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Fix get_last_event_in_room_before_stream_ordering(...) finding the wrong last event (#17295)

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PR where this was introduced: https://github.com/matrix-org/synapse/pull/14817

### What does this affect?

`get_last_event_in_room_before_stream_ordering(...)` is used in Sync v2 in a lot of different state calculations.

`get_last_event_in_room_before_stream_ordering(...)`  is also used in `/rooms/{roomId}/members`
This commit is contained in:
Eric Eastwood 2024-06-13 11:00:52 -05:00 committed by GitHub
parent c6eb99c878
commit ebdce69f6a
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3 changed files with 289 additions and 11 deletions
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1
changelog.d/17295.bugfix Normal file
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@ -0,0 +1 @@
Fix edge case in `/sync` returning the wrong the state when using sharded event persisters.

30
synapse/storage/databases/main/stream.py
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@ -914,12 +914,23 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
def get_last_event_in_room_before_stream_ordering_txn(
txn: LoggingTransaction,
) -> Optional[str]:
# We need to handle the fact that the stream tokens can be vector
# clocks. We do this by getting all rows between the minimum and
# maximum stream ordering in the token, plus one row less than the
# minimum stream ordering. We then filter the results against the
# token and return the first row that matches.
# We're looking for the closest event at or before the token. We need to
# handle the fact that the stream token can be a vector clock (with an
# `instance_map`) and events can be persisted on different instances
# (sharded event persisters). The first subquery handles the events that
# would be within the vector clock and gets all rows between the minimum and
# maximum stream ordering in the token which need to be filtered against the
# `instance_map`. The second subquery handles the "before" case and finds
# the first row before the token. We then filter out any results past the
# token's vector clock and return the first row that matches.
min_stream = end_token.stream
max_stream = end_token.get_max_stream_pos()
# We use `union all` because we don't need any of the deduplication logic
# (`union` is really a union + distinct). `UNION ALL` does preserve the
# ordering of the operand queries but there is no actual gurantee that it
# has this behavior in all scenarios so we need the extra `ORDER BY` at the
# bottom.
sql = """
SELECT * FROM (
SELECT instance_name, stream_ordering, topological_ordering, event_id
@ -931,7 +942,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
AND rejections.event_id IS NULL
ORDER BY stream_ordering DESC
) AS a
UNION
UNION ALL
SELECT * FROM (
SELECT instance_name, stream_ordering, topological_ordering, event_id
FROM events
@ -943,15 +954,16 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
ORDER BY stream_ordering DESC
LIMIT 1
) AS b
ORDER BY stream_ordering DESC
"""
txn.execute(
sql,
(
room_id,
end_token.stream,
end_token.get_max_stream_pos(),
min_stream,
max_stream,
room_id,
end_token.stream,
min_stream,
),
)

269
tests/storage/test_stream.py
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@ -19,7 +19,10 @@
#
#
from typing import List
import logging
from typing import List, Tuple
from immutabledict import immutabledict
from twisted.test.proto_helpers import MemoryReactor
@ -28,11 +31,13 @@ from synapse.api.filtering import Filter
from synapse.rest import admin
from synapse.rest.client import login, room
from synapse.server import HomeServer
from synapse.types import JsonDict
from synapse.types import JsonDict, PersistedEventPosition, RoomStreamToken
from synapse.util import Clock
from tests.unittest import HomeserverTestCase
logger = logging.getLogger(__name__)
class PaginationTestCase(HomeserverTestCase):
"""
@ -268,3 +273,263 @@ class PaginationTestCase(HomeserverTestCase):
}
chunk = self._filter_messages(filter)
self.assertEqual(chunk, [self.event_id_1, self.event_id_2, self.event_id_none])
class GetLastEventInRoomBeforeStreamOrderingTestCase(HomeserverTestCase):
"""
Test `get_last_event_in_room_before_stream_ordering(...)`
"""
servlets = [
admin.register_servlets,
room.register_servlets,
login.register_servlets,
]
def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
self.store = hs.get_datastores().main
self.event_sources = hs.get_event_sources()
def _update_persisted_instance_name_for_event(
self, event_id: str, instance_name: str
) -> None:
"""
Update the `instance_name` that persisted the the event in the database.
"""
return self.get_success(
self.store.db_pool.simple_update_one(
"events",
keyvalues={"event_id": event_id},
updatevalues={"instance_name": instance_name},
)
)
def _send_event_on_instance(
self, instance_name: str, room_id: str, access_token: str
) -> Tuple[JsonDict, PersistedEventPosition]:
"""
Send an event in a room and mimic that it was persisted by a specific
instance/worker.
"""
event_response = self.helper.send(
room_id, f"{instance_name} message", tok=access_token
)
self._update_persisted_instance_name_for_event(
event_response["event_id"], instance_name
)
event_pos = self.get_success(
self.store.get_position_for_event(event_response["event_id"])
)
return event_response, event_pos
def test_before_room_created(self) -> None:
"""
Test that no event is returned if we are using a token before the room was even created
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")
before_room_token = self.event_sources.get_current_token()
room_id = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
last_event = self.get_success(
self.store.get_last_event_in_room_before_stream_ordering(
room_id=room_id,
end_token=before_room_token.room_key,
)
)
self.assertIsNone(last_event)
def test_after_room_created(self) -> None:
"""
Test that an event is returned if we are using a token after the room was created
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")
room_id = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
after_room_token = self.event_sources.get_current_token()
last_event = self.get_success(
self.store.get_last_event_in_room_before_stream_ordering(
room_id=room_id,
end_token=after_room_token.room_key,
)
)
self.assertIsNotNone(last_event)
def test_activity_in_other_rooms(self) -> None:
"""
Test to make sure that the last event in the room is returned even if the
`stream_ordering` has advanced from activity in other rooms.
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")
room_id1 = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
event_response = self.helper.send(room_id1, "target!", tok=user1_tok)
# Create another room to advance the stream_ordering
self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
after_room_token = self.event_sources.get_current_token()
last_event = self.get_success(
self.store.get_last_event_in_room_before_stream_ordering(
room_id=room_id1,
end_token=after_room_token.room_key,
)
)
# Make sure it's the event we expect (which also means we know it's from the
# correct room)
self.assertEqual(last_event, event_response["event_id"])
def test_activity_after_token_has_no_effect(self) -> None:
"""
Test to make sure we return the last event before the token even if there is
activity after it.
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")
room_id1 = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
event_response = self.helper.send(room_id1, "target!", tok=user1_tok)
after_room_token = self.event_sources.get_current_token()
# Send some events after the token
self.helper.send(room_id1, "after1", tok=user1_tok)
self.helper.send(room_id1, "after2", tok=user1_tok)
last_event = self.get_success(
self.store.get_last_event_in_room_before_stream_ordering(
room_id=room_id1,
end_token=after_room_token.room_key,
)
)
# Make sure it's the last event before the token
self.assertEqual(last_event, event_response["event_id"])
def test_last_event_within_sharded_token(self) -> None:
"""
Test to make sure we can find the last event that that is *within* the sharded
token (a token that has an `instance_map` and looks like
`m{min_pos}~{writer1}.{pos1}~{writer2}.{pos2}`). We are specifically testing
that we can find an event within the tokens minimum and instance
`stream_ordering`.
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")
room_id1 = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
event_response1, event_pos1 = self._send_event_on_instance(
"worker1", room_id1, user1_tok
)
event_response2, event_pos2 = self._send_event_on_instance(
"worker1", room_id1, user1_tok
)
event_response3, event_pos3 = self._send_event_on_instance(
"worker1", room_id1, user1_tok
)
# Create another room to advance the `stream_ordering` on the same worker
# so we can sandwich event3 in the middle of the token
room_id2 = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
event_response4, event_pos4 = self._send_event_on_instance(
"worker1", room_id2, user1_tok
)
# Assemble a token that encompasses event1 -> event4 on worker1
end_token = RoomStreamToken(
stream=event_pos2.stream,
instance_map=immutabledict({"worker1": event_pos4.stream}),
)
# Send some events after the token
self.helper.send(room_id1, "after1", tok=user1_tok)
self.helper.send(room_id1, "after2", tok=user1_tok)
last_event = self.get_success(
self.store.get_last_event_in_room_before_stream_ordering(
room_id=room_id1,
end_token=end_token,
)
)
# Should find closest event at/before the token in room1
self.assertEqual(
last_event,
event_response3["event_id"],
f"We expected {event_response3['event_id']} but saw {last_event} which corresponds to "
+ str(
{
"event1": event_response1["event_id"],
"event2": event_response2["event_id"],
"event3": event_response3["event_id"],
}
),
)
def test_last_event_before_sharded_token(self) -> None:
"""
Test to make sure we can find the last event that is *before* the sharded token
(a token that has an `instance_map` and looks like
`m{min_pos}~{writer1}.{pos1}~{writer2}.{pos2}`).
"""
user1_id = self.register_user("user1", "pass")
user1_tok = self.login(user1_id, "pass")
room_id1 = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
event_response1, event_pos1 = self._send_event_on_instance(
"worker1", room_id1, user1_tok
)
event_response2, event_pos2 = self._send_event_on_instance(
"worker1", room_id1, user1_tok
)
# Create another room to advance the `stream_ordering` on the same worker
room_id2 = self.helper.create_room_as(user1_id, tok=user1_tok, is_public=True)
event_response3, event_pos3 = self._send_event_on_instance(
"worker1", room_id2, user1_tok
)
event_response4, event_pos4 = self._send_event_on_instance(
"worker1", room_id2, user1_tok
)
# Assemble a token that encompasses event3 -> event4 on worker1
end_token = RoomStreamToken(
stream=event_pos3.stream,
instance_map=immutabledict({"worker1": event_pos4.stream}),
)
# Send some events after the token
self.helper.send(room_id1, "after1", tok=user1_tok)
self.helper.send(room_id1, "after2", tok=user1_tok)
last_event = self.get_success(
self.store.get_last_event_in_room_before_stream_ordering(
room_id=room_id1,
end_token=end_token,
)
)
# Should find closest event at/before the token in room1
self.assertEqual(
last_event,
event_response2["event_id"],
f"We expected {event_response2['event_id']} but saw {last_event} which corresponds to "
+ str(
{
"event1": event_response1["event_id"],
"event2": event_response2["event_id"],
}
),
)