c++11 线程池学习笔记 (二) 线程池

学习内容来自以下地址

http://www.cnblogs.com/qicosmos/p/4772486.html

github https://github.com/qicosmos/cosmos

有了任务队列 在程序运行之初 就预开启多个执行任务的线程 等待任务队列中传来的元素 对元素进行处理 执行完毕后 也不销毁线程 而是等待下个元素进行处理 

使用std::list<std::shared_ptr<std::thread>> m_threadgroup; 变量记录线程指针 方便管理

测试例子中传递的元素类型定义为 td::function<void()> 即一个返回类型为void 无输入参数的函数

对应代码为using Task = std::function<void()>;

每当队列中添加该元素TASK 则有线程从队列中取出执行

代码如下

#pragma once

#include <list>
#include <mutex>
#include <thread>
#include <condition_variable>
#include <iostream>

using namespace std;

template<typename T>
class SyncQueue {
public:
    SyncQueue(int maxSize):m_maxSize(maxSize),m_needStop(false){}
    void Put(const T& x) {
        Add(x);
    }
    void Put(T&& x) {
        Add(std::forward<T>(x));
    }
    void Take(std::list<T>& list) {
        std::unique_lock<std::mutex> locker(m_mutex);
        m_notEmpty.wait(locker, [this] {return m_needStop || NotEmpty(); });
        if (m_needStop)
            return;
        list = std::move(m_queue);
        m_notFull.notify_one();
    }

    void Take(T& t) {
        std::unique_lock<std::mutex> locker(m_mutex);
        m_notEmpty.wait(locker, [this] {return m_needStop || NotEmpty(); });
        if (m_needStop)
            return;
        t = m_queue.front();
        m_queue.pop_front();
        m_notFull.notify_one();
    }

    void Stop() {
        {
            std::lock_guard<std::mutex> locker(m_mutex);
            m_needStop = true;
        }
        m_notFull.notify_all();
        m_notEmpty.notify_all();
    }

    bool Empty() {
        std::lock_guard<std::mutex> locker(m_mutex);
        return m_queue.empty();
    }

    bool Full() {
        std::lock_guard<std::mutex> locker(m_mutex);
        return m_queue.size() == m_maxSize;
    }

    size_t Size() {
        std::lock_guard<std::mutex> locker(m_mutex);
        return m_queue.size();
    }

    int Count() {
        return m_queue.size();
    }
private:
    bool NotFull()const {
        bool full = m_queue.size() >= m_maxSize;
        if (full)
            cout << "buffer area is full,wait..." << endl;
        return !full;
    }
    bool NotEmpty()const {
        bool empty = m_queue.empty();
        if (empty)
            cout << "buffer area is empty,wait... " << 
                " threadID: " << this_thread::get_id() <<endl;
        return !empty;
    }

    template<typename F>
    void Add(F&& x) {
        std::unique_lock<std::mutex> locker(m_mutex);
        m_notFull.wait(locker, [this] {return m_needStop || NotFull(); });
        if (m_needStop)
            return;
        m_queue.push_back(std::forward<F>(x));
        m_notEmpty.notify_one();
    }
private:
    std::list<T> m_queue;
    std::mutex m_mutex;
    std::condition_variable m_notEmpty;
    std::condition_variable m_notFull;
    int m_maxSize;
    bool m_needStop;
};

// ThreadPool.cpp: 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <list>
#include <thread>
#include <functional>
#include <memory>
#include <atomic>
#include "SyncQueue.h"

const int MaxTaskCount = 100;
class ThreadPool {
    using Task = std::function<void()>;
public:
    ThreadPool(int numThreads = std::thread::hardware_concurrency()) :m_queue(MaxTaskCount) {
        Start(numThreads);
    }
    ~ThreadPool(void) {
        Stop();
    }
    void Stop() {
        std::call_once(m_flag, [this] {StopThreadGroup(); });
    }
    void AddTask(Task&& task) {
        m_queue.Put(std::forward<Task>(task));
    }
    void AddTask(const Task& task) {
        m_queue.Put(task);
    }

    void Start(int numThreads) {
        m_running = true;
        for (int i = 0; i < numThreads; i++) {
            m_threadgroup.push_back(std::make_shared<std::thread>(&ThreadPool::RunInThread, this));
        }
    }
private:
    void RunInThread() {
        while(m_running) {
            std::list<Task> list;
            m_queue.Take(list);

            for (auto& task : list) {
                if (!m_running)
                    return;
                task();
            }
        }
    }

    void StopThreadGroup() {
        m_queue.Stop();
        m_running = false;
        for (auto thread : m_threadgroup) {
            if (thread)
                thread->join();
        }
        m_threadgroup.clear();
    }
    std::list<std::shared_ptr<std::thread>> m_threadgroup;
    SyncQueue<Task> m_queue;
    atomic_bool m_running;
    std::once_flag m_flag;
};

//=========================================================
void TestThdPool() 
{
    ThreadPool pool;
    pool.Start(2);

    std::thread thd1([&pool] {
        for (int i = 0; i < 10; i++) {
            auto thdId = this_thread::get_id();
            pool.AddTask([thdId] {
                std::cout << "thread1 id : " << thdId << std::endl;
            });
        }
    });

    std::thread thd2([&pool] {
        for (int i = 0; i < 10; i++) {
            auto thdId = this_thread::get_id();
            pool.AddTask([thdId] {
                std::cout << "thread2 id : " << thdId << std::endl;
            });
        }
    });

    this_thread::sleep_for(std::chrono::seconds(2));
    getchar();
    pool.Stop();
    thd1.join();
    thd2.join();
}


int main()
{
    TestThdPool();
    return 0;
}

运行情况如下：

buffer area is empty,wait... threadID: 10244
buffer area is empty,wait... threadID: 8168
buffer area is empty,wait... threadID: 10136
buffer area is empty,wait... threadID: 5812
buffer area is empty,wait... threadID: 4064
buffer area is empty,wait... threadID: 7872
thread1 id : 9712buffer area is empty,wait... threadID:
8168
thread1 id : 9712
buffer area is empty,wait... threadID: 10244thread1 id : 9712

thread2 id : buffer area is empty,wait... threadID: thread2 id : 65206520
5812

thread2 id : thread1 id : thread2 id : 9712buffer area is empty,wait... threadID: thread2 id : 65206520
6520
thread2 id :
6520
thread2 id :
6520thread1 id :
40649712
thread2 id :
6520buffer area is empty,wait... threadID: thread2 id : 6520

thread1 id : 97125812

thread1 id : 9712buffer area is empty,wait... threadID: thread1 id : 10136

9712
buffer area is empty,wait... threadID: 7872thread1 id : 9712

thread2 id : 6520buffer area is empty,wait... threadID:
10244
thread1 id : 9712
buffer area is empty,wait... threadID: 8168