Faster remote room joins: stream the un-partial-stating of events over replication. [rei:frrj/streams/unpsr] (#14545)

synapse/handlers/federation_event.py

@@ -610,6 +610,8 @@ class FederationEventHandler:
             self._state_storage_controller.notify_event_un_partial_stated(
                 event.event_id
             )
+            # Notify that there's a new row in the un_partial_stated_events stream.
+            self._notifier.notify_replication()
 
     @trace
     async def backfill(