Periodically send pings to detect dead Redis connections (#9218)

This is done by creating a custom `RedisFactory` subclass that
periodically pings all connections in its pool.

We also ensure that the `replyTimeout` param is non-null, so that we
timeout waiting for the reply to those pings (and thus triggering a
reconnect).

1 files changed, 6 insertions, 2 deletions

diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py
index 317796d5e0..58d46a5951 100644
--- a/synapse/replication/tcp/handler.py
+++ b/synapse/replication/tcp/handler.py
@@ -15,6 +15,7 @@
 # limitations under the License.
 import logging
 from typing import (
+    TYPE_CHECKING,
     Any,
     Awaitable,
     Dict,
@@ -63,6 +64,9 @@ from synapse.replication.tcp.streams import (
     TypingStream,
 )
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
@@ -88,7 +92,7 @@ class ReplicationCommandHandler:
     back out to connections.
     """
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         self._replication_data_handler = hs.get_replication_data_handler()
         self._presence_handler = hs.get_presence_handler()
         self._store = hs.get_datastore()
@@ -300,7 +304,7 @@ class ReplicationCommandHandler:
 
             # First create the connection for sending commands.
             outbound_redis_connection = lazyConnection(
-                reactor=hs.get_reactor(),
+                hs=hs,
                 host=hs.config.redis_host,
                 port=hs.config.redis_port,
                 password=hs.config.redis.redis_password,