sql_class.cc, mysql_priv.h:

  Added accessor to handler data.

sql/mysql_priv.h

@@ -489,6 +489,7 @@ inline THD *_current_thd(void)
 my_bool thd_in_lock_tables(const THD *thd);
 my_bool thd_tablespace_op(const THD *thd);
 const char *thd_proc_info(THD *thd, const char *info);
+void **thd_ha_data(const THD *thd, const struct handlerton *hton);
 
 /*
   External variables

sql/sql_class.cc

@@ -186,6 +186,11 @@ const char *thd_proc_info(THD *thd, const char *info)
   return old_info;
 }
 
+void **thd_ha_data(const THD *thd, const struct handlerton *hton)
+{
+  return (void **) thd->ha_data + hton->slot;
+}
+
 
 /*
   Pass nominal parameters to Statement constructor only to ensure that