diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py
index bf4f1a5949..b14a3d9fca 100644
--- a/synapse/replication/tcp/handler.py
+++ b/synapse/replication/tcp/handler.py
@@ -81,9 +81,6 @@ class ReplicationCommandHandler:
self._instance_id = hs.get_instance_id()
self._instance_name = hs.get_instance_name()
- # Set of streams that we've caught up with.
- self._streams_connected = set() # type: Set[str]
-
self._streams = {
stream.NAME: stream(hs) for stream in STREAMS_MAP.values()
} # type: Dict[str, Stream]
@@ -99,9 +96,13 @@ class ReplicationCommandHandler:
# The factory used to create connections.
self._factory = None # type: Optional[ReconnectingClientFactory]
- # The currently connected connections.
+ # The currently connected connections. (The list of places we need to send
+ # outgoing replication commands to.)
self._connections = [] # type: List[AbstractConnection]
+ # For each connection, the incoming streams that are coming from that connection
+ self._streams_by_connection = {} # type: Dict[AbstractConnection, Set[str]]
+
LaterGauge(
"synapse_replication_tcp_resource_total_connections",
"",
@@ -257,9 +258,11 @@ class ReplicationCommandHandler:
# 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.
+ # make sure that we've processed a POSITION for this stream *on this
+ # connection*. (A POSITION on another connection is no good, as there
+ # is no guarantee that we have seen all the intermediate updates.)
+ sbc = self._streams_by_connection.get(conn)
+ if not sbc or stream_name not in sbc:
# Let's drop the row for now, on the assumption we'll receive a
# `POSITION` soon and we'll catch up correctly then.
logger.debug(
@@ -302,21 +305,25 @@ class ReplicationCommandHandler:
# Ignore POSITION that are just our own echoes
return
- stream = self._streams.get(cmd.stream_name)
+ 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", cmd.stream_name)
+ 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(cmd.stream_name):
+ 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.
- self._streams_connected.discard(cmd.stream_name)
+ 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(cmd.stream_name, [])
+ self._pending_batches.pop(stream_name, [])
# Find where we previously streamed up to.
current_token = stream.current_token()
@@ -326,6 +333,12 @@ class ReplicationCommandHandler:
# 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,
@@ -341,16 +354,18 @@ class ReplicationCommandHandler:
for token, rows in _batch_updates(updates):
await self.on_rdata(
- cmd.stream_name,
+ 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.token)
+ await self._replication_data_handler.on_position(stream_name, cmd.token)
- self._streams_connected.add(cmd.stream_name)
+ self._streams_by_connection.setdefault(conn, set()).add(stream_name)
async def on_REMOTE_SERVER_UP(
self, conn: AbstractConnection, cmd: RemoteServerUpCommand
@@ -408,6 +423,12 @@ class ReplicationCommandHandler:
def lost_connection(self, connection: AbstractConnection):
"""Called when a connection is closed/lost.
"""
+ # we no longer need _streams_by_connection for this connection.
+ streams = self._streams_by_connection.pop(connection, None)
+ if streams:
+ logger.info(
+ "Lost replication connection; streams now disconnected: %s", streams
+ )
try:
self._connections.remove(connection)
except ValueError:
diff --git a/synapse/replication/tcp/redis.py b/synapse/replication/tcp/redis.py
index 41c623d737..db69f92557 100644
--- a/synapse/replication/tcp/redis.py
+++ b/synapse/replication/tcp/redis.py
@@ -18,7 +18,7 @@ from typing import TYPE_CHECKING
import txredisapi
-from synapse.logging.context import PreserveLoggingContext
+from synapse.logging.context import make_deferred_yieldable
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.replication.tcp.commands import (
Command,
@@ -41,8 +41,14 @@ logger = logging.getLogger(__name__)
class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
"""Connection to redis subscribed to replication stream.
- Parses incoming messages from redis into replication commands, and passes
- them to `ReplicationCommandHandler`
+ This class fulfils two functions:
+
+ (a) it implements the twisted Protocol API, where it handles the SUBSCRIBEd redis
+ connection, parsing *incoming* messages into replication commands, and passing them
+ to `ReplicationCommandHandler`
+
+ (b) it implements the AbstractConnection API, where it sends *outgoing* commands
+ onto outbound_redis_connection.
Due to the vagaries of `txredisapi` we don't want to have a custom
constructor, so instead we expect the defined attributes below to be set
@@ -50,8 +56,8 @@ class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
Attributes:
handler: The command handler to handle incoming commands.
- stream_name: The *redis* stream name to subscribe to (not anything to
- do with Synapse replication streams).
+ stream_name: The *redis* stream name to subscribe to and publish from
+ (not anything to do with Synapse replication streams).
outbound_redis_connection: The connection to redis to use to send
commands.
"""
@@ -61,13 +67,23 @@ class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
outbound_redis_connection = None # type: txredisapi.RedisProtocol
def connectionMade(self):
+ logger.info("Connected to redis")
super().connectionMade()
- logger.info("Connected to redis instance")
- self.subscribe(self.stream_name)
- self.send_command(ReplicateCommand())
-
+ run_as_background_process("subscribe-replication", self._send_subscribe)
self.handler.new_connection(self)
+ async def _send_subscribe(self):
+ # it's important to make sure that we only send the REPLICATE command once we
+ # have successfully subscribed to the stream - otherwise we might miss the
+ # POSITION response sent back by the other end.
+ logger.info("Sending redis SUBSCRIBE for %s", self.stream_name)
+ await make_deferred_yieldable(self.subscribe(self.stream_name))
+ logger.info(
+ "Successfully subscribed to redis stream, sending REPLICATE command"
+ )
+ await self._async_send_command(ReplicateCommand())
+ logger.info("REPLICATE successfully sent")
+
def messageReceived(self, pattern: str, channel: str, message: str):
"""Received a message from redis.
"""
@@ -120,8 +136,8 @@ class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
logger.warning("Unhandled command: %r", cmd)
def connectionLost(self, reason):
+ logger.info("Lost connection to redis")
super().connectionLost(reason)
- logger.info("Lost connection to redis instance")
self.handler.lost_connection(self)
def send_command(self, cmd: Command):
@@ -130,6 +146,10 @@ class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
Args:
cmd (Command)
"""
+ run_as_background_process("send-cmd", self._async_send_command, cmd)
+
+ async def _async_send_command(self, cmd: Command):
+ """Encode a replication command and send it over our outbound connection"""
string = "%s %s" % (cmd.NAME, cmd.to_line())
if "\n" in string:
raise Exception("Unexpected newline in command: %r", string)
@@ -140,15 +160,9 @@ class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
# remote instances.
tcp_outbound_commands_counter.labels(cmd.NAME, "redis").inc()
- async def _send():
- with PreserveLoggingContext():
- # Note that we use the other connection as we can't send
- # commands using the subscription connection.
- await self.outbound_redis_connection.publish(
- self.stream_name, encoded_string
- )
-
- run_as_background_process("send-cmd", _send)
+ await make_deferred_yieldable(
+ self.outbound_redis_connection.publish(self.stream_name, encoded_string)
+ )
class RedisDirectTcpReplicationClientFactory(txredisapi.SubscriberFactory):
|
