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 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)