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Merge moonlight.home:/home/tomash/src/mysql_ab/mysql-5.0-bug23527

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into  moonlight.home:/home/tomash/src/mysql_ab/mysql-5.1-bug23527
This commit is contained in:
kroki/tomash@moonlight.home 2007-01-25 20:04:57 +03:00
commit d1df34129f
1 changed files with 17 additions and 1 deletions
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18
sql/sql_cache.cc
View file

@ -1761,8 +1761,18 @@ void Query_cache::free_cache()
{
DBUG_ENTER("Query_cache::free_cache");
if (query_cache_size > 0)
{
flush_cache();
/*
There may be two free_cache() calls in progress, because we
release 'structure_guard_mutex' in flush_cache(). When the second
flush_cache() wakes up from the wait on 'COND_flush_finished', the
first call to free_cache() has done its job. So we have to test
'query_cache_size > 0' the second time to see if the cache wasn't
reset by other thread, or if it was reset and was re-enabled then.
If the cache was reset, then we have nothing to do here.
*/
if (query_cache_size > 0)
{
#ifndef DBUG_OFF
if (bins[0].free_blocks == 0)
{
@ -1804,6 +1814,12 @@ void Query_cache::free_cache()
flush_in_progress flag and releases the lock, so other threads may
proceed skipping the cache as if it is disabled. Concurrent
flushes are performed in turn.
After flush_cache() call, the cache is flushed, all the freed
memory is accumulated in bin[0], and the 'structure_guard_mutex'
is locked. However, since we could release the mutex during
execution, the rest of the cache state could have been changed,
and should not be relied on.
*/
void Query_cache::flush_cache()