Source/WTF/wtf/ParallelJobsLibdispatch.h

/*
 * Copyright (C) 2011 University of Szeged
 * Copyright (C) 2011 Gabor Loki <loki@webkit.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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 UNIVERSITY OF SZEGED ``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 UNIVERSITY OF SZEGED 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.
 */

#pragma once

#if ENABLE(THREADING_LIBDISPATCH)

#include <dispatch/dispatch.h>

namespace WTF {

class ParallelEnvironment {
    WTF_MAKE_FAST_ALLOCATED;
public:
    typedef void (*ThreadFunction)(void*);

    ParallelEnvironment(ThreadFunction threadFunction, size_t sizeOfParameter, int requestedJobNumber)
        : m_threadFunction(threadFunction)
        , m_sizeOfParameter(sizeOfParameter)
        , m_numberOfJobs(requestedJobNumber)
    {
        // We go with the requested number of jobs. libdispatch will distribute the work optimally.
        ASSERT_ARG(requestedJobNumber, requestedJobNumber > 0);
    }

    int numberOfJobs()
    {
        return m_numberOfJobs;
    }

    void execute(unsigned char* parameters)
    {
        static dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

        dispatch_apply(m_numberOfJobs, globalQueue, ^(size_t i) { (*m_threadFunction)(parameters + (m_sizeOfParameter * i)); });
    }

private:
    ThreadFunction m_threadFunction;
    size_t m_sizeOfParameter;
    int m_numberOfJobs;
};

} // namespace WTF

#endif // ENABLE(THREADING_LIBDISPATCH)