cmd.stream_name) - self._pending_batches.clear() + + # 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(cmd.stream_name, []) # Find where we previously streamed up to. current_token = self._replication_data_handler.get_streams_to_replicate().get( @@ -239,12 +258,17 @@ class ReplicationCommandHandler: ) return - # Fetch all updates between then and now. - limited = True - while limited: - updates, current_token, limited = await stream.get_updates_since( - current_token, cmd.token - ) + # 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: + ( + updates, + current_token, + missing_updates, + ) = await stream.get_updates_since(current_token, cmd.token) + if updates: await self.on_rdata( cmd.stream_name, @@ -255,13 +279,6 @@ class ReplicationCommandHandler: # We've now caught up to position sent to us, notify handler. await self._replication_data_handler.on_position(cmd.stream_name, cmd.token) - # Handle any RDATA that came in while we were catching up. - rows = self._pending_batches.pop(cmd.stream_name, []) - if rows: - await self._replication_data_handler.on_rdata( - cmd.stream_name, rows[-1].token, rows - ) - self._streams_connected.add(cmd.stream_name) async def on_SYNC(self, cmd: SyncCommand): |