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| -rw-r--r-- | changelog.d/17064.bugfix | 1 | ||||
| -rw-r--r-- | synapse/handlers/sync.py | 36 |
2 files changed, 37 insertions, 0 deletions
diff --git a/changelog.d/17064.bugfix b/changelog.d/17064.bugfix new file mode 100644 index 0000000000..99ed435d75 --- /dev/null +++ b/changelog.d/17064.bugfix @@ -0,0 +1 @@ +Fix various long-standing bugs which could cause incorrect state to be returned from `/sync` in certain situations. diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py index 554c820f79..7c29c15540 100644 --- a/synapse/handlers/sync.py +++ b/synapse/handlers/sync.py @@ -1259,6 +1259,42 @@ class SyncHandler: await_full_state = True lazy_load_members = False + # For a non-gappy sync if the events in the timeline are simply a linear + # chain (i.e. no merging/branching of the graph), then we know the state + # delta between the end of the previous sync and start of the new one is + # empty. + # + # c.f. #16941 for an example of why we can't do this for all non-gappy + # syncs. + is_linear_timeline = False + if batch.events: + prev_event_id = batch.events[0].event_id + for e in batch.events[1:]: + if e.prev_event_ids() != [prev_event_id]: + break + else: + is_linear_timeline = True + + if is_linear_timeline and not batch.limited: + state_ids: StateMap[str] = {} + if lazy_load_members: + if members_to_fetch and batch.events: + # We're lazy-loading, so the client might need some more + # member events to understand the events in this timeline. + # So we fish out all the member events corresponding to the + # timeline here. The caller will then dedupe any redundant + # ones. + + state_ids = await self._state_storage_controller.get_state_ids_for_event( + batch.events[0].event_id, + # we only want members! + state_filter=StateFilter.from_types( + (EventTypes.Member, member) for member in members_to_fetch + ), + await_full_state=False, + ) + return state_ids + if batch: state_at_timeline_start = ( await self._state_storage_controller.get_state_ids_for_event( |