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// UNSUPPORTED: c++03, c++98, c++11, c++14
12
13// <shared_mutex>
14
15// class shared_mutex;
16
17// bool try_lock();
18
19#include <shared_mutex>
20#include <thread>
21#include <cstdlib>
22#include <cassert>
23
24std::shared_mutex m;
25
26typedef std::chrono::system_clock Clock;
27typedef Clock::time_point time_point;
28typedef Clock::duration duration;
29typedef std::chrono::milliseconds ms;
30typedef std::chrono::nanoseconds ns;
31
32void f()
33{
34    time_point t0 = Clock::now();
35    assert(!m.try_lock());
36    assert(!m.try_lock());
37    assert(!m.try_lock());
38    while(!m.try_lock())
39        ;
40    time_point t1 = Clock::now();
41    m.unlock();
42    ns d = t1 - t0 - ms(250);
43    assert(d < ms(200));  // within 200ms
44}
45
46int main()
47{
48    m.lock();
49    std::thread t(f);
50    std::this_thread::sleep_for(ms(250));
51    m.unlock();
52    t.join();
53}
54