parallelisation.hpp

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/*
 * parallelisation.hpp
 *
 * Some utility functions for parallelisation.
 
 *  Created on: 16 Oct 2022
 *   Author(s): Jorn Reniers, Volkan Kumtepeli
 */
 
 
#pragma once
 
#include "../settings/settings.hpp"
 
#include <thread>
#include <vector>
 
namespace slide {
 
template <typename Tfun> // #TODO change with parallel algorithms.
void run(Tfun task_indv, int i_end, unsigned int numMaxParallelWorkers = settings::numMaxParallelWorkers)
{
 
  auto task_par = [&](int i_begin, int i_end_, int Nth) {
    while (i_begin < i_end_) {
      task_indv(i_begin);
      i_begin += Nth;
    }
  };
 
  if constexpr (settings::isParallel) {
    if (numMaxParallelWorkers == 1)
      task_par(0, i_end, 1);
    else {
      if (numMaxParallelWorkers < 1)
        numMaxParallelWorkers = std::thread::hardware_concurrency();
 
      const unsigned int N_th_max = std::min(numMaxParallelWorkers, std::thread::hardware_concurrency());
 
      std::vector<std::thread> threads;
      threads.reserve(N_th_max);
 
      for (unsigned int i_begin = 0; i_begin < N_th_max; i_begin++) 
      {
 
        threads.emplace_back(task_par, i_begin, i_end, N_th_max);
      }
 
      for (auto &th : threads) {
        if (th.joinable())
          th.join();
      }
    }
  } else {
    task_par(0, i_end, 1);
  }
}
} // namespace slide