From 29269d9d3f3419a3d92cdd80dae4a37e2d99a395 Mon Sep 17 00:00:00 2001 From: Eric Eastwood Date: Tue, 27 Sep 2022 15:55:43 -0500 Subject: [PATCH] Fix `have_seen_event` cache not being invalidated (#13863) Fix https://github.com/matrix-org/synapse/issues/13856 Fix https://github.com/matrix-org/synapse/issues/13865 > Discovered while trying to make Synapse fast enough for [this MSC2716 test for importing many batches](https://github.com/matrix-org/complement/pull/214#discussion_r741678240). As an example, disabling the `have_seen_event` cache saves 10 seconds for each `/messages` request in that MSC2716 Complement test because we're not making as many federation requests for `/state` (speeding up `have_seen_event` itself is related to https://github.com/matrix-org/synapse/issues/13625) > > But this will also make `/messages` faster in general so we can include it in the [faster `/messages` milestone](https://github.com/matrix-org/synapse/milestone/11). > > *-- https://github.com/matrix-org/synapse/issues/13856* ### The problem `_invalidate_caches_for_event` doesn't run in monolith mode which means we never even tried to clear the `have_seen_event` and other caches. And even in worker mode, it only runs on the workers, not the master (AFAICT). Additionally there was bug with the key being wrong so `_invalidate_caches_for_event` never invalidates the `have_seen_event` cache even when it does run. Because we were using the `@cachedList` wrong, it was putting items in the cache under keys like `((room_id, event_id),)` with a `set` in a `set` (ex. `(('!TnCIJPKzdQdUlIyXdQ:test', '$Iu0eqEBN7qcyF1S9B3oNB3I91v2o5YOgRNPwi_78s-k'),)`) and we we're trying to invalidate with just `(room_id, event_id)` which did nothing. --- changelog.d/13863.bugfix | 1 + .../storage/databases/main/events_worker.py | 40 ++--- synapse/util/caches/descriptors.py | 6 + .../databases/main/test_events_worker.py | 152 ++++++++++++------ tests/util/caches/test_descriptors.py | 33 +++- 5 files changed, 165 insertions(+), 67 deletions(-) create mode 100644 changelog.d/13863.bugfix diff --git a/changelog.d/13863.bugfix b/changelog.d/13863.bugfix new file mode 100644 index 000000000..74264a4fa --- /dev/null +++ b/changelog.d/13863.bugfix @@ -0,0 +1 @@ +Fix `have_seen_event` cache not being invalidated after we persist an event which causes inefficiency effects like extra `/state` federation calls. diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py index 52914febf..7cdc9fe98 100644 --- a/synapse/storage/databases/main/events_worker.py +++ b/synapse/storage/databases/main/events_worker.py @@ -1474,32 +1474,38 @@ class EventsWorkerStore(SQLBaseStore): # the batches as big as possible. results: Set[str] = set() - for chunk in batch_iter(event_ids, 500): - r = await self._have_seen_events_dict( - [(room_id, event_id) for event_id in chunk] + for event_ids_chunk in batch_iter(event_ids, 500): + events_seen_dict = await self._have_seen_events_dict( + room_id, event_ids_chunk + ) + results.update( + eid for (eid, have_event) in events_seen_dict.items() if have_event ) - results.update(eid for ((_rid, eid), have_event) in r.items() if have_event) return results - @cachedList(cached_method_name="have_seen_event", list_name="keys") + @cachedList(cached_method_name="have_seen_event", list_name="event_ids") async def _have_seen_events_dict( - self, keys: Collection[Tuple[str, str]] - ) -> Dict[Tuple[str, str], bool]: + self, + room_id: str, + event_ids: Collection[str], + ) -> Dict[str, bool]: """Helper for have_seen_events Returns: - a dict {(room_id, event_id)-> bool} + a dict {event_id -> bool} """ # if the event cache contains the event, obviously we've seen it. cache_results = { - (rid, eid) - for (rid, eid) in keys - if await self._get_event_cache.contains((eid,)) + event_id + for event_id in event_ids + if await self._get_event_cache.contains((event_id,)) } results = dict.fromkeys(cache_results, True) - remaining = [k for k in keys if k not in cache_results] + remaining = [ + event_id for event_id in event_ids if event_id not in cache_results + ] if not remaining: return results @@ -1511,23 +1517,21 @@ class EventsWorkerStore(SQLBaseStore): sql = "SELECT event_id FROM events AS e WHERE " clause, args = make_in_list_sql_clause( - txn.database_engine, "e.event_id", [eid for (_rid, eid) in remaining] + txn.database_engine, "e.event_id", remaining ) txn.execute(sql + clause, args) found_events = {eid for eid, in txn} # ... and then we can update the results for each key - results.update( - {(rid, eid): (eid in found_events) for (rid, eid) in remaining} - ) + results.update({eid: (eid in found_events) for eid in remaining}) await self.db_pool.runInteraction("have_seen_events", have_seen_events_txn) return results @cached(max_entries=100000, tree=True) async def have_seen_event(self, room_id: str, event_id: str) -> bool: - res = await self._have_seen_events_dict(((room_id, event_id),)) - return res[(room_id, event_id)] + res = await self._have_seen_events_dict(room_id, [event_id]) + return res[event_id] def _get_current_state_event_counts_txn( self, txn: LoggingTransaction, room_id: str diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py index 3909f1cae..039196646 100644 --- a/synapse/util/caches/descriptors.py +++ b/synapse/util/caches/descriptors.py @@ -431,6 +431,12 @@ class DeferredCacheListDescriptor(_CacheDescriptorBase): cache: DeferredCache[CacheKey, Any] = cached_method.cache num_args = cached_method.num_args + if num_args != self.num_args: + raise Exception( + "Number of args (%s) does not match underlying cache_method_name=%s (%s)." + % (self.num_args, self.cached_method_name, num_args) + ) + @functools.wraps(self.orig) def wrapped(*args: Any, **kwargs: Any) -> "defer.Deferred[Dict]": # If we're passed a cache_context then we'll want to call its diff --git a/tests/storage/databases/main/test_events_worker.py b/tests/storage/databases/main/test_events_worker.py index 67401272a..32a798d74 100644 --- a/tests/storage/databases/main/test_events_worker.py +++ b/tests/storage/databases/main/test_events_worker.py @@ -35,66 +35,45 @@ from synapse.util import Clock from synapse.util.async_helpers import yieldable_gather_results from tests import unittest +from tests.test_utils.event_injection import create_event, inject_event class HaveSeenEventsTestCase(unittest.HomeserverTestCase): + servlets = [ + admin.register_servlets, + room.register_servlets, + login.register_servlets, + ] + def prepare(self, reactor, clock, hs): + self.hs = hs self.store: EventsWorkerStore = hs.get_datastores().main - # insert some test data - for rid in ("room1", "room2"): - self.get_success( - self.store.db_pool.simple_insert( - "rooms", - {"room_id": rid, "room_version": 4}, - ) - ) + self.user = self.register_user("user", "pass") + self.token = self.login(self.user, "pass") + self.room_id = self.helper.create_room_as(self.user, tok=self.token) self.event_ids: List[str] = [] - for idx, rid in enumerate( - ( - "room1", - "room1", - "room1", - "room2", + for i in range(3): + event = self.get_success( + inject_event( + hs, + room_version=RoomVersions.V7.identifier, + room_id=self.room_id, + sender=self.user, + type="test_event_type", + content={"body": f"foobarbaz{i}"}, + ) ) - ): - event_json = {"type": f"test {idx}", "room_id": rid} - event = make_event_from_dict(event_json, room_version=RoomVersions.V4) - event_id = event.event_id - self.get_success( - self.store.db_pool.simple_insert( - "events", - { - "event_id": event_id, - "room_id": rid, - "topological_ordering": idx, - "stream_ordering": idx, - "type": event.type, - "processed": True, - "outlier": False, - }, - ) - ) - self.get_success( - self.store.db_pool.simple_insert( - "event_json", - { - "event_id": event_id, - "room_id": rid, - "json": json.dumps(event_json), - "internal_metadata": "{}", - "format_version": 3, - }, - ) - ) - self.event_ids.append(event_id) + self.event_ids.append(event.event_id) def test_simple(self): with LoggingContext(name="test") as ctx: res = self.get_success( - self.store.have_seen_events("room1", [self.event_ids[0], "event19"]) + self.store.have_seen_events( + self.room_id, [self.event_ids[0], "eventdoesnotexist"] + ) ) self.assertEqual(res, {self.event_ids[0]}) @@ -104,7 +83,9 @@ class HaveSeenEventsTestCase(unittest.HomeserverTestCase): # a second lookup of the same events should cause no queries with LoggingContext(name="test") as ctx: res = self.get_success( - self.store.have_seen_events("room1", [self.event_ids[0], "event19"]) + self.store.have_seen_events( + self.room_id, [self.event_ids[0], "eventdoesnotexist"] + ) ) self.assertEqual(res, {self.event_ids[0]}) self.assertEqual(ctx.get_resource_usage().db_txn_count, 0) @@ -116,11 +97,86 @@ class HaveSeenEventsTestCase(unittest.HomeserverTestCase): # looking it up should now cause no db hits with LoggingContext(name="test") as ctx: res = self.get_success( - self.store.have_seen_events("room1", [self.event_ids[0]]) + self.store.have_seen_events(self.room_id, [self.event_ids[0]]) ) self.assertEqual(res, {self.event_ids[0]}) self.assertEqual(ctx.get_resource_usage().db_txn_count, 0) + def test_persisting_event_invalidates_cache(self): + """ + Test to make sure that the `have_seen_event` cache + is invalidated after we persist an event and returns + the updated value. + """ + event, event_context = self.get_success( + create_event( + self.hs, + room_id=self.room_id, + sender=self.user, + type="test_event_type", + content={"body": "garply"}, + ) + ) + + with LoggingContext(name="test") as ctx: + # First, check `have_seen_event` for an event we have not seen yet + # to prime the cache with a `false` value. + res = self.get_success( + self.store.have_seen_events(event.room_id, [event.event_id]) + ) + self.assertEqual(res, set()) + + # That should result in a single db query to lookup + self.assertEqual(ctx.get_resource_usage().db_txn_count, 1) + + # Persist the event which should invalidate or prefill the + # `have_seen_event` cache so we don't return stale values. + persistence = self.hs.get_storage_controllers().persistence + self.get_success( + persistence.persist_event( + event, + event_context, + ) + ) + + with LoggingContext(name="test") as ctx: + # Check `have_seen_event` again and we should see the updated fact + # that we have now seen the event after persisting it. + res = self.get_success( + self.store.have_seen_events(event.room_id, [event.event_id]) + ) + self.assertEqual(res, {event.event_id}) + + # That should result in a single db query to lookup + self.assertEqual(ctx.get_resource_usage().db_txn_count, 1) + + def test_invalidate_cache_by_room_id(self): + """ + Test to make sure that all events associated with the given `(room_id,)` + are invalidated in the `have_seen_event` cache. + """ + with LoggingContext(name="test") as ctx: + # Prime the cache with some values + res = self.get_success( + self.store.have_seen_events(self.room_id, self.event_ids) + ) + self.assertEqual(res, set(self.event_ids)) + + # That should result in a single db query to lookup + self.assertEqual(ctx.get_resource_usage().db_txn_count, 1) + + # Clear the cache with any events associated with the `room_id` + self.store.have_seen_event.invalidate((self.room_id,)) + + with LoggingContext(name="test") as ctx: + res = self.get_success( + self.store.have_seen_events(self.room_id, self.event_ids) + ) + self.assertEqual(res, set(self.event_ids)) + + # Since we cleared the cache, it should result in another db query to lookup + self.assertEqual(ctx.get_resource_usage().db_txn_count, 1) + class EventCacheTestCase(unittest.HomeserverTestCase): """Test that the various layers of event cache works.""" diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py index 48e616ac7..90861fe52 100644 --- a/tests/util/caches/test_descriptors.py +++ b/tests/util/caches/test_descriptors.py @@ -13,7 +13,7 @@ # See the License for the specific language governing permissions and # limitations under the License. import logging -from typing import Set +from typing import Iterable, Set, Tuple from unittest import mock from twisted.internet import defer, reactor @@ -1008,3 +1008,34 @@ class CachedListDescriptorTestCase(unittest.TestCase): obj.inner_context_was_finished, "Tried to restart a finished logcontext" ) self.assertEqual(current_context(), SENTINEL_CONTEXT) + + def test_num_args_mismatch(self): + """ + Make sure someone does not accidentally use @cachedList on a method with + a mismatch in the number args to the underlying single cache method. + """ + + class Cls: + @descriptors.cached(tree=True) + def fn(self, room_id, event_id): + pass + + # This is wrong ❌. `@cachedList` expects to be given the same number + # of arguments as the underlying cached function, just with one of + # the arguments being an iterable + @descriptors.cachedList(cached_method_name="fn", list_name="keys") + def list_fn(self, keys: Iterable[Tuple[str, str]]): + pass + + # Corrected syntax ✅ + # + # @cachedList(cached_method_name="fn", list_name="event_ids") + # async def list_fn( + # self, room_id: str, event_ids: Collection[str], + # ) + + obj = Cls() + + # Make sure this raises an error about the arg mismatch + with self.assertRaises(Exception): + obj.list_fn([("foo", "bar")])