evolution-gaming / kafka-journal / 11401243087

94%

Build Type

push

Committed by web-flow

Commit Message

optimization of `append + delete` actions leads to inconsistent state in metajournal table (#676)

We optimize actions to reduce load on Cassandra when in single poll we
get actions like:
* append @ 5
* append @ 6
* delete till 6

Optimization removed previous append actions, when `delete` would remove
them after insertion.

The optimization keeps the `journal` table in shape, but it fails to
update `metajournal` table, like when:
* `metajournal` table has entry with `deleteTo: 4; seqNr: 4`
* after receiving above-mentioned batch, we update `deleteTo` to `4` and
`seqNr` stays as it was
* result is that we have `deleteTo: 4; seqNr: 4` (as `DeleteTo` got
clamped down to existing `seqNr` to not overshoot future events in
journal) - we lost updates: `seqNr: 6` and didn't update `deleteTo: 6`

This happens rarely, usually when client is quiet for some time and then
issues "closing" statements.

As this optimization drops `append @ 6`, it misses update of
`expire_after` column in Cassandra.

Run Details

13 of 15 new or added lines in 1 file covered. (86.67%)

12 existing lines in 11 files now uncovered.

3181 of 3826 relevant lines covered (83.14%)

1.4 hits per line