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

#ifdef _WIN32
#include <windows.h>
#endif

// 1.Promise(生产者)和Future(消费者)
void workTh1(std::promise<int> prom)
{
    std::this_thread::sleep_for(std::chrono::seconds(5));
    prom.set_value(98);
}

void testTaskTh1()
{
    std::promise<int> prm;
    auto fut = prm.get_future();

    std::thread t(workTh1, std::move(prm));

    std::cout << "准备打印内容..." << std::endl;
    std::cout << fut.get() << std::endl;
    std::cout << "打印内容结束..." << std::endl;

    t.join();
}

// 2.std::packaged_task本质上是一个包装器, 包装可调用对象，内部使用了std::promise.
int someFunc(int a, int b)
{
    std::this_thread::sleep_for(std::chrono::seconds(3));
    return a + b;
}

void testTaskTh2()
{
    std::packaged_task<int(int, int)> pt(someFunc);
    auto fut = pt.get_future();
    std::thread t(std::move(pt), 33, 55);
    t.join();
    std::cout << __FUNCTION__ << " over, ret = " << fut.get() << std::endl;
}

// 3.异步运行任务（更高级的用法，不用关心开线程打包这种操作）
void testTaskTh3()
{
    auto fut = std::async(std::launch::async, someFunc, 11, 22);
    std::cout << __FUNCTION__ << " over, ret = " << fut.get() << std::endl;
}

int main()
{
#ifdef _WIN32
    SetConsoleOutputCP(CP_UTF8);
#endif
    testTaskTh3();
    return 0;
}