postgresql/contrib/userlock/user_locks.c
Tom Lane 140b078d2a Improve LockAcquire API per my recent proposal. All error conditions
are now reported via elog, eliminating the need to test the result code
at most call sites.  Make it possible for the caller to distinguish a
freshly acquired lock from one already held in the current transaction.
Use that capability to avoid redundant AcceptInvalidationMessages() calls
in LockRelation().
2005-05-29 22:45:02 +00:00

82 lines
1.5 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"
#define SET_LOCKTAG_USERLOCK(locktag,id1,id2) \
((locktag).locktag_field1 = MyDatabaseId, \
(locktag).locktag_field2 = (id1), \
(locktag).locktag_field3 = (id2), \
(locktag).locktag_field4 = 0, \
(locktag).locktag_type = LOCKTAG_USERLOCK)
int
user_lock(uint32 id1, uint32 id2, LOCKMODE lockmode)
{
LOCKTAG tag;
SET_LOCKTAG_USERLOCK(tag, id1, id2);
return (LockAcquire(USER_LOCKMETHOD, &tag, InvalidTransactionId,
lockmode, true) != LOCKACQUIRE_NOT_AVAIL);
}
int
user_unlock(uint32 id1, uint32 id2, LOCKMODE lockmode)
{
LOCKTAG tag;
SET_LOCKTAG_USERLOCK(tag, id1, id2);
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(void)
{
LockReleaseAll(USER_LOCKMETHOD, true);
return true;
}