diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 9d37e2a86f..39964726c5 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -2002,7 +2002,7 @@ class SyncHandler:
"""
user_id = sync_config.user.to_string()
- # Note: we get the users room list *before* we get the current token, this
+ # Note: we get the users room list *before* we get the `now_token`, this
# avoids checking back in history if rooms are joined after the token is fetched.
token_before_rooms = self.event_sources.get_current_token()
mutable_joined_room_ids = set(await self.store.get_rooms_for_user(user_id))
@@ -2014,10 +2014,10 @@ class SyncHandler:
now_token = self.event_sources.get_current_token()
log_kv({"now_token": now_token})
- # Since we fetched the users room list before the token, there's a small window
- # during which membership events may have been persisted, so we fetch these now
- # and modify the joined room list for any changes between the get_rooms_for_user
- # call and the get_current_token call.
+ # Since we fetched the users room list before calculating the `now_token` (see
+ # above), there's a small window during which membership events may have been
+ # persisted, so we fetch these now and modify the joined room list for any
+ # changes between the get_rooms_for_user call and the get_current_token call.
membership_change_events = []
if since_token:
membership_change_events = await self.store.get_membership_changes_for_user(
@@ -2027,16 +2027,19 @@ class SyncHandler:
self.rooms_to_exclude_globally,
)
- mem_last_change_by_room_id: Dict[str, EventBase] = {}
+ last_membership_change_by_room_id: Dict[str, EventBase] = {}
for event in membership_change_events:
- mem_last_change_by_room_id[event.room_id] = event
+ last_membership_change_by_room_id[event.room_id] = event
# For the latest membership event in each room found, add/remove the room ID
# from the joined room list accordingly. In this case we only care if the
# latest change is JOIN.
- for room_id, event in mem_last_change_by_room_id.items():
+ for room_id, event in last_membership_change_by_room_id.items():
assert event.internal_metadata.stream_ordering
+ # As a shortcut, skip any events that happened before we got our
+ # `get_rooms_for_user()` snapshot (any changes are already represented
+ # in that list).
if (
event.internal_metadata.stream_ordering
< token_before_rooms.room_key.stream
|
