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_timed_mutex;
13 
14 // bool try_lock();
15 
16 #include <shared_mutex>
17 #include <thread>
18 #include <cstdlib>
19 #include <cassert>
20 
21 #if _LIBCPP_STD_VER > 11
22 
23 std::shared_timed_mutex m;
24 
25 typedef std::chrono::system_clock Clock;
26 typedef Clock::time_point time_point;
27 typedef Clock::duration duration;
28 typedef std::chrono::milliseconds ms;
29 typedef std::chrono::nanoseconds ns;
30 
f()31 void f()
32 {
33     time_point t0 = Clock::now();
34     assert(!m.try_lock());
35     assert(!m.try_lock());
36     assert(!m.try_lock());
37     while(!m.try_lock())
38         ;
39     time_point t1 = Clock::now();
40     m.unlock();
41     ns d = t1 - t0 - ms(250);
42     assert(d < ms(200));  // within 200ms
43 }
44 
45 #endif  // _LIBCPP_STD_VER > 11
46 
main()47 int main()
48 {
49 #if _LIBCPP_STD_VER > 11
50     m.lock();
51     std::thread t(f);
52     std::this_thread::sleep_for(ms(250));
53     m.unlock();
54     t.join();
55 #endif  // _LIBCPP_STD_VER > 11
56 }
57