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: no-threads
10 // UNSUPPORTED: c++03, c++11
11 
12 // <shared_mutex>
13 
14 // template <class Mutex> class shared_lock;
15 
16 // explicit shared_lock(mutex_type& m);
17 
18 // template<class _Mutex> shared_lock(shared_lock<_Mutex>)
19 //     -> shared_lock<_Mutex>;  // C++17
20 
21 #include <atomic>
22 #include <cassert>
23 #include <shared_mutex>
24 #include <thread>
25 #include <type_traits>
26 #include <vector>
27 
28 #include "make_test_thread.h"
29 #include "test_macros.h"
30 
31 struct Monitor {
32   bool lock_shared_called   = false;
33   bool unlock_shared_called = false;
34 };
35 
36 struct TrackedMutex {
37   Monitor* monitor = nullptr;
38 
39   void lock_shared() {
40     if (monitor != nullptr)
41       monitor->lock_shared_called = true;
42   }
43   void unlock_shared() {
44     if (monitor != nullptr)
45       monitor->unlock_shared_called = true;
46   }
47 };
48 
49 template <class Mutex>
50 void test() {
51   // Basic sanity test
52   {
53     Mutex mutex;
54     std::vector<std::thread> threads;
55     std::atomic<bool> ready(false);
56     for (int i = 0; i != 5; ++i) {
57       threads.push_back(support::make_test_thread([&] {
58         while (!ready) {
59           // spin
60         }
61 
62         std::shared_lock<Mutex> lock(mutex);
63         assert(lock.owns_lock());
64       }));
65     }
66 
67     ready = true;
68     for (auto& t : threads)
69       t.join();
70   }
71 
72   // Test CTAD
73   {
74 #if TEST_STD_VER >= 17
75     Mutex mutex;
76     std::shared_lock lock(mutex);
77     static_assert(std::is_same<decltype(lock), std::shared_lock<Mutex>>::value);
78 #endif
79   }
80 }
81 
82 int main(int, char**) {
83 #if TEST_STD_VER >= 17
84   test<std::shared_mutex>();
85 #endif
86   test<std::shared_timed_mutex>();
87   test<TrackedMutex>();
88 
89   // Use shared_lock with a dummy mutex class that tracks whether each
90   // operation has been called or not.
91   {
92     Monitor monitor;
93     TrackedMutex mutex{&monitor};
94 
95     std::shared_lock<TrackedMutex> lock(mutex);
96     assert(monitor.lock_shared_called);
97     assert(lock.owns_lock());
98 
99     lock.unlock();
100     assert(monitor.unlock_shared_called);
101   }
102 
103   return 0;
104 }
105