diff options
| -rw-r--r-- | synapse/storage/event_push_actions.py | 68 | ||||
| -rw-r--r-- | tests/storage/test_event_push_actions.py | 67 |
2 files changed, 120 insertions, 15 deletions
diff --git a/synapse/storage/event_push_actions.py b/synapse/storage/event_push_actions.py index 54b54dcc6a..a8c303e11e 100644 --- a/synapse/storage/event_push_actions.py +++ b/synapse/storage/event_push_actions.py @@ -493,15 +493,15 @@ class EventPushActionsWorkerStore(SQLBaseStore): """Gets the stream ordering corresponding to a given timestamp. Specifically, finds the stream_ordering of the first event that was - received after the timestamp. This is done by a binary search on the - events table, since there is no index on received_ts, so is + received on or after the timestamp. This is done by a binary search on + the events table, since there is no index on received_ts, so is relatively slow. Args: ts (int): timestamp in millis Returns: - Deferred[int]: stream ordering of the first event received after + Deferred[int]: stream ordering of the first event received on/after the timestamp """ return self.runInteraction( @@ -510,16 +510,24 @@ class EventPushActionsWorkerStore(SQLBaseStore): ts, ) - def _find_first_stream_ordering_after_ts_txn(self, txn, ts): + @staticmethod + def _find_first_stream_ordering_after_ts_txn(txn, ts): """ - Find the stream_ordering of the first event that was received after - a given timestamp. This is relatively slow as there is no index on - received_ts but we can then use this to delete push actions before + Find the stream_ordering of the first event that was received on or + after a given timestamp. This is relatively slow as there is no index + on received_ts but we can then use this to delete push actions before this. received_ts must necessarily be in the same order as stream_ordering and stream_ordering is indexed, so we manually binary search using stream_ordering + + Args: + txn (twisted.enterprise.adbapi.Transaction): + ts (int): timestamp to search for + + Returns: + int: stream ordering """ txn.execute("SELECT MAX(stream_ordering) FROM events") max_stream_ordering = txn.fetchone()[0] @@ -527,23 +535,53 @@ class EventPushActionsWorkerStore(SQLBaseStore): if max_stream_ordering is None: return 0 + # We want the first stream_ordering in which received_ts is greater + # than or equal to ts. Call this point X. + # + # We maintain the invariants: + # + # range_start <= X <= range_end + # range_start = 0 - range_end = max_stream_ordering - + range_end = max_stream_ordering + 1 + + # Given a stream_ordering, look up the timestamp at that + # stream_ordering. + # + # The array may be sparse (we may be missing some stream_orderings). + # We treat the gaps as the same as having the same value as the + # preceding entry, because we will pick the lowest stream_ordering + # which satisfies our requirement of received_ts >= ts. + # + # For example, if our array of events indexed by stream_ordering is + # [10, <none>, 20], we should treat this as being equivalent to + # [10, 10, 20]. + # sql = ( "SELECT received_ts FROM events" - " WHERE stream_ordering > ?" - " ORDER BY stream_ordering" + " WHERE stream_ordering <= ?" + " ORDER BY stream_ordering DESC" " LIMIT 1" ) - while range_end - range_start > 1: - middle = int((range_end + range_start) / 2) + while range_end - range_start > 0: + middle = (range_end + range_start) // 2 txn.execute(sql, (middle,)) - middle_ts = txn.fetchone()[0] + row = txn.fetchone() + if row is None: + # no rows with stream_ordering<=middle + range_start = middle + 1 + continue + + middle_ts = row[0] if ts > middle_ts: - range_start = middle + # we got a timestamp lower than the one we were looking for. + # definitely need to look higher: X > middle. + range_start = middle + 1 else: + # we got a timestamp higher than (or the same as) the one we + # were looking for. We aren't yet sure about the point we + # looked up, but we can be sure that X <= middle. range_end = middle return range_end diff --git a/tests/storage/test_event_push_actions.py b/tests/storage/test_event_push_actions.py index 6c1aad149b..dbaaa12e23 100644 --- a/tests/storage/test_event_push_actions.py +++ b/tests/storage/test_event_push_actions.py @@ -127,3 +127,70 @@ class EventPushActionsStoreTestCase(tests.unittest.TestCase): yield _assert_counts(1, 1) yield _rotate(10) yield _assert_counts(1, 1) + + @tests.unittest.DEBUG + @defer.inlineCallbacks + def test_find_first_stream_ordering_after_ts(self): + def add_event(so, ts): + return self.store._simple_insert("events", { + "stream_ordering": so, + "received_ts": ts, + "event_id": "event%i" % so, + "type": "", + "room_id": "", + "content": "", + "processed": True, + "outlier": False, + "topological_ordering": 0, + "depth": 0, + }) + + # start with the base case where there are no events in the table + r = yield self.store.find_first_stream_ordering_after_ts(11) + self.assertEqual(r, 0) + + # now with one event + yield add_event(2, 10) + r = yield self.store.find_first_stream_ordering_after_ts(9) + self.assertEqual(r, 2) + r = yield self.store.find_first_stream_ordering_after_ts(10) + self.assertEqual(r, 2) + r = yield self.store.find_first_stream_ordering_after_ts(11) + self.assertEqual(r, 3) + + # add a bunch of dummy events to the events table + for (stream_ordering, ts) in ( + (3, 110), + (4, 120), + (5, 120), + (10, 130), + (20, 140), + ): + yield add_event(stream_ordering, ts) + + r = yield self.store.find_first_stream_ordering_after_ts(110) + self.assertEqual(r, 3, + "First event after 110ms should be 3, was %i" % r) + + # 4 and 5 are both after 12: we want 4 rather than 5 + r = yield self.store.find_first_stream_ordering_after_ts(120) + self.assertEqual(r, 4, + "First event after 120ms should be 4, was %i" % r) + + r = yield self.store.find_first_stream_ordering_after_ts(129) + self.assertEqual(r, 10, + "First event after 129ms should be 10, was %i" % r) + + # check we can get the last event + r = yield self.store.find_first_stream_ordering_after_ts(140) + self.assertEqual(r, 20, + "First event after 14ms should be 20, was %i" % r) + + # off the end + r = yield self.store.find_first_stream_ordering_after_ts(160) + self.assertEqual(r, 21) + + # check we can find an event at ordering zero + yield add_event(0, 5) + r = yield self.store.find_first_stream_ordering_after_ts(1) + self.assertEqual(r, 0) |