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 // <shared_mutex>
13 
14 // template <class Mutex> class shared_lock;
15 
16 // bool try_lock();
17 
18 #include <shared_mutex>
19 #include <cassert>
20 
21 #include "test_macros.h"
22 
23 bool try_lock_called = false;
24 
25 struct mutex
26 {
27     bool try_lock_shared()
28     {
29         try_lock_called = !try_lock_called;
30         return try_lock_called;
31     }
32     void unlock_shared() {}
33 };
34 
35 mutex m;
36 
37 int main(int, char**)
38 {
39     std::shared_lock<mutex> lk(m, std::defer_lock);
40     assert(lk.try_lock() == true);
41     assert(try_lock_called == true);
42     assert(lk.owns_lock() == true);
43 #ifndef TEST_HAS_NO_EXCEPTIONS
44     try
45     {
46         TEST_IGNORE_NODISCARD lk.try_lock();
47         assert(false);
48     }
49     catch (std::system_error& e)
50     {
51         assert(e.code().value() == EDEADLK);
52     }
53 #endif
54     lk.unlock();
55     assert(lk.try_lock() == false);
56     assert(try_lock_called == false);
57     assert(lk.owns_lock() == false);
58     lk.release();
59 #ifndef TEST_HAS_NO_EXCEPTIONS
60     try
61     {
62         TEST_IGNORE_NODISCARD lk.try_lock();
63         assert(false);
64     }
65     catch (std::system_error& e)
66     {
67         assert(e.code().value() == EPERM);
68     }
69 #endif
70 
71   return 0;
72 }
73