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
21std::mutex m;
22
23typedef std::chrono::system_clock Clock;
24typedef Clock::time_point time_point;
25typedef Clock::duration duration;
26typedef std::chrono::milliseconds ms;
27typedef std::chrono::nanoseconds ns;
28
29void 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
43int 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