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 // <condition_variable>
12 
13 // class condition_variable;
14 
15 // void wait(unique_lock<mutex>& lock);
16 
17 #include <condition_variable>
18 #include <mutex>
19 #include <thread>
20 #include <cassert>
21 
22 std::condition_variable cv;
23 std::mutex mut;
24 
25 int test1 = 0;
26 int test2 = 0;
27 
28 void f()
29 {
30     std::unique_lock<std::mutex> lk(mut);
31     assert(test2 == 0);
32     test1 = 1;
33     cv.notify_one();
34     while (test2 == 0)
35         cv.wait(lk);
36     assert(test2 != 0);
37 }
38 
39 int main(int, char**)
40 {
41     std::unique_lock<std::mutex>lk(mut);
42     std::thread t(f);
43     assert(test1 == 0);
44     while (test1 == 0)
45         cv.wait(lk);
46     assert(test1 != 0);
47     test2 = 1;
48     lk.unlock();
49     cv.notify_one();
50     t.join();
51 
52   return 0;
53 }
54