MDEV-7943 - pthread_getspecific() takes 0.76% in OLTP RO

Pass THD to Sort_and_group_tracker::report_sorting().
This reduces number of pthread_getspecific() calls from 292 to 290.

sql/sql_analyze_stmt.cc

@@ -67,7 +67,7 @@ void Filesort_tracker::print_json_members(Json_writer *writer)
       Tracker object to be used with filesort
 */
 
-Filesort_tracker *Sort_and_group_tracker::report_sorting()
+Filesort_tracker *Sort_and_group_tracker::report_sorting(THD *thd)
 {
   DBUG_ASSERT(cur_action < MAX_QEP_ACTIONS);
 
@@ -79,13 +79,13 @@ Filesort_tracker *Sort_and_group_tracker::report_sorting()
       varied_executions= true;
       cur_action++;
       if (!dummy_fsort_tracker)
-        dummy_fsort_tracker= new (current_thd->mem_root) Filesort_tracker();
+        dummy_fsort_tracker= new (thd->mem_root) Filesort_tracker();
       return dummy_fsort_tracker;
     }
     return qep_actions_data[cur_action++].filesort_tracker;
   }
 
-  Filesort_tracker *fs_tracker= new(current_thd->mem_root)Filesort_tracker();
+  Filesort_tracker *fs_tracker= new(thd->mem_root)Filesort_tracker();
   qep_actions_data[cur_action].filesort_tracker= fs_tracker;
   qep_actions[cur_action++]= EXPL_ACTION_FILESORT;
 

sql/sql_analyze_stmt.h

@@ -396,7 +396,7 @@ class Sort_and_group_tracker : public Sql_alloc
       @return 
         Tracker object to be used with filesort
   */
-  Filesort_tracker *report_sorting();
+  Filesort_tracker *report_sorting(THD *thd);
   
   friend class Iterator;
   /*************** Statistics retrieval interface ***************/

sql/sql_select.cc

@@ -21058,7 +21058,7 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order,
   filesort_retval= filesort(thd, table, join->sortorder, length,
                             select, filesort_limit, 0,
                             &examined_rows, &found_rows, 
-                            join->explain->ops_tracker.report_sorting());
+                            join->explain->ops_tracker.report_sorting(thd));
   table->sort.found_records= filesort_retval;
   tab->records= found_rows;                     // For SQL_CALC_ROWS