cleanup a bunch of stuff related to compare and swap requests

Summary

• fix: used to sometimes report incorrect raft term immediately after restarting

• fix: use picodata's system connection pool for CAS requests

• fix: unify which term is used for cas predicates

CAS predicates should always contain the current raft term, because this is what's explicitly checked in proc_cas.

Note that this will sometimes result in a EntryTermMismatch error because the latest applied entry may have a different term in case the election has started but not finished yet.

We could add this check to all the client cas precondition checks, but it's not a big deal, because we handle the situation correctly anyways.

• refactor: move wait_index into compare_and_swap

• refactor: compare_and_swap now accepts a deadline instead of a timeout

• refactor: massage compare_and_swap a bit

• fix: unify all places where we call compare_and_swap and wait for the result

• fix: check if DdlPrepare was rolled back before waiting for DdlCommit

Rolled back as in raft log roll back, which can happen when a leader changes to one who doesn't have the entry we persisted. Not to be confused with DdlAbort.

• fix: cas requests are always reconstructed before retrying

• fix: TermMismatch was always retriable, when did it stop?

• doc: add comments to retriable error codes explaing why they are retriable

---

• Cherry-pick to: none
• Docs follow-up: not necessary

changed milestone to %24.6 - Plugins and Tiers

requested review from @rosik

assigned to @gmoshkin

added 1 commit

• abe13a16 - refactor: move version bumping from governor Downgrade to update_instance

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changed title from fix: check if DdlPrepare was rolled back before waiting for DdlCommit to cleanup a bunch of stuff related to compare and swap requests

added 1 commit

• ed95d2d9 - refactor: move version bumping from governor Downgrade to update_instance

Compare with previous version

TermMismatch was always retriable, when did it stop?

Кажется тут — !1110 (diffs)

added 1 deleted label

added 17 commits

• ed95d2d9...2e89c858 - 4 commits from branch master
• 2e89c858...3638d336 - 3 earlier commits
• 9a3ddb19 - fix: check if DdlPrepare was rolled back before waiting for DdlCommit
• 185341d0 - fix: unify all places where we call compare_and_swap and wait for the result
• 904a10fe - refactor: massage compare_and_swap a bit
• 2a45387d - refactor: compare_and_swap now accepts a deadline instead of a timeout
• 15327a9f - refactor: move wait_index into compare_and_swap
• 575a9f29 - fix: unify which term is used for cas predicates
• bb855e66 - fix: use picodata's system connection pool for CAS requests
• 5e1d1efa - fix: used to sometimes report incorrect raft term immediately after restarting
• 96911a06 - refactor: move version bumping from governor Downgrade to update_instance
• 8b418218 - refactor: make sure current state is always set from target state

Compare with previous version

resolved all threads

enabled an automatic merge when the pipeline for 8b418218 succeeds

approved this merge request

merged

changed milestone to %24.5 - Lowercase