From 957e3d74fc70f92bb9ed3c709f87752bf77a8c90 Mon Sep 17 00:00:00 2001 From: Eric Eastwood Date: Wed, 14 Sep 2022 13:57:50 -0500 Subject: Keep track when we try and fail to process a pulled event (#13589) We can follow-up this PR with: 1. Only try to backfill from an event if we haven't tried recently -> https://github.com/matrix-org/synapse/issues/13622 1. When we decide to backfill that event again, process it in the background so it doesn't block and make `/messages` slow when we know it will probably fail again -> https://github.com/matrix-org/synapse/issues/13623 1. Generally track failures everywhere we try and fail to pull an event over federation -> https://github.com/matrix-org/synapse/issues/13700 Fix https://github.com/matrix-org/synapse/issues/13621 Part of https://github.com/matrix-org/synapse/issues/13356 Mentioned in [internal doc](https://docs.google.com/document/d/1lvUoVfYUiy6UaHB6Rb4HicjaJAU40-APue9Q4vzuW3c/edit#bookmark=id.qv7cj51sv9i5) --- tests/handlers/test_federation_event.py | 222 ++++++++++++++++++++++++++++++++ 1 file changed, 222 insertions(+) (limited to 'tests/handlers') diff --git a/tests/handlers/test_federation_event.py b/tests/handlers/test_federation_event.py index 51c8dd6498..b5b89405a4 100644 --- a/tests/handlers/test_federation_event.py +++ b/tests/handlers/test_federation_event.py @@ -227,3 +227,225 @@ class FederationEventHandlerTests(unittest.FederatingHomeserverTestCase): if prev_exists_as_outlier: self.mock_federation_transport_client.get_event.assert_not_called() + + def test_process_pulled_event_records_failed_backfill_attempts( + self, + ) -> None: + """ + Test to make sure that failed backfill attempts for an event are + recorded in the `event_failed_pull_attempts` table. + + In this test, we pretend we are processing a "pulled" event via + backfill. The pulled event has a fake `prev_event` which our server has + obviously never seen before so it attempts to request the state at that + `prev_event` which expectedly fails because it's a fake event. Because + the server can't fetch the state at the missing `prev_event`, the + "pulled" event fails the history check and is fails to process. + + We check that we correctly record the number of failed pull attempts + of the pulled event and as a sanity check, that the "pulled" event isn't + persisted. + """ + OTHER_USER = f"@user:{self.OTHER_SERVER_NAME}" + main_store = self.hs.get_datastores().main + + # Create the room + user_id = self.register_user("kermit", "test") + tok = self.login("kermit", "test") + room_id = self.helper.create_room_as(room_creator=user_id, tok=tok) + room_version = self.get_success(main_store.get_room_version(room_id)) + + # We expect an outbound request to /state_ids, so stub that out + self.mock_federation_transport_client.get_room_state_ids.return_value = make_awaitable( + { + # Mimic the other server not knowing about the state at all. + # We want to cause Synapse to throw an error (`Unable to get + # missing prev_event $fake_prev_event`) and fail to backfill + # the pulled event. + "pdu_ids": [], + "auth_chain_ids": [], + } + ) + # We also expect an outbound request to /state + self.mock_federation_transport_client.get_room_state.return_value = make_awaitable( + StateRequestResponse( + # Mimic the other server not knowing about the state at all. + # We want to cause Synapse to throw an error (`Unable to get + # missing prev_event $fake_prev_event`) and fail to backfill + # the pulled event. + auth_events=[], + state=[], + ) + ) + + pulled_event = make_event_from_dict( + self.add_hashes_and_signatures_from_other_server( + { + "type": "test_regular_type", + "room_id": room_id, + "sender": OTHER_USER, + "prev_events": [ + # The fake prev event will make the pulled event fail + # the history check (`Unable to get missing prev_event + # $fake_prev_event`) + "$fake_prev_event" + ], + "auth_events": [], + "origin_server_ts": 1, + "depth": 12, + "content": {"body": "pulled"}, + } + ), + room_version, + ) + + # The function under test: try to process the pulled event + with LoggingContext("test"): + self.get_success( + self.hs.get_federation_event_handler()._process_pulled_event( + self.OTHER_SERVER_NAME, pulled_event, backfilled=True + ) + ) + + # Make sure our failed pull attempt was recorded + backfill_num_attempts = self.get_success( + main_store.db_pool.simple_select_one_onecol( + table="event_failed_pull_attempts", + keyvalues={"event_id": pulled_event.event_id}, + retcol="num_attempts", + ) + ) + self.assertEqual(backfill_num_attempts, 1) + + # The function under test: try to process the pulled event again + with LoggingContext("test"): + self.get_success( + self.hs.get_federation_event_handler()._process_pulled_event( + self.OTHER_SERVER_NAME, pulled_event, backfilled=True + ) + ) + + # Make sure our second failed pull attempt was recorded (`num_attempts` was incremented) + backfill_num_attempts = self.get_success( + main_store.db_pool.simple_select_one_onecol( + table="event_failed_pull_attempts", + keyvalues={"event_id": pulled_event.event_id}, + retcol="num_attempts", + ) + ) + self.assertEqual(backfill_num_attempts, 2) + + # And as a sanity check, make sure the event was not persisted through all of this. + persisted = self.get_success( + main_store.get_event(pulled_event.event_id, allow_none=True) + ) + self.assertIsNone( + persisted, + "pulled event that fails the history check should not be persisted at all", + ) + + def test_process_pulled_event_clears_backfill_attempts_after_being_successfully_persisted( + self, + ) -> None: + """ + Test to make sure that failed pull attempts + (`event_failed_pull_attempts` table) for an event are cleared after the + event is successfully persisted. + + In this test, we pretend we are processing a "pulled" event via + backfill. The pulled event succesfully processes and the backward + extremeties are updated along with clearing out any failed pull attempts + for those old extremities. + + We check that we correctly cleared failed pull attempts of the + pulled event. + """ + OTHER_USER = f"@user:{self.OTHER_SERVER_NAME}" + main_store = self.hs.get_datastores().main + + # Create the room + user_id = self.register_user("kermit", "test") + tok = self.login("kermit", "test") + room_id = self.helper.create_room_as(room_creator=user_id, tok=tok) + room_version = self.get_success(main_store.get_room_version(room_id)) + + # allow the remote user to send state events + self.helper.send_state( + room_id, + "m.room.power_levels", + {"events_default": 0, "state_default": 0}, + tok=tok, + ) + + # add the remote user to the room + member_event = self.get_success( + event_injection.inject_member_event(self.hs, room_id, OTHER_USER, "join") + ) + + initial_state_map = self.get_success( + main_store.get_partial_current_state_ids(room_id) + ) + + auth_event_ids = [ + initial_state_map[("m.room.create", "")], + initial_state_map[("m.room.power_levels", "")], + member_event.event_id, + ] + + pulled_event = make_event_from_dict( + self.add_hashes_and_signatures_from_other_server( + { + "type": "test_regular_type", + "room_id": room_id, + "sender": OTHER_USER, + "prev_events": [member_event.event_id], + "auth_events": auth_event_ids, + "origin_server_ts": 1, + "depth": 12, + "content": {"body": "pulled"}, + } + ), + room_version, + ) + + # Fake the "pulled" event failing to backfill once so we can test + # if it's cleared out later on. + self.get_success( + main_store.record_event_failed_pull_attempt( + pulled_event.room_id, pulled_event.event_id, "fake cause" + ) + ) + # Make sure we have a failed pull attempt recorded for the pulled event + backfill_num_attempts = self.get_success( + main_store.db_pool.simple_select_one_onecol( + table="event_failed_pull_attempts", + keyvalues={"event_id": pulled_event.event_id}, + retcol="num_attempts", + ) + ) + self.assertEqual(backfill_num_attempts, 1) + + # The function under test: try to process the pulled event + with LoggingContext("test"): + self.get_success( + self.hs.get_federation_event_handler()._process_pulled_event( + self.OTHER_SERVER_NAME, pulled_event, backfilled=True + ) + ) + + # Make sure the failed pull attempts for the pulled event are cleared + backfill_num_attempts = self.get_success( + main_store.db_pool.simple_select_one_onecol( + table="event_failed_pull_attempts", + keyvalues={"event_id": pulled_event.event_id}, + retcol="num_attempts", + allow_none=True, + ) + ) + self.assertIsNone(backfill_num_attempts) + + # And as a sanity check, make sure the "pulled" event was persisted. + persisted = self.get_success( + main_store.get_event(pulled_event.event_id, allow_none=True) + ) + self.assertIsNotNone(persisted, "pulled event was not persisted at all") -- cgit 1.4.1