postgres/contrib/userlock/user_locks.c
Tom Lane d8d9ed931e Add support to lock manager for conditionally locking a lock (ie,
return without waiting if we can't get the lock immediately).
Not used yet, but will be needed for concurrent VACUUM.
2001-06-22 00:04:59 +00:00

101 lines
1.8 KiB
C

/*
* user_locks.c --
*
* 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 "postgres.h"
#include "miscadmin.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "user_locks.h"
int
user_lock(uint32 id1, uint32 id2, LOCKMODE lockmode)
{
LOCKTAG tag;
memset(&tag, 0, sizeof(LOCKTAG));
tag.dbId = MyDatabaseId;
tag.relId = 0;
tag.objId.blkno = (BlockNumber) id2;
tag.offnum = (OffsetNumber) (id1 & 0xffff);
return LockAcquire(USER_LOCKMETHOD, &tag, InvalidTransactionId,
lockmode, true);
}
int
user_unlock(uint32 id1, uint32 id2, LOCKMODE lockmode)
{
LOCKTAG tag;
memset(&tag, 0, sizeof(LOCKTAG));
tag.dbId = MyDatabaseId;
tag.relId = 0;
tag.objId.blkno = (BlockNumber) id2;
tag.offnum = (OffsetNumber) (id1 & 0xffff);
return LockRelease(USER_LOCKMETHOD, &tag, InvalidTransactionId, lockmode);
}
int
user_write_lock(uint32 id1, uint32 id2)
{
return user_lock(id1, id2, ExclusiveLock);
}
int
user_write_unlock(uint32 id1, uint32 id2)
{
return user_unlock(id1, id2, ExclusiveLock);
}
int
user_write_lock_oid(Oid oid)
{
return user_lock(0, oid, ExclusiveLock);
}
int
user_write_unlock_oid(Oid oid)
{
return user_unlock(0, oid, ExclusiveLock);
}
int
user_unlock_all()
{
PROC *proc;
SHMEM_OFFSET location;
ShmemPIDLookup(MyProcPid, &location);
if (location == INVALID_OFFSET)
{
elog(NOTICE, "UserUnlockAll: unable to get proc ptr");
return -1;
}
proc = (PROC *) MAKE_PTR(location);
return LockReleaseAll(USER_LOCKMETHOD, proc, false, InvalidTransactionId);
}
/* end of file */
/*
* Local Variables:
* tab-width: 4
* c-indent-level: 4
* c-basic-offset: 4
* End:
*/