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Fixed bug #30201.

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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:
  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 this function has been
  modified to remove incomplete query block.
This commit is contained in:
unknown 2007-08-22 18:15:54 +05:00
parent 92abaeee0c
commit 891b1659fc
1 changed files with 27 additions and 18 deletions
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45
sql/sql_cache.cc
View File

@ -710,6 +710,12 @@ void query_cache_end_of_result(THD *thd)
if (thd->net.query_cache_query == 0)
DBUG_VOID_RETURN;
if (thd->killed)
{
query_cache_abort(&thd->net);
DBUG_VOID_RETURN;
}
#ifdef EMBEDDED_LIBRARY
query_cache_insert(&thd->net, (char*)thd,
emb_count_querycache_size(thd));
@ -727,27 +733,30 @@ 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);
Query_cache_block *last_result_block;
ulong allign_size;
ulong len;
if (header->result() == 0)
{
DBUG_PRINT("error", ("End of data with no result blocks; "
"Query '%s' removed from cache.", header->query()));
/*
Extra safety: empty result should not happen in the normal call
to this function. In the release version that query should be ignored
and removed from QC.
*/
DBUG_ASSERT(0);
query_cache.free_query(query_block);
goto end;
}
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);
#ifndef DBUG_OFF
if (header->result() == 0)
{
DBUG_PRINT("error", ("end of data whith no result. query '%s'",
header->query()));
query_cache.wreck(__LINE__, "");
/*
We do not need call of BLOCK_UNLOCK_WR(query_block); here because
query_cache.wreck() switched query cache off but left content
untouched for investigation (it is debugging method).
*/
goto end;
}
#endif
header->found_rows(current_thd->limit_found_rows);
header->result()->type= Query_cache_block::RESULT;
header->writer(0);