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Add support to lock manager for conditionally locking a lock (ie,

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return without waiting if we can't get the lock immediately).
Not used yet, but will be needed for concurrent VACUUM.
This commit is contained in:
Tom Lane
2001-06-22 00:04:59 +00:00
parent 986915c181
commit d8d9ed931e
6 changed files with 112 additions and 86 deletions
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15
contrib/userlock/user_locks.c
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@ -1,27 +1,23 @@
/*
* user_locks.c --
*
* This loadable module, together with my user-lock.patch applied to the
* backend, provides support for user-level long-term cooperative locks.
* This loadable module provides support for user-level long-term
* cooperative locks.
*
* Copyright (C) 1999, Massimo Dal Zotto <dz@cs.unitn.it>
*
* This software is distributed under the GNU General Public License
* either version 2, or (at your option) any later version.
*/
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "postgres.h"
#include "miscadmin.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "utils/elog.h"
#include "user_locks.h"
int
user_lock(uint32 id1, uint32 id2, LOCKMODE lockmode)
{
@ -33,7 +29,8 @@ user_lock(uint32 id1, uint32 id2, LOCKMODE lockmode)
tag.objId.blkno = (BlockNumber) id2;
tag.offnum = (OffsetNumber) (id1 & 0xffff);
return LockAcquire(USER_LOCKMETHOD, &tag, InvalidTransactionId, lockmode);
return LockAcquire(USER_LOCKMETHOD, &tag, InvalidTransactionId,
lockmode, true);
}
int