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: libcpp-has-no-experimental-stop_token
11 // UNSUPPORTED: c++03, c++11, c++14, c++17
12 // XFAIL: availability-synchronization_library-missing
13
14 // void join();
15
16 #include <atomic>
17 #include <cassert>
18 #include <chrono>
19 #include <concepts>
20 #include <functional>
21 #include <system_error>
22 #include <thread>
23 #include <type_traits>
24 #include <vector>
25
26 #include "make_test_thread.h"
27 #include "test_macros.h"
28
main(int,char **)29 int main(int, char**) {
30 // Effects: Blocks until the thread represented by *this has completed.
31 {
32 std::atomic_int calledTimes = 0;
33 std::vector<std::jthread> jts;
34 constexpr auto numberOfThreads = 10u;
35 jts.reserve(numberOfThreads);
36 for (auto i = 0u; i < numberOfThreads; ++i) {
37 jts.emplace_back(support::make_test_jthread([&] {
38 std::this_thread::sleep_for(std::chrono::milliseconds(2));
39 calledTimes.fetch_add(1, std::memory_order_relaxed);
40 }));
41 }
42
43 for (auto i = 0u; i < numberOfThreads; ++i) {
44 jts[i].join();
45 }
46
47 // If join did block, calledTimes must equal to numberOfThreads
48 // If join did not block, there is a chance that the check below happened
49 // before test threads incrementing the counter, thus calledTimed would
50 // be less than numberOfThreads.
51 // This is not going to catch issues 100%. Creating more threads to increase
52 // the probability of catching the issue
53 assert(calledTimes.load(std::memory_order_relaxed) == numberOfThreads);
54 }
55
56 // Synchronization: The completion of the thread represented by *this synchronizes with
57 // ([intro.multithread]) the corresponding successful join() return.
58 {
59 bool flag = false;
60 std::jthread jt = support::make_test_jthread([&] { flag = true; });
61 jt.join();
62 assert(flag); // non atomic write is visible to the current thread
63 }
64
65 // Postconditions: The thread represented by *this has completed. get_id() == id().
66 {
67 std::jthread jt = support::make_test_jthread([] {});
68 assert(jt.get_id() != std::jthread::id());
69 jt.join();
70 assert(jt.get_id() == std::jthread::id());
71 }
72
73 #if !defined(TEST_HAS_NO_EXCEPTIONS)
74 // Throws: system_error when an exception is required ([thread.req.exception]).
75 // invalid_argument - if the thread is not joinable.
76 {
77 std::jthread jt;
78 try {
79 jt.join();
80 assert(false);
81 } catch (const std::system_error& err) {
82 assert(err.code() == std::errc::invalid_argument);
83 }
84 }
85
86 #endif
87
88 return 0;
89 }
90