1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// UNSUPPORTED: libcpp-has-no-threads
11// UNSUPPORTED: c++98, c++03
12
13// <future>
14
15// class future<R>
16
17// template <class Clock, class Duration>
18//   future_status
19//   wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
20
21#include <future>
22#include <atomic>
23#include <cassert>
24
25enum class WorkerThreadState { Uninitialized, AllowedToRun, Exiting };
26typedef std::chrono::milliseconds ms;
27
28std::atomic<WorkerThreadState> thread_state(WorkerThreadState::Uninitialized);
29
30void set_worker_thread_state(WorkerThreadState state)
31{
32    thread_state.store(state, std::memory_order_relaxed);
33}
34
35void wait_for_worker_thread_state(WorkerThreadState state)
36{
37    while (thread_state.load(std::memory_order_relaxed) != state);
38}
39
40void func1(std::promise<int> p)
41{
42    wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
43    p.set_value(3);
44    set_worker_thread_state(WorkerThreadState::Exiting);
45}
46
47int j = 0;
48
49void func3(std::promise<int&> p)
50{
51    wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
52    j = 5;
53    p.set_value(j);
54    set_worker_thread_state(WorkerThreadState::Exiting);
55}
56
57void func5(std::promise<void> p)
58{
59    wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
60    p.set_value();
61    set_worker_thread_state(WorkerThreadState::Exiting);
62}
63
64int main()
65{
66    typedef std::chrono::high_resolution_clock Clock;
67    {
68        typedef int T;
69        std::promise<T> p;
70        std::future<T> f = p.get_future();
71        std::thread(func1, std::move(p)).detach();
72        assert(f.valid());
73        assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
74        assert(f.valid());
75
76        // allow the worker thread to produce the result and wait until the worker is done
77        set_worker_thread_state(WorkerThreadState::AllowedToRun);
78        wait_for_worker_thread_state(WorkerThreadState::Exiting);
79
80        assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
81        assert(f.valid());
82        Clock::time_point t0 = Clock::now();
83        f.wait();
84        Clock::time_point t1 = Clock::now();
85        assert(f.valid());
86        assert(t1-t0 < ms(5));
87    }
88    {
89        typedef int& T;
90        std::promise<T> p;
91        std::future<T> f = p.get_future();
92        std::thread(func3, std::move(p)).detach();
93        assert(f.valid());
94        assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
95        assert(f.valid());
96
97        // allow the worker thread to produce the result and wait until the worker is done
98        set_worker_thread_state(WorkerThreadState::AllowedToRun);
99        wait_for_worker_thread_state(WorkerThreadState::Exiting);
100
101        assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
102        assert(f.valid());
103        Clock::time_point t0 = Clock::now();
104        f.wait();
105        Clock::time_point t1 = Clock::now();
106        assert(f.valid());
107        assert(t1-t0 < ms(5));
108    }
109    {
110        typedef void T;
111        std::promise<T> p;
112        std::future<T> f = p.get_future();
113        std::thread(func5, std::move(p)).detach();
114        assert(f.valid());
115        assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
116        assert(f.valid());
117
118        // allow the worker thread to produce the result and wait until the worker is done
119        set_worker_thread_state(WorkerThreadState::AllowedToRun);
120        wait_for_worker_thread_state(WorkerThreadState::Exiting);
121
122        assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
123        assert(f.valid());
124        Clock::time_point t0 = Clock::now();
125        f.wait();
126        Clock::time_point t1 = Clock::now();
127        assert(f.valid());
128        assert(t1-t0 < ms(5));
129    }
130}
131