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
23std::mutex m;
24
25typedef std::chrono::system_clock Clock;
26typedef Clock::time_point time_point;
27typedef Clock::duration duration;
28typedef std::chrono::milliseconds ms;
29typedef std::chrono::nanoseconds ns;
30
31void 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
45int 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