diff --git a/synapse/replication/tcp/commands.py b/synapse/replication/tcp/commands.py
index c04f622816..ea5937a20c 100644
--- a/synapse/replication/tcp/commands.py
+++ b/synapse/replication/tcp/commands.py
@@ -149,7 +149,7 @@ class RdataCommand(Command):
class PositionCommand(Command):
- """Sent by the server to tell the client the stream postition without
+ """Sent by the server to tell the client the stream position without
needing to send an RDATA.
Format::
@@ -188,7 +188,7 @@ class ErrorCommand(_SimpleCommand):
class PingCommand(_SimpleCommand):
- """Sent by either side as a keep alive. The data is arbitary (often timestamp)
+ """Sent by either side as a keep alive. The data is arbitrary (often timestamp)
"""
NAME = "PING"
diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py
index cbcf46f3ae..e6a2e2598b 100644
--- a/synapse/replication/tcp/handler.py
+++ b/synapse/replication/tcp/handler.py
@@ -112,8 +112,8 @@ class ReplicationCommandHandler:
"replication_position", clock=self._clock
)
- # Map of stream to batched updates. See RdataCommand for info on how
- # batching works.
+ # Map of stream name to batched updates. See RdataCommand for info on
+ # how batching works.
self._pending_batches = {} # type: Dict[str, List[Any]]
# The factory used to create connections.
@@ -123,7 +123,8 @@ class ReplicationCommandHandler:
# outgoing replication commands to.)
self._connections = [] # type: List[AbstractConnection]
- # For each connection, the incoming streams that are coming from that connection
+ # For each connection, the incoming stream names that are coming from
+ # that connection.
self._streams_by_connection = {} # type: Dict[AbstractConnection, Set[str]]
LaterGauge(
@@ -310,7 +311,28 @@ class ReplicationCommandHandler:
# 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.instance_name, cmd.token, rows)
+
+ stream = self._streams.get(stream_name)
+ if not stream:
+ logger.error("Got RDATA for unknown stream: %s", stream_name)
+ return
+
+ # 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
|
