gecko-dev/nsprpub/pr/include/prrwlock.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is the Netscape Portable Runtime (NSPR).
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998-2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License Version 2 or later (the
* "GPL"), in which case the provisions of the GPL are applicable
* instead of those above. If you wish to allow use of your
* version of this file only under the terms of the GPL and not to
* allow others to use your version of this file under the MPL,
* indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by
* the GPL. If you do not delete the provisions above, a recipient
* may use your version of this file under either the MPL or the
* GPL.
*/
/*
** File: prrwlock.h
** Description: API to basic reader-writer lock functions of NSPR.
**
**/
#ifndef prrwlock_h___
#define prrwlock_h___
#include "prtypes.h"
PR_BEGIN_EXTERN_C
/*
* PRRWLock --
*
* The reader writer lock, PRRWLock, is an opaque object to the clients
* of NSPR. All routines operate on a pointer to this opaque entity.
*/
typedef struct PRRWLock PRRWLock;
#define PR_RWLOCK_RANK_NONE 0
/***********************************************************************
** FUNCTION: PR_NewRWLock
** DESCRIPTION:
** Returns a pointer to a newly created reader-writer lock object.
** INPUTS: Lock rank
** Lock name
** OUTPUTS: void
** RETURN: PRRWLock*
** If the lock cannot be created because of resource constraints, NULL
** is returned.
**
***********************************************************************/
NSPR_API(PRRWLock*) PR_NewRWLock(PRUint32 lock_rank, const char *lock_name);
/***********************************************************************
** FUNCTION: PR_DestroyRWLock
** DESCRIPTION:
** Destroys a given RW lock object.
** INPUTS: PRRWLock *lock - Lock to be freed.
** OUTPUTS: void
** RETURN: None
***********************************************************************/
NSPR_API(void) PR_DestroyRWLock(PRRWLock *lock);
/***********************************************************************
** FUNCTION: PR_RWLock_Rlock
** DESCRIPTION:
** Apply a read lock (non-exclusive) on a RWLock
** INPUTS: PRRWLock *lock - Lock to be read-locked.
** OUTPUTS: void
** RETURN: None
***********************************************************************/
NSPR_API(void) PR_RWLock_Rlock(PRRWLock *lock);
/***********************************************************************
** FUNCTION: PR_RWLock_Wlock
** DESCRIPTION:
** Apply a write lock (exclusive) on a RWLock
** INPUTS: PRRWLock *lock - Lock to write-locked.
** OUTPUTS: void
** RETURN: None
***********************************************************************/
NSPR_API(void) PR_RWLock_Wlock(PRRWLock *lock);
/***********************************************************************
** FUNCTION: PR_RWLock_Unlock
** DESCRIPTION:
** Release a RW lock. Unlocking an unlocked lock has undefined results.
** INPUTS: PRRWLock *lock - Lock to unlocked.
** OUTPUTS: void
** RETURN: void
***********************************************************************/
NSPR_API(void) PR_RWLock_Unlock(PRRWLock *lock);
PR_END_EXTERN_C
#endif /* prrwlock_h___ */