Semaphore.h

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//
// Copyright (c) 2009, Markus Rickert
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
 
#ifndef _RL_UTIL_SEMAPHORE_H_
#define _RL_UTIL_SEMAPHORE_H_
 
#include <cstdlib>
 
#ifdef WIN32
#include <windows.h>
#else // WIN32
#include <semaphore.h>
#endif // WIN32
 
namespace rl
{
    namespace util
    {
        class Semaphore
        {
        public:
            explicit Semaphore(const ::std::size_t& n) :
#ifdef WIN32
                semaphore(CreateSemaphore(NULL, n, n, NULL))
#else // WIN32
                semaphore()
#endif // WIN32
            {
#ifndef WIN32
                sem_init(&(*this).semaphore, 0, n);
#endif // WIN32
            }
            
            virtual ~Semaphore()
            {
#ifdef WIN32
                CloseHandle((*this).semaphore);
#else // WIN32
                sem_destroy(&(*this).semaphore);
#endif // WIN32
            }
            
            Semaphore& operator++()
            {
                (*this).release();
                return (*this);
            }
            
            Semaphore& operator--()
            {
                (*this).acquire();
                return (*this);
            }
            
            void acquire()
            {
#ifdef WIN32
                WaitForSingleObject((*this).semaphore, INFINITE);
#else // WIN32
                sem_wait(&(*this).semaphore);
#endif // WIN32
            }
            
            void release()
            {
#ifdef WIN32
                ReleaseSemaphore((*this).semaphore, 1, NULL);
#else // WIN32
                sem_post(&(*this).semaphore);
#endif // WIN32
            }
            
            bool tryAcquire()
            {
#ifdef WIN32
                return WaitForSingleObject((*this).semaphore, 0) == WAIT_OBJECT_0 ? false : true;
#else // WIN32
                return sem_trywait(&(*this).semaphore) == 0 ? true : false;
#endif // WIN32
            }
            
        protected:
            
        private:
#ifdef WIN32
            HANDLE semaphore;
#else // WIN32
            sem_t semaphore;
#endif // WIN32
        };
    }
}
 
#endif // _RL_UTIL_SEMAPHORE_H_