Extended debug_sync_control life time

It now lives from THD constructor to THD destructor. Reset before THD is
released to a cache. Change user doesn't reset debug_sync_control anymore.

Needed to be able to make use of DEBUG_SYNC() at later stages like
ha_close_connection().

sql/debug_sync.cc

@@ -287,12 +287,6 @@ void debug_sync_end_thread(THD *thd)
   {
     st_debug_sync_control *ds_control= thd->debug_sync_control;
 
-    /*
-      This synchronization point can be used to synchronize on thread end.
-      This is the latest point in a THD's life, where this can be done.
-    */
-    DEBUG_SYNC(thd, "thread_end");
-
     if (ds_control->ds_action)
     {
       st_debug_sync_action *action= ds_control->ds_action;
@@ -322,6 +316,20 @@ void debug_sync_end_thread(THD *thd)
 }
 
 
+void debug_sync_reset_thread(THD *thd)
+{
+  if (thd->debug_sync_control)
+  {
+    /*
+      This synchronization point can be used to synchronize on thread end.
+      This is the latest point in a THD's life, where this can be done.
+    */
+    DEBUG_SYNC(thd, "thread_end");
+    thd->debug_sync_control->ds_active= 0;
+  }
+}
+
+
 /**
   Move a string by length.
 

sql/debug_sync.h

@@ -41,10 +41,14 @@ extern int  debug_sync_init(void);
 extern void debug_sync_end(void);
 extern void debug_sync_init_thread(THD *thd);
 extern void debug_sync_end_thread(THD *thd);
+void debug_sync_reset_thread(THD *thd);
 extern bool debug_sync_set_action(THD *thd, const char *action_str, size_t len);
 extern bool debug_sync_update(THD *thd, char *val_str, size_t len);
 extern uchar *debug_sync_value_ptr(THD *thd);
-
+#else
+static inline void debug_sync_init_thread(THD *thd) {}
+static inline void debug_sync_end_thread(THD *thd) {}
+static inline void debug_sync_reset_thread(THD *thd) {}
 #endif /* defined(ENABLED_DEBUG_SYNC) */
 
 #endif /* DEBUG_SYNC_INCLUDED */

sql/sql_class.cc

@@ -840,6 +840,7 @@ THD::THD(my_thread_id id, bool is_wsrep_applier)
   reset_open_tables_state(this);
 
   init();
+  debug_sync_init_thread(this);
 #if defined(ENABLED_PROFILING)
   profiling.set_thd(this);
 #endif
@@ -1320,11 +1321,6 @@ void THD::init()
   /* Set to handle counting of aborted connections */
   userstat_running= opt_userstat_running;
   last_global_update_time= current_connect_time= time(NULL);
-#if defined(ENABLED_DEBUG_SYNC)
-  /* Initialize the Debug Sync Facility. See debug_sync.cc. */
-  debug_sync_init_thread(this);
-#endif /* defined(ENABLED_DEBUG_SYNC) */
-
 #ifndef EMBEDDED_LIBRARY
   session_tracker.enable(this);
 #endif //EMBEDDED_LIBRARY
@@ -1576,11 +1572,6 @@ void THD::cleanup(void)
   }
   wt_thd_destroy(&transaction.wt);
 
-#if defined(ENABLED_DEBUG_SYNC)
-  /* End the Debug Sync Facility. See debug_sync.cc. */
-  debug_sync_end_thread(this);
-#endif /* defined(ENABLED_DEBUG_SYNC) */
-
   my_hash_free(&user_vars);
   my_hash_free(&sequences);
   sp_cache_clear(&sp_proc_cache);
@@ -1634,6 +1625,7 @@ void THD::free_connection()
 #if defined(ENABLED_PROFILING)
   profiling.restart();                          // Reset profiling
 #endif
+  debug_sync_reset_thread(this);
 }
 
 /*
@@ -1742,6 +1734,7 @@ THD::~THD()
     lf_hash_put_pins(tdc_hash_pins);
   if (xid_hash_pins)
     lf_hash_put_pins(xid_hash_pins);
+  debug_sync_end_thread(this);
   /* Ensure everything is freed */
   status_var.local_memory_used-= sizeof(THD);