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