Merge branch 'develop' of github.com:matrix-org/synapse into anoa/e2e…

…_as_room_stream_token

synapse/handlers/appservice.py

@@ -238,6 +238,12 @@ async def _notify_interested_services_ephemeral(
         with Measure(self.clock, "notify_interested_services_ephemeral"):
             for service in services:
                 if stream_key == "typing_key":
+                    # Note that we don't persist the token (via set_type_stream_id_for_appservice)
+                    # for typing_key due to performance reasons and due to their highly
+                    # ephemeral nature.
+                    #
+                    # Instead we simply grab the latest typing updates in _handle_typing
+                    # and, if they apply to this application service, send it off.
                     events = await self._handle_typing(service, new_token)
                     if events:
                         self.scheduler.submit_ephemeral_events_for_as(service, events)