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 // explicit shared_lock(mutex_type& m);
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     time_point t1;
38     {
39     std::shared_lock<std::shared_timed_mutex> ul(m);
40     t1 = Clock::now();
41     }
42     ns d = t1 - t0 - ms(250);
43     assert(d < ms(50));  // within 50ms
44 }
45 
g()46 void g()
47 {
48     time_point t0 = Clock::now();
49     time_point t1;
50     {
51     std::shared_lock<std::shared_timed_mutex> ul(m);
52     t1 = Clock::now();
53     }
54     ns d = t1 - t0;
55     assert(d < ms(50));  // within 50ms
56 }
57 
58 #endif  // _LIBCPP_STD_VER > 11
59 
main()60 int main()
61 {
62 #if _LIBCPP_STD_VER > 11
63     m.lock();
64     std::vector<std::thread> v;
65     for (int i = 0; i < 5; ++i)
66         v.push_back(std::thread(f));
67     std::this_thread::sleep_for(ms(250));
68     m.unlock();
69     for (auto& t : v)
70         t.join();
71     m.lock_shared();
72     for (auto& t : v)
73         t = std::thread(g);
74     std::thread q(f);
75     std::this_thread::sleep_for(ms(250));
76     m.unlock_shared();
77     for (auto& t : v)
78         t.join();
79     q.join();
80 #endif  // _LIBCPP_STD_VER > 11
81 }
82