Rename get_tcp_replication to get_replication_command_handler. (#12192)

Since the object it returns is a ReplicationCommandHandler.

This is clean-up from adding support to Redis where the command handler
was added as an additional layer of abstraction from the TCP protocol.

synapse/replication/tcp/client.py

@@ -462,6 +462,8 @@ class FederationSenderHandler:
 
                 # We ACK this token over replication so that the master can drop
                 # its in memory queues
-                self._hs.get_tcp_replication().send_federation_ack(current_position)
+                self._hs.get_replication_command_handler().send_federation_ack(
+                    current_position
+                )
         except Exception:
             logger.exception("Error updating federation stream position")

synapse/replication/tcp/handler.py

@@ -295,9 +295,7 @@ class ReplicationCommandHandler:
             raise Exception("Unrecognised command %s in stream queue", cmd.NAME)
 
     def start_replication(self, hs: "HomeServer") -> None:
-        """Helper method to start a replication connection to the remote server
-        using TCP.
-        """
+        """Helper method to start replication."""
         if hs.config.redis.redis_enabled:
             from synapse.replication.tcp.redis import (
                 RedisDirectTcpReplicationClientFactory,

synapse/replication/tcp/redis.py

@@ -325,7 +325,7 @@ class RedisDirectTcpReplicationClientFactory(SynapseRedisFactory):
             password=hs.config.redis.redis_password,
         )
 
-        self.synapse_handler = hs.get_tcp_replication()
+        self.synapse_handler = hs.get_replication_command_handler()
         self.synapse_stream_name = hs.hostname
 
         self.synapse_outbound_redis_connection = outbound_redis_connection

synapse/replication/tcp/resource.py

@@ -44,7 +44,7 @@ class ReplicationStreamProtocolFactory(ServerFactory):
     """Factory for new replication connections."""
 
     def __init__(self, hs: "HomeServer"):
-        self.command_handler = hs.get_tcp_replication()
+        self.command_handler = hs.get_replication_command_handler()
         self.clock = hs.get_clock()
         self.server_name = hs.config.server.server_name
 
@@ -85,7 +85,7 @@ class ReplicationStreamer:
         self.is_looping = False
         self.pending_updates = False
 
-        self.command_handler = hs.get_tcp_replication()
+        self.command_handler = hs.get_replication_command_handler()
 
         # Set of streams to replicate.
         self.streams = self.command_handler.get_streams_to_replicate()