From e8f30a76caa4394ebb3e77c56df951e3626b3fdd Mon Sep 17 00:00:00 2001 From: David Robertson Date: Fri, 30 Sep 2022 11:54:53 +0100 Subject: Fix overflows in /messages backfill calculation (#13936) * Reproduce bug * Compute `least_function` first * Substitute `least_function` with an f-string * Bugfix: avoid overflow Co-authored-by: Eric Eastwood --- tests/storage/test_event_federation.py | 61 +++++++++++++++++++++++++++------- 1 file changed, 49 insertions(+), 12 deletions(-) (limited to 'tests/storage') diff --git a/tests/storage/test_event_federation.py b/tests/storage/test_event_federation.py index 398f338b66..59b8910907 100644 --- a/tests/storage/test_event_federation.py +++ b/tests/storage/test_event_federation.py @@ -766,9 +766,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): self.store.get_backfill_points_in_room(room_id, depth_map["B"], limit=100) ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] - self.assertListEqual( - backfill_event_ids, ["b6", "b5", "b4", "2", "b3", "b2", "b1"] - ) + self.assertEqual(backfill_event_ids, ["b6", "b5", "b4", "2", "b3", "b2", "b1"]) # Try at "A" backfill_points = self.get_success( @@ -814,7 +812,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] # Only the backfill points that we didn't record earlier exist here. - self.assertListEqual(backfill_event_ids, ["b6", "2", "b1"]) + self.assertEqual(backfill_event_ids, ["b6", "2", "b1"]) def test_get_backfill_points_in_room_attempted_event_retry_after_backoff_duration( self, @@ -860,7 +858,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): self.store.get_backfill_points_in_room(room_id, depth_map["A"], limit=100) ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] - self.assertListEqual(backfill_event_ids, ["b3", "b2"]) + self.assertEqual(backfill_event_ids, ["b3", "b2"]) # Now advance time by 20 hours (above 2^4 because we made 4 attemps) and # see if we can now backfill it @@ -871,7 +869,48 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): self.store.get_backfill_points_in_room(room_id, depth_map["A"], limit=100) ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] - self.assertListEqual(backfill_event_ids, ["b3", "b2", "b1"]) + self.assertEqual(backfill_event_ids, ["b3", "b2", "b1"]) + + def test_get_backfill_points_in_room_works_after_many_failed_pull_attempts_that_could_naively_overflow( + self, + ) -> None: + """ + A test that reproduces #13929 (Postgres only). + + Test to make sure we can still get backfill points after many failed pull + attempts that cause us to backoff to the limit. Even if the backoff formula + would tell us to wait for more seconds than can be expressed in a 32 bit + signed int. + """ + setup_info = self._setup_room_for_backfill_tests() + room_id = setup_info.room_id + depth_map = setup_info.depth_map + + # Pretend that we have tried and failed 10 times to backfill event b1. + for _ in range(10): + self.get_success( + self.store.record_event_failed_pull_attempt(room_id, "b1", "fake cause") + ) + + # If the backoff periods grow without limit: + # After the first failed attempt, we would have backed off for 1 << 1 = 2 hours. + # After the second failed attempt we would have backed off for 1 << 2 = 4 hours, + # so after the 10th failed attempt we should backoff for 1 << 10 == 1024 hours. + # Wait 1100 hours just so we have a nice round number. + self.reactor.advance(datetime.timedelta(hours=1100).total_seconds()) + + # 1024 hours in milliseconds is 1024 * 3600000, which exceeds the largest 32 bit + # signed integer. The bug we're reproducing is that this overflow causes an + # error in postgres preventing us from fetching a set of backwards extremities + # to retry fetching. + backfill_points = self.get_success( + self.store.get_backfill_points_in_room(room_id, depth_map["A"], limit=100) + ) + + # We should aim to fetch all backoff points: b1's latest backoff period has + # expired, and we haven't tried the rest. + backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] + self.assertEqual(backfill_event_ids, ["b3", "b2", "b1"]) def _setup_room_for_insertion_backfill_tests(self) -> _BackfillSetupInfo: """ @@ -965,9 +1004,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): ) ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] - self.assertListEqual( - backfill_event_ids, ["insertion_eventB", "insertion_eventA"] - ) + self.assertEqual(backfill_event_ids, ["insertion_eventB", "insertion_eventA"]) # Try at "insertion_eventA" backfill_points = self.get_success( @@ -1011,7 +1048,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] # Only the backfill points that we didn't record earlier exist here. - self.assertListEqual(backfill_event_ids, ["insertion_eventB"]) + self.assertEqual(backfill_event_ids, ["insertion_eventB"]) def test_get_insertion_event_backward_extremities_in_room_attempted_event_retry_after_backoff_duration( self, @@ -1069,7 +1106,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): ) ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] - self.assertListEqual(backfill_event_ids, []) + self.assertEqual(backfill_event_ids, []) # Now advance time by 20 hours (above 2^4 because we made 4 attemps) and # see if we can now backfill it @@ -1083,7 +1120,7 @@ class EventFederationWorkerStoreTestCase(tests.unittest.HomeserverTestCase): ) ) backfill_event_ids = [backfill_point[0] for backfill_point in backfill_points] - self.assertListEqual(backfill_event_ids, ["insertion_eventA"]) + self.assertEqual(backfill_event_ids, ["insertion_eventA"]) @attr.s -- cgit 1.4.1