Fix instantiation of message retention purge jobs

When figuring out which topological token to start a purge job at, we
need to do the following:

1. Figure out a timestamp before which events will be purged
2. Select the first stream ordering after that timestamp
3. Select info about the first event after that stream ordering
4. Build a topological token from that info

In some situations (e.g. quiet rooms with a short max_lifetime), there
might not be an event after the stream ordering at step 3, therefore we
abort the purge with the error `No event found`. To mitigate that, this
patch fetches the first event _before_ the stream ordering, instead of
after.
This commit is contained in:
Brendan Abolivier 2020-01-15 18:56:18 +00:00
parent b5ce7f5874
commit 855af069a4
No known key found for this signature in database
GPG key ID: 1E015C145F1916CD
2 changed files with 48 additions and 13 deletions

View file

@ -156,7 +156,7 @@ class PaginationHandler(object):
stream_ordering = yield self.store.find_first_stream_ordering_after_ts(ts)
r = yield self.store.get_room_event_after_stream_ordering(
r = yield self.store.get_room_event_before_stream_ordering(
room_id, stream_ordering,
)
if not r:

View file

@ -536,21 +536,56 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
Deferred[(int, int, str)]:
(stream ordering, topological ordering, event_id)
"""
return self.db.runInteraction(
"get_room_event_after_stream_ordering",
self.get_room_event_around_stream_ordering_txn,
room_id, stream_ordering, "f",
)
def _f(txn):
def get_room_event_before_stream_ordering(self, room_id, stream_ordering):
"""Gets details of the first event in a room at or before a stream ordering
Args:
room_id (str):
stream_ordering (int):
Returns:
Deferred[(int, int, str)]:
(stream ordering, topological ordering, event_id)
"""
return self.db.runInteraction(
"get_room_event_before_stream_ordering",
self.get_room_event_around_stream_ordering_txn,
room_id, stream_ordering, "f",
)
def get_room_event_around_stream_ordering_txn(
self, txn, room_id, stream_ordering, dir="f"
):
"""Gets details of the first event in a room at or either after or before a
stream ordering, depending on the provided direction.
Args:
room_id (str):
stream_ordering (int):
dir (str): Direction in which we're looking towards in the room's history,
either "f" (forward) or "b" (backward).
Returns:
Deferred[(int, int, str)]:
(stream ordering, topological ordering, event_id)
"""
sql = (
"SELECT stream_ordering, topological_ordering, event_id"
" FROM events"
" WHERE room_id = ? AND stream_ordering >= ?"
" WHERE room_id = ? AND stream_ordering %s ?"
" AND NOT outlier"
" ORDER BY stream_ordering"
" LIMIT 1"
)
) % ("<=" if dir == "b" else ">=",)
txn.execute(sql, (room_id, stream_ordering))
return txn.fetchone()
return self.db.runInteraction("get_room_event_after_stream_ordering", _f)
@defer.inlineCallbacks
def get_room_events_max_id(self, room_id=None):
"""Returns the current token for rooms stream.