Merge pull request #2944 from matrix-org/erikj/fix_sync_race

Fix race in sync when joining room

2 files changed, 27 insertions, 2 deletions

diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 057b1be4d5..826fad307e 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -754,7 +754,7 @@ class EventsStore(EventsWorkerStore):
 
                 for member in members_changed:
                     self._invalidate_cache_and_stream(
-                        txn, self.get_rooms_for_user, (member,)
+                        txn, self.get_rooms_for_user_with_stream_ordering, (member,)
                     )
 
                 for host in set(get_domain_from_id(u) for u in members_changed):
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index d79877dac7..52e19e16b0 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -38,6 +38,11 @@ RoomsForUser = namedtuple(
     ("room_id", "sender", "membership", "event_id", "stream_ordering")
 )
 
+GetRoomsForUserWithStreamOrdering = namedtuple(
+    "_GetRoomsForUserWithStreamOrdering",
+    ("room_id", "stream_ordering",)
+)
+
 
 # We store this using a namedtuple so that we save about 3x space over using a
 # dict.
@@ -181,12 +186,32 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         return results
 
     @cachedInlineCallbacks(max_entries=500000, iterable=True)
-    def get_rooms_for_user(self, user_id):
+    def get_rooms_for_user_with_stream_ordering(self, user_id):
         """Returns a set of room_ids the user is currently joined to
+
+        Args:
+            user_id (str)
+
+        Returns:
+            Deferred[frozenset[GetRoomsForUserWithStreamOrdering]]: Returns
+            the rooms the user is in currently, along with the stream ordering
+            of the most recent join for that user and room.
         """
         rooms = yield self.get_rooms_for_user_where_membership_is(
             user_id, membership_list=[Membership.JOIN],
         )
+        defer.returnValue(frozenset(
+            GetRoomsForUserWithStreamOrdering(r.room_id, r.stream_ordering)
+            for r in rooms
+        ))
+
+    @defer.inlineCallbacks
+    def get_rooms_for_user(self, user_id, on_invalidate=None):
+        """Returns a set of room_ids the user is currently joined to
+        """
+        rooms = yield self.get_rooms_for_user_with_stream_ordering(
+            user_id, on_invalidate=on_invalidate,
+        )
         defer.returnValue(frozenset(r.room_id for r in rooms))
 
     @cachedInlineCallbacks(max_entries=500000, cache_context=True, iterable=True)