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

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into  moonlight.home:/home/tomash/src/mysql_ab/mysql-5.0-bug23527
This commit is contained in:
kroki/tomash@moonlight.home 2007-01-25 20:10:40 +03:00
commit f4f51a017a
1 changed files with 17 additions and 1 deletions
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18
sql/sql_cache.cc
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@ -1765,8 +1765,18 @@ void Query_cache::free_cache()
{ {
DBUG_ENTER("Query_cache::free_cache"); DBUG_ENTER("Query_cache::free_cache");
if (query_cache_size > 0) if (query_cache_size > 0)
{
flush_cache(); 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 #ifndef DBUG_OFF
if (bins[0].free_blocks == 0) if (bins[0].free_blocks == 0)
{ {
@ -1808,6 +1818,12 @@ void Query_cache::free_cache()
flush_in_progress flag and releases the lock, so other threads may flush_in_progress flag and releases the lock, so other threads may
proceed skipping the cache as if it is disabled. Concurrent proceed skipping the cache as if it is disabled. Concurrent
flushes are performed in turn. 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() void Query_cache::flush_cache()