merge from 5.1 for bug#11764633

libmysqld/lib_sql.cc

@@ -50,6 +50,23 @@ extern "C" void unireg_clear(int exit_code)
   DBUG_VOID_RETURN;
 }
 
+/*
+  Wrapper error handler for embedded server to call client/server error 
+  handler based on whether thread is in client/server context
+*/
+
+static void embedded_error_handler(uint error, const char *str, myf MyFlags)
+{
+  DBUG_ENTER("embedded_error_handler");
+
+  /* 
+    If current_thd is NULL, it means restore_global has been called and 
+    thread is in client context, then call client error handler else call 
+    server error handler.
+  */
+  DBUG_RETURN(current_thd ? my_message_sql(error, str, MyFlags):
+              my_message_stderr(error, str, MyFlags));
+}
 
 /*
   Reads error information from the MYSQL_DATA and puts
@@ -106,7 +123,8 @@ emb_advanced_command(MYSQL *mysql, enum enum_server_command command,
   if (mysql->status != MYSQL_STATUS_READY)
   {
     set_mysql_error(mysql, CR_COMMANDS_OUT_OF_SYNC, unknown_sqlstate);
-    return 1;
+    result= 1;
+    goto end;
   }
 
   /* Clear result variables */
@@ -147,6 +165,9 @@ emb_advanced_command(MYSQL *mysql, enum enum_server_command command,
 #if defined(ENABLED_PROFILING)
   thd->profiling.finish_current_query();
 #endif
+
+end:
+  thd->restore_globals();
   return result;
 }
 
@@ -545,7 +566,10 @@ int init_embedded_server(int argc, char **argv, char **groups)
     return 1;
   }
 
-  error_handler_hook = my_message_sql;
+  /* 
+    set error_handler_hook to embedded_error_handler wrapper.
+  */
+  error_handler_hook= embedded_error_handler;
 
   acl_error= 0;
 #ifndef NO_EMBEDDED_ACCESS_CHECKS

sql/mysqld.h

@@ -216,6 +216,10 @@ extern char err_shared_dir[];
 extern TYPELIB thread_handling_typelib;
 extern my_decimal decimal_zero;
 
+/*
+  THR_MALLOC is a key which will be used to set/get MEM_ROOT** for a thread,
+  using my_pthread_setspecific_ptr()/my_thread_getspecific_ptr().
+*/
 extern pthread_key(MEM_ROOT**,THR_MALLOC);
 
 #ifdef HAVE_PSI_INTERFACE
@@ -503,6 +507,10 @@ get_thread_running()
 extern "C" THD *_current_thd_noinline();
 #define _current_thd() _current_thd_noinline()
 #else
+/*
+  THR_THD is a key which will be used to set/get THD* for a thread,
+  using my_pthread_setspecific_ptr()/my_thread_getspecific_ptr().
+*/
 extern pthread_key(THD*, THR_THD);
 inline THD *_current_thd(void)
 {

sql/sql_class.cc

@@ -1354,6 +1354,25 @@ bool THD::store_globals()
   return 0;
 }
 
+/*
+  Remove the thread specific info (THD and mem_root pointer) stored during
+  store_global call for this thread.
+*/
+bool THD::restore_globals()
+{
+  /*
+    Assert that thread_stack is initialized: it's necessary to be able
+    to track stack overrun.
+  */
+  DBUG_ASSERT(thread_stack);
+  
+  /* Undocking the thread specific data. */
+  my_pthread_setspecific_ptr(THR_THD, NULL);
+  my_pthread_setspecific_ptr(THR_MALLOC, NULL);
+  
+  return 0;
+}
+
 
 /*
   Cleanup after query.

sql/sql_class.h

@@ -2199,6 +2199,7 @@ public:
   void cleanup(void);
   void cleanup_after_query();
   bool store_globals();
+  bool restore_globals();
 #ifdef SIGNAL_WITH_VIO_CLOSE
   inline void set_active_vio(Vio* vio)
   {