1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // UNSUPPORTED: no-threads
10 // UNSUPPORTED: c++03
11 
12 // <future>
13 
14 // class future<R>
15 
16 // template <class Clock, class Duration>
17 //   future_status
18 //   wait_until(const chrono::time_point<Clock, Duration>& abs_time) const;
19 
20 #include <atomic>
21 #include <cassert>
22 #include <chrono>
23 #include <future>
24 
25 #include "make_test_thread.h"
26 #include "test_macros.h"
27 
28 enum class WorkerThreadState { Uninitialized, AllowedToRun, Exiting };
29 typedef std::chrono::milliseconds ms;
30 
31 std::atomic<WorkerThreadState> thread_state(WorkerThreadState::Uninitialized);
32 
33 void set_worker_thread_state(WorkerThreadState state)
34 {
35   thread_state.store(state, std::memory_order_relaxed);
36 }
37 
38 void wait_for_worker_thread_state(WorkerThreadState state)
39 {
40   while (thread_state.load(std::memory_order_relaxed) != state)
41     std::this_thread::yield();
42 }
43 
44 void func1(std::promise<int> p)
45 {
46   wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
47   p.set_value(3);
48   set_worker_thread_state(WorkerThreadState::Exiting);
49 }
50 
51 int j = 0;
52 
53 void func3(std::promise<int&> p)
54 {
55   wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
56   j = 5;
57   p.set_value(j);
58   set_worker_thread_state(WorkerThreadState::Exiting);
59 }
60 
61 void func5(std::promise<void> p)
62 {
63   wait_for_worker_thread_state(WorkerThreadState::AllowedToRun);
64   p.set_value();
65   set_worker_thread_state(WorkerThreadState::Exiting);
66 }
67 
68 int main(int, char**)
69 {
70   typedef std::chrono::high_resolution_clock Clock;
71   {
72     typedef int T;
73     std::promise<T> p;
74     std::future<T> f = p.get_future();
75     support::make_test_thread(func1, std::move(p)).detach();
76     assert(f.valid());
77     assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
78     assert(f.valid());
79 
80     // allow the worker thread to produce the result and wait until the worker is done
81     set_worker_thread_state(WorkerThreadState::AllowedToRun);
82     wait_for_worker_thread_state(WorkerThreadState::Exiting);
83 
84     assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
85     assert(f.valid());
86     f.wait();
87     assert(f.valid());
88   }
89   {
90     typedef int& T;
91     std::promise<T> p;
92     std::future<T> f = p.get_future();
93     support::make_test_thread(func3, std::move(p)).detach();
94     assert(f.valid());
95     assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
96     assert(f.valid());
97 
98     // allow the worker thread to produce the result and wait until the worker is done
99     set_worker_thread_state(WorkerThreadState::AllowedToRun);
100     wait_for_worker_thread_state(WorkerThreadState::Exiting);
101 
102     assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
103     assert(f.valid());
104     f.wait();
105     assert(f.valid());
106   }
107   {
108     typedef void T;
109     std::promise<T> p;
110     std::future<T> f = p.get_future();
111     support::make_test_thread(func5, std::move(p)).detach();
112     assert(f.valid());
113     assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::timeout);
114     assert(f.valid());
115 
116     // allow the worker thread to produce the result and wait until the worker is done
117     set_worker_thread_state(WorkerThreadState::AllowedToRun);
118     wait_for_worker_thread_state(WorkerThreadState::Exiting);
119 
120     assert(f.wait_until(Clock::now() + ms(10)) == std::future_status::ready);
121     assert(f.valid());
122     f.wait();
123     assert(f.valid());
124   }
125 
126   return 0;
127 }
128