diff --git a/changelog.d/5825.bugfix b/changelog.d/5825.bugfix
new file mode 100644
index 0000000000..fb2c6f821d
--- /dev/null
+++ b/changelog.d/5825.bugfix
@@ -0,0 +1 @@
+Fix bug where user `/sync` stream could get wedged in rare circumstances.
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 4007284e5b..98da2318a0 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -781,9 +781,17 @@ class SyncHandler(object):
lazy_load_members=lazy_load_members,
)
elif batch.limited:
- state_at_timeline_start = yield self.store.get_state_ids_for_event(
- batch.events[0].event_id, state_filter=state_filter
- )
+ if batch:
+ state_at_timeline_start = yield self.store.get_state_ids_for_event(
+ batch.events[0].event_id, state_filter=state_filter
+ )
+ else:
+ # Its not clear how we get here, but empirically we do
+ # (#5407). Logging has been added elsewhere to try and
+ # figure out where this state comes from.
+ state_at_timeline_start = yield self.get_state_at(
+ room_id, stream_position=now_token, state_filter=state_filter
+ )
# for now, we disable LL for gappy syncs - see
# https://github.com/vector-im/riot-web/issues/7211#issuecomment-419976346
@@ -803,9 +811,17 @@ class SyncHandler(object):
room_id, stream_position=since_token, state_filter=state_filter
)
- current_state_ids = yield self.store.get_state_ids_for_event(
- batch.events[-1].event_id, state_filter=state_filter
- )
+ if batch:
+ current_state_ids = yield self.store.get_state_ids_for_event(
+ batch.events[-1].event_id, state_filter=state_filter
+ )
+ else:
+ # Its not clear how we get here, but empirically we do
+ # (#5407). Logging has been added elsewhere to try and
+ # figure out where this state comes from.
+ current_state_ids = yield self.get_state_at(
+ room_id, stream_position=now_token, state_filter=state_filter
+ )
state_ids = _calculate_state(
timeline_contains=timeline_state,
@@ -1755,6 +1771,21 @@ class SyncHandler(object):
newly_joined_room=newly_joined,
)
+ if not batch and batch.limited:
+ # This resulted in #5407, which is weird, so lets log! We do it
+ # here as we have the maximum amount of information.
+ user_id = sync_result_builder.sync_config.user.to_string()
+ logger.info(
+ "Issue #5407: Found limited batch with no events. user %s, room %s,"
+ " sync_config %s, newly_joined %s, events %s, batch %s.",
+ user_id,
+ room_id,
+ sync_config,
+ newly_joined,
+ events,
+ batch,
+ )
+
if newly_joined:
# debug for https://github.com/matrix-org/synapse/issues/4422
issue4422_logger.debug(
|
