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 // class shared_timed_mutex;
15 
16 // bool try_lock();
17 
18 #include <shared_mutex>
19 #include <atomic>
20 #include <cassert>
21 #include <chrono>
22 #include <thread>
23 
24 #include "make_test_thread.h"
25 
26 int main(int, char**) {
27   // Try to exclusive-lock a mutex that is not locked yet. This should succeed.
28   {
29     std::shared_timed_mutex m;
30     bool succeeded = m.try_lock();
31     assert(succeeded);
32     m.unlock();
33   }
34 
35   // Try to exclusive-lock a mutex that is already locked exclusively. This should fail.
36   {
37     std::shared_timed_mutex m;
38     m.lock();
39 
40     std::thread t = support::make_test_thread([&] {
41       bool succeeded = m.try_lock();
42       assert(!succeeded);
43     });
44     t.join();
45 
46     m.unlock();
47   }
48 
49   // Try to exclusive-lock a mutex that is already share-locked. This should fail.
50   {
51     std::shared_timed_mutex m;
52     m.lock_shared();
53 
54     std::thread t = support::make_test_thread([&] {
55       bool succeeded = m.try_lock();
56       assert(!succeeded);
57     });
58     t.join();
59 
60     m.unlock_shared();
61   }
62 
63   return 0;
64 }
65