ofxsMultiThread.h

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#ifndef _ofxsMultiThread_H_
#define _ofxsMultiThread_H_
/*
 * OFX Support Library, a library that skins the OFX plug-in API with C++ classes.
 * Copyright (C) 2004-2007 The Open Effects Association Ltd
 * Author Bruno Nicoletti bruno@thefoundry.co.uk
 *
 * 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.
 * Neither the name The Open Effects Association Ltd, nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * 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 OWNER 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.
 *
 * The Open Effects Association Ltd
 * 1 Wardour St
 * London W1D 6PA
 * England
 *
 *
 *
 */

/** @file This file contains core code that wraps OFX 'objects' with C++ classes.
 *
 * This file only holds code that is visible to a plugin implementation, and so hides much
 * of the direct OFX objects and any library side only functions.
 */

#include "ofxsCore.h"

typedef struct OfxMutex* OfxMutexHandle;

namespace OFX {

/** @brief Multi thread namespace */
namespace MultiThread {

/** @brief Class that wraps up SMP multi-processing */
class Processor
{
private:
        /** @brief Function to pass to the multi thread suite */
        static void staticMultiThreadFunction( unsigned int threadIndex, unsigned int threadMax, void* customArg );

public:
        Processor();
        virtual ~Processor();

        /** @brief function that will be called in each thread. ID is from 0..nThreads-1 nThreads are the number of threads it is being run over */
        virtual void multiThreadFunction( const unsigned int threadID, const unsigned int nThreads ) = 0;

        /** @brief call this to kick off multi threading
         *
         * The nCPUs is 0, the maximum allowable number of CPUs will be used.
         */
        virtual void multiThread( const unsigned int nCPUs = 0 );
};

/** @brief Has the current thread been spawned from an MP */
bool isSpawnedThread( void );

/** @brief The number of CPUs that can be used for MP-ing */
unsigned int getNumCPUs( void );

/** @brief The index of the current thread. From 0 to numCPUs() - 1 */
unsigned int getThreadIndex( void );

/** @brief An OFX mutex */
class Mutex
{
protected:
        OfxMutexHandle _handle; /**< @brief The handle */

public:
        /** @brief ctor */
        Mutex( int lockCount = 0 );

        /** @brief dtor */
        virtual ~Mutex( void );

        /** @brief lock it, blocks until lock is gained */
        void lock();

        /** @brief unlock it */
        void unlock();

        /** @brief attempt to lock, non-blocking
         *
         * \brief returns
         * - true if the lock was achieved
         * - false if it could not
         */
        bool tryLock();
};

/// a class to wrap around a mutex which is exception safe
/// it locks the mutex on construction and unlocks it on destruction
class AutoMutex
{
protected:
        Mutex& _mutex;

public:
        /// ctor, acquires the lock
        explicit AutoMutex( Mutex& m )
                : _mutex( m )
        {
                _mutex.lock();
        }

        /// dtor, releases the lock
        virtual ~AutoMutex()
        {
                _mutex.unlock();
        }

};
};
};

#endif