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 // <future>
11 
12 // class future<R>
13 
14 // void wait() const;
15 
16 #include <future>
17 #include <cassert>
18 
func1(std::promise<int> p)19 void func1(std::promise<int> p)
20 {
21     std::this_thread::sleep_for(std::chrono::milliseconds(500));
22     p.set_value(3);
23 }
24 
25 int j = 0;
26 
func3(std::promise<int &> p)27 void func3(std::promise<int&> p)
28 {
29     std::this_thread::sleep_for(std::chrono::milliseconds(500));
30     j = 5;
31     p.set_value(j);
32 }
33 
func5(std::promise<void> p)34 void func5(std::promise<void> p)
35 {
36     std::this_thread::sleep_for(std::chrono::milliseconds(500));
37     p.set_value();
38 }
39 
main()40 int main()
41 {
42     typedef std::chrono::high_resolution_clock Clock;
43     typedef std::chrono::duration<double, std::milli> ms;
44     {
45         typedef int T;
46         std::promise<T> p;
47         std::future<T> f = p.get_future();
48         std::thread(func1, std::move(p)).detach();
49         assert(f.valid());
50         f.wait();
51         assert(f.valid());
52         Clock::time_point t0 = Clock::now();
53         f.wait();
54         Clock::time_point t1 = Clock::now();
55         assert(f.valid());
56         assert(t1-t0 < ms(5));
57     }
58     {
59         typedef int& T;
60         std::promise<T> p;
61         std::future<T> f = p.get_future();
62         std::thread(func3, std::move(p)).detach();
63         assert(f.valid());
64         f.wait();
65         assert(f.valid());
66         Clock::time_point t0 = Clock::now();
67         f.wait();
68         Clock::time_point t1 = Clock::now();
69         assert(f.valid());
70         assert(t1-t0 < ms(5));
71     }
72     {
73         typedef void T;
74         std::promise<T> p;
75         std::future<T> f = p.get_future();
76         std::thread(func5, std::move(p)).detach();
77         assert(f.valid());
78         f.wait();
79         assert(f.valid());
80         Clock::time_point t0 = Clock::now();
81         f.wait();
82         Clock::time_point t1 = Clock::now();
83         assert(f.valid());
84         assert(t1-t0 < ms(5));
85     }
86 }
87