From e3b3907c4f6f6dbfd650272e7c65880d04e5789e Mon Sep 17 00:00:00 2001
From: Konstantin Osipov <kostja@sun.com>
Date: Wed, 2 Dec 2009 19:15:40 +0300
Subject: Backport of:
------------------------------------------------------------ revno: 2630.4.32
committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w2
timestamp: Thu 2008-06-19 16:39:58 +0400 message: WL#3726 "DDL locking for
all metadata objects".
After-review fixes in progress.
Ensure that metadata locking subsystem properly handles
out-of-memory conditions. Clarified MDL interface by
separating release of locks and removal of lock requests
from the context.
sql/lock.cc:
mdl_release_lock(), mdl_acquire_exclusive_locks() and
mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
mdl_remove_lock() to do this.
sql/mdl.cc:
Ensured that metadata locking subsystem properly handles
out-of-memory conditions.
Introduced new MDL_INITIALIZED state for metadata lock
request which is used in all cases when lock is not acquired
and we have not associated request with object respesenting
lock.
MDL_PENDING is now only used for requests for exclusive locks
which are added to the MDL_LOCK::waiting_exclusive queue.
mdl_release_lock(), mdl_acquire_exclusive_locks() and
mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
newly introduced mdl_remove_lock() to do this.
Also renamed mdl_release_all_locks_for_name() to
emphasize that it also actually removes lock requests
from the context.
Finally mdl_try_acquire_exclusive_lock() is now returs
information about encountered lock conflict in separate
out parameter since its return value is used for distinguishing
between error (e.g. due to OOM) and success.
sql/mdl.h:
Introduced new MDL_INITIALIZED state for metadata lock
request which is used in all cases when lock is not acquired
and we have not associated request with object respesenting
lock.
MDL_PENDING is now only used for requests for exclusive locks
which are added to the MDL_LOCK::waiting_exclusive queue.
mdl_release_lock(), mdl_acquire_exclusive_locks() and
mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
newly introduced mdl_remove_lock() to do this.
Also renamed mdl_release_all_locks_for_name() to
emphasize that it also actually removes lock requests
from the context.
Finally mdl_try_acquire_exclusive_lock() is now returs
information about encountered lock conflict in separate
out parameter since its return value is used for distinguishing
between error (e.g. due to OOM) and success.
sql/sql_base.cc:
mdl_release_lock(), mdl_acquire_exclusive_locks() and mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
mdl_remove_lock() to do this.
Also adjusted open_table() to ensure that it
releases/removes metadata locks in case of error
after adding/acquiring them (unless keeping these
lock requests is required for recovering action).
sql/sql_delete.cc:
mdl_release_lock(), mdl_acquire_exclusive_locks() and mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
mdl_remove_lock() to do this.
sql/sql_handler.cc:
mdl_release_lock(), mdl_acquire_exclusive_locks() and mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
mdl_remove_lock() to do this.
sql/sql_show.cc:
mdl_release_lock(), mdl_acquire_exclusive_locks() and mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
mdl_remove_lock() to do this.
sql/sql_table.cc:
Renamed mdl_release_all_locks_for_name() to emphasize
that it also actually removes lock requests from the context.
mdl_release_lock(), mdl_acquire_exclusive_locks() and mdl_try_acquire_exclusive_lock() are no longer responsible
for removal of metadata lock requests from the context.
One should explicitly call mdl_remove_all_locks() and
mdl_remove_lock() to do this.
Finally mdl_try_acquire_exclusive_lock() is now returs
information about encountered lock conflict in separate
out parameter since its return value is used for distinguishing
between error (e.g. due to OOM) and success.
---
sql/sql_delete.cc | 9 +++++++++
1 file changed, 9 insertions(+)
(limited to 'sql/sql_delete.cc')
diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index 630cf73076c..4827d48e1c5 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -1170,7 +1170,10 @@ bool mysql_truncate(THD *thd, TABLE_LIST *table_list, bool dont_send_ok)
mdl_set_lock_type(mdl_lock_data, MDL_EXCLUSIVE);
mdl_add_lock(&thd->mdl_context, mdl_lock_data);
if (mdl_acquire_exclusive_locks(&thd->mdl_context))
+ {
+ mdl_remove_lock(&thd->mdl_context, mdl_lock_data);
DBUG_RETURN(TRUE);
+ }
pthread_mutex_lock(&LOCK_open);
tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table_list->db,
table_list->table_name);
@@ -1200,12 +1203,18 @@ end:
my_ok(thd); // This should return record count
}
if (mdl_lock_data)
+ {
mdl_release_lock(&thd->mdl_context, mdl_lock_data);
+ mdl_remove_lock(&thd->mdl_context, mdl_lock_data);
+ }
}
else if (error)
{
if (mdl_lock_data)
+ {
mdl_release_lock(&thd->mdl_context, mdl_lock_data);
+ mdl_remove_lock(&thd->mdl_context, mdl_lock_data);
+ }
}
DBUG_RETURN(error);
--
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