Remove the corresponding calls, add module-level doc-comments with
explanations on what the hell is going on.

This also fixes some flaky tests including #1294

Turns out blocking inside proc_replication_demote is not safe, as it may
lead to deadlocking if a replicaset master switchover happens during
a replicaset catch-up via raft snapshot. The symptom of the problem was
the flakiness of the tests (for example issue #1294).

Closes #1294

This reverts commit ec2b760a.

Added a `wait_index` parameter to `proc_replication_demote` to improve
synchronization during demotion operations.

Diana Tikhonova authored 3 months ago and Diana Tikhonova committed 2 months ago

Key updates include:
Adding the term field to relevant RPC requests (ConfigureReplicationRequest, ReplicationSyncRequest, and DemoteRequest).
Utilizing node.status().check_term(req.term) in critical sections of the replication logic.

This patch changes when we update current_master_name during consistent
master switchover. Now it is updated as soon as we determine that the
new master has synchronized it's vclock with the old master.

As a result we can now block expel of a non-last replica in cases where
other replicas are offline, which is crucial because instances can
easily become offline due to temporary network issues.

Now we assume instance may not respond if
- target state is Offline (non-graceful assumed)
- current state is Expelled

godzie44 authored 6 months ago and Georgy Moshkin committed 5 months ago

Closes #664

Georgy Moshkin authored 6 months ago and Yaroslav Dynnikov committed 5 months ago

Strictness!

Move vshard related fields from _pico_property to _pico_tier
and adapt it in governor algorithm

This reverts commit d7e93cfc.

There's still some raft operations which we can't switch to
compare_and_swap yet unfortunately.

Closes #875

I'm not sure but I think it was added before we switched to counting
vshard config versions. Basically it was fixing the same A-B-A problem
but only in a single case.

Just goes to show how you shouldn't apply hacky fixes to problems you
don't fully understand.

BTW nobody is ever reading this message, the commit only removes the
code so nobody will ever bump into it going over git blame...