Add a cache around server ACL checking (#16360)

* Pre-compiles the server ACLs onto an object per room and
  invalidates them when new events come in.
* Converts the server ACL checking into Rust.

2 files changed, 11 insertions, 0 deletions

diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py

index 7c62cdfaef..0cc8e990d9 100644
--- a/synapse/handlers/federation_event.py
+++ b/synapse/handlers/federation_event.py
@@ -2342,6 +2342,12 @@ class FederationEventHandler:
             # TODO retrieve the previous state, and exclude join -> join transitions
             self._notifier.notify_user_joined_room(event.event_id, event.room_id)
 
+        # If this is a server ACL event, clear the cache in the storage controller.
+        if event.type == EventTypes.ServerACL:
+            self._state_storage_controller.get_server_acl_for_room.invalidate(
+                (event.room_id,)
+            )
+
     def _sanity_check_event(self, ev: EventBase) -> None:
         """
         Do some early sanity checks of a received event
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py

index c036578a3d..44dbbf81dd 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -1730,6 +1730,11 @@ class EventCreationHandler:
                         event.event_id, event.room_id
                     )
 
+            if event.type == EventTypes.ServerACL:
+                self._storage_controllers.state.get_server_acl_for_room.invalidate(
+                    (event.room_id,)
+                )
+
             await self._maybe_kick_guest_users(event, context)
 
             if event.type == EventTypes.CanonicalAlias: