diff options
| -rw-r--r-- | synapse/replication/tcp/streams/events.py | 113 | ||||
| -rw-r--r-- | synapse/storage/data_stores/main/events_worker.py | 46 |
2 files changed, 129 insertions, 30 deletions
diff --git a/synapse/replication/tcp/streams/events.py b/synapse/replication/tcp/streams/events.py index 051114596b..aa50492569 100644 --- a/synapse/replication/tcp/streams/events.py +++ b/synapse/replication/tcp/streams/events.py @@ -15,11 +15,12 @@ # limitations under the License. import heapq -from typing import Iterable, Tuple, Type +from collections import Iterable +from typing import List, Tuple, Type import attr -from ._base import Stream, Token, db_query_to_update_function +from ._base import Stream, StreamUpdateResult, Token """Handling of the 'events' replication stream @@ -117,30 +118,106 @@ class EventsStream(Stream): def __init__(self, hs): self._store = hs.get_datastore() super().__init__( - self._store.get_current_events_token, - db_query_to_update_function(self._update_function), + self._store.get_current_events_token, self._update_function, ) async def _update_function( - self, from_token: Token, current_token: Token, limit: int - ) -> Iterable[tuple]: + self, from_token: Token, current_token: Token, target_row_count: int + ) -> StreamUpdateResult: + + # the events stream merges together three separate sources: + # * new events + # * current_state changes + # * events which were previously outliers, but have now been de-outliered. + # + # The merge operation is complicated by the fact that we only have a single + # "stream token" which is supposed to indicate how far we have got through + # all three streams. It's therefore no good to return rows 1-1000 from the + # "new events" table if the state_deltas are limited to rows 1-100 by the + # target_row_count. + # + # In other words: we must pick a new upper limit, and must return *all* rows + # up to that point for each of the three sources. + # + # Start by trying to split the target_row_count up. We expect to have a + # negligible number of ex-outliers, and a rough approximation based on recent + # traffic on sw1v.org shows that there are approximately the same number of + # event rows between a given pair of stream ids as there are state + # updates, so let's split our target_row_count among those two types. The target + # is only an approximation - it doesn't matter if we end up going a bit over it. + + target_row_count //= 2 + + # now we fetch up to that many rows from the events table + event_rows = await self._store.get_all_new_forward_event_rows( - from_token, current_token, limit - ) - event_updates = ( - (row[0], EventsStreamEventRow.TypeId, row[1:]) for row in event_rows - ) + from_token, current_token, target_row_count + ) # type: List[Tuple] + + # we rely on get_all_new_forward_event_rows strictly honouring the limit, so + # that we know it is safe to just take upper_limit = event_rows[-1][0]. + assert ( + len(event_rows) <= target_row_count + ), "get_all_new_forward_event_rows did not honour row limit" + + # if we hit the limit on event_updates, there's no point in going beyond the + # last stream_id in the batch for the other sources. + + if len(event_rows) == target_row_count: + limited = True + upper_limit = event_rows[-1][0] # type: int + else: + limited = False + upper_limit = current_token + + # next up is the state delta table state_rows = await self._store.get_all_updated_current_state_deltas( - from_token, current_token, limit - ) - state_updates = ( - (row[0], EventsStreamCurrentStateRow.TypeId, row[1:]) for row in state_rows - ) + from_token, upper_limit, target_row_count + ) # type: List[Tuple] + + # again, if we've hit the limit there, we'll need to limit the other sources + assert len(state_rows) < target_row_count + if len(state_rows) == target_row_count: + assert state_rows[-1][0] <= upper_limit + upper_limit = state_rows[-1][0] + limited = True + + # FIXME: is it a given that there is only one row per stream_id in the + # state_deltas table (so that we can be sure that we have got all of the + # rows for upper_limit)? + + # finally, fetch the ex-outliers rows. We assume there are few enough of these + # not to bother with the limit. - all_updates = heapq.merge(event_updates, state_updates) + ex_outliers_rows = await self._store.get_ex_outlier_stream_rows( + from_token, upper_limit + ) # type: List[Tuple] - return all_updates + # we now need to turn the raw database rows returned into tuples suitable + # for the replication protocol (basically, we add an identifier to + # distinguish the row type). At the same time, we can limit the event_rows + # to the max stream_id from state_rows. + + event_updates = ( + (stream_id, (EventsStreamEventRow.TypeId, rest)) + for (stream_id, *rest) in event_rows + if stream_id <= upper_limit + ) # type: Iterable[Tuple[int, Tuple]] + + state_updates = ( + (stream_id, (EventsStreamCurrentStateRow.TypeId, rest)) + for (stream_id, *rest) in state_rows + ) # type: Iterable[Tuple[int, Tuple]] + + ex_outliers_updates = ( + (stream_id, (EventsStreamEventRow.TypeId, rest)) + for (stream_id, *rest) in ex_outliers_rows + ) # type: Iterable[Tuple[int, Tuple]] + + # we need to return a sorted list, so merge them together. + updates = list(heapq.merge(event_updates, state_updates, ex_outliers_updates)) + return updates, upper_limit, limited @classmethod def parse_row(cls, row): diff --git a/synapse/storage/data_stores/main/events_worker.py b/synapse/storage/data_stores/main/events_worker.py index accde349a7..ce8be72bfe 100644 --- a/synapse/storage/data_stores/main/events_worker.py +++ b/synapse/storage/data_stores/main/events_worker.py @@ -973,8 +973,18 @@ class EventsWorkerStore(SQLBaseStore): return self._stream_id_gen.get_current_token() def get_all_new_forward_event_rows(self, last_id, current_id, limit): - if last_id == current_id: - return defer.succeed([]) + """Returns new events, for the Events replication stream + + Args: + last_id: the last stream_id from the previous batch. + current_id: the maximum stream_id to return up to + limit: the maximum number of rows to return + + Returns: Deferred[List[Tuple]] + a list of events stream rows. Each tuple consists of a stream id as + the first element, followed by fields suitable for casting into an + EventsStreamRow. + """ def get_all_new_forward_event_rows(txn): sql = ( @@ -989,13 +999,26 @@ class EventsWorkerStore(SQLBaseStore): " LIMIT ?" ) txn.execute(sql, (last_id, current_id, limit)) - new_event_updates = txn.fetchall() + return txn.fetchall() - if len(new_event_updates) == limit: - upper_bound = new_event_updates[-1][0] - else: - upper_bound = current_id + return self.db.runInteraction( + "get_all_new_forward_event_rows", get_all_new_forward_event_rows + ) + + def get_ex_outlier_stream_rows(self, last_id, current_id): + """Returns de-outliered events, for the Events replication stream + Args: + last_id: the last stream_id from the previous batch. + current_id: the maximum stream_id to return up to + + Returns: Deferred[List[Tuple]] + a list of events stream rows. Each tuple consists of a stream id as + the first element, followed by fields suitable for casting into an + EventsStreamRow. + """ + + def get_ex_outlier_stream_rows_txn(txn): sql = ( "SELECT event_stream_ordering, e.event_id, e.room_id, e.type," " state_key, redacts, relates_to_id" @@ -1006,15 +1029,14 @@ class EventsWorkerStore(SQLBaseStore): " LEFT JOIN event_relations USING (event_id)" " WHERE ? < event_stream_ordering" " AND event_stream_ordering <= ?" - " ORDER BY event_stream_ordering DESC" + " ORDER BY event_stream_ordering ASC" ) - txn.execute(sql, (last_id, upper_bound)) - new_event_updates.extend(txn) - return new_event_updates + txn.execute(sql, (last_id, current_id)) + return txn.fetchall() return self.db.runInteraction( - "get_all_new_forward_event_rows", get_all_new_forward_event_rows + "get_ex_outlier_stream_rows", get_ex_outlier_stream_rows_txn ) def get_all_new_backfill_event_rows(self, last_id, current_id, limit): |