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 // <shared_mutex>
11 
12 // class shared_mutex;
13 
14 // template <class Rep, class Period>
15 //     bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
16 
17 #include <shared_mutex>
18 #include <thread>
19 #include <cstdlib>
20 #include <cassert>
21 
22 #if _LIBCPP_STD_VER > 11
23 
24 std::shared_mutex m;
25 
26 typedef std::chrono::steady_clock Clock;
27 typedef Clock::time_point time_point;
28 typedef Clock::duration duration;
29 typedef std::chrono::milliseconds ms;
30 typedef std::chrono::nanoseconds ns;
31 
f1()32 void f1()
33 {
34     time_point t0 = Clock::now();
35     assert(m.try_lock_for(ms(300)) == true);
36     time_point t1 = Clock::now();
37     m.unlock();
38     ns d = t1 - t0 - ms(250);
39     assert(d < ms(50));  // within 50ms
40 }
41 
f2()42 void f2()
43 {
44     time_point t0 = Clock::now();
45     assert(m.try_lock_for(ms(250)) == false);
46     time_point t1 = Clock::now();
47     ns d = t1 - t0 - ms(250);
48     assert(d < ms(50));  // within 50ms
49 }
50 
51 #endif  // _LIBCPP_STD_VER > 11
52 
main()53 int main()
54 {
55 #if _LIBCPP_STD_VER > 11
56     {
57         m.lock();
58         std::thread t(f1);
59         std::this_thread::sleep_for(ms(250));
60         m.unlock();
61         t.join();
62     }
63     {
64         m.lock();
65         std::thread t(f2);
66         std::this_thread::sleep_for(ms(300));
67         m.unlock();
68         t.join();
69     }
70 #endif  // _LIBCPP_STD_VER > 11
71 }
72