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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.
This commit is contained in:
gshchepa/uchum@gleb.loc 2007-08-22 18:15:54 +05:00
parent 3d44204e84
commit f3d0f62d10
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);