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 // <mutex>
13 
14 // class mutex;
15 
16 // bool try_lock();
17 
18 #include <mutex>
19 #include <thread>
20 #include <cstdlib>
21 #include <cassert>
22 
23 std::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 
main()45 int main()
46 {
47     m.lock();
48     std::thread t(f);
49     std::this_thread::sleep_for(ms(250));
50     m.unlock();
51     t.join();
52 }
53