Split presence out of master (#9820)

synapse/replication/tcp/handler.py

@@ -55,6 +55,8 @@ from synapse.replication.tcp.streams import (
     CachesStream,
     EventsStream,
     FederationStream,
+    PresenceFederationStream,
+    PresenceStream,
     ReceiptsStream,
     Stream,
     TagAccountDataStream,
@@ -99,6 +101,10 @@ class ReplicationCommandHandler:
         self._instance_id = hs.get_instance_id()
         self._instance_name = hs.get_instance_name()
 
+        self._is_presence_writer = (
+            hs.get_instance_name() in hs.config.worker.writers.presence
+        )
+
         self._streams = {
             stream.NAME: stream(hs) for stream in STREAMS_MAP.values()
         }  # type: Dict[str, Stream]
@@ -153,6 +159,14 @@ class ReplicationCommandHandler:
 
                 continue
 
+            if isinstance(stream, (PresenceStream, PresenceFederationStream)):
+                # Only add PresenceStream as a source on the instance in charge
+                # of presence.
+                if self._is_presence_writer:
+                    self._streams_to_replicate.append(stream)
+
+                continue
+
             # Only add any other streams if we're on master.
             if hs.config.worker_app is not None:
                 continue
@@ -350,7 +364,7 @@ class ReplicationCommandHandler:
     ) -> Optional[Awaitable[None]]:
         user_sync_counter.inc()
 
-        if self._is_master:
+        if self._is_presence_writer:
             return self._presence_handler.update_external_syncs_row(
                 cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
             )
@@ -360,7 +374,7 @@ class ReplicationCommandHandler:
     def on_CLEAR_USER_SYNC(
         self, conn: IReplicationConnection, cmd: ClearUserSyncsCommand
     ) -> Optional[Awaitable[None]]:
-        if self._is_master:
+        if self._is_presence_writer:
             return self._presence_handler.update_external_syncs_clear(cmd.instance_id)
         else:
             return None

synapse/replication/tcp/streams/_base.py

@@ -272,15 +272,22 @@ class PresenceStream(Stream):
     NAME = "presence"
     ROW_TYPE = PresenceStreamRow
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         store = hs.get_datastore()
 
-        if hs.config.worker_app is None:
-            # on the master, query the presence handler
+        if hs.get_instance_name() in hs.config.worker.writers.presence:
+            # on the presence writer, query the presence handler
             presence_handler = hs.get_presence_handler()
-            update_function = presence_handler.get_all_presence_updates
+
+            from synapse.handlers.presence import PresenceHandler
+
+            assert isinstance(presence_handler, PresenceHandler)
+
+            update_function = (
+                presence_handler.get_all_presence_updates
+            )  # type: UpdateFunction
         else:
-            # Query master process
+            # Query presence writer process
             update_function = make_http_update_function(hs, self.NAME)
 
         super().__init__(