C++ 线程池 + 消息队列 代码实现

1. 消息队列- ConcurrentQueue

消息队列用一个类:ConcurrentQueue进行封装，拥有成员**_queue**，来存放元素；内部实现push，pop函数，来对队列进行入队和出队操作。

message_queue.h

#ifndef NET_FRAME_CONCURRENT_QUEUE_H
#define NET_FRAME_CONCURRENT_QUEUE_H
 
#include 
#include 
#include 

template<class Type>
/*消息队列实现*/
class ConcurrentQueue {
    ConcurrentQueue& operator=(const ConcurrentQueue&) = delete;

    ConcurrentQueue(const ConcurrentQueue& other) = delete;

public:
    ConcurrentQueue() : _queue(), _mutex(), _condition() { }

    virtual ~ConcurrentQueue() { }

    void Push(Type record) {
        std::lock_guard <std::mutex> lock(_mutex);
        _queue.push(record);
        //每增加一个元素，用条件变量进行通知。
        _condition.notify_one();
    }

    bool Pop(Type& record, bool isBlocked = true) {
        if (isBlocked) {
            std::unique_lock <std::mutex> lock(_mutex);
            //当队列为空就进行wait阻塞等待。
            while (_queue.empty()) {
                _condition.wait(lock);
            }
        }
        else // If user wants to retrieve data in non-blocking mode
        {
            std::lock_guard <std::mutex> lock(_mutex);
            if (_queue.empty()) {
                return false;
            }
        }

        record = std::move(_queue.front());
        _queue.pop();
        return true;
    }

    int32_t Size() {
        std::lock_guard <std::mutex> lock(_mutex);
        return _queue.size();
    }

    bool Empty() {
        std::lock_guard <std::mutex> lock(_mutex);
        return _queue.empty();
    }

private:
    std::queue <Type> _queue;
    mutable std::mutex _mutex;
    std::condition_variable _condition;
};
 
 
#endif //NET_FRAME_CONCURRENT_QUEUE_H

2. 线程池-ThreadPool

封装了ThreadPool类，该类需要指定线程的数量_threads，包含用来存放线程的_workers容器。
在创建线程的时候，需要指定线程的处理函数lambda表达式以及元素的处理函数_handler：将消息队列的元素取出，然后作为_handler函数的形参进行处理。

Submit方法用于往消息队列里增加元素。

thread_pool.h

#ifndef NET_FRAME_THREAD_POOL_H
#define NET_FRAME_THREAD_POOL_H
 
#include "message_queue.h"
 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
 
#define MIN_THREADS 10
 
 
template<class Type>
class ThreadPool {
    ThreadPool& operator=(const ThreadPool&) = delete;

    ThreadPool(const ThreadPool& other) = delete;

public:
    ThreadPool(int32_t threads, std::function<void(Type& record)> handler);

    virtual ~ThreadPool();

    void Submit(Type record);

private:

private:
    bool _shutdown;
    int32_t _threads;
    std::function<void(Type& record)> _handler;
    std::vector <std::thread> _workers;
    ConcurrentQueue <Type> _tasks;
};

template<class Type>
ThreadPool<Type>::ThreadPool(int32_t threads, std::function<void(Type &record)> handler)
        : _shutdown(false),
            _threads(threads),
            _handler(handler),
            _workers(),
            _tasks() {
    if (_threads < MIN_THREADS)
        _threads = MIN_THREADS;


    for (int32_t i = 0; i < _threads; ++i)
        _workers.emplace_back(
                [this] {
                    while (!_shutdown) {
                        Type record;
                        this->_tasks.Pop(record, true);
                        this->_handler(record);
                    }
                }
        );
}


template<class Type>
ThreadPool<Type>::~ThreadPool() {
    for (std::thread &worker: _workers)
        worker.join();
}


template<class Type>
void ThreadPool<Type>::Submit(Type record) {
    _tasks.Push(record);
}
 
 
 
 
#endif //NET_FRAME_THREAD_POOL_H

3. 测试代码

#include"message_queue.h"
#include"thread_pool.h"
#include

std::mutex mutex_;

void threadProcess(int value){
    std::unique_lock<std::mutex> lock_(mutex_);
    std::cout<<"current threadId:"<<std::this_thread::get_id()<<" value:"<<value<<std::endl;
}
int main(){
    std::cout<<"main threadId:"<<std::this_thread::get_id()<<std::endl;
    ThreadPool<int> threadPool(15,threadProcess);
    for(int i=0;i<100000;++i){
        threadPool.Submit(i);
    }
    return 0;
}

4.运行截图

ps-ef |grep main

top -H -p 23796
可以看出有16个进程正在运行。