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 
11 // ALLOW_RETRIES: 2
12 
13 // <mutex>
14 
15 // class recursive_mutex;
16 
17 // bool try_lock();
18 
19 #include <mutex>
20 #include <thread>
21 #include <cstdlib>
22 #include <cassert>
23 
24 #include "make_test_thread.h"
25 #include "test_macros.h"
26 
27 std::recursive_mutex m;
28 
29 typedef std::chrono::system_clock Clock;
30 typedef Clock::time_point time_point;
31 typedef Clock::duration duration;
32 typedef std::chrono::milliseconds ms;
33 typedef std::chrono::nanoseconds ns;
34 
35 void f()
36 {
37     time_point t0 = Clock::now();
38     assert(!m.try_lock());
39     assert(!m.try_lock());
40     assert(!m.try_lock());
41     while(!m.try_lock())
42         ;
43     time_point t1 = Clock::now();
44     assert(m.try_lock());
45     m.unlock();
46     m.unlock();
47     ns d = t1 - t0 - ms(250);
48     assert(d < ms(200));  // within 200ms
49 }
50 
51 int main(int, char**)
52 {
53     m.lock();
54     std::thread t = support::make_test_thread(f);
55     std::this_thread::sleep_for(ms(250));
56     m.unlock();
57     t.join();
58 
59   return 0;
60 }
61