Relax memory barrier for lock_word.
rw_lock_lock_word_decr() - used to acquire rw-lock, thus we only need to issue
ACQUIRE when we succeed locking.
rw_lock_x_lock_func_nowait() - same as above, but used to attempt to acquire
X-lock.
rw_lock_s_unlock_func() - used to release S-lock, RELEASE is what we need here.
rw_lock_x_unlock_func() - used to release X-lock. Ideally we'd need only RELEASE
here, but due to mess with waiters (they must be loaded after lock_word is
stored) we have to issue both ACQUIRE and RELEASE.
rw_lock_sx_unlock_func() - same as above, but used to release SX-lock.
rw_lock_s_lock_spin(), rw_lock_x_lock_func(), rw_lock_sx_lock_func() -
fetch-and-store to waiters has to issue only ACQUIRE memory barrier, so that
waiters are stored before lock_word is loaded.
Note that there is violation of RELEASE-ACQUIRE protocol here, because we do
on lock:
my_atomic_fas32_explicit((int32*) &lock->waiters, 1, MY_MEMORY_ORDER_ACQUIRE);
my_atomic_load32_explicit(&lock->lock_word, MY_MEMORY_ORDER_RELAXED);
on unlock
my_atomic_add32_explicit(&lock->lock_word, X_LOCK_DECR, MY_MEMORY_ORDER_ACQ_REL);
my_atomic_load32_explicit((int32*) &lock->waiters, MY_MEMORY_ORDER_RELAXED);
That is we kind of synchronize ACQUIRE on lock_word with ACQUIRE on waiters.
It was there before this patch. Simple fix may have negative performance impact.
Proper fix requires refactoring of lock_word.
Relax memory barrier for waiters: these 2 stores must be completed before
os_event_set() finishes. This is guaranteed by RELEASE barrier issued by
mutex.exit() of os_event_set().
Remove volatile modifier from waiters: it's not supposed for inter-thread
communication, use appropriate atomic operations instead.
Changed waiters to int32_t, my_atomic friendly type.
* again, as in 10.2, NOW is a keyword only if followed by parentheses
* use AS OF CURRENT_TIMESTAMP or AS OF NOW()
* AS OF CURRENT_TIMESTAMP and AS OF NOW() mean AS OF NOW(6),
not AS OF NOW(0), (same behavior as in a DEFAULT clause)
LOCK_thd_data was used to protect both THD data and
ensure that the THD is not deleted while it was in use
This patch moves the THD delete protection to LOCK_thd_kill,
which already protects the THD for kill.
The benefits are:
- More well defined what LOCK_thd_data protects
- LOCK_thd_data usage is now much simpler and easier to verify
- Less chance of deadlocks in SHOW PROCESS LIST as there is less
chance of interactions between mutexes
- Remove not needed LOCK_thread_count from
thd_get_error_context_description()
- Fewer mutex taken for thd->awake()
Other things:
- Don't take mysys->var mutex in show processlist to check if thread
is kill marked
- thd->awake() now automatically takes the LOCK_thd_kill mutex
(Simplifies code)
- Apc uses LOCK_thd_kill instead of LOCK_thd_data
This will allow show processlist to continue, without blocking
all new connections, if some threads gets stuck while holding
LOCK_thd_data or mysys_var->mutex
Connections that has mutex 'stuck' are marked as 'Busy' in 'Command'
Todo:
Make F_BACKOFF to do 'pause' instead of just (1)
- Remove not used thd_rpl_is_parallel()
- Remove not used mysql_notify_thread_having_shared_lock()
- Remove not needed LOCK_thread_count from MYSQL_BIN_LOG::reset_logs()
- LOCK_thread_count is not protecting against rollback, so this
code and comment is not needed
- Remove mutex_locks in slave.cc that are not needed.
Added THD::assert_not_linked() to ensure that it was safe to remove
- Fixed not repeatable test load_data_stmt_view
- Updated binlog_killed to test removal of mutex
(thanks to Andrei Elkin for test)
- More code comments
Allow DROP TABLE `#mysql50##sql-...._.` to drop tables that were
being rebuilt by ALGORITHM=INPLACE
NOTE: If the server is killed after the table-rebuilding ALGORITHM=INPLACE
commits inside InnoDB but before the .frm file has been replaced, then
the recovery will involve something else than DROP TABLE.
NOTE: If the server is killed in a true inplace ALTER TABLE commits
inside InnoDB but before the .frm file has been replaced, then we
are really out of luck. To properly handle that situation, we would
need a transactional mysql.ddl_fixup table that directs recovery to
rename or remove files.
prepare_inplace_alter_table_dict(): Use the altered_table->s->table_name
for generating the new_table_name.
table_name_t::part_suffix: The start of the partition name suffix.
table_name_t::dbend(): Return the end of the schema name.
table_name_t::dblen(): Return the length of the schema name, in bytes.
table_name_t::basename(): Return the name without the schema name.
table_name_t::part(): Return the partition name, or NULL if none.
row_drop_table_for_mysql(): Assert for #sql, not #sql-ib.
fseg_alloc_free_page_low(): Remove a bogus and redundant assertion about
fil_space_t::purpose. The debug function fsp_space_modify_check()
is asserting something similar, but more accurately.
When logging ROW_T_INSERT or ROW_T_UPDATE records, we did not normalize
the DB_TRX_ID of the current transaction into 0 if the current transaction
had started (modifying other tables) before the ALTER TABLE started.
MDEV-13654 introduced this normalization for ROW_T_DELETE
and for all operations with ADD PRIMARY KEY, in row_log_table_get_pk().
This was missing bug fix from MySQL wsrep i.e. Galera.
Problem was that if stored procedure declares a handler that
catches deadlock error, then the error may have been
cleared in method sp_rcontext::handle_sql_condition().
Use wsrep_conflict_state correctly to determine is the
error already sent to client.
Add test case for both this bug and MDEV-12837: WSREP: BF
lock wait long. Test requires both fixes to pass.
Problem was a merge error from MySQL wsrep i.e. Galera.
wsrep_on_check
New check function. Galera can't be enabled
if innodb-lock-schedule-algorithm=VATS.
innobase_kill_query
In Galera async kill we could own lock mutex.
innobase_init
If Variance-Aware-Transaction-Sheduling Algorithm (VATS) is
used on Galera we fall back to First-Come-First-Served (FCFS)
with notice to user.
Changed innodb-lock-schedule-algorithm as read-only parameter
as it was designed to be.
lock_reset_lock_and_trx_wait
Use ib::hex() to print out transaction ID.
lock_rec_other_has_expl_req,
lock_rec_other_has_conflicting,
RecLock::add_to_waitq
lock_rec_lock_slow
lock_table_other_has_incompatible
lock_rec_insert_check_and_lock
lock_prdt_other_has_conflicting
Change pointer to conflicting lock to normal pointer as this
pointer contents could be changed later.
RecLock::create
Conclicting lock pointer is moved to last parameter with
default value NULL. This conflicting transaction could
be selected as victim in Galera if requesting transaction
is BF (brute force) transaction. In this case contents
of conflicting lock pointer will be changed. Use ib::hex() to print
transaction ids.
Introduce the debug flag trx_t::persistent_stats to suppress the
assertion for the updates of persistent statistics during fast
shutdown.
dict_stats_exec_sql(): Do execute the statement even though shutdown
has been initiated.
