do_parallel.hpp

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// SPDX-FileCopyrightText: 2006-2024 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2024 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <algorithm>
#include <functional>
#include <future>
#include <omp.h>
#include <vector>
 
#include <hibf/misc/divide_and_ceil.hpp>
 
namespace raptor
{
 
template <typename algorithm_t>
void do_parallel(algorithm_t && worker, size_t const num_records, size_t const threads)
{
    size_t const chunk_size = seqan::hibf::divide_and_ceil(num_records, threads * threads);
    size_t const number_of_chunks = seqan::hibf::divide_and_ceil(num_records, chunk_size);
 
#pragma omp parallel for schedule(dynamic) num_threads(threads)
    for (size_t i = 0; i < number_of_chunks; ++i)
    {
        size_t const start = chunk_size * i;
        size_t const extent = i == (number_of_chunks - 1) ? num_records - i * chunk_size : chunk_size;
        std::invoke(worker, start, extent);
    }
}
 
template <typename algorithm_t>
void do_parallel(algorithm_t && worker, size_t const num_records, size_t const threads, bool const output_results)
{
    std::vector<decltype(std::async(std::launch::async, worker, size_t{}, size_t{}, bool{}))> tasks;
    size_t const records_per_thread = num_records / threads;
 
    for (size_t i = 0; i < threads; ++i)
    {
        size_t const start = records_per_thread * i;
        size_t const extent = i == (threads - 1) ? num_records - i * records_per_thread : records_per_thread;
        tasks.emplace_back(std::async(std::launch::async, worker, start, extent, output_results));
    }
 
    for (auto && task : tasks)
        task.get();
}
 
} // namespace raptor