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 // FLAKY_TEST.
14 
15 // <future>
16 
17 // class shared_future<R>
18 
19 // template <class Clock, class Duration>
20 //   future_status
21 //   wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
22 
23 #include <future>
24 #include <atomic>
25 #include <cassert>
26 
27 enum class WorkerThreadState { Uninitialized, AllowedToRun, Exiting };
28 typedef std::chrono::milliseconds ms;
29 
30 std::atomic<WorkerThreadState> thread_state(WorkerThreadState::Uninitialized);
31 
set_worker_thread_state(WorkerThreadState state)32 void set_worker_thread_state(WorkerThreadState state)
33 {
34     thread_state.store(state, std::memory_order_relaxed);
35 }
36 
wait_for_worker_thread_state(WorkerThreadState state)37 void wait_for_worker_thread_state(WorkerThreadState state)
38 {
39     while (thread_state.load(std::memory_order_relaxed) != state);
40 }
41 
func1(std::promise<int> p)42 void func1(std::promise<int> p)
43 {
44     wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
45     p.set_value(3);
46     set_worker_thread_state(WorkerThreadState::Exiting);
47 }
48 
49 int j = 0;
50 
func3(std::promise<int &> p)51 void func3(std::promise<int&> p)
52 {
53     wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
54     j = 5;
55     p.set_value(j);
56     set_worker_thread_state(WorkerThreadState::Exiting);
57 }
58 
func5(std::promise<void> p)59 void func5(std::promise<void> p)
60 {
61     wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
62     p.set_value();
63     set_worker_thread_state(WorkerThreadState::Exiting);
64 }
65 
main()66 int main()
67 {
68     typedef std::chrono::high_resolution_clock Clock;
69     {
70         typedef int T;
71         std::promise<T> p;
72         std::shared_future<T> f = p.get_future();
73         std::thread(func1, std::move(p)).detach();
74         assert(f.valid());
75         assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
76         assert(f.valid());
77 
78         // allow the worker thread to produce the result and wait until the worker is done
79         set_worker_thread_state(WorkerThreadState::AllowedToRun);
80         wait_for_worker_thread_state(WorkerThreadState::Exiting);
81 
82         assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
83         assert(f.valid());
84         Clock::time_point t0 = Clock::now();
85         f.wait();
86         Clock::time_point t1 = Clock::now();
87         assert(f.valid());
88         assert(t1-t0 < ms(5));
89     }
90     {
91         typedef int& T;
92         std::promise<T> p;
93         std::shared_future<T> f = p.get_future();
94         std::thread(func3, std::move(p)).detach();
95         assert(f.valid());
96         assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
97         assert(f.valid());
98 
99         // allow the worker thread to produce the result and wait until the worker is done
100         set_worker_thread_state(WorkerThreadState::AllowedToRun);
101         wait_for_worker_thread_state(WorkerThreadState::Exiting);
102 
103         assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
104         assert(f.valid());
105         Clock::time_point t0 = Clock::now();
106         f.wait();
107         Clock::time_point t1 = Clock::now();
108         assert(f.valid());
109         assert(t1-t0 < ms(5));
110     }
111     {
112         typedef void T;
113         std::promise<T> p;
114         std::shared_future<T> f = p.get_future();
115         std::thread(func5, std::move(p)).detach();
116         assert(f.valid());
117         assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
118         assert(f.valid());
119 
120         // allow the worker thread to produce the result and wait until the worker is done
121         set_worker_thread_state(WorkerThreadState::AllowedToRun);
122         wait_for_worker_thread_state(WorkerThreadState::Exiting);
123 
124         assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
125         assert(f.valid());
126         Clock::time_point t0 = Clock::now();
127         f.wait();
128         Clock::time_point t1 = Clock::now();
129         assert(f.valid());
130         assert(t1-t0 < ms(5));
131     }
132 }
133