c++多线程异步通讯

1.源码实现

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

using namespace std;
using namespace std::this_thread;
using namespace std::chrono;

/*费时操作*/
void work1(promise<int> &prom, int a, int b)
{
    cout << "work 1 开始计算: " << endl;
    sleep_for(seconds(3));
    prom.set_value(a+b);
}

int work2(int a, int b)
{
    cout << "work 2 开始计算: " << endl;
    sleep_for(seconds(2));
    return a + b;
}

int work3(int a, int b)
{
    cout << "work 3 开始计算: " << endl;
    sleep_for(seconds(2));
    return a + b;
}

int main()
{
    /*promise内部包装了一个值*/
    promise<int> prom;
    future<int> f1 = prom.get_future(); /*使用get_future函数获取future*/
    thread(work1, ref(prom), 1, 2).detach();
    f1.wait();  /*等待值设定*/

    cout << "计算结果: " << f1.get() << endl;

    /*packaged_task包装一个操作*/
    packaged_task<int(int, int)> task(work2);
    future<int> f2 = task.get_future(); /*使用get_future函数获取future*/
    thread(move(task), 11, 22).detach();
    f2.wait();

    cout << "计算结果: " << f2.get() << endl;

    /*async内部是一个线程*/
    future<int> f3 = async(work3, 45, 34);
    f3.wait();

    cout << "计算结果: " << f3.get() << endl;

    return 0;
}

2.编译源码

$ g++ -o example example.cpp -lpthread -std=c++11

3.运行及其结果

$ ./example
work 1 开始计算: 
计算结果: 3
work 2 开始计算: 
计算结果: 33
work 3 开始计算: 
计算结果: 79