opencv/modules/core/src/parallel.cpp

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#include "precomp.hpp"

#if !defined HAVE_TBB && !defined HAVE_OPENMP && !defined HAVE_GCD && !defined HAVE_CONCURRENCY && !defined HAVE_CSTRIPES
    #ifdef __APPLE__
        #define HAVE_GCD
    #elif defined _MSC_VER && _MSC_VER >= 1600
        #define HAVE_CONCURRENCY
    #endif
#endif

#ifdef HAVE_CONCURRENCY
    #include <ppl.h>
#elif defined HAVE_OPENMP
    #include <omp.h>
#elif defined HAVE_GCD
    #include <dispatch/dispatch.h>
#elif defined HAVE_TBB
    #include "tbb/tbb_stddef.h"
    #if TBB_VERSION_MAJOR*100 + TBB_VERSION_MINOR >= 202
        #include "tbb/tbb.h"
        #include "tbb/task.h"
        #undef min
        #undef max
    #else
        #undef HAVE_TBB
    #endif // end TBB version
#elif defined HAVE_CSTRIPES
    #include "C=.h"
    #undef shared
#endif

/*
    HAVE_TBB - using TBB
    HAVE_GCD - using GCD
    HAVE_OPENMP - using OpenMP
    HAVE_CONCURRENCY - using visual studio 2010 concurrency
*/

namespace cv
{
    class ParallelLoopBodyWrapper
    {
    public:
        ParallelLoopBodyWrapper(const ParallelLoopBody& _body, const Range& _r, double _nstripes)
        {
            body = &_body;
            wholeRange = _r;
            double len = wholeRange.end - wholeRange.start;
            nstripes = cvRound(_nstripes < 0 ? len : MIN(MAX(_nstripes, 1.), len));
        }
        void operator()(const Range& sr) const
        {
            Range r;
            r.start = (int)(wholeRange.start +
                            ((size_t)sr.start*(wholeRange.end - wholeRange.start) + nstripes/2)/nstripes);
            r.end = sr.end >= nstripes ? wholeRange.end : (int)(wholeRange.start +
                            ((size_t)sr.end*(wholeRange.end - wholeRange.start) + nstripes/2)/nstripes);
            (*body)(r);
        }
        Range stripeRange() const { return Range(0, nstripes); }

    protected:
        const ParallelLoopBody* body;
        Range wholeRange;
        int nstripes;
    };
    
    ParallelLoopBody::~ParallelLoopBody() {}

#if defined HAVE_TBB
    class ProxyLoopBody : public ParallelLoopBodyWrapper
    {
    public:
        ProxyLoopBody(const ParallelLoopBody& _body, const Range& _r, double _nstripes)
        : ParallelLoopBodyWrapper(_body, _r, _nstripes)
        {}

        void operator ()(const tbb::blocked_range<int>& range) const
        {
            this->ParallelLoopBodyWrapper::operator()(Range(range.begin(), range.end()));
        }
    };
#elif defined HAVE_GCD

    typedef ParallelLoopBodyWrapper ProxyLoopBody;
    static
    void block_function(void* context, size_t index)
    {
        ProxyLoopBody* ptr_body = static_cast<ProxyLoopBody*>(context);
        (*ptr_body)(Range(index, index + 1));
    }
#elif defined HAVE_CONCURRENCY    
    class ProxyLoopBody : public ParallelLoopBodyWrapper
    {
    public:
        ProxyLoopBody(const ParallelLoopBody& _body, const Range& _r, double _nstripes)
        : ParallelLoopBodyWrapper(_body, _r, _nstripes)
        {}
        
        void operator ()(int i) const
        {
            this->ParallelLoopBodyWrapper::operator()(Range(i, i + 1));
        }
    };
#else
    typedef ParallelLoopBodyWrapper ProxyLoopBody;
#endif

    void parallel_for_(const Range& range, const ParallelLoopBody& body, double nstripes)
    {
        ProxyLoopBody pbody(body, range, nstripes);
        Range stripeRange = pbody.stripeRange();
        
#if defined HAVE_TBB

        tbb::parallel_for(tbb::blocked_range<int>(stripeRange.start, stripeRange.end), pbody);

#elif defined HAVE_CONCURRENCY

        Concurrency::parallel_for(stripeRange.start, stripeRange.end, pbody);

#elif defined HAVE_OPENMP

#pragma omp parallel for schedule(dynamic)
        for (int i = stripeRange.start; i < stripeRange.end; ++i)
            pbody(Range(i, i + 1));

#elif defined HAVE_GCD

        dispatch_queue_t concurrent_queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
        dispatch_apply_f(stripeRange.end - stripeRange.start, concurrent_queue, &pbody, block_function);

#elif defined HAVE_CSTRIPES

        parallel()
        {
            int offset = stripeRange.start;
            int len = stripeRange.end - offset;
            Range r(offset + CPX_RANGE_START(len), offset + CPX_RANGE_END(len));
            pbody(r);
            barrier();
        }

#else

        pbody(stripeRange);

#endif
    }

} // namespace cv