Backport of:

------------------------------------------------------------
revno: 2630.4.20
committer: Dmitry Lenev <dlenev@mysql.com>
branch nick: mysql-6.0-3726-w2
timestamp: Wed 2008-06-04 16:27:06 +0400
message:
  WL#3726 "DDL locking for all metadata objects"

  After review fixes in progress.

  Got rid of TABLE_LIST::mdl_upgradable member and related functions
  by using special flag which to be passed to open_table() which
  asks it to take upgradable metadata lock on table being opened.

sql/mysql_priv.h

@@ -1488,7 +1488,7 @@ inline int open_and_lock_tables(THD *thd, TABLE_LIST *tables)
 }
 /* simple open_and_lock_tables without derived handling for single table */
 TABLE *open_n_lock_single_table(THD *thd, TABLE_LIST *table_l,
-                                thr_lock_type lock_type);
+                                thr_lock_type lock_type, uint flags);
 bool open_normal_and_derived_tables(THD *thd, TABLE_LIST *tables, uint flags);
 int lock_tables(THD *thd, TABLE_LIST *tables, uint counter, uint flags,
                 bool *need_reopen);
@@ -2040,6 +2040,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count,
 #define MYSQL_OPEN_TEMPORARY_ONLY               0x0004
 #define MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY      0x0008
 #define MYSQL_LOCK_PERF_SCHEMA                  0x0010
+#define MYSQL_OPEN_TAKE_UPGRADABLE_MDL          0x0020
 
 void mysql_unlock_tables(THD *thd, MYSQL_LOCK *sql_lock);
 void mysql_unlock_read_tables(THD *thd, MYSQL_LOCK *sql_lock);

sql/sql_base.cc

@@ -2598,6 +2598,9 @@ void table_share_release_hook(void *share)
                           No version number checking is done.
                           MYSQL_OPEN_TEMPORARY_ONLY - Open only temporary
                           table not the base table or view.
+                          MYSQL_OPEN_TAKE_UPGRADABLE_MDL - Obtain upgradable
+                          metadata lock for tables on which we are going to
+                          take some kind of write table-level lock.
 
   IMPLEMENTATION
     Uses a cache of open tables to find a table not in use.
@@ -2825,7 +2828,8 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
   {
     bool retry;
 
-    if (table_list->mdl_upgradable)
+    if (flags & MYSQL_OPEN_TAKE_UPGRADABLE_MDL &&
+        table_list->lock_type >= TL_WRITE_ALLOW_WRITE)
       mdl_set_upgradable(mdl_lock_data);
     mdl_set_lock_priority(mdl_lock_data, (flags & MYSQL_LOCK_IGNORE_FLUSH) ?
                                          MDL_HIGH_PRIO : MDL_NORMAL_PRIO);
@@ -4146,7 +4150,6 @@ static int add_merge_table_list(TABLE_LIST *tlist)
 
     /* Set lock type. */
     child_l->lock_type= tlist->lock_type;
-    child_l->mdl_upgradable= tlist->mdl_upgradable;
 
     /* Set parent reference. */
     child_l->parent_l= tlist;
@@ -4905,6 +4908,8 @@ static bool check_lock_and_start_stmt(THD *thd, TABLE *table,
   @param[in]    thd             thread handle
   @param[in]    table_l         table to open is first table in this list
   @param[in]    lock_type       lock to use for table
+  @param[in]    flags           options to be used while opening and locking
+                                table (see open_table(), mysql_lock_tables())
 
   @return       table
     @retval     != NULL         OK, opened table returned
@@ -4930,7 +4935,7 @@ static bool check_lock_and_start_stmt(THD *thd, TABLE *table,
 */
 
 TABLE *open_n_lock_single_table(THD *thd, TABLE_LIST *table_l,
-                                thr_lock_type lock_type)
+                                thr_lock_type lock_type, uint flags)
 {
   TABLE_LIST *save_next_global;
   DBUG_ENTER("open_n_lock_single_table");
@@ -4946,7 +4951,7 @@ TABLE *open_n_lock_single_table(THD *thd, TABLE_LIST *table_l,
   table_l->required_type= FRMTYPE_TABLE;
 
   /* Open the table. */
-  if (simple_open_n_lock_tables(thd, table_l))
+  if (open_and_lock_tables_derived(thd, table_l, FALSE, flags))
     table_l->table= NULL; /* Just to be sure. */
 
   /* Restore list. */

sql/sql_insert.cc

@@ -2304,7 +2304,7 @@ void kill_delayed_threads(void)
 bool Delayed_insert::open_and_lock_table()
 {
   if (!(table= open_n_lock_single_table(&thd, &table_list,
-                                        TL_WRITE_DELAYED)))
+                                        TL_WRITE_DELAYED, 0)))
   {
     thd.fatal_error();				// Abort waiting inserts
     return TRUE;

sql/sql_parse.cc

@@ -47,7 +47,6 @@
    "FUNCTION" : "PROCEDURE")
 
 static bool execute_sqlcom_select(THD *thd, TABLE_LIST *all_tables);
-static void adjust_mdl_locks_upgradability(TABLE_LIST *tables);
 
 const char *any_db="*any*";	// Special symbol for check_access
 
@@ -3608,9 +3607,9 @@ case SQLCOM_PREPARE:
     thd->options|= OPTION_TABLE_LOCK;
     alloc_mdl_locks(all_tables, &thd->locked_tables_root);
     thd->mdl_el_root= &thd->locked_tables_root;
-    adjust_mdl_locks_upgradability(all_tables);
 
-    if (!(res= simple_open_n_lock_tables(thd, all_tables)))
+    if (!(res= open_and_lock_tables_derived(thd, all_tables, FALSE,
+                                            MYSQL_OPEN_TAKE_UPGRADABLE_MDL)))
     {
 #ifdef HAVE_QUERY_CACHE
       if (thd->variables.query_cache_wlock_invalidate)
@@ -8106,21 +8105,6 @@ bool parse_sql(THD *thd,
   return ret_value;
 }
 
-
-/**
-   Auxiliary function which marks metadata locks for all tables
-   on which we plan to take write lock as upgradable.
-*/
-
-static void adjust_mdl_locks_upgradability(TABLE_LIST *tables)
-{
-  for (TABLE_LIST *tab= tables; tab; tab= tab->next_global)
-  {
-    if (tab->lock_type >= TL_WRITE_ALLOW_WRITE)
-      tab->mdl_upgradable= TRUE;
-  }
-}
-
 /**
   @} (end of group Runtime_Environment)
 */

sql/sql_table.cc

@@ -4617,7 +4617,8 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
       if (view_operator_func == NULL)
         table->required_type=FRMTYPE_TABLE;
 
-      open_and_lock_tables(thd, table);
+      open_and_lock_tables_derived(thd, table, TRUE,
+                                   MYSQL_OPEN_TAKE_UPGRADABLE_MDL);
       thd->no_warnings_for_error= 0;
       table->next_global= save_next_global;
       table->next_local= save_next_local;
@@ -5074,7 +5075,6 @@ bool mysql_restore_table(THD* thd, TABLE_LIST* table_list)
 bool mysql_repair_table(THD* thd, TABLE_LIST* tables, HA_CHECK_OPT* check_opt)
 {
   DBUG_ENTER("mysql_repair_table");
-  set_all_mdl_upgradable(tables);
   DBUG_RETURN(mysql_admin_table(thd, tables, check_opt,
 				"repair", TL_WRITE, 1,
                                 test(check_opt->sql_flags & TT_USEFRM),
@@ -5087,7 +5087,6 @@ bool mysql_repair_table(THD* thd, TABLE_LIST* tables, HA_CHECK_OPT* check_opt)
 bool mysql_optimize_table(THD* thd, TABLE_LIST* tables, HA_CHECK_OPT* check_opt)
 {
   DBUG_ENTER("mysql_optimize_table");
-  set_all_mdl_upgradable(tables);
   DBUG_RETURN(mysql_admin_table(thd, tables, check_opt,
 				"optimize", TL_WRITE, 1,0,0,0,
 				&handler::ha_optimize, 0));
@@ -6604,9 +6603,8 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
     DBUG_RETURN(error);
   }
 
-  table_list->mdl_upgradable= TRUE;
-
-  if (!(table= open_n_lock_single_table(thd, table_list, TL_WRITE_ALLOW_READ)))
+  if (!(table= open_n_lock_single_table(thd, table_list, TL_WRITE_ALLOW_READ,
+                                        MYSQL_OPEN_TAKE_UPGRADABLE_MDL)))
     DBUG_RETURN(TRUE);
   table->use_all_columns();
   mdl_lock_data= table->mdl_lock_data;
@@ -7898,7 +7896,7 @@ bool mysql_checksum_table(THD *thd, TABLE_LIST *tables,
 
     strxmov(table_name, table->db ,".", table->table_name, NullS);
 
-    t= table->table= open_n_lock_single_table(thd, table, TL_READ);
+    t= table->table= open_n_lock_single_table(thd, table, TL_READ, 0);
     thd->clear_error();			// these errors shouldn't get client
 
     protocol->prepare_for_resend();

sql/sql_view.cc

@@ -1329,10 +1329,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
         anyway.
       */
       for (tbl= view_main_select_tables; tbl; tbl= tbl->next_local)
-      {
         tbl->lock_type= table->lock_type;
-        tbl->mdl_upgradable= table->mdl_upgradable;
-      }
       /*
         If the view is mergeable, we might want to
         INSERT/UPDATE/DELETE into tables of this view. Preserve the

sql/table.h

@@ -1371,11 +1371,6 @@ struct TABLE_LIST
     */
     TAKE_EXCLUSIVE_MDL
   } open_type;
-  /**
-     Indicates that for this table/view we need to take shared metadata
-     lock which should be upgradable to exclusive metadata lock.
-  */
-  bool mdl_upgradable;
   bool          internal_tmp_table;
   /** TRUE if an alias for this table was specified in the SQL. */
   bool          is_alias;
@@ -1796,14 +1791,4 @@ size_t max_row_length(TABLE *table, const uchar *data);
 
 void alloc_mdl_locks(TABLE_LIST *table_list, MEM_ROOT *root);
 
-/**
-   Helper function which allows to mark all elements in table list
-   as requiring upgradable metadata locks.
-*/
-
-inline void set_all_mdl_upgradable(TABLE_LIST *tables)
-{
-  for (; tables; tables= tables->next_global)
-    tables->mdl_upgradable= TRUE;
-}
 #endif /* TABLE_INCLUDED */