Under unknown circumstances, the SQL layer may wrongly disregard an
invocation of thd_mark_transaction_to_rollback() when an InnoDB
transaction had been aborted (rolled back) due to one of the following errors:
* HA_ERR_LOCK_DEADLOCK
* HA_ERR_RECORD_CHANGED (if innodb_snapshot_isolation=ON)
* HA_ERR_LOCK_WAIT_TIMEOUT (if innodb_rollback_on_timeout=ON)
Such an error used to cause a crash of InnoDB during transaction commit.
These changes aim to catch and report the error earlier, so that not only
this crash can be avoided but also the original root cause be found and
fixed more easily later.
The idea of this fix is from Michael 'Monty' Widenius.
HA_ERR_ROLLBACK: A new error code that will be translated into
ER_ROLLBACK_ONLY, signalling that the current transaction
has been aborted and the only allowed action is ROLLBACK.
trx_t::state: Add TRX_STATE_ABORTED that is like
TRX_STATE_NOT_STARTED, but noting that the transaction had been
rolled back and aborted.
trx_t::is_started(): Replaces trx_is_started().
ha_innobase: Check the transaction state in various places.
Simplify the logic around SAVEPOINT.
ha_innobase::is_valid_trx(): Replaces ha_innobase::is_read_only().
The InnoDB logic around transaction savepoints, commit, and rollback
was unnecessarily complex and might have contributed to this
inconsistency. So, we are simplifying that logic as well.
trx_savept_t: Replace with const undo_no_t*. When we rollback to
a savepoint, all we need to know is the number of undo log records
that must survive.
trx_named_savept_t, DB_NO_SAVEPOINT: Remove. We can store undo_no_t
directly in the space allocated at innobase_hton->savepoint_offset.
fts_trx_create(): Do not copy previous savepoints.
fts_savepoint_rollback(): If a savepoint was not found, roll back
everything after the default savepoint of fts_trx_create().
The test innodb_fts.savepoint is extended to cover this code.
Reviewed by: Vladislav Lesin
Tested by: Matthias Leich
1. The merge aeccbbd926 has overwritten
lock0lock.cc, and the changes of MDEV-29622 and MDEV-29635 were
partially lost, this commit restores the changes.
2. innodb.deadlock_wait_thr_race test:
The following hang was found during testing.
There is deadlock_report_before_lock_releasing sync point in
Deadlock::report(), which is waiting for sel_cont signal under lock_sys_t
lock. The signal must be issued after "UPDATE t SET b = 100" rollback,
and that rollback is executing undo record, which is blocked
on dict_sys latch request. dict_sys is locked by the thread of statistics
update(dict_stats_save()), and during that update lock_sys lock is
requested, and can't be acquired as Deadlock::report() holds it. We have
to disable statistics update to make the test stable.
But even if statistics update is disabled, and transaction with consistent
snapshot is started at the very beginning of the test to prevent purging,
the purge can still be invoked for system tables, and it tries to open
system table by id, what causes dict_sys.freeze() call and dict_sys
latching. What, in combination with lock_sys::xx_lock() causes the same
deadlock as described above. We need to disable purging globally for the
test as well.
All the above is applicable to innodb.deadlock_wait_lock_race test also.
Returning DB_SUCCESS unconditionally if !trx->lock.wait_lock in
lock_trx_handle_wait() is wrong. Because even if
trx->lock.was_chosen_as_deadlock_victim was not set before the first check
in lock_trx_handle_wait(), it can be set after
the check, and trx->lock.wait_lock can be reset by another thread from
lock_reset_lock_and_trx_wait() if the transaction was chosen as deadlock
victim. In this case lock_trx_handle_wait() will return DB_SUCCESS even
the transaction was marked as deadlock victim, and continue execution
instead of rolling back.
The fix is to check trx->lock.was_chosen_as_deadlock_victim once more if
trx->lock.wait_lock is reset, as trx->lock.wait_lock can be reset only
after trx->lock.was_chosen_as_deadlock_victim was set if the transaction
was chosen as deadlock victim.
