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 // <shared_mutex>
13 
14 // template <class Mutex> class shared_lock;
15 
16 // shared_lock(mutex_type& m, try_to_lock_t);
17 
18 #include <shared_mutex>
19 #include <thread>
20 #include <vector>
21 #include <cstdlib>
22 #include <cassert>
23 
24 #if _LIBCPP_STD_VER > 11
25 
26 std::shared_timed_mutex m;
27 
28 typedef std::chrono::system_clock Clock;
29 typedef Clock::time_point time_point;
30 typedef Clock::duration duration;
31 typedef std::chrono::milliseconds ms;
32 typedef std::chrono::nanoseconds ns;
33 
f()34 void f()
35 {
36     time_point t0 = Clock::now();
37     {
38         std::shared_lock<std::shared_timed_mutex> lk(m, std::try_to_lock);
39         assert(lk.owns_lock() == false);
40     }
41     {
42         std::shared_lock<std::shared_timed_mutex> lk(m, std::try_to_lock);
43         assert(lk.owns_lock() == false);
44     }
45     {
46         std::shared_lock<std::shared_timed_mutex> lk(m, std::try_to_lock);
47         assert(lk.owns_lock() == false);
48     }
49     while (true)
50     {
51         std::shared_lock<std::shared_timed_mutex> lk(m, std::try_to_lock);
52         if (lk.owns_lock())
53             break;
54     }
55     time_point t1 = Clock::now();
56     ns d = t1 - t0 - ms(250);
57     assert(d < ms(200));  // within 200ms
58 }
59 
60 #endif  // _LIBCPP_STD_VER > 11
61 
main()62 int main()
63 {
64 #if _LIBCPP_STD_VER > 11
65     m.lock();
66     std::vector<std::thread> v;
67     for (int i = 0; i < 5; ++i)
68         v.push_back(std::thread(f));
69     std::this_thread::sleep_for(ms(250));
70     m.unlock();
71     for (auto& t : v)
72         t.join();
73 #endif  // _LIBCPP_STD_VER > 11
74 }
75