postgres/contrib/userlock/user_locks.c

/*
 * 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.
 *
 * Copyright (c) 1998, Massimo Dal Zotto <dz@cs.unitn.it>
 *
 * This file 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/lock.h"
#include "storage/proc.h"
#include "storage/multilev.h"
#include "utils/elog.h"

#include "user_locks.h"

int
user_lock(unsigned int id1, unsigned int id2, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	memset(&tag, 0, sizeof(LOCKTAG));
	tag.dbId  = MyDatabaseId;
	tag.relId = 0;
	tag.tupleId.ip_blkid.bi_hi = id2 >> 16;
	tag.tupleId.ip_blkid.bi_lo = id2 & 0xffff;
	tag.tupleId.ip_posid = (unsigned short) (id1 & 0xffff);

	return LockAcquire(USER_LOCKMETHOD, &tag, lockmode);
}

int
user_unlock(unsigned int id1, unsigned int id2, LOCKMODE lockmode)
{
	LOCKTAG		tag;

	memset(&tag, 0, sizeof(LOCKTAG));
	tag.dbId  = MyDatabaseId;
	tag.relId = 0;
	tag.tupleId.ip_blkid.bi_hi = id2 >> 16;
	tag.tupleId.ip_blkid.bi_lo = id2 & 0xffff;
	tag.tupleId.ip_posid = (unsigned short) (id1 & 0xffff);

	return LockRelease(USER_LOCKMETHOD, &tag, lockmode);
}

int
user_write_lock(unsigned int id1, unsigned int id2)
{
	return user_lock(id1, id2, WRITE_LOCK);
}


int
user_write_unlock(unsigned int id1, unsigned int id2)
{
	return user_unlock(id1, id2, WRITE_LOCK);
}

int
user_write_lock_oid(Oid oid)
{
	return user_lock(0, oid, WRITE_LOCK);
}

int
user_write_unlock_oid(Oid oid)
{
	return user_unlock(0, oid, WRITE_LOCK);
}

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->lockQueue);
}

/* end of file */

/*
 * Local variables:
 *  tab-width: 4
 *  c-indent-level: 4
 *  c-basic-offset: 4
 * End:
 */