c++ 多線程， 處理數據轉換

示例代碼，

#include <iostream>
#include <future>
#include <thread>
#include <vector>


template <typename T, typename R>
struct Task{
    typedef  std::vector<T>     value_source;
    typedef  std::vector<R>     value_result;

    Task(uint32_t numbers = 4):m_thread(numbers){

    }

    template <typename CONVERT>
    void go_task(const value_source &source, value_result &result, CONVERT conver_func){
        std::vector<std::vector<T>>  split_source(m_thread);
        std::vector<std::vector<R>>  split_result(m_thread);

        auto one_size = source.size() / m_thread;
        auto sp_size = source.size() % one_size;        //find surplus
        std::vector<std::future<value_result>> vec_ff;


        for(int i = 0; i < m_thread; i++){
            if(i == m_thread - 1 && sp_size != 0){  //add surplus to last thread
                split_source[i].assign(source.begin() + i * one_size, source.begin() + (i + 1) * one_size + sp_size);
            }else{
                split_source[i].assign(source.begin() + i * one_size, source.begin() + (i + 1) * one_size);
            }
            std::packaged_task<value_result(value_source)>  task([&](const value_source &d){
                value_result ret;
                for(auto itr : d){
                    ret.push_back( conver_func(itr));

                }
                return ret;
            });
            vec_ff.push_back(task.get_future());
            std::thread(std::move(task), split_source[i]).detach();
        }


        for(int i = 0; i < m_thread; i++){
            vec_ff[i].wait();
            split_result[i] = vec_ff[i].get();
        }

        for(auto i = 0 ; i < m_thread; i++){
            result.insert(result.end(), split_result[i].begin(), split_result[i].end());
        }


    }

private:
    uint32_t  m_thread;
};



int main()
{
    std::vector<int> source;
    for(uint32_t i = 0; i < 100; i++){
        source.push_back(i);
    }

    Task<int, int> task;
    std::vector<int> ret;
    task.go_task(source, ret, [](int i ){
        return i  * -1;
    });

    for(auto itr : ret){
        std::cout << itr << " ";
    }

    return 0;
}

示例。