Backport of:

-----------------------------------------------------------
2497.479.10 Sergei Golubchik    2008-08-27
            proc_info_hook, mysys access to thd->proc_info

This patch is necessary for backport of WL#4284 "Transactional
DDL locking".


include/my_global.h:
  proc_info_hook
include/my_sys.h:
   proc_info_hook
mysys/my_static.c:
  proc_info_hook
sql/mysqld.cc:
  proc_info_hook
sql/sql_class.cc:
  proc_info_hook

include/my_sys.h

@@ -235,6 +235,9 @@ extern void (*fatal_error_handler_hook)(uint my_err, const char *str,
 extern uint my_file_limit;
 extern ulong my_thread_stack_size;
 
+extern const char *(*proc_info_hook)(void *, const char *, const char *,
+                                     const char *, const unsigned int);
+
 #ifdef HAVE_LARGE_PAGES
 extern my_bool my_use_large_pages;
 extern uint    my_large_page_size;

mysys/my_static.c

@@ -92,6 +92,19 @@ void (*error_handler_hook)(uint error,const char *str,myf MyFlags)=
 void (*fatal_error_handler_hook)(uint error,const char *str,myf MyFlags)=
   my_message_no_curses;
 
+static const char *proc_info_dummy(void *a __attribute__((unused)),
+                                   const char *b __attribute__((unused)),
+                                   const char *c __attribute__((unused)),
+                                   const char *d __attribute__((unused)),
+                                   const unsigned int e __attribute__((unused)))
+{
+  return 0;
+}
+
+/* this is to be able to call set_thd_proc_info from the C code */
+const char *(*proc_info_hook)(void *, const char *, const char *, const char *,
+                              const unsigned int)= proc_info_dummy;
+
 #if defined(ENABLED_DEBUG_SYNC)
 /**
   Global pointer to be set if callback function is defined

sql/mysqld.cc

@@ -3828,6 +3828,10 @@ static int init_server_components()
     }
   }
 
+  proc_info_hook= (const char *(*)(void *, const char *, const char *,
+                                   const char *, const unsigned int))
+                  set_thd_proc_info;
+
   if (xid_cache_init())
   {
     sql_print_error("Out of memory");

sql/sql_class.cc

@@ -252,6 +252,9 @@ const char *set_thd_proc_info(THD *thd, const char *info,
                               const char *calling_file,
                               const unsigned int calling_line)
 {
+  if (!thd)
+    thd= current_thd;
+
   const char *old_info= thd->proc_info;
   DBUG_PRINT("proc_info", ("%s:%d  %s", calling_file, calling_line,
                            (info != NULL) ? info : "(null)"));