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++98, c++03, c++11
12 
13 // FLAKY_TEST.
14 
15 // <shared_mutex>
16 
17 // class timed_mutex;
18 
19 // template <class Rep, class Period>
20 //   shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
21 
22 #include <shared_mutex>
23 #include <thread>
24 #include <vector>
25 #include <cstdlib>
26 #include <cassert>
27 
28 #include "test_macros.h"
29 
30 std::shared_timed_mutex m;
31 
32 typedef std::chrono::steady_clock Clock;
33 typedef Clock::time_point time_point;
34 typedef Clock::duration duration;
35 typedef std::chrono::milliseconds ms;
36 typedef std::chrono::nanoseconds ns;
37 
38 ms WaitTime = ms(250);
39 
40 // Thread sanitizer causes more overhead and will sometimes cause this test
41 // to fail. To prevent this we give Thread sanitizer more time to complete the
42 // test.
43 #if !defined(TEST_HAS_SANITIZERS)
44 ms Tolerance = ms(50);
45 #else
46 ms Tolerance = ms(50 * 5);
47 #endif
48 
49 
f1()50 void f1()
51 {
52     time_point t0 = Clock::now();
53     std::shared_lock<std::shared_timed_mutex> lk(m, WaitTime + Tolerance);
54     assert(lk.owns_lock() == true);
55     time_point t1 = Clock::now();
56     ns d = t1 - t0 - WaitTime;
57     assert(d < Tolerance);  // within 50ms
58 }
59 
f2()60 void f2()
61 {
62     time_point t0 = Clock::now();
63     std::shared_lock<std::shared_timed_mutex> lk(m, WaitTime);
64     assert(lk.owns_lock() == false);
65     time_point t1 = Clock::now();
66     ns d = t1 - t0 - WaitTime;
67     assert(d < Tolerance);  // within 50ms
68 }
69 
main()70 int main()
71 {
72     {
73         m.lock();
74         std::vector<std::thread> v;
75         for (int i = 0; i < 5; ++i)
76             v.push_back(std::thread(f1));
77         std::this_thread::sleep_for(WaitTime);
78         m.unlock();
79         for (auto& t : v)
80             t.join();
81     }
82     {
83         m.lock();
84         std::vector<std::thread> v;
85         for (int i = 0; i < 5; ++i)
86             v.push_back(std::thread(f2));
87         std::this_thread::sleep_for(WaitTime + Tolerance);
88         m.unlock();
89         for (auto& t : v)
90             t.join();
91     }
92 }
93