c++11多线程学习笔记之三 condition_variable使用

从windows角度来说，condition_variable类似event。

阻塞等待出发，不过condition_variable可以批量出发。

代码如下:

// 1111111.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <thread>
#include <mutex>
#include <condition_variable>

std::mutex gmtx; 
std::condition_variable gcv; 
bool gready = false;

void do_print_id(int id)
{
    std::unique_lock<std::mutex> lock(gmtx);
    while (!gready)
        gcv.wait(lock);
    std::cout << "thread " << id << std::endl;
}

void go()
{
    std::unique_lock<std::mutex> lock(gmtx);
    gready = true;
    gcv.notify_all();
}



int _tmain(int argc, _TCHAR* argv[])
{
    std::thread thread[50];
    for (int i = 0; i < 50; ++i)
        thread[i] = std::thread(do_print_id, i);

    std::cout << "start..." << std::endl;
    //触发激活
    go();

    //等待线程结束执行
    for (auto & th : thread)
        th.join();

    return 0;
}

显示如下:

start...
thread 7
thread 3
thread 2
thread 9
thread 6
thread 5
thread 1
thread 0
thread 4
thread 8
请按任意键继续. . .

#pragma once
// 参考http://www.cnblogs.com/qicosmos/archive/2013/05/30/3107975.html
#include <thread>
#include <condition_variable>
#include <mutex>
#include <list>
#include <iostream>

using namespace std;

template<typename T>
class SimpleSyncQueue {
public:
void PutWithLock(const T& x)
{
std::lock_guard<std::mutex> locker(m_mutex);
m_queue.emplace_back(x);
m_notEmpty.notify_one();
}
template<typename U>
void PutWithLock(const T&& x)
{
std::lock_guard<std::mutex> locker(m_mutex);
m_queue.emplace_back(std::forward<U>(x));
m_notEmpty.notify_one();
}
void PopWithLock(T& x)
{
std::unique_lock<std::mutex> locker(m_mutex);
while (m_queue.empty())
m_notEmpty.wait(locker);
x = m_queue.front();
m_queue.pop_front();
}
private:
std::list<T> m_queue;
std::mutex m_mutex;
std::condition_variable m_notEmpty;
};