cxx/test/thread/futures/futures.unique_future/wait.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <future>

// class future<R>

// void wait() const;

#include <future>
#include <cassert>

void func1(std::promise<int>& p)
{
    std::this_thread::sleep_for(std::chrono::milliseconds(500));
    p.set_value(3);
}

int j = 0;

void func3(std::promise<int&>& p)
{
    std::this_thread::sleep_for(std::chrono::milliseconds(500));
    j = 5;
    p.set_value(j);
}

void func5(std::promise<void>& p)
{
    std::this_thread::sleep_for(std::chrono::milliseconds(500));
    p.set_value();
}

int main()
{
    typedef std::chrono::high_resolution_clock Clock;
    typedef std::chrono::duration<double, std::milli> ms;
    {
        typedef int T;
        std::promise<T> p;
        std::future<T> f = p.get_future();
        std::thread(func1, std::move(p)).detach();
        assert(f.valid());
        f.wait();
        assert(f.valid());
        Clock::time_point t0 = Clock::now();
        f.wait();
        Clock::time_point t1 = Clock::now();
        assert(f.valid());
        assert(t1-t0 < ms(5));
    }
    {
        typedef int& T;
        std::promise<T> p;
        std::future<T> f = p.get_future();
        std::thread(func3, std::move(p)).detach();
        assert(f.valid());
        f.wait();
        assert(f.valid());
        Clock::time_point t0 = Clock::now();
        f.wait();
        Clock::time_point t1 = Clock::now();
        assert(f.valid());
        assert(t1-t0 < ms(5));
    }
    {
        typedef void T;
        std::promise<T> p;
        std::future<T> f = p.get_future();
        std::thread(func5, std::move(p)).detach();
        assert(f.valid());
        f.wait();
        assert(f.valid());
        Clock::time_point t0 = Clock::now();
        f.wait();
        Clock::time_point t1 = Clock::now();
        assert(f.valid());
        assert(t1-t0 < ms(5));
    }
}