semaphore.h

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#ifndef SEMAPHORE_CLASS
#define SEMAPHORE_CLASS

/*****************************************************************************\
*                                                                             *
*  Name   : semaphore                                                         *
*  Author : Chris Koeritz                                                     *
*                                                                             *
*******************************************************************************
* Copyright (c) 1998-$now By Author.  This program is free software; you can  *
* redistribute it and/or modify it under the terms of the GNU General Public  *
* License as published by the Free Software Foundation; either version 2 of   *
* the License or (at your option) any later version.  This is online at:      *
*     http://www.fsf.org/copyleft/gpl.html                                    *
* Please send any updates to: fred@gruntose.com                               *
\*****************************************************************************/

#include "mechanisms_dll.h"

#include <basis/object_base.h>


class MECHANISMS_CLASS_STYLE semaphore : public synchronizer_base
{
public:
  semaphore(int concurrent_locks, int initial_locks_available);

  virtual ~semaphore();

  IMPLEMENT_CLASS_NAME("semaphore");

  void wait();

  void signal();

  // synonyms for wait and signal from the dawn of operating systems.
  inline void P() { wait(); }
  inline void V() { signal(); }
    // synonym for signal(); V stands for "verhogen", meaning to increment.

  // these implement the synchronizer_base virtual methods.
  virtual void establish_lock();
  virtual void repeal_lock();

private:
  int _max_users;  
  int _locks_available;  
  mutex *_wait_guard;  
  mutex *_signal_guard;  
  int _current_state;
};

#endif

---