Fix bug in calculating state for non-gappy syncs (#16942)

Unfortunately, the optimisation we applied here for non-gappy syncs is
not actually valid.

Fixes https://github.com/element-hq/synapse/issues/16941.

~~Based on https://github.com/element-hq/synapse/pull/16930.~~
Requires https://github.com/matrix-org/sytest/pull/1374.
This commit is contained in:
Richard van der Hoff 2024-04-04 17:15:35 +01:00 committed by GitHub
parent 230b709d9d
commit 0e68e9b7f4
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5 changed files with 144 additions and 55 deletions

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@ -1 +1 @@
Fix a long-standing bug which could cause state to be omitted from `/sync` responses when certain events are filtered out of the timeline.
Fix various long-standing bugs which could cause incorrect state to be returned from `/sync` in certain situations.

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@ -1 +1 @@
Fix a long-standing bug which could cause incorrect state to be returned from `/sync` for rooms where the user has left.
Fix various long-standing bugs which could cause incorrect state to be returned from `/sync` in certain situations.

1
changelog.d/16942.bugfix Normal file
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@ -0,0 +1 @@
Fix various long-standing bugs which could cause incorrect state to be returned from `/sync` in certain situations.

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@ -1195,6 +1195,8 @@ class SyncHandler:
)
if batch:
# Strictly speaking, this returns the state *after* the first event in the
# timeline, but that is good enough here.
state_at_timeline_start = (
await self._state_storage_controller.get_state_ids_for_event(
batch.events[0].event_id,
@ -1257,25 +1259,25 @@ class SyncHandler:
await_full_state = True
lazy_load_members = False
if batch.limited:
if batch:
state_at_timeline_start = (
await self._state_storage_controller.get_state_ids_for_event(
batch.events[0].event_id,
state_filter=state_filter,
await_full_state=await_full_state,
)
)
else:
# We can get here if the user has ignored the senders of all
# the recent events.
state_at_timeline_start = await self.get_state_at(
room_id,
stream_position=end_token,
if batch:
state_at_timeline_start = (
await self._state_storage_controller.get_state_ids_for_event(
batch.events[0].event_id,
state_filter=state_filter,
await_full_state=await_full_state,
)
)
else:
# We can get here if the user has ignored the senders of all
# the recent events.
state_at_timeline_start = await self.get_state_at(
room_id,
stream_position=end_token,
state_filter=state_filter,
await_full_state=await_full_state,
)
if batch.limited:
# for now, we disable LL for gappy syncs - see
# https://github.com/vector-im/riot-web/issues/7211#issuecomment-419976346
# N.B. this slows down incr syncs as we are now processing way
@ -1290,47 +1292,28 @@ class SyncHandler:
# about them).
state_filter = StateFilter.all()
state_at_previous_sync = await self.get_state_at(
room_id,
stream_position=since_token,
state_filter=state_filter,
await_full_state=await_full_state,
)
state_at_previous_sync = await self.get_state_at(
room_id,
stream_position=since_token,
state_filter=state_filter,
await_full_state=await_full_state,
)
state_at_timeline_end = await self.get_state_at(
room_id,
stream_position=end_token,
state_filter=state_filter,
await_full_state=await_full_state,
)
state_at_timeline_end = await self.get_state_at(
room_id,
stream_position=end_token,
state_filter=state_filter,
await_full_state=await_full_state,
)
state_ids = _calculate_state(
timeline_contains=timeline_state,
timeline_start=state_at_timeline_start,
timeline_end=state_at_timeline_end,
previous_timeline_end=state_at_previous_sync,
lazy_load_members=lazy_load_members,
)
else:
state_ids = {}
if lazy_load_members:
if members_to_fetch and batch.events:
# We're returning an incremental sync, with no
# "gap" since the previous sync, so normally there would be
# no state to return.
# But 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 = _calculate_state(
timeline_contains=timeline_state,
timeline_start=state_at_timeline_start,
timeline_end=state_at_timeline_end,
previous_timeline_end=state_at_previous_sync,
lazy_load_members=lazy_load_members,
)
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
async def _find_missing_partial_state_memberships(

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@ -435,6 +435,111 @@ class SyncTestCase(tests.unittest.HomeserverTestCase):
[s2_event],
)
def test_state_includes_changes_on_ungappy_syncs(self) -> None:
"""Test `state` where the sync is not gappy.
We start with a DAG like this:
E1
| S2
|
--|---
|
E3
... and initialsync with `limit=1`, represented by the horizontal dashed line.
At this point, we do not expect S2 to appear in the response at all (since
it is excluded from the timeline by the `limit`, and the state is based on the
state after the most recent event before the sync token (E3), which doesn't
include S2.
Now more events arrive, and we do an incremental sync:
E1
| S2
|
E3 |
|
--|------|----
| |
E4 |
/
E5
This is the last chance for us to tell the client about S2, so it *must* be
included in the response.
"""
alice = self.register_user("alice", "password")
alice_tok = self.login(alice, "password")
alice_requester = create_requester(alice)
room_id = self.helper.create_room_as(alice, is_public=True, tok=alice_tok)
# Do an initial sync to get a known starting point.
initial_sync_result = self.get_success(
self.sync_handler.wait_for_sync_for_user(
alice_requester, generate_sync_config(alice)
)
)
last_room_creation_event_id = (
initial_sync_result.joined[0].timeline.events[-1].event_id
)
# Send a state event, and a regular event, both using the same prev ID
with self._patch_get_latest_events([last_room_creation_event_id]):
s2_event = self.helper.send_state(room_id, "s2", {}, tok=alice_tok)[
"event_id"
]
e3_event = self.helper.send(room_id, "e3", tok=alice_tok)["event_id"]
# Another initial sync, with limit=1
initial_sync_result = self.get_success(
self.sync_handler.wait_for_sync_for_user(
alice_requester,
generate_sync_config(
alice,
filter_collection=FilterCollection(
self.hs, {"room": {"timeline": {"limit": 1}}}
),
),
)
)
room_sync = initial_sync_result.joined[0]
self.assertEqual(room_sync.room_id, room_id)
self.assertEqual(
[e.event_id for e in room_sync.timeline.events],
[e3_event],
)
self.assertNotIn(s2_event, [e.event_id for e in room_sync.state.values()])
# More events, E4 and E5
with self._patch_get_latest_events([e3_event]):
e4_event = self.helper.send(room_id, "e4", tok=alice_tok)["event_id"]
e5_event = self.helper.send(room_id, "e5", tok=alice_tok)["event_id"]
# Now incremental sync
incremental_sync = self.get_success(
self.sync_handler.wait_for_sync_for_user(
alice_requester,
generate_sync_config(alice),
since_token=initial_sync_result.next_batch,
)
)
# The state event should appear in the 'state' section of the response.
room_sync = incremental_sync.joined[0]
self.assertEqual(room_sync.room_id, room_id)
self.assertFalse(room_sync.timeline.limited)
self.assertEqual(
[e.event_id for e in room_sync.timeline.events],
[e4_event, e5_event],
)
self.assertEqual(
[e.event_id for e in room_sync.state.values()],
[s2_event],
)
@parameterized.expand(
[
(False, False),