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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* 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 the Initial Developer are Copyright (C) 1998-2000
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef prsem_h___
#define prsem_h___
/*
** API for counting semaphores. Semaphores are counting synchronizing
** variables based on a lock and a condition variable. They are lightweight
** contention control for a given count of resources.
*/
#include "prtypes.h"
#ifdef VBOX_WITH_XPCOM_NAMESPACE_CLEANUP
#define PR_NewSem VBoxNsprPR_NewSem
#define PR_DestroySem VBoxNsprPR_DestroySem
#define PR_WaitSem VBoxNsprPR_WaitSem
#define PR_PostSem VBoxNsprPR_PostSem
#define PR_GetValueSem VBoxNsprPR_GetValueSem
#endif /* VBOX_WITH_XPCOM_NAMESPACE_CLEANUP */
PR_BEGIN_EXTERN_C
typedef struct PRSemaphore PRSemaphore;
/*
** Create a new semaphore object.
*/
NSPR_API(PRSemaphore*) PR_NewSem(PRUintn value);
/*
** Destroy the given semaphore object.
**
*/
NSPR_API(void) PR_DestroySem(PRSemaphore *sem);
/*
** Wait on a Semaphore.
**
** This routine allows a calling thread to wait or proceed depending upon the
** state of the semahore sem. The thread can proceed only if the counter value
** of the semaphore sem is currently greater than 0. If the value of semaphore
** sem is positive, it is decremented by one and the routine returns immediately
** allowing the calling thread to continue. If the value of semaphore sem is 0,
** the calling thread blocks awaiting the semaphore to be released by another
** thread.
**
** This routine can return PR_PENDING_INTERRUPT if the waiting thread
** has been interrupted.
*/
NSPR_API(PRStatus) PR_WaitSem(PRSemaphore *sem);
/*
** This routine increments the counter value of the semaphore. If other threads
** are blocked for the semaphore, then the scheduler will determine which ONE
** thread will be unblocked.
*/
NSPR_API(void) PR_PostSem(PRSemaphore *sem);
/*
** Returns the value of the semaphore referenced by sem without affecting
** the state of the semaphore. The value represents the semaphore vaule
F** at the time of the call, but may not be the actual value when the
** caller inspects it.
*/
NSPR_API(PRUintn) PR_GetValueSem(PRSemaphore *sem);
PR_END_EXTERN_C
#endif /* prsem_h___ */
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