Fixed refresh_status function.

sql/sql_class.cc:
  Improved documentation on add_to_status().
sql/sql_parse.cc:
  Changed refresh status to take thd as argument to avoid current_thd.
  Removed add_to_status away from loop, as it is not necessary for each
  variable, only required for each thread. In this case only the current
  thread.

sql/sql_class.cc

@@ -445,7 +445,12 @@ THD::~THD()
 
 
 /*
-  Add to one status variable another status variable
+  Add all status variables to another status variable array
+
+  SYNOPSIS
+   add_to_status()
+   to_var       add to this array
+   from_var     from this array
 
   NOTES
     This function assumes that all variables are long/ulong.

sql/sql_parse.cc

@@ -6538,7 +6538,7 @@ bool reload_acl_and_cache(THD *thd, ulong options, TABLE_LIST *tables,
   if (options & REFRESH_HOSTS)
     hostname_cache_refresh();
   if (thd && (options & REFRESH_STATUS))
-    refresh_status();
+    refresh_status(thd);
   if (options & REFRESH_THREADS)
     flush_thread_cache();
 #ifdef HAVE_REPLICATION
@@ -6624,20 +6624,18 @@ void kill_one_thread(THD *thd, ulong id, bool only_kill_query)
 
 /* Clear most status variables */
 
-static void refresh_status(void)
+static void refresh_status(THD *thd)
 {
   pthread_mutex_lock(&LOCK_status);
+
+  /* We must update the global status before cleaning up the thread */
+  add_to_status(&global_status_var, &thd->status_var);
+  bzero((char*) &thd->status_var, sizeof(thd->status_var));
+
   for (struct show_var_st *ptr=status_vars; ptr->name; ptr++)
   {
     if (ptr->type == SHOW_LONG)
       *(ulong*) ptr->value= 0;
-    else if (ptr->type == SHOW_LONG_STATUS)
-    {
-      THD *thd= current_thd;
-      /* We must update the global status before cleaning up the thread */
-      add_to_status(&global_status_var, &thd->status_var);
-      bzero((char*) &thd->status_var, sizeof(thd->status_var));
-    }
   }
   /* Reset the counters of all key caches (default and named). */
   process_key_caches(reset_key_cache_counters);