Faster joins: do not wait for full state when creating events to send

changelog.d/14403.misc

@@ -0,0 +1 @@
+Faster joins: do not wait for full state when creating events to send.

synapse/events/builder.py

@@ -128,6 +128,7 @@ async def build(
                 state_filter=StateFilter.from_types(
                     auth_types_for_event(self.room_version, self)
                 ),
+                await_full_state=False,
             )
             auth_event_ids = self._event_auth_handler.compute_auth_events(
                 self, state_ids

synapse/state/__init__.py

@@ -190,6 +190,7 @@ async def compute_state_after_events(
         room_id: str,
         event_ids: Collection[str],
         state_filter: Optional[StateFilter] = None,
+        await_full_state: bool = True,
     ) -> StateMap[str]:
         """Fetch the state after each of the given event IDs. Resolve them and return.
 
@@ -206,7 +207,9 @@ async def compute_state_after_events(
             holds the resolution of the states after the given event IDs.
         """
         logger.debug("calling resolve_state_groups from compute_state_after_events")
-        ret = await self.resolve_state_groups_for_events(room_id, event_ids)
+        ret = await self.resolve_state_groups_for_events(
+            room_id, event_ids, await_full_state
+        )
         return await ret.get_state(self._state_storage_controller, state_filter)
 
     async def get_current_user_ids_in_room(