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// [[nodiscard]] bool stop_requested() const noexcept;
15// Returns: true if *this has ownership of a stop state that has received a stop request; otherwise, false.
16
17#include <cassert>
18#include <chrono>
19#include <concepts>
20#include <optional>
21#include <stop_token>
22#include <type_traits>
23
24#include "make_test_thread.h"
25#include "test_macros.h"
26
27template <class T>
28concept IsStopRequestedNoexcept = requires(const T& t) {
29 { t.stop_requested() } noexcept;
30};
31
32static_assert(IsStopRequestedNoexcept<std::stop_token>);
33
34int main(int, char**) {
35 // no state
36 {
37 const std::stop_token st;
38 assert(!st.stop_requested());
39 }
40
41 // has state
42 {
43 std::stop_source ss;
44 const auto st = ss.get_token();
45 assert(!st.stop_requested());
46
47 ss.request_stop();
48 assert(st.stop_requested());
49 }
50
51 // already requested before constructor
52 {
53 std::stop_source ss;
54 ss.request_stop();
55 const auto st = ss.get_token();
56 assert(st.stop_requested());
57 }
58
59 // stop_token should share the state
60 {
61 std::optional<std::stop_source> ss{std::in_place};
62 ss->request_stop();
63 const auto st = ss->get_token();
64
65 ss.reset();
66 assert(st.stop_requested());
67 }
68
69 // single stop_source, multiple stop_token
70 {
71 std::stop_source ss;
72 const auto st1 = ss.get_token();
73 const auto st2 = ss.get_token();
74 assert(!st1.stop_requested());
75 assert(!st2.stop_requested());
76
77 ss.request_stop();
78 assert(st1.stop_requested());
79 assert(st2.stop_requested());
80 }
81
82 // multiple stop_source, multiple stop_token
83 {
84 std::stop_source ss1;
85 std::stop_source ss2;
86
87 const auto st1 = ss1.get_token();
88 const auto st2 = ss2.get_token();
89 assert(!st1.stop_requested());
90 assert(!st2.stop_requested());
91
92 ss1.request_stop();
93 assert(st1.stop_requested());
94 assert(!st2.stop_requested());
95 }
96
97 // multiple threads
98 {
99 std::stop_source ss;
100 const auto st = ss.get_token();
101 assert(!st.stop_requested());
102
103 std::thread t = support::make_test_thread([&]() { ss.request_stop(); });
104
105 t.join();
106 assert(st.stop_requested());
107 }
108
109 // maybe concurrent calls
110 {
111 std::stop_source ss;
112 const auto st = ss.get_token();
113 assert(!st.stop_requested());
114
115 std::thread t = support::make_test_thread([&]() { ss.request_stop(); });
116
117 while (!st.stop_requested()) {
118 // should eventually exit the loop
119 std::this_thread::yield();
120 }
121
122 t.join();
123 }
124
125 // [thread.stoptoken.intro] A call to request_stop that returns true
126 // synchronizes with a call to stop_requested on an associated stop_token
127 // or stop_source object that returns true.
128 {
129 std::stop_source ss;
130 const auto st = ss.get_token();
131 assert(!st.stop_requested());
132
133 bool flag = false;
134
135 std::thread t = support::make_test_thread([&]() {
136 using namespace std::chrono_literals;
137 std::this_thread::sleep_for(1ms);
138
139 // happens-before request_stop
140 flag = true;
141 auto b = ss.request_stop();
142 assert(b);
143 });
144
145 while (!st.stop_requested()) {
146 std::this_thread::yield();
147 }
148
149 // write should be visible to the current thread
150 assert(flag == true);
151
152 t.join();
153 }
154
155 return 0;
156}
157

source code of libcxx/test/std/thread/thread.stoptoken/stoptoken/stop_requested.pass.cpp