diff options
Diffstat (limited to 'synapse/storage/databases')
| -rw-r--r-- | synapse/storage/databases/main/event_federation.py | 90 |
1 files changed, 78 insertions, 12 deletions
diff --git a/synapse/storage/databases/main/event_federation.py b/synapse/storage/databases/main/event_federation.py index 3251fca6fb..17f2fd4458 100644 --- a/synapse/storage/databases/main/event_federation.py +++ b/synapse/storage/databases/main/event_federation.py @@ -726,17 +726,35 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas async def get_backfill_points_in_room( self, room_id: str, + current_depth: int, + limit: int, ) -> List[Tuple[str, int]]: """ - Gets the oldest events(backwards extremities) in the room along with the - approximate depth. Sorted by depth, highest to lowest (descending). + Get the backward extremities to backfill from in the room along with the + approximate depth. + + Only returns events that are at a depth lower than or + equal to the `current_depth`. Sorted by depth, highest to lowest (descending) + so the closest events to the `current_depth` are first in the list. + + We ignore extremities that are newer than the user's current scroll position + (ie, those with depth greater than `current_depth`) as: + 1. we don't really care about getting events that have happened + after our current position; and + 2. by the nature of paginating and scrolling back, we have likely + previously tried and failed to backfill from that extremity, so + to avoid getting "stuck" requesting the same backfill repeatedly + we drop those extremities. Args: room_id: Room where we want to find the oldest events + current_depth: The depth at the user's current scrollback position + limit: The max number of backfill points to return Returns: List of (event_id, depth) tuples. Sorted by depth, highest to lowest - (descending) + (descending) so the closest events to the `current_depth` are first + in the list. """ def get_backfill_points_in_room_txn( @@ -785,6 +803,18 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas */ AND edge.is_state is ? /* False */ /** + * We only want backwards extremities that are older than or at + * the same position of the given `current_depth` (where older + * means less than the given depth) because we're looking backwards + * from the `current_depth` when backfilling. + * + * current_depth (ignore events that come after this, ignore 2-4) + * | + * ▼ + * <oldest-in-time> [0]<--[1]<--[2]<--[3]<--[4] <newest-in-time> + */ + AND event.depth <= ? /* current_depth */ + /** * Exponential back-off (up to the upper bound) so we don't retry the * same backfill point over and over. ex. 2hr, 4hr, 8hr, 16hr, etc. * @@ -798,11 +828,13 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas OR ? /* current_time */ >= failed_backfill_attempt_info.last_attempt_ts + /*least*/%s((1 << failed_backfill_attempt_info.num_attempts) * ? /* step */, ? /* upper bound */) ) /** - * Sort from highest to the lowest depth. Then tie-break on - * alphabetical order of the event_ids so we get a consistent - * ordering which is nice when asserting things in tests. + * Sort from highest (closest to the `current_depth`) to the lowest depth + * because the closest are most relevant to backfill from first. + * Then tie-break on alphabetical order of the event_ids so we get a + * consistent ordering which is nice when asserting things in tests. */ ORDER BY event.depth DESC, backward_extrem.event_id DESC + LIMIT ? """ if isinstance(self.database_engine, PostgresEngine): @@ -817,9 +849,11 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas ( room_id, False, + current_depth, self._clock.time_msec(), 1000 * BACKFILL_EVENT_EXPONENTIAL_BACKOFF_STEP_SECONDS, 1000 * BACKFILL_EVENT_BACKOFF_UPPER_BOUND_SECONDS, + limit, ), ) @@ -835,18 +869,34 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas async def get_insertion_event_backward_extremities_in_room( self, room_id: str, + current_depth: int, + limit: int, ) -> List[Tuple[str, int]]: """ Get the insertion events we know about that we haven't backfilled yet - along with the approximate depth. Sorted by depth, highest to lowest - (descending). + along with the approximate depth. Only returns insertion events that are + at a depth lower than or equal to the `current_depth`. Sorted by depth, + highest to lowest (descending) so the closest events to the + `current_depth` are first in the list. + + We ignore insertion events that are newer than the user's current scroll + position (ie, those with depth greater than `current_depth`) as: + 1. we don't really care about getting events that have happened + after our current position; and + 2. by the nature of paginating and scrolling back, we have likely + previously tried and failed to backfill from that insertion event, so + to avoid getting "stuck" requesting the same backfill repeatedly + we drop those insertion event. Args: room_id: Room where we want to find the oldest events + current_depth: The depth at the user's current scrollback position + limit: The max number of insertion event extremities to return Returns: List of (event_id, depth) tuples. Sorted by depth, highest to lowest - (descending) + (descending) so the closest events to the `current_depth` are first + in the list. """ def get_insertion_event_backward_extremities_in_room_txn( @@ -870,6 +920,18 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas WHERE insertion_event_extremity.room_id = ? /** + * We only want extremities that are older than or at + * the same position of the given `current_depth` (where older + * means less than the given depth) because we're looking backwards + * from the `current_depth` when backfilling. + * + * current_depth (ignore events that come after this, ignore 2-4) + * | + * ▼ + * <oldest-in-time> [0]<--[1]<--[2]<--[3]<--[4] <newest-in-time> + */ + AND event.depth <= ? /* current_depth */ + /** * Exponential back-off (up to the upper bound) so we don't retry the * same backfill point over and over. ex. 2hr, 4hr, 8hr, 16hr, etc * @@ -883,11 +945,13 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas OR ? /* current_time */ >= failed_backfill_attempt_info.last_attempt_ts + /*least*/%s((1 << failed_backfill_attempt_info.num_attempts) * ? /* step */, ? /* upper bound */) ) /** - * Sort from highest to the lowest depth. Then tie-break on - * alphabetical order of the event_ids so we get a consistent - * ordering which is nice when asserting things in tests. + * Sort from highest (closest to the `current_depth`) to the lowest depth + * because the closest are most relevant to backfill from first. + * Then tie-break on alphabetical order of the event_ids so we get a + * consistent ordering which is nice when asserting things in tests. */ ORDER BY event.depth DESC, insertion_event_extremity.event_id DESC + LIMIT ? """ if isinstance(self.database_engine, PostgresEngine): @@ -901,9 +965,11 @@ class EventFederationWorkerStore(SignatureWorkerStore, EventsWorkerStore, SQLBas sql % (least_function,), ( room_id, + current_depth, self._clock.time_msec(), 1000 * BACKFILL_EVENT_EXPONENTIAL_BACKOFF_STEP_SECONDS, 1000 * BACKFILL_EVENT_BACKOFF_UPPER_BOUND_SECONDS, + limit, ), ) return cast(List[Tuple[str, int]], txn.fetchall()) |