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++03
11 
12 // <future>
13 
14 // template <class F, class... Args>
15 //     future<typename result_of<F(Args...)>::type>
16 //     async(F&& f, Args&&... args);
17 
18 // template <class F, class... Args>
19 //     future<typename result_of<F(Args...)>::type>
20 //     async(launch policy, F&& f, Args&&... args);
21 
22 // This test is designed to cause and allow TSAN to detect the race condition
23 // reported in PR23293: https://llvm.org/PR23293
24 
25 #include <future>
26 #include <chrono>
27 #include <thread>
28 #include <memory>
29 #include <cassert>
30 
31 #include "test_macros.h"
32 
33 int f_async() {
34     typedef std::chrono::milliseconds ms;
35     std::this_thread::sleep_for(ms(200));
36     return 42;
37 }
38 
39 bool ran = false;
40 
41 int f_deferred() {
42     ran = true;
43     return 42;
44 }
45 
46 void test_each() {
47     {
48         std::future<int> f = std::async(f_async);
49         int const result = f.get();
50         assert(result == 42);
51     }
52     {
53         std::future<int> f = std::async(std::launch::async, f_async);
54         int const result = f.get();
55         assert(result == 42);
56     }
57     {
58         ran = false;
59         std::future<int> f = std::async(std::launch::deferred, f_deferred);
60         assert(ran == false);
61         int const result = f.get();
62         assert(ran == true);
63         assert(result == 42);
64     }
65 }
66 
67 int main(int, char**) {
68     for (int i=0; i < 25; ++i) test_each();
69 
70   return 0;
71 }
72