bk commit into 5.0 tree (gshchepa:1.2498) BUG#30201

[<gshchepa]

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ChangeSet@stripped, 2007-08-22 11:34:29+05:00, gshchepa@stripped +1 -0
  Fixed bug #30201.
  Killing a SELECT query with KILL QUERY or KILL CONNECTION
  causes a server crash if the query cache is enabled.
  
  Normal evaluation of a query may be interrupted by the
  KILL QUERY/CONNECTION statement, in this case the mysql_execute_command
  function returns TRUE, and the thd->killed flag has true value.
  In this case the result of the query may
  be cached incompletely (omitting call to query_cache_insert inside
  the net_real_write function), and next call to query_cache_end_of_result
  may lead to server crash.
  Thus, the query_cache_end_of_result function has been modified to abort
  query cache in the case of killed thread.
  

  sql/sql_cache.cc@stripped, 2007-08-22 11:07:03+05:00, gshchepa@stripped +16 -7
    Fixed bug #30201.
    The  query_cache_end_of_result function has been modified to abort query
    cache in the case of query execution failure. Also the code using the
    result of query has been moved to the place after the assertion code.

diff -Nrup a/sql/sql_cache.cc b/sql/sql_cache.cc
--- a/sql/sql_cache.cc	2007-05-10 17:54:53 +05:00
+++ b/sql/sql_cache.cc	2007-08-22 11:07:03 +05:00
@@ -706,6 +706,12 @@ void query_cache_end_of_result(THD *thd)
   Query_cache_block *query_block;
   DBUG_ENTER("query_cache_end_of_result");
 
+  if (thd->killed)
+  {
+    query_cache_abort(&thd->net);
+    DBUG_VOID_RETURN;
+  }
+
   /* See the comment on double-check locking usage above. */
   if (thd->net.query_cache_query == 0)
     DBUG_VOID_RETURN;
@@ -727,13 +733,10 @@ void query_cache_end_of_result(THD *thd)
     DUMP(&query_cache);
     BLOCK_LOCK_WR(query_block);
     Query_cache_query *header= query_block->query();
-    Query_cache_block *last_result_block= header->result()->prev;
-    ulong allign_size= ALIGN_SIZE(last_result_block->used);
-    ulong len= max(query_cache.min_allocation_unit, allign_size);
-    if (last_result_block->length >= query_cache.min_allocation_unit + len)
-      query_cache.split_block(last_result_block,len);
+    Query_cache_block *last_result_block;
+    ulong allign_size;
+    ulong len;
 
-#ifndef DBUG_OFF
     if (header->result() == 0)
     {
       DBUG_PRINT("error", ("end of data whith no result. query '%s'",
@@ -747,7 +750,13 @@ void query_cache_end_of_result(THD *thd)
       */
       goto end;
     }
-#endif
+
+    last_result_block= header->result()->prev;
+    allign_size= ALIGN_SIZE(last_result_block->used);
+    len= max(query_cache.min_allocation_unit, allign_size);
+    if (last_result_block->length >= query_cache.min_allocation_unit + len)
+      query_cache.split_block(last_result_block,len);
+
     header->found_rows(current_thd->limit_found_rows);
     header->result()->type= Query_cache_block::RESULT;
     header->writer(0);