From d225b6b3ebea419bdf0e6c0f1476544053f2dcbf Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Tue, 23 Jul 2024 14:03:14 +0100 Subject: [PATCH] Speed up SS room sorting (#17468) We do this by bulk fetching the latest stream ordering. --------- Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com> --- changelog.d/17468.misc | 1 + synapse/handlers/sliding_sync.py | 43 +++--- .../databases/main/event_federation.py | 5 + synapse/storage/databases/main/stream.py | 123 +++++++++++++++++- synapse/util/caches/stream_change_cache.py | 12 +- tests/util/test_stream_change_cache.py | 4 +- 6 files changed, 159 insertions(+), 29 deletions(-) create mode 100644 changelog.d/17468.misc diff --git a/changelog.d/17468.misc b/changelog.d/17468.misc new file mode 100644 index 000000000..d90877620 --- /dev/null +++ b/changelog.d/17468.misc @@ -0,0 +1 @@ +Speed up sorting of the room list in sliding sync. diff --git a/synapse/handlers/sliding_sync.py b/synapse/handlers/sliding_sync.py index 886d7c715..554ab59bf 100644 --- a/synapse/handlers/sliding_sync.py +++ b/synapse/handlers/sliding_sync.py @@ -1230,34 +1230,33 @@ class SlidingSyncHandler: # Assemble a map of room ID to the `stream_ordering` of the last activity that the # user should see in the room (<= `to_token`) last_activity_in_room_map: Dict[str, int] = {} + for room_id, room_for_user in sync_room_map.items(): - # If they are fully-joined to the room, let's find the latest activity - # at/before the `to_token`. - if room_for_user.membership == Membership.JOIN: - last_event_result = ( - await self.store.get_last_event_pos_in_room_before_stream_ordering( - room_id, to_token.room_key - ) - ) - - # If the room has no events at/before the `to_token`, this is probably a - # mistake in the code that generates the `sync_room_map` since that should - # only give us rooms that the user had membership in during the token range. - assert last_event_result is not None - - _, event_pos = last_event_result - - last_activity_in_room_map[room_id] = event_pos.stream - else: - # Otherwise, if the user has left/been invited/knocked/been banned from - # a room, they shouldn't see anything past that point. + if room_for_user.membership != Membership.JOIN: + # If the user has left/been invited/knocked/been banned from a + # room, they shouldn't see anything past that point. # - # FIXME: It's possible that people should see beyond this point in - # invited/knocked cases if for example the room has + # FIXME: It's possible that people should see beyond this point + # in invited/knocked cases if for example the room has # `invite`/`world_readable` history visibility, see # https://github.com/matrix-org/matrix-spec-proposals/pull/3575#discussion_r1653045932 last_activity_in_room_map[room_id] = room_for_user.event_pos.stream + # For fully-joined rooms, we find the latest activity at/before the + # `to_token`. + joined_room_positions = ( + await self.store.bulk_get_last_event_pos_in_room_before_stream_ordering( + [ + room_id + for room_id, room_for_user in sync_room_map.items() + if room_for_user.membership == Membership.JOIN + ], + to_token.room_key, + ) + ) + + last_activity_in_room_map.update(joined_room_positions) + return sorted( sync_room_map.values(), # Sort by the last activity (stream_ordering) in the room diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py index 24abab4a2..715846865 100644 --- a/synapse/storage/databases/main/event_federation.py +++ b/synapse/storage/databases/main/event_federation.py @@ -1313,6 +1313,11 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas # We want to make the cache more effective, so we clamp to the last # change before the given ordering. last_change = self._events_stream_cache.get_max_pos_of_last_change(room_id) # type: ignore[attr-defined] + if last_change is None: + # If the room isn't in the cache we know that the last change was + # somewhere before the earliest known position of the cache, so we + # can clamp to that. + last_change = self._events_stream_cache.get_earliest_known_position() # type: ignore[attr-defined] # We don't always have a full stream_to_exterm_id table, e.g. after # the upgrade that introduced it, so we make sure we never ask for a diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py index e74e0d2e9..b034361ae 100644 --- a/synapse/storage/databases/main/stream.py +++ b/synapse/storage/databases/main/stream.py @@ -78,10 +78,11 @@ from synapse.storage.database import ( from synapse.storage.databases.main.events_worker import EventsWorkerStore from synapse.storage.engines import BaseDatabaseEngine, PostgresEngine, Sqlite3Engine from synapse.storage.util.id_generators import MultiWriterIdGenerator -from synapse.types import PersistedEventPosition, RoomStreamToken +from synapse.types import PersistedEventPosition, RoomStreamToken, StrCollection from synapse.util.caches.descriptors import cached from synapse.util.caches.stream_change_cache import StreamChangeCache from synapse.util.cancellation import cancellable +from synapse.util.iterutils import batch_iter if TYPE_CHECKING: from synapse.server import HomeServer @@ -1293,6 +1294,126 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore): get_last_event_pos_in_room_before_stream_ordering_txn, ) + async def bulk_get_last_event_pos_in_room_before_stream_ordering( + self, + room_ids: StrCollection, + end_token: RoomStreamToken, + ) -> Dict[str, int]: + """Bulk fetch the stream position of the latest events in the given + rooms + """ + + min_token = end_token.stream + max_token = end_token.get_max_stream_pos() + results: Dict[str, int] = {} + + # First, we check for the rooms in the stream change cache to see if we + # can just use the latest position from it. + missing_room_ids: Set[str] = set() + for room_id in room_ids: + stream_pos = self._events_stream_cache.get_max_pos_of_last_change(room_id) + if stream_pos and stream_pos <= min_token: + results[room_id] = stream_pos + else: + missing_room_ids.add(room_id) + + # Next, we query the stream position from the DB. At first we fetch all + # positions less than the *max* stream pos in the token, then filter + # them down. We do this as a) this is a cheaper query, and b) the vast + # majority of rooms will have a latest token from before the min stream + # pos. + + def bulk_get_last_event_pos_txn( + txn: LoggingTransaction, batch_room_ids: StrCollection + ) -> Dict[str, int]: + # This query fetches the latest stream position in the rooms before + # the given max position. + clause, args = make_in_list_sql_clause( + self.database_engine, "room_id", batch_room_ids + ) + sql = f""" + SELECT room_id, ( + SELECT stream_ordering FROM events AS e + LEFT JOIN rejections USING (event_id) + WHERE e.room_id = r.room_id + AND stream_ordering <= ? + AND NOT outlier + AND rejection_reason IS NULL + ORDER BY stream_ordering DESC + LIMIT 1 + ) + FROM rooms AS r + WHERE {clause} + """ + txn.execute(sql, [max_token] + args) + return {row[0]: row[1] for row in txn} + + recheck_rooms: Set[str] = set() + for batched in batch_iter(missing_room_ids, 1000): + result = await self.db_pool.runInteraction( + "bulk_get_last_event_pos_in_room_before_stream_ordering", + bulk_get_last_event_pos_txn, + batched, + ) + + # Check that the stream position for the rooms are from before the + # minimum position of the token. If not then we need to fetch more + # rows. + for room_id, stream in result.items(): + if stream <= min_token: + results[room_id] = stream + else: + recheck_rooms.add(room_id) + + if not recheck_rooms: + return results + + # For the remaining rooms we need to fetch all rows between the min and + # max stream positions in the end token, and filter out the rows that + # are after the end token. + # + # This query should be fast as the range between the min and max should + # be small. + + def bulk_get_last_event_pos_recheck_txn( + txn: LoggingTransaction, batch_room_ids: StrCollection + ) -> Dict[str, int]: + clause, args = make_in_list_sql_clause( + self.database_engine, "room_id", batch_room_ids + ) + sql = f""" + SELECT room_id, instance_name, stream_ordering + FROM events + WHERE ? < stream_ordering AND stream_ordering <= ? + AND NOT outlier + AND rejection_reason IS NULL + AND {clause} + ORDER BY stream_ordering ASC + """ + txn.execute(sql, [min_token, max_token] + args) + + # We take the max stream ordering that is less than the token. Since + # we ordered by stream ordering we just need to iterate through and + # take the last matching stream ordering. + txn_results: Dict[str, int] = {} + for row in txn: + room_id = row[0] + event_pos = PersistedEventPosition(row[1], row[2]) + if not event_pos.persisted_after(end_token): + txn_results[room_id] = event_pos.stream + + return txn_results + + for batched in batch_iter(recheck_rooms, 1000): + recheck_result = await self.db_pool.runInteraction( + "bulk_get_last_event_pos_in_room_before_stream_ordering_recheck", + bulk_get_last_event_pos_recheck_txn, + batched, + ) + results.update(recheck_result) + + return results + async def get_current_room_stream_token_for_room_id( self, room_id: str ) -> RoomStreamToken: diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py index 91c335f85..16fcb0020 100644 --- a/synapse/util/caches/stream_change_cache.py +++ b/synapse/util/caches/stream_change_cache.py @@ -327,7 +327,7 @@ class StreamChangeCache: for entity in r: self._entity_to_key.pop(entity, None) - def get_max_pos_of_last_change(self, entity: EntityType) -> int: + def get_max_pos_of_last_change(self, entity: EntityType) -> Optional[int]: """Returns an upper bound of the stream id of the last change to an entity. @@ -335,7 +335,11 @@ class StreamChangeCache: entity: The entity to check. Return: - The stream position of the latest change for the given entity or - the earliest known stream position if the entitiy is unknown. + The stream position of the latest change for the given entity, if + known """ - return self._entity_to_key.get(entity, self._earliest_known_stream_pos) + return self._entity_to_key.get(entity) + + def get_earliest_known_position(self) -> int: + """Returns the earliest position in the cache.""" + return self._earliest_known_stream_pos diff --git a/tests/util/test_stream_change_cache.py b/tests/util/test_stream_change_cache.py index 5d38718a5..af1199ef8 100644 --- a/tests/util/test_stream_change_cache.py +++ b/tests/util/test_stream_change_cache.py @@ -249,5 +249,5 @@ class StreamChangeCacheTests(unittest.HomeserverTestCase): self.assertEqual(cache.get_max_pos_of_last_change("bar@baz.net"), 3) self.assertEqual(cache.get_max_pos_of_last_change("user@elsewhere.org"), 4) - # Unknown entities will return the stream start position. - self.assertEqual(cache.get_max_pos_of_last_change("not@here.website"), 1) + # Unknown entities will return None + self.assertEqual(cache.get_max_pos_of_last_change("not@here.website"), None)