parallel_backend.hpp
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// 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_BACKEND_HPP
#define OPENCV_CORE_PARALLEL_BACKEND_HPP
#include "opencv2/core/cvdef.h"
#include <memory>
namespace cv { namespace parallel {
#ifndef CV_API_CALL
#define CV_API_CALL
#endif
/** @addtogroup core_parallel_backend
* @{
* API below is provided to resolve problem of CPU resource over-subscription by multiple thread pools from different multi-threading frameworks.
* This is common problem for cases when OpenCV compiled threading framework is different from the Users Applications framework.
*
* Applications can replace OpenCV `parallel_for()` backend with own implementation (to reuse Application's thread pool).
*
*
* ### Backend API usage examples
*
* #### Intel TBB
*
* - include header with simple implementation of TBB backend:
* @snippet parallel_backend/example-tbb.cpp tbb_include
* - execute backend replacement code:
* @snippet parallel_backend/example-tbb.cpp tbb_backend
* - configuration of compiler/linker options is responsibility of Application's scripts
*
* #### OpenMP
*
* - include header with simple implementation of OpenMP backend:
* @snippet parallel_backend/example-openmp.cpp openmp_include
* - execute backend replacement code:
* @snippet parallel_backend/example-openmp.cpp openmp_backend
* - Configuration of compiler/linker options is responsibility of Application's scripts
*
*
* ### Plugins support
*
* Runtime configuration options:
* - change backend priority: `OPENCV_PARALLEL_PRIORITY_<backend>=9999`
* - disable backend: `OPENCV_PARALLEL_PRIORITY_<backend>=0`
* - specify list of backends with high priority (>100000): `OPENCV_PARALLEL_PRIORITY_LIST=TBB,OPENMP`. Unknown backends are registered as new plugins.
*
*/
/** Interface for parallel_for backends implementations
*
* @sa setParallelForBackend
*/
class CV_EXPORTS ParallelForAPI
{
public:
virtual ~ParallelForAPI();
typedef void (CV_API_CALL *FN_parallel_for_body_cb_t)(int start, int end, void* data);
virtual void parallel_for(int tasks, FN_parallel_for_body_cb_t body_callback, void* callback_data) = 0;
virtual int getThreadNum() const = 0;
virtual int getNumThreads() const = 0;
virtual int setNumThreads(int nThreads) = 0;
virtual const char* getName() const = 0;
};
/** @brief Replace OpenCV parallel_for backend
*
* Application can replace OpenCV `parallel_for()` backend with own implementation.
*
* @note This call is not thread-safe. Consider calling this function from the `main()` before any other OpenCV processing functions (and without any other created threads).
*/
CV_EXPORTS void setParallelForBackend(const std::shared_ptr<ParallelForAPI>& api, bool propagateNumThreads = true);
/** @brief Change OpenCV parallel_for backend
*
* @note This call is not thread-safe. Consider calling this function from the `main()` before any other OpenCV processing functions (and without any other created threads).
*/
CV_EXPORTS_W bool setParallelForBackend(const std::string& backendName, bool propagateNumThreads = true);
//! @}
}} // namespace
#endif // OPENCV_CORE_PARALLEL_BACKEND_HPP