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 // template <class Mutex> class shared_lock;
18 
19 // explicit shared_lock(mutex_type& m);
20 
21 // template<class _Mutex> shared_lock(shared_lock<_Mutex>)
22 //     -> shared_lock<_Mutex>;  // C++17
23 
24 #include <shared_mutex>
25 #include <thread>
26 #include <vector>
27 #include <cstdlib>
28 #include <cassert>
29 
30 #include "test_macros.h"
31 
32 typedef std::chrono::system_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 std::shared_timed_mutex m;
50 
f()51 void f()
52 {
53     time_point t0 = Clock::now();
54     time_point t1;
55     {
56     std::shared_lock<std::shared_timed_mutex> ul(m);
57     t1 = Clock::now();
58     }
59     ns d = t1 - t0 - WaitTime;
60     assert(d < Tolerance);  // within tolerance
61 }
62 
g()63 void g()
64 {
65     time_point t0 = Clock::now();
66     time_point t1;
67     {
68     std::shared_lock<std::shared_timed_mutex> ul(m);
69     t1 = Clock::now();
70     }
71     ns d = t1 - t0;
72     assert(d < Tolerance);  // within tolerance
73 }
74 
main()75 int main()
76 {
77     std::vector<std::thread> v;
78     {
79         m.lock();
80         for (int i = 0; i < 5; ++i)
81             v.push_back(std::thread(f));
82         std::this_thread::sleep_for(WaitTime);
83         m.unlock();
84         for (auto& t : v)
85             t.join();
86     }
87     {
88         m.lock_shared();
89         for (auto& t : v)
90             t = std::thread(g);
91         std::thread q(f);
92         std::this_thread::sleep_for(WaitTime);
93         m.unlock_shared();
94         for (auto& t : v)
95             t.join();
96         q.join();
97     }
98 
99 #ifdef __cpp_deduction_guides
100     std::shared_lock sl(m);
101     static_assert((std::is_same<decltype(sl), std::shared_lock<decltype(m)>>::value), "" );
102 #endif
103 }
104