MDEV-24258 Merge dict_sys.mutex into dict_sys.latchbb-10.6-MDEV-24258

Thanks to the preparation, dict_sys.latch was only being
acquired in exclusive mode. Thus, it could theoretically
have been replaced with a mutex. But, we can do better
and merge dict_sys.mutex into dict_sys.latch. Generally,
every occurrence of dict_sys.mutex_lock() will be replaced
with dict_sys.lock().

Much of the current use of dict_sys.lock() will be replaced
with dict_sys.freeze(), which we will reintroduce for the
new shared mode.

The PERFORMANCE_SCHEMA instrumentation for dict_sys_mutex
will be removed along with dict_sys.mutex. The dict_sys.latch
will remain instrumented as dict_operation_lock.

As demonstrated by the test perfschema.sxlock_func, there
will be less contention on dict_sys.latch, because some previous
use of exclusive latches will be replaced with shared latches.

fts_parse_sql_no_dict_lock(): Replaced with pars_sql().

fts_get_table_name_prefix(): Merged to fts_optimize_create().

dict_stats_update_transient_for_index(): Deduplicated some code.

ha_innobase::info_low(), dict_stats_stop_bg(): Use a combination
of dict_sys.latch and table->stats_mutex_lock() to cover the
changes of BG_STAT_SHOULD_QUIT, because the flag is being read
in dict_stats_update_persistent() while not holding dict_sys.latch.

row_discard_tablespace_for_mysql(): Protect stats_bg_flag by
exclusive dict_sys.latch, like most other code does.

row_quiesce_table_has_fts_index(): Remove unnecessary mutex
acquisition. FLUSH TABLES...FOR EXPORT is protected by MDL.

row_import::set_root_by_heuristic(): Remove unnecessary mutex
acquisition. ALTER TABLE...IMPORT TABLESPACE is protected by MDL.

row_ins_sec_index_entry_low(): Replace a call
to dict_set_corrupted_index_cache_only(). Reads of index->type
were not really protected by dict_sys.mutex, and writes
(flagging an index corrupted) should be extremely rare.

1 files changed, 1 insertions, 3 deletions

diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
index 81e0a3d2b79..d76a98e83e7 100644
--- a/storage/innobase/srv/srv0srv.cc
+++ b/storage/innobase/srv/srv0srv.cc
@@ -1297,7 +1297,7 @@ void srv_monitor_task(void*)
 			    || waited == threshold / 2
 			    || waited == threshold / 4 * 3) {
 				ib::warn() << "Long wait (" << waited
-					   << " seconds) for dict_sys.mutex";
+					   << " seconds) for dict_sys.latch";
 			}
 		}
 	}
@@ -1371,8 +1371,6 @@ void purge_sys_t::stop_SYS()
 /** Stop purge during FLUSH TABLES FOR EXPORT */
 void purge_sys_t::stop()
 {
-  dict_sys.assert_not_locked();
-
   for (;;)
   {
     latch.wr_lock(SRW_LOCK_CALL);