Fixup synapse.replication to pass mypy checks (#6667)

synapse/replication/tcp/client.py

@@ -16,7 +16,7 @@
 """
 
 import logging
-from typing import Dict
+from typing import Dict, List, Optional
 
 from twisted.internet import defer
 from twisted.internet.protocol import ReconnectingClientFactory
@@ -28,6 +28,7 @@ from synapse.replication.tcp.protocol import (
 )
 
 from .commands import (
+    Command,
     FederationAckCommand,
     InvalidateCacheCommand,
     RemovePusherCommand,
@@ -89,15 +90,15 @@ class ReplicationClientHandler(AbstractReplicationClientHandler):
 
         # Any pending commands to be sent once a new connection has been
         # established
-        self.pending_commands = []
+        self.pending_commands = []  # type: List[Command]
 
         # Map from string -> deferred, to wake up when receiveing a SYNC with
         # the given string.
         # Used for tests.
-        self.awaiting_syncs = {}
+        self.awaiting_syncs = {}  # type: Dict[str, defer.Deferred]
 
         # The factory used to create connections.
-        self.factory = None
+        self.factory = None  # type: Optional[ReplicationClientFactory]
 
     def start_replication(self, hs):
         """Helper method to start a replication connection to the remote server
@@ -235,4 +236,5 @@ class ReplicationClientHandler(AbstractReplicationClientHandler):
         # We don't reset the delay any earlier as otherwise if there is a
         # problem during start up we'll end up tight looping connecting to the
         # server.
-        self.factory.resetDelay()
+        if self.factory:
+            self.factory.resetDelay()