Semaphore.h

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/*********************************************************\
 *  File: Semaphore.h                                    *
 *
 *  Copyright (C) 2002-2012 The PixelLight Team (http://www.pixellight.org/)
 *
 *  This file is part of PixelLight.
 *
 *  PixelLight is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  PixelLight is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with PixelLight. If not, see <http://www.gnu.org/licenses/>.
\*********************************************************/


#ifndef __PLCORE_SEMAPHORE_H__
#define __PLCORE_SEMAPHORE_H__
#pragma once


//[-------------------------------------------------------]
//[ Includes                                              ]
//[-------------------------------------------------------]
#include "PLCore/PLCore.h"


//[-------------------------------------------------------]
//[ Namespace                                             ]
//[-------------------------------------------------------]
namespace PLCore {


//[-------------------------------------------------------]
//[ Forward declarations                                  ]
//[-------------------------------------------------------]
class SemaphoreImpl;


//[-------------------------------------------------------]
//[ Classes                                               ]
//[-------------------------------------------------------]
/**
*  @brief
*    Counting semaphore class
*
*  @note
*    - Implementation of the bridge design pattern, this class is the abstraction
*/
class Semaphore {


    //[-------------------------------------------------------]
    //[ Public functions                                      ]
    //[-------------------------------------------------------]
    public:
        /**
        *  @brief
        *    Constructor
        *
        *  @param[in] nValue
        *    Initial value of the semaphore (usually >0)
        *  @param[in] nMaxValue
        *    Maximum value of the semaphore
        */
        PLCORE_API Semaphore(uint32 nValue, uint32 nMaxValue);

        /**
        *  @brief
        *    Destructor
        */
        PLCORE_API ~Semaphore();

        /**
        *  @brief
        *    Locks the semaphore
        *
        *  @return
        *    'true' if successful, 'false' on error
        *
        *  @note
        *    - Other known names for this operation: p, wait, acquire, down
        *    - Blocking if no 'signal' left
        *    - Use the lock method with a timeout to avoid potential deadlocks
        */
        inline bool Lock();

        /**
        *  @brief
        *    Locks the semaphore, but only wait until timeout
        *
        *  @param[in] nTimeout
        *    Timeout in milliseconds
        *
        *  @return
        *    'true' if successful, 'false' on error
        *
        *  @note
        *    - 'nTimeout = 0' means: Return immediately if no 'signal' left
        *
        *  @see
        *    - Lock()
        */
        inline bool TryLock(uint64 nTimeout);

        /**
        *  @brief
        *    Unlocks the semaphore
        *
        *  @return
        *    'true' if successful, 'false' on error
        *
        *  @note
        *    - Other known names for this operation: v, signal, release, up
        */
        inline bool Unlock();

        /**
        *  @brief
        *    Gets the current value of the semaphore
        *
        *  @return
        *    Current semaphore value (number of 'signals' left)
        */
        inline uint32 GetValue() const;


    //[-------------------------------------------------------]
    //[ Private functions                                     ]
    //[-------------------------------------------------------]
    private:
        /**
        *  @brief
        *    Copy constructor
        *
        *  @param[in] cSource
        *    Source to copy from
        */
        Semaphore(const Semaphore &cSource);

        /**
        *  @brief
        *    Copy operator
        *
        *  @param[in] cSource
        *    Source to copy from
        *
        *  @return
        *    Reference to this instance
        */
        Semaphore &operator =(const Semaphore &cSource);


    //[-------------------------------------------------------]
    //[ Private data                                          ]
    //[-------------------------------------------------------]
    private:
        SemaphoreImpl *m_pSemaphoreImpl;    /**< Pointer to the system specific implementation (assumed to be never a null pointer!) */
        uint32         m_nValue;            /**< Current value of the semaphore */


};


//[-------------------------------------------------------]
//[ Namespace                                             ]
//[-------------------------------------------------------]
} // PLCore


//[-------------------------------------------------------]
//[ Implementation                                        ]
//[-------------------------------------------------------]
#include "PLCore/System/Semaphore.inl"


#endif // __PLCORE_SEMAPHORE_H__