openmp_wrapper.h

#ifndef LIGHTGBM_OPENMP_WRAPPER_H_
#define LIGHTGBM_OPENMP_WRAPPER_H_
#ifdef _OPENMP
 
#include <omp.h>
#include <exception>
#include <stdexcept>
#include <mutex>
#include <vector>
#include <memory>
#include "log.h"
 
class ThreadExceptionHelper {
public:
  ThreadExceptionHelper() {
    ex_ptr_ = nullptr;
  }
 
  ~ThreadExceptionHelper() {
    ReThrow();
  }
  void ReThrow() {
    if (ex_ptr_ != nullptr) {
      std::rethrow_exception(ex_ptr_);
    }
  }
  void CaptureException() {
    // only catch first exception.
    if (ex_ptr_ != nullptr) { return; }
    std::unique_lock<std::mutex> guard(lock_);
    if (ex_ptr_ != nullptr) { return; }
    ex_ptr_ = std::current_exception();
  }
private:
  std::exception_ptr ex_ptr_;
  std::mutex lock_;
};
 
#define OMP_INIT_EX() ThreadExceptionHelper omp_except_helper
#define OMP_LOOP_EX_BEGIN() try {
#define OMP_LOOP_EX_END() } \
catch(std::exception& ex) { Log::Warning(ex.what()); omp_except_helper.CaptureException(); } \
catch(...) { omp_except_helper.CaptureException();  }
#define OMP_THROW_EX() omp_except_helper.ReThrow()
 
#else
 
#ifdef _MSC_VER
  #pragma warning(disable: 4068)  // disable unknown pragma warning
#endif
 
#ifdef __cplusplus
  extern "C" {
#endif
  inline void omp_set_num_threads(int) {}
  inline void omp_set_nested(int) {}
  inline int omp_get_num_threads() {return 1;}
  inline int omp_get_thread_num() {return 0;}
#ifdef __cplusplus
};  // extern "C"
#endif
 
#define OMP_INIT_EX()
#define OMP_LOOP_EX_BEGIN()
#define OMP_LOOP_EX_END()
#define OMP_THROW_EX()
 
#endif
 
 
 
#endif /* LIGHTGBM_OPENMP_WRAPPER_H_ */