bzr push into mysql-trunk branch (Dmitry.Lenev:3900 to 3901) WL#5772

[Dmitry Lenev]

 3901 Dmitry Lenev	2012-05-17
      WL#5772 "Add partitioned Table Definition Cache to avoid
      using LOCK_open and its derivatives in DML queries".
      
      Review change #12:
      - Changed Table_cache::free_table_all() not to use hash
        look up.

    modified:
      sql/sql_base.cc
      sql/sql_base.h
 3900 Dmitry Lenev	2012-05-17
      WL#5772 "Add partitioned Table Definition Cache to avoid
      using LOCK_open and its derivatives in DML queries".
      
      Review changes #11:
      - Removed wrong assert.
      - Fix some lines to better follow coding style.

    modified:
      sql/sql_base.cc
=== modified file 'sql/sql_base.cc'
--- a/sql/sql_base.cc	2012-05-17 03:46:29 +0000
+++ b/sql/sql_base.cc	2012-05-17 11:14:28 +0000
@@ -9809,34 +9809,42 @@ void tdc_flush_unused_tables()
 
    @param  thd          Thread context
    @param  remove_type  Type of removal. @sa tdc_remove_table().
-   @param  key          Key identifying table.
-   @param  key_length   Length of key.
+   @param  share        TABLE_SHARE for the table to be removed.
 
    @note Caller should own LOCK_open and locks on all table cache
          instances.
 */
 void Table_cache::free_table_all(THD *thd,
                                  enum_tdc_remove_table_type remove_type,
-                                 const char *key, uint key_length)
+                                 TABLE_SHARE *share)
 {
+  Table_cache_element *cache_el[MAX_TABLE_CACHES];
+
   Table_cache::assert_owner_all_and_tdc();
 
+  /*
+    Freeing last TABLE instance for the share will destroy the share
+    and corresponding TABLE_SHARE::cache_element[] array. To make
+    iteration over this array safe, even when share is destroyed in
+    the middle of iteration, we create copy of this array on the stack
+    and iterate over it.
+  */
+  memcpy(&cache_el, share->cache_element,
+         table_cache_instances * sizeof(Table_cache_element *));
+
   for (uint i= 0; i < table_cache_instances; i++)
   {
-    Table_cache_element *el;
-
-    if ((el= (Table_cache_element*)my_hash_search(&m_table_cache[i].m_cache,
-                                                  (uchar*) key, key_length)))
+    if (cache_el[i])
     {
-      Table_cache_element::TABLE_list::Iterator it(el->free_tables);
+      Table_cache_element::TABLE_list::Iterator it(cache_el[i]->free_tables);
       TABLE *table;
 
 #ifndef DBUG_OFF
       if (remove_type == TDC_RT_REMOVE_ALL)
-        DBUG_ASSERT(el->used_tables.is_empty());
+        DBUG_ASSERT(cache_el[i]->used_tables.is_empty());
       else if (remove_type == TDC_RT_REMOVE_NOT_OWN)
       {
-        Table_cache_element::TABLE_list::Iterator it2(el->used_tables);
+        Table_cache_element::TABLE_list::Iterator it2(cache_el[i]->used_tables);
         while ((table= it2++))
         {
           if (table->in_use != thd)
@@ -9921,7 +9929,7 @@ void tdc_remove_table(THD *thd, enum_tdc
         used.
       */
       share->version= 0;
-      Table_cache::free_table_all(thd, remove_type, key, key_length);
+      Table_cache::free_table_all(thd, remove_type, share);
     }
     else
       (void) my_hash_delete(&table_def_cache, (uchar*) share);

=== modified file 'sql/sql_base.h'
--- a/sql/sql_base.h	2012-05-16 07:52:08 +0000
+++ b/sql/sql_base.h	2012-05-17 11:14:28 +0000
@@ -738,7 +738,7 @@ public:
 
   static void free_table_all(THD *thd,
                              enum_tdc_remove_table_type remove_type,
-                             const char *key, uint key_length);
+                             TABLE_SHARE *share);
 
   static void free_all_unused_tables();
 

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