Check cache before invalidating group sessions on member event

Author: tulir

mautrix/client/state_store/abstract.py

@@ -143,6 +143,9 @@ async def update_state(self, evt: StateEvent) -> None:
         if evt.type == EventType.ROOM_POWER_LEVELS:
             await self.set_power_levels(evt.room_id, evt.content)
         elif evt.type == EventType.ROOM_MEMBER:
+            evt.unsigned["mautrix_prev_membership"] = await self.get_member(
+                evt.room_id, UserID(evt.state_key)
+            )
             await self.set_member(evt.room_id, UserID(evt.state_key), evt.content)
         elif evt.type == EventType.ROOM_ENCRYPTION:
             await self.set_encryption_info(evt.room_id, evt.content)

mautrix/crypto/machine.py

@@ -18,6 +18,7 @@
     DeviceOTKCount,
     EncryptionAlgorithm,
     EventType,
+    Member,
     Membership,
     StateEvent,
     ToDeviceEvent,
@@ -172,10 +173,18 @@ async def handle_member_event(self, evt: StateEvent) -> None:
         if prev == cur or ignored_changes.get(prev) == cur:
             return
         src = getattr(evt, "source", None)
+        prev_cache = evt.unsigned.get("mautrix_prev_membership")
+        if isinstance(prev_cache, Member) and prev_cache.membership == cur:
+            self.log.debug(
+                f"Got duplicate membership state event in {evt.room_id} changing {evt.state_key} "
+                f"from {prev} to {cur}, cached state was {prev_cache} (event ID: {evt.event_id}, "
+                f"sync source: {src})"
+            )
+            return
         self.log.debug(
             f"Got membership state event in {evt.room_id} changing {evt.state_key} from "
-            f"{prev} to {cur} (event ID: {evt.event_id}, sync source: {src}), "
-            "invalidating group session"
+            f"{prev} to {cur} (event ID: {evt.event_id}, sync source: {src}, "
+            f"cached: {prev_cache.membership}), invalidating group session"
         )
         await self.crypto_store.remove_outbound_group_session(evt.room_id)