semaphor.h

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/*
 * semaphor.h
 *
 * Thread synchronisation semaphore class.
 *
 * Portable Windows Library
 *
 * Copyright (c) 1993-1998 Equivalence Pty. Ltd.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (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 Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
 *
 * Portions are Copyright (C) 1993 Free Software Foundation, Inc.
 * All Rights Reserved.
 *
 * Contributor(s): ______________________________________.
 *
 * $Log: semaphor.h,v $
 * Revision 1.22  2007/09/05 11:58:47  csoutheren
 * Fixed build on MacOSX
 *
 * Revision 1.21  2005/11/25 03:43:47  csoutheren
 * Fixed function argument comments to be compatible with Doxygen
 *
 * Revision 1.20  2005/11/14 22:29:13  csoutheren
 * Reverted Wait and Signal to non-const - there is no way we can guarantee that all
 * descendant classes everywhere will be changed over, so we have to keep the
 * original  API
 *
 * Revision 1.19  2005/11/04 06:34:20  csoutheren
 * Added new class PSync as abstract base class for all mutex/sempahore classes
 * Changed PCriticalSection to use Wait/Signal rather than Enter/Leave
 * Changed Wait/Signal to be const member functions
 * Renamed PMutex to PTimedMutex and made PMutex synonym for PCriticalSection.
 * This allows use of very efficient mutex primitives in 99% of cases where timed waits
 * are not needed
 *
 * Revision 1.18  2003/09/17 05:41:59  csoutheren
 * Removed recursive includes
 *
 * Revision 1.17  2003/09/17 01:18:02  csoutheren
 * Removed recursive include file system and removed all references
 * to deprecated coooperative threading support
 *
 * Revision 1.16  2002/09/16 01:08:59  robertj
 * Added #define so can select if #pragma interface/implementation is used on
 *   platform basis (eg MacOS) rather than compiler, thanks Robert Monaghan.
 *
 * Revision 1.15  2002/01/23 04:26:36  craigs
 * Added copy constructors for PSemaphore, PMutex and PSyncPoint to allow
 * use of default copy constructors for objects containing instances of
 * these classes
 *
 * Revision 1.14  2001/11/23 00:55:18  robertj
 * Changed PWaitAndSignal so works inside const functions.
 *
 * Revision 1.13  2001/06/01 04:00:21  yurik
 * Removed dependency on obsolete function
 *
 * Revision 1.12  2001/05/22 12:49:32  robertj
 * Did some seriously wierd rewrite of platform headers to eliminate the
 *   stupid GNU compiler warning about braces not matching.
 *
 * Revision 1.11  2001/04/23 00:34:29  robertj
 * Added ability for PWaitAndSignal to not wait on semaphore.
 *
 * Revision 1.10  2001/01/27 23:40:09  yurik
 * WinCE port-related - CreateEvent used instead of CreateSemaphore
 *
 * Revision 1.9  2000/12/19 22:20:26  dereks
 * Add video channel classes to connect to the PwLib PVideoInputDevice class.
 * Add PFakeVideoInput class to generate test images for video.
 *
 * Revision 1.8  1999/03/09 02:59:50  robertj
 * Changed comments to doc++ compatible documentation.
 *
 * Revision 1.7  1999/02/16 08:11:10  robertj
 * MSVC 6.0 compatibility changes.
 *
 * Revision 1.6  1998/11/19 05:17:37  robertj
 * Added PWaitAndSignal class for easier mutexing.
 *
 * Revision 1.5  1998/09/23 06:21:19  robertj
 * Added open source copyright license.
 *
 * Revision 1.4  1998/03/20 03:16:11  robertj
 * Added special classes for specific sepahores, PMutex and PSyncPoint.
 *
 * Revision 1.3  1995/12/10 11:34:50  robertj
 * Fixed incorrect order of parameters in semaphore constructor.
 *
 * Revision 1.2  1995/11/21 11:49:42  robertj
 * Added timeout on semaphore wait.
 *
 * Revision 1.1  1995/08/01 21:41:24  robertj
 * Initial revision
 *
 */

#ifndef _PSEMAPHORE
#define _PSEMAPHORE

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#include <ptlib/psync.h>
#include <limits.h>
#include <ptlib/critsec.h>

class PSemaphore : public PSync
{
  PCLASSINFO(PSemaphore, PSync);

  public:
    PSemaphore(
      unsigned initial, 
      unsigned maximum  
    );

    PSemaphore(const PSemaphore &);

    ~PSemaphore();

    virtual void Wait();

    virtual BOOL Wait(
      const PTimeInterval & timeout // Amount of time to wait for semaphore.
    );

    virtual void Signal();

    virtual BOOL WillBlock() const;

  private:
    PSemaphore & operator=(const PSemaphore &) { return *this; }


// Include platform dependent part of class
#ifdef _WIN32
#include "msos/ptlib/semaphor.h"
#else
#include "unix/ptlib/semaphor.h"
#endif
};

#endif

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