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 notify_one();
16 
17 #include <condition_variable>
18 #include <atomic>
19 #include <mutex>
20 #include <thread>
21 #include <cassert>
22 
23 
24 std::condition_variable cv;
25 std::mutex mut;
26 
27 std::atomic_int test1(0);
28 std::atomic_int test2(0);
29 
30 void f1()
31 {
32     std::unique_lock<std::mutex> lk(mut);
33     assert(test1 == 0);
34     while (test1 == 0)
35         cv.wait(lk);
36     assert(test1 == 1);
37     test1 = 2;
38 }
39 
40 void f2()
41 {
42     std::unique_lock<std::mutex> lk(mut);
43     assert(test2 == 0);
44     while (test2 == 0)
45         cv.wait(lk);
46     assert(test2 == 1);
47     test2 = 2;
48 }
49 
50 int main(int, char**)
51 {
52     std::thread t1(f1);
53     std::thread t2(f2);
54     std::this_thread::sleep_for(std::chrono::milliseconds(100));
55     {
56         std::unique_lock<std::mutex>lk(mut);
57         test1 = 1;
58         test2 = 1;
59     }
60     cv.notify_one();
61     {
62         std::this_thread::sleep_for(std::chrono::milliseconds(100));
63         std::unique_lock<std::mutex>lk(mut);
64     }
65     if (test1 == 2)
66     {
67         assert(test2 == 1);
68         t1.join();
69         test1 = 0;
70     }
71     else if (test2 == 2)
72     {
73         assert(test1 == 1);
74         t2.join();
75         test2 = 0;
76     }
77     else
78         assert(false);
79     cv.notify_one();
80     {
81         std::this_thread::sleep_for(std::chrono::milliseconds(100));
82         std::unique_lock<std::mutex>lk(mut);
83     }
84     if (test1 == 2)
85     {
86         assert(test2 == 0);
87         t1.join();
88         test1 = 0;
89     }
90     else if (test2 == 2)
91     {
92         assert(test1 == 0);
93         t2.join();
94         test2 = 0;
95     }
96     else
97         assert(false);
98 
99   return 0;
100 }
101