Security-review finding F2: two concurrent acquire() calls on the same
MigrationLock instance could each check out a connection; the second
pg_advisory_lock would overwrite this.client, leaking the first locked
connection until session end.
acquire() now memoizes the in-flight acquire in acquireInFlight and
returns it on re-entry, so exactly one connection is checked out and no
locked connection leaks. The memo is cleared once the acquire settles.
tryAcquire()/release() paths unchanged.
Locked in by:
- static criterion test: acquireInFlight field, re-entry guard returns
the in-flight acquire, memo cleared on settle
- mutation probe: removing the re-entry guard fails the criterion
- real-stack probe: two concurrent acquire() calls on one instance leave
pool.totalCount at 1 (exactly one connection), the lock granted once,
nothing left after release; probe fails (hangs) on the pre-fix code
- CI job comment updated to reflect the re-entrancy criterion
implementer