Reverted patch for new usage of open_count as it caused more problems than it solved

Cleaned up patch for checking locks for multi-table updates


myisam/mi_close.c:
  Reverted patch for new usage of open_counts
myisam/mi_locking.c:
  Reverted patch for new usage of open_counts
sql/ha_myisam.cc:
  Reverted patch for new usage of open_counts
sql/handler.cc:
  Removed compiler warning
sql/sql_acl.cc:
  Removed compiler warning
sql/sql_table.cc:
  No need to unlock after failed call to external_lock()
sql/sql_update.cc:
  Cleaned up (and made it more secure) patch for checking locks for multi-table updates

1 files changed, 67 insertions, 43 deletions

diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index a17742df03b..cdcc90e8651 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -387,6 +387,24 @@ err:
 ***************************************************************************/
 
 /*
+  Get table map for list of Item_field
+*/
+
+static table_map get_table_map(List<Item> *items)
+{
+  List_iterator_fast<Item> item_it(*items);
+  Item_field *item;
+  table_map map= 0;
+
+  while ((item= (Item_field *) item_it++)) 
+    map|= item->used_tables();
+  DBUG_PRINT("info",("table_map: 0x%08x", map));
+  return map;
+}
+
+
+
+/*
   Setup multi-update handling and call SELECT to do the join
 */
 
@@ -401,59 +419,45 @@ int mysql_multi_update(THD *thd,
   int res;
   multi_update *result;
   TABLE_LIST *tl;
-  const bool locked= !(thd->locked_tables);
+  const bool using_lock_tables= thd->locked_tables != 0;
   DBUG_ENTER("mysql_multi_update");
 
+  thd->select_limit= HA_POS_ERROR;
+
   for (;;)
   {
-    table_map update_map= 0;
-    int tnr= 0;
+    table_map update_map;
+    int tnr;
     
     if ((res= open_tables(thd, table_list)))
       DBUG_RETURN(res);
 
-    /*
-      Only need to call lock_tables if (thd->locked_tables == NULL)
-    */
-    if (locked && ((res= lock_tables(thd, table_list))))
+    /* Only need to call lock_tables if we are not using LOCK TABLES */
+    if (!using_lock_tables && ((res= lock_tables(thd, table_list))))
       DBUG_RETURN(res);
 
-    thd->select_limit=HA_POS_ERROR;
-
     /*
       Ensure that we have update privilege for all tables and columns in the
       SET part
       While we are here, initialize the table->map field.
     */
-    for (tl= table_list ; tl ; tl=tl->next)
+    for (tl= table_list,tnr=0 ; tl ; tl=tl->next)
     {
       TABLE *table= tl->table;
       table->grant.want_privilege= (UPDATE_ACL & ~table->grant.privilege);
       table->map= (table_map) 1 << (tnr++);
     }
 
-    if (!setup_fields(thd, table_list, *fields, 1, 0, 0))
-    {
-      List_iterator_fast<Item> field_it(*fields);
-      Item_field *item;
-
-      while ((item= (Item_field *) field_it++)) 
-	update_map|= item->used_tables();
-
-      DBUG_PRINT("info",("update_map=0x%08x", update_map));
-    }
-    else
+    if (setup_fields(thd, table_list, *fields, 1, 0, 0))
       DBUG_RETURN(-1);
 
-    /*
-      Unlock the tables in preparation for relocking
-    */
-    if (locked) 
+    update_map= get_table_map(fields);
+
+    /* Unlock the tables in preparation for relocking */
+    if (!using_lock_tables)
     {      
-      pthread_mutex_lock(&LOCK_open);
       mysql_unlock_tables(thd, thd->lock); 
       thd->lock= 0;
-      pthread_mutex_unlock(&LOCK_open);
     }
 
     /*
@@ -474,26 +478,48 @@ int mysql_multi_update(THD *thd,
 	tl->lock_type= TL_READ;
 	tl->updating= 0;
       }
-      if (locked)
+      if (!using_lock_tables)
 	tl->table->reginfo.lock_type= tl->lock_type;
     }
 
+    /* Relock the tables with the correct modes */
+    res= lock_tables(thd,table_list);
+    if (using_lock_tables)
+    {
+      if (res)
+        DBUG_RETURN(res);
+      break;                                 // Don't have to do setup_field()
+    }
+
     /*
-      Relock the tables
+      We must setup fields again as the file may have been reopened
+      during lock_tables 
     */
-    if (!(res=lock_tables(thd,table_list)))
-      break;
-      
-    if (!locked)
-      DBUG_RETURN(res);
 
-    List_iterator_fast<Item> field_it(*fields);
-    Item_field *item;
+    {
+      List_iterator_fast<Item> field_it(*fields);
+      Item_field *item;
 
-    while ((item= (Item_field *) field_it++)) 
-    /*  item->cleanup();		XXX Use this instead in MySQL 4.1+ */
-      item->field= item->result_field= 0;
+      while ((item= (Item_field *) field_it++)) 
+#if MYSQL_VERSION < 40100
+        item->field= item->result_field= 0;
+#else
+        item->cleanup();
+#endif
+    }
+    if (setup_fields(thd, table_list, *fields, 1, 0, 0))
+      DBUG_RETURN(-1);
+    /*
+      If lock succeded and the table map didn't change since the above lock
+      we can continue.
+    */
+    if (!res && update_map == get_table_map(fields))
+      break;
 
+    /*
+      There was some very unexpected changes in the table definition between
+      open tables and lock tables. Close tables and try again.
+    */
     close_thread_tables(thd);
   }
 
@@ -548,7 +574,7 @@ int multi_update::prepare(List<Item> &not_used_values)
 {
   TABLE_LIST *table_ref;
   SQL_LIST update;
-  table_map tables_to_update= 0;
+  table_map tables_to_update;
   Item_field *item;
   List_iterator_fast<Item> field_it(*fields);
   List_iterator_fast<Item> value_it(*values);
@@ -559,8 +585,7 @@ int multi_update::prepare(List<Item> &not_used_values)
   thd->cuted_fields=0L;
   thd->proc_info="updating main table";
 
-  while ((item= (Item_field *) field_it++))
-    tables_to_update|= item->used_tables();
+  tables_to_update= get_table_map(fields);
 
   if (!tables_to_update)
   {
@@ -624,7 +649,6 @@ int multi_update::prepare(List<Item> &not_used_values)
 
   /* Split fields into fields_for_table[] and values_by_table[] */
 
-  field_it.rewind();
   while ((item= (Item_field *) field_it++))
   {
     Item *value= value_it++;