prsem.h
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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"
- 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___ */