Directly lookup local membership instead of getting all members in a room first (`get_users_in_room` mis-use) (#13608)

See https://github.com/matrix-org/synapse/pull/13575#discussion_r953023755

1 files changed, 4 insertions, 2 deletions

diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index acd3de06f6..72157d5a36 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -761,8 +761,10 @@ class EventCreationHandler:
     async def _is_server_notices_room(self, room_id: str) -> bool:
         if self.config.servernotices.server_notices_mxid is None:
             return False
-        user_ids = await self.store.get_users_in_room(room_id)
-        return self.config.servernotices.server_notices_mxid in user_ids
+        is_server_notices_room = await self.store.check_local_user_in_room(
+            user_id=self.config.servernotices.server_notices_mxid, room_id=room_id
+        )
+        return is_server_notices_room
 
     async def assert_accepted_privacy_policy(self, requester: Requester) -> None:
         """Check if a user has accepted the privacy policy