parallel_for.openmp.hpp

// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html.
 
#ifndef OPENCV_CORE_PARALLEL_FOR_OPENMP_HPP
#define OPENCV_CORE_PARALLEL_FOR_OPENMP_HPP
 
#include "opencv2/core/parallel/parallel_backend.hpp"
 
#if !defined(_OPENMP) && !defined(OPENCV_SKIP_OPENMP_PRESENSE_CHECK)
#error "This file must be compiled with enabled OpenMP"
#endif
 
#include <omp.h>
 
namespace cv { namespace parallel { namespace openmp {
 
class ParallelForBackend : public ParallelForAPI
{
protected:
    int numThreads;
    int numThreadsMax;
public:
    ParallelForBackend()
    {
        numThreads = 0;
        numThreadsMax = omp_get_max_threads();
    }
 
    virtual ~ParallelForBackend() {}
 
    virtual void parallel_for(int tasks, FN_parallel_for_body_cb_t body_callback, void* callback_data) CV_OVERRIDE
    {
#pragma omp parallel for schedule(dynamic) num_threads(numThreads > 0 ? numThreads : numThreadsMax)
        for (int i = 0; i < tasks; ++i)
            body_callback(i, i + 1, callback_data);
    }
 
    virtual int getThreadNum() const CV_OVERRIDE
    {
        return omp_get_thread_num();
    }
 
    virtual int getNumThreads() const CV_OVERRIDE
    {
        return numThreads > 0
               ? numThreads
               : numThreadsMax;
    }
 
    virtual int setNumThreads(int nThreads) CV_OVERRIDE
    {
        int oldNumThreads = numThreads;
        numThreads = nThreads;
        // nothing needed as numThreads is used in #pragma omp parallel for directly
        return oldNumThreads;
    }
 
    const char* getName() const CV_OVERRIDE
    {
        return "openmp";
    }
};
 
}}}  // namespace
 
#endif  // OPENCV_CORE_PARALLEL_FOR_OPENMP_HPP