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 
12 // <thread>
13 
14 // template <class Rep, class Period>
15 //   void sleep_for(const chrono::duration<Rep, Period>& rel_time);
16 
17 #include <thread>
18 #include <cstdlib>
19 #include <cassert>
20 #include <cstring>
21 #include <signal.h>
22 #include <sys/time.h>
23 
sig_action(int)24 void sig_action(int) {}
25 
main()26 int main()
27 {
28     int ec;
29     struct sigaction action;
30     action.sa_handler = &sig_action;
31     sigemptyset(&action.sa_mask);
32     action.sa_flags = 0;
33 
34     ec = sigaction(SIGALRM, &action, nullptr);
35     assert(!ec);
36 
37     struct itimerval it;
38     std::memset(&it, 0, sizeof(itimerval));
39     it.it_value.tv_sec = 0;
40     it.it_value.tv_usec = 250000;
41     // This will result in a SIGALRM getting fired resulting in the nanosleep
42     // inside sleep_for getting EINTR.
43     ec = setitimer(ITIMER_REAL, &it, nullptr);
44     assert(!ec);
45 
46     typedef std::chrono::system_clock Clock;
47     typedef Clock::time_point time_point;
48     typedef Clock::duration duration;
49     std::chrono::milliseconds ms(500);
50     time_point t0 = Clock::now();
51     std::this_thread::sleep_for(ms);
52     time_point t1 = Clock::now();
53     std::chrono::nanoseconds ns = (t1 - t0) - ms;
54     std::chrono::nanoseconds err = 5 * ms / 100;
55     // The time slept is within 5% of 500ms
56     assert(std::abs(ns.count()) < err.count());
57 }
58