Consider the following:
1) balancer emits split decision
2) split compaction starts
3) split decision is revoked
4) emits merge decision
5) completes merge, before compaction in step 2 finishes
After last step, split compaction initiated in step 2 can fail
because it works with the global tablet map, rather than the
map when the compaction started. With the global state changing
under its feet, on merge, the mutation splitting writer will
think it's going backwards since sibling tablets are merged.
This problem was also seen when running load-and-stream, where
split initiated by the sstable writer failed, split completed,
and the unsplit sstable is left in the table dir, causing
problems in the restart.
To fix this, let's make split compaction always work with
the state when it started, not a global state.
Fixes#24153.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
68f23d54d8