1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // UNSUPPORTED: libcpp-has-no-threads
10 // UNSUPPORTED: c++98, c++03, c++11
11 
12 // FLAKY_TEST.
13 
14 // <shared_mutex>
15 
16 // class timed_mutex;
17 
18 // template <class Rep, class Period>
19 //   shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
20 
21 #include <shared_mutex>
22 #include <thread>
23 #include <vector>
24 #include <cstdlib>
25 #include <cassert>
26 
27 #include "test_macros.h"
28 
29 std::shared_timed_mutex m;
30 
31 typedef std::chrono::steady_clock Clock;
32 typedef Clock::time_point time_point;
33 typedef Clock::duration duration;
34 typedef std::chrono::milliseconds ms;
35 typedef std::chrono::nanoseconds ns;
36 
37 ms WaitTime = ms(250);
38 
39 // Thread sanitizer causes more overhead and will sometimes cause this test
40 // to fail. To prevent this we give Thread sanitizer more time to complete the
41 // test.
42 #if !defined(TEST_HAS_SANITIZERS)
43 ms Tolerance = ms(50);
44 #else
45 ms Tolerance = ms(50 * 5);
46 #endif
47 
48 
49 void f1()
50 {
51     time_point t0 = Clock::now();
52     std::shared_lock<std::shared_timed_mutex> lk(m, WaitTime + Tolerance);
53     assert(lk.owns_lock() == true);
54     time_point t1 = Clock::now();
55     ns d = t1 - t0 - WaitTime;
56     assert(d < Tolerance);  // within 50ms
57 }
58 
59 void f2()
60 {
61     time_point t0 = Clock::now();
62     std::shared_lock<std::shared_timed_mutex> lk(m, WaitTime);
63     assert(lk.owns_lock() == false);
64     time_point t1 = Clock::now();
65     ns d = t1 - t0 - WaitTime;
66     assert(d < Tolerance);  // within 50ms
67 }
68 
69 int main(int, char**)
70 {
71     {
72         m.lock();
73         std::vector<std::thread> v;
74         for (int i = 0; i < 5; ++i)
75             v.push_back(std::thread(f1));
76         std::this_thread::sleep_for(WaitTime);
77         m.unlock();
78         for (auto& t : v)
79             t.join();
80     }
81     {
82         m.lock();
83         std::vector<std::thread> v;
84         for (int i = 0; i < 5; ++i)
85             v.push_back(std::thread(f2));
86         std::this_thread::sleep_for(WaitTime + Tolerance);
87         m.unlock();
88         for (auto& t : v)
89             t.join();
90     }
91 
92   return 0;
93 }
94