1 files changed, 19 insertions, 5 deletions
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 9f5b83ed54..64d298408d 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -943,6 +943,8 @@ class SyncHandler:
timeline_state = {}
+ # Membership events to fetch that can be found in the room state, or in
+ # the case of partial state rooms, the auth events of timeline events.
members_to_fetch = set()
first_event_by_sender_map = {}
for event in batch.events:
@@ -964,9 +966,19 @@ class SyncHandler:
# (if we are) to fix https://github.com/vector-im/riot-web/issues/7209
# We only need apply this on full state syncs given we disabled
# LL for incr syncs in #3840.
- members_to_fetch.add(sync_config.user.to_string())
-
- state_filter = StateFilter.from_lazy_load_member_list(members_to_fetch)
+ # We don't insert ourselves into `members_to_fetch`, because in some
+ # rare cases (an empty event batch with a now_token after the user's
+ # leave in a partial state room which another local user has
+ # joined), the room state will be missing our membership and there
+ # is no guarantee that our membership will be in the auth events of
+ # timeline events when the room is partial stated.
+ state_filter = StateFilter.from_lazy_load_member_list(
+ members_to_fetch.union((sync_config.user.to_string(),))
+ )
+ else:
+ state_filter = StateFilter.from_lazy_load_member_list(
+ members_to_fetch
+ )
# We are happy to use partial state to compute the `/sync` response.
# Since partial state may not include the lazy-loaded memberships we
@@ -988,7 +1000,9 @@ class SyncHandler:
# sync's timeline and the start of the current sync's timeline.
# See the docstring above for details.
state_ids: StateMap[str]
-
+ # We need to know whether the state we fetch may be partial, so check
+ # whether the room is partial stated *before* fetching it.
+ is_partial_state_room = await self.store.is_partial_state_room(room_id)
if full_state:
if batch:
state_at_timeline_end = (
@@ -1119,7 +1133,7 @@ class SyncHandler:
# If we only have partial state for the room, `state_ids` may be missing the
# memberships we wanted. We attempt to find some by digging through the auth
# events of timeline events.
- if lazy_load_members and await self.store.is_partial_state_room(room_id):
+ if lazy_load_members and is_partial_state_room:
assert members_to_fetch is not None
assert first_event_by_sender_map is not None
|
