bk commit into 5.1 tree (thek:1.2558)

[kpettersson]

Below is the list of changes that have just been committed into a local
5.1 repository of thek. When thek does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
For information on how to access the public repository
see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2007-06-19 09:13:17+02:00, thek@adventure.(none) +1 -0
  Merge adventure.(none):/home/thek/Development/cpp/bug28211/my51-bug28211
  into  adventure.(none):/home/thek/Development/cpp/mysql-5.1-runtime
  MERGE: 1.2475.78.1

  sql/sql_cache.cc@stripped, 2007-06-19 09:13:14+02:00, thek@adventure.(none) +0 -0
    Auto merged
    MERGE: 1.109.2.1

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	thek
# Host:	adventure.(none)
# Root:	/home/thek/Development/cpp/mysql-5.1-runtime/RESYNC

--- 1.112/sql/sql_cache.cc	2007-06-01 10:12:02 +02:00
+++ 1.113/sql/sql_cache.cc	2007-06-19 09:13:14 +02:00
@@ -1459,40 +1459,62 @@ void Query_cache::invalidate(THD *thd, c
   DBUG_VOID_RETURN;
 }
 
-/*
-  Remove all cached queries that uses the given database
+/**
+   @brief Remove all cached queries that uses the given database
 */
-
 void Query_cache::invalidate(char *db)
 {
+  bool restart= FALSE;
   DBUG_ENTER("Query_cache::invalidate (db)");
   STRUCT_LOCK(&structure_guard_mutex);
   if (query_cache_size > 0 && !flush_in_progress)
   {
-    DUMP(this);
-  restart_search:
     if (tables_blocks)
     {
-      Query_cache_block *curr= tables_blocks;
-      Query_cache_block *next;
-      do
-      {
-        next= curr->next;
-        if (strcmp(db, (char*)(curr->table()->db())) == 0)
-          invalidate_table(curr);
+      Query_cache_block *table_block = tables_blocks;
+      do {
+        restart= FALSE;
+        do
+        {
+          Query_cache_block *next= table_block->next;
+          Query_cache_table *table = table_block->table();
+          if (strcmp(table->db(),db) == 0)
+            invalidate_table(table_block);
+
+          table_block= next;
+
+          /*
+            If our root node to used tables became null then the last element
+            in the table list was removed when a query was invalidated;
+            Terminate the search.
+          */
+          if (tables_blocks == 0)
+          {
+            table_block= tables_blocks;
+          }
+          /*
+            If the iterated list has changed underlying structure;
+            we need to restart the search.
+          */
+          else if (table_block->type == Query_cache_block::FREE)
+          {
+            restart= TRUE;
+            table_block= tables_blocks;
+          }
+          /* 
+            The used tables are linked in a circular list;
+            loop until we return to the begining.
+          */
+        } while (table_block != tables_blocks);
         /*
-          invalidate_table can freed block on which point 'next' (if
-          table of this block used only in queries which was deleted
-          by invalidate_table). As far as we do not allocate new blocks
-          and mark all headers of freed blocks as 'FREE' (even if they are
-          merged with other blocks) we can just test type of block
-          to be sure that block is not deleted
+           Invalidating a table will also mean that all cached queries using
+           this table also will be invalidated. This will in turn change the
+           list of tables associated with these queries and the linked list of
+           used table will be changed. Because of this we might need to restart
+           the search when a table has been invalidated.
         */
-        if (next->type == Query_cache_block::FREE)
-          goto restart_search;
-        curr= next;
-      } while (curr != tables_blocks);
-    }
+      } while (restart);
+    } // end if( tables_blocks )
   }
   STRUCT_UNLOCK(&structure_guard_mutex);
 
@@ -2395,6 +2417,7 @@ Query_cache::register_tables_from_list(T
                   (ulong) tables_used->table,
                   (ulong) tables_used->table->s->table_cache_key.length,
                   (ulong) tables_used->table->s->table_cache_key.str));
+
       if (!insert_table(tables_used->table->s->table_cache_key.length,
                         tables_used->table->s->table_cache_key.str,
                         block_table,
@@ -2461,9 +2484,8 @@ my_bool Query_cache::register_all_tables
 
   n= register_tables_from_list(tables_used, 0, block_table);
 
-  if (n)
+  if (n==0)
   {
-    DBUG_PRINT("qcache", ("failed at table %d", (int) n));
     /* Unlink the tables we allocated above */
     for (Query_cache_block_table *tmp = block->table(0) ;
 	 tmp != block_table;
@@ -2953,8 +2975,11 @@ Query_cache::double_linked_list_exclude(
   {
     point->next->prev = point->prev;
     point->prev->next = point->next;
+    /*
+       If the root is removed; select a new root
+    */
     if (point == *list_pointer)
-      *list_pointer = point->next;
+      *list_pointer= point->next;
   }
   DBUG_VOID_RETURN;
 }
@@ -3752,7 +3777,7 @@ void Query_cache::tables_dump()
       Query_cache_table *table = table_block->table();
       DBUG_PRINT("qcache", ("'%s' '%s'", table->db(), table->table()));
       table_block = table_block->next;
-    } while ( table_block != tables_blocks);
+    } while (table_block != tables_blocks);
   }
   else
     DBUG_PRINT("qcache", ("no tables in list"));