/********************************************************************
**                Image Component Library (ICL)                    **
**                                                                 **
** Copyright (C) 2006-2013 CITEC, University of Bielefeld          **
**                         Neuroinformatics Group                  **
** Website: www.iclcv.org and                                      **
**          http://opensource.cit-ec.de/projects/icl               **
**                                                                 **
** File   : ICLUtils/src/ICLUtils/Semaphore.h                      **
** Module : ICLUtils                                               **
** Authors: Christof Elbrechter                                    **
**                                                                 **
**                                                                 **
** GNU LESSER GENERAL PUBLIC LICENSE                               **
** This file may be used under the terms of the GNU Lesser General **
** Public License version 3.0 as published by the                  **
**                                                                 **
** Free Software Foundation and appearing in the file LICENSE.LGPL **
** included in the packaging of this file.  Please review the      **
** following information to ensure the license requirements will   **
** be met: http://www.gnu.org/licenses/lgpl-3.0.txt                **
**                                                                 **
** The development of this software was supported by the           **
** Excellence Cluster EXC 277 Cognitive Interaction Technology.    **
** The Excellence Cluster EXC 277 is a grant of the Deutsche       **
** Forschungsgemeinschaft (DFG) in the context of the German       **
** Excellence Initiative.                                          **
**                                                                 **
********************************************************************/

#pragma once

#include <ICLUtils/CompatMacros.h>
#include <ICLUtils/ShallowCopyable.h>


namespace icl{
  namespace utils{
    
    /** \cond */
    class ICLUtils_API SemaphoreImpl;
    class ICLUtils_API SemaphoreImplDelOp{
      public: static void delete_func(SemaphoreImpl *impl);
    };
    /** \endcond */
    
    
    /// Simple Semaphore implementation wrapping the standard linux "sem_t"-struct \ingroup THREAD
    class ICLUtils_API Semaphore : public ShallowCopyable<SemaphoreImpl, SemaphoreImplDelOp>{
      public:
      /// create a semaphore initialized with n resources
      Semaphore(int n=1);
      
      /// releases a resource
      void operator++(int dummy);
      
      /// acquires a new resource
      void operator--(int dummy);
      
      /// releases val resources
      void operator+=(int val);
      
      /// acquires val resources
      void operator-=(int val);
      
      /// releases val resources
      void acquire(int val=1){ (*this)-=val; }
  
      /// acquires val resources
      void release(int val=1){ (*this)+=val; }
      
      /// trys to acquire one resource if successfull it returns true else false
      bool tryAcquire();
      
      /// releases one resource only if resources are aqcuired
      bool tryRelease();
      
      /// returns the current value
      int getValue();
      
      /// returns the semaphores max-value
      int getMaxValue();
    };
    
  } // namespace utils
}