transaction: clear prewrite locks on rollback of a failed pessimistic commit#547
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transaction: clear prewrite locks on rollback of a failed pessimistic commit#547eduralph wants to merge 3 commits into
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… commit After a 2PC commit fails at prewrite, the already-placed prewrite (2PC) locks must be rolled back. The terminal pessimistic rollback sent PessimisticRollback, which only removes LockType::Pessimistic locks, so it silently left the prewrite locks behind while still returning Ok — leaving keys locked until TTL expiry and lock resolution. Roll back a pessimistic transaction that has started committing with BatchRollback (as the optimistic path and client-go's commit cleanup do), which clears locks by start_ts regardless of type. A pessimistic transaction rolled back before commit (locks still pessimistic) continues to use the narrower PessimisticRollback. Adds a failpoint regression test. Closes tikv#545 Signed-off-by: Eduard Ralph <eduard@ralphovi.net>
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📝 WalkthroughWalkthroughTransaction rollback now preserves whether commit reached prewrite, then uses that state to choose the rollback RPC. New failpoint tests cover lock cleanup after failed pessimistic commits and a rollback retry. ChangesPessimistic Rollback Lock Cleanup Fix
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In `@src/transaction/transaction.rs`:
- Around line 704-708: The rollback path in transaction logic recomputes
`prewritten` from `get_status()` after the status has already moved to
`StartedRollback`, so retrying `rollback()` can lose the fact that the txn had
started committing. Update `transaction::Transaction`/`rollback()` to persist
this rollback mode across retries, either by storing a dedicated flag or
preserving the commit-start state before the transition, and use that saved
state when choosing between `BatchRollback` and `PessimisticRollback`.
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src/transaction/transaction.rstests/failpoint_tests.rs
…llback rollback() recomputed `prewritten` from `get_status() == StartedCommit`, but transit_status permits re-entry from StartedRollback and a failed rollback leaves the status there. On retry, get_status() no longer reads StartedCommit, so `prewritten` became false and a pessimistic txn that had started committing fell back to PessimisticRollback, re-leaking the 2PC prewrite locks the previous commit fixed. Persist the flag on Transaction: set it when commit() enters the commit path and read it in rollback(), so it survives the StartedCommit -> StartedRollback transition and any rollback retry. Signed-off-by: Eduard Ralph <eduard@ralphovi.net>
Add a `before-rollback` failpoint in `Committer::rollback` and a regression test (`txn_pessimistic_rollback_retry_clears_prewrite_locks`) that forces the first rollback attempt to fail, then asserts the retry still clears the 2PC prewrite lock. This guards the `prewritten` flag now persisted across the StartedCommit -> StartedRollback transition: recomputing it from status on a retry would fall back to PessimisticRollback and leak the lock again. Refs tikv#545 Signed-off-by: Eduard Ralph <eduard@ralphovi.net>
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After a 2PC commit fails at prewrite, the already-placed prewrite (2PC) locks must be rolled back. The terminal pessimistic rollback sent PessimisticRollback, which only removes LockType::Pessimistic locks, so it silently left the prewrite locks behind while still returning Ok — leaving keys locked until TTL expiry and lock resolution.
Roll back a pessimistic transaction that has started committing with BatchRollback (as the optimistic path and client-go's commit cleanup do), which clears locks by start_ts regardless of type. A pessimistic transaction rolled back before commit (locks still pessimistic) continues to use the narrower PessimisticRollback.
Adds a failpoint regression test.
Closes #545
Signed-off-by: Eduard Ralph eduard@ralphovi.net
Summary by CodeRabbit
commit()fails after the prewrite/2PC stage, ensuring correct cleanup of any remaining 2PC and pessimistic locks.