Simplify thd_wait_begin. given how seldom they are called, calling current_thd...

Simplify thd_wait_begin. given how seldom they are called, calling current_thd one more time  is not going to be anything performance relevant.

Also use thd_wait_begin/end for thr_lock and sync callbacks.

sql/scheduler.cc

@@ -46,28 +46,20 @@ static bool no_threads_end(THD *thd, bool put_in_cache)
 /**@{*/
 extern "C"
 {
-static void scheduler_wait_lock_begin(void) {
-  THD *thd=current_thd;
-  if(thd)
-    MYSQL_CALLBACK(thd->scheduler, thd_wait_begin, (thd, THD_WAIT_TABLE_LOCK));
+static void scheduler_wait_lock_begin(void) { 
+  thd_wait_begin(NULL, THD_WAIT_TABLE_LOCK);
 }
 
 static void scheduler_wait_lock_end(void) {
-  THD *thd=current_thd;
-  if(thd)
-    MYSQL_CALLBACK(thd->scheduler, thd_wait_end, (thd));
+  thd_wait_end(NULL);
 }
 
 static void scheduler_wait_sync_begin(void) {
-  THD *thd=current_thd;
-  if(thd)
-   MYSQL_CALLBACK(thd->scheduler, thd_wait_begin, (thd, THD_WAIT_TABLE_LOCK));
+  thd_wait_begin(NULL, THD_WAIT_SYNC);
 }
 
 static void scheduler_wait_sync_end(void) {
-  THD *thd=current_thd;
-  if(thd)
-    MYSQL_CALLBACK(thd->scheduler, thd_wait_end, (thd));
+  thd_wait_end(NULL);
 }
 };
 /**@}*/

sql/sql_class.cc

@@ -3935,13 +3935,10 @@ extern "C" bool thd_sqlcom_can_generate_row_events(const MYSQL_THD thd)
 */
 extern "C" void thd_wait_begin(MYSQL_THD thd, int wait_type)
 {
-
-  if (unlikely(!thread_scheduler) || !thread_scheduler->thd_wait_begin)
-   return;
-  if (thd == NULL)
+  if (!thd)
   {
-    thd=current_thd;
-    if(unlikely(thd == NULL))
+    thd= current_thd;
+    if (unlikely(!thd))
       return;
   }
   MYSQL_CALLBACK(thd->scheduler, thd_wait_begin, (thd, wait_type));
@@ -3956,16 +3953,13 @@ extern "C" void thd_wait_begin(MYSQL_THD thd, int wait_type)
 */
 extern "C" void thd_wait_end(MYSQL_THD thd)
 {
-  if (unlikely(!thread_scheduler) || ! thread_scheduler->thd_wait_begin)
-   return;
-  if (thd == NULL)
+  if (!thd)
   {
-    thd=current_thd;
-    if(unlikely(thd == NULL))
+    thd= current_thd;
+    if (unlikely(!thd))
       return;
   }
-  if(likely(thd->scheduler == thread_scheduler))
-    thread_scheduler->thd_wait_end(thd);
+  MYSQL_CALLBACK(thd->scheduler, thd_wait_end, (thd));
 }
 
 #endif // INNODB_COMPATIBILITY_HOOKS */