茅厕级C++任务队列——最大的优势就是没有优势

ゝ一世哀愁。 2023-01-20 13:56 26阅读 0赞

#include <iostream>
    #include <functional>
    #include <queue>
    #include <atomic>
    #include <mutex>
    #include <thread>
    #include <future>
    #include <memory>
    #include <chrono>
    #include <list>
    using namespace std;
    
    //状态类别
    enum class Status
    { 
        //停止
        STOP,
        //开始
        START
    };
    /** * @brief 用于初步封装线程 * */
    class ThreadPackage
    { 
    private:
        //线程需要执行的目标函数封装
        shared_ptr<function<void()>> _fun = nullptr;
        //所属线程的智能指针
        shared_ptr<thread> t1 = nullptr;
    
    public:
        //等待释放的线程
        std::mutex _wait_release_m;
        //初始线程状态
        Status _thread_status = Status::STOP;
        //默认构造函数
        ThreadPackage(){ };
        //析构函数
        ~ThreadPackage();
        //设置目标功能函数
        void setWork(shared_ptr<function<void()>> fun);
        //开始执行
        void start();
    };
    ThreadPackage::~ThreadPackage()
    { 
        //查看是否执行完成，未执行完成则等待完成
        if (t1->joinable())
        { 
            t1->join();
        }
    };
    void ThreadPackage::start()
    { 
        //初始化状态
        _thread_status = Status::START;
        // 封装线程
        t1 = make_shared<thread>([this]() { 
            std::unique_lock<std::mutex> lk(_wait_release_m);
            this->_thread_status = Status::START;
            (*(this->_fun))();
            this->_thread_status = Status::STOP;
        });
    }
    void ThreadPackage::setWork(shared_ptr<function<void()>> fun)
    { 
        this->_fun = fun;
    }
    
    class ThreadPool
    { 
    
    public:
        ThreadPool(int pool_size);
        ThreadPool(){ };
        ~ThreadPool(){ };
        // 添加任务
        template <typename F, typename... Args>
        decltype(auto) add_task(F &&func, Args &&...args);
    
    private:
        //检查线程是否执行完成
        shared_ptr<thread> t_check;
        //用于释放已结束的线程
        shared_ptr<thread> t_realse;
        //添加任务到执行队列的线程
        shared_ptr<thread> t_dispatch;
    
        //同时执行的最大线程数
        std::atomic<int> _pool_size;
        //线程池状态
        Status _status = Status::STOP;
        //待执行任务队列
        queue<function<void()>> _wait_work_q;
        //等待添加到待执行任务队列锁
        std::mutex _wait_add_work_m;
        //等待添加到待执行任务队列的队列
        queue<function<void()>> _add_wait_work_q;
        //正在工作线程列表的锁
        std::mutex _working_m;
        //执行的线程链表
        list<shared_ptr<ThreadPackage>> _starting_l;
        //等待释放列表锁
        std::mutex _wait_release_m;
        //等待释放的线程链表
        list<shared_ptr<ThreadPackage>> _wait_release_l;
        //释放函数
        void release();
        //添加任务到执行队列的函数
        void dispatch();
        //检查线程是否执行完成的函数
        void check();
    };
    void ThreadPool::release()
    { 
        while (true)
        { 
            { 
                std::unique_lock<std::mutex> lk(_wait_release_m);
                for (auto i = _wait_release_l.begin(); i != _wait_release_l.end(); ++i)
                { 
                    if ((*i)->_thread_status == Status::STOP)
                    { 
                        std::unique_lock<std::mutex> lk((*i)->_wait_release_m);
                        _wait_release_l.erase(i);
                        break;
                    }
                }
            }
    
            std::this_thread::yield();
        }
    }
    
    void ThreadPool::dispatch()
    { 
        while (true)
        { 
            if (_wait_work_q.size() > 0 && _starting_l.size() < _pool_size)
            { 
                auto _temp_wait_task = _wait_work_q.front();
                _wait_work_q.pop();
                auto _temp_thread_package = std::make_shared<ThreadPackage>();
                _temp_thread_package->setWork(make_shared<function<void()>>(_temp_wait_task));
                _temp_thread_package->start();
                std::unique_lock<std::mutex> lk(_working_m);
                _starting_l.emplace_back(_temp_thread_package);
            }
            if (_add_wait_work_q.size() > 0)
            { 
                { 
                    std::unique_lock<std::mutex> lk(_wait_add_work_m);
                    auto _temp_add_wait_task = _add_wait_work_q.front();
                    _add_wait_work_q.pop();
                    _wait_work_q.push(_temp_add_wait_task);
                }
            }
            std::this_thread::yield();
        }
    }
    
    void ThreadPool::check()
    { 
        while (true)
        { 
            { 
                std::unique_lock<std::mutex> lk(_working_m);
                for (auto i = _starting_l.begin(); i != _starting_l.end(); ++i)
                { 
    
                    if ((*i)->_thread_status == Status::STOP)
                    { 
                        std::unique_lock<std::mutex> lk(_wait_release_m);
                        _wait_release_l.emplace_back(*i);
                        i = _starting_l.erase(i);
                        break;
                    }
                }
            }
            std::this_thread::yield();
        }
    }
    ThreadPool::ThreadPool(int pool_size)
    { 
        this->_pool_size = pool_size;
        t_check = make_shared<thread>(bind(&ThreadPool::check, this));
        t_realse = make_shared<thread>(bind(&ThreadPool::release, this));
        t_dispatch = make_shared<thread>(bind(&ThreadPool::dispatch, this));
    }
    
    /** * @brief 主要核心思想就这一个模板函数，用于将原始函数封装成 * * @tparam F 目标函数类型 * @tparam Args 函数的参数类型 * @param func 目标函数 * @param args 目标参数 * @return decltype(auto) 自动推导返回值 */
    template <typename F, typename... Args>
    decltype(auto) ThreadPool::add_task(F &&func, Args &&...args)
    { 
        //推导最后的返回值类型
        using res_type = typename std::result_of<F(Args...)>::type;
        //封装为packaged_task的智能指针类型
        auto task = std::make_shared<std::packaged_task<res_type()>>(
            std::bind(std::forward<F>(func), std::forward<Args>(args)...));
        //获取用于异步胡获取返回值的future
        std::future<res_type> res = task->get_future();
        { 
            //尝试获取待添加队列锁
            std::unique_lock<std::mutex> lk(_wait_add_work_m);
            //添加到待添加任务队列
            _add_wait_work_q.emplace([task]() {  (*task)(); });
        }
        return res;
    }
    int wc(int n)
    { 
        int all = 1;
        for (int i = 1; i < 100000000; ++i)
        { 
            all *= i;
            all %= 100000007;
        }
        cout << n << " ";
        return all;
    }
    int main()
    { 
        vector<future<int>> temp;
        auto s1 = clock();
        ThreadPool pt(10);
    
        for (int i = 0; i < 8; ++i)
        { 
            temp.emplace_back(pt.add_task(wc, 1));
        }
        auto s2 = clock();
        for (int i = 0; i < temp.size(); ++i)
        { 
            temp[i].get();
        }
        auto s3 = clock();
        cout << endl;
        for (int i = 0; i < 8; ++i)
        { 
            wc(2);
        }
        auto s4 = clock();
        cout << endl;
        thread t1(wc, 3), t2(wc, 3), t3(wc, 3), t4(wc, 3), t5(wc, 3), t6(wc, 3), t7(wc, 3), t8(wc, 3);
        t1.join();
        t2.join();
        t3.join();
        t4.join();
        t5.join();
        t6.join();
        t7.join();
        t8.join();
        auto s5 = clock();
        cout << "end\n";
        std::cout << (s2 - s1) << "\t" << (s3 - s1) << "\t" << (s4 - s3) << "\t" << (s5 - s4) << std::endl;
    
        while (true)
        { 
            std::this_thread::yield();
        }
    
        getchar();
        return 0;
    }