1// -*- C++ -*-
 2//===----------------------------------------------------------------------===//
 3//
 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 5// See https://llvm.org/LICENSE.txt for license information.
 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 7//
 8//===----------------------------------------------------------------------===//
 9
10#ifndef _LIBCPP___STOP_TOKEN_STOP_SOURCE_H
11#define _LIBCPP___STOP_TOKEN_STOP_SOURCE_H
12
13#include <__config>
14#include <__stop_token/intrusive_shared_ptr.h>
15#include <__stop_token/stop_state.h>
16#include <__stop_token/stop_token.h>
17#include <__utility/move.h>
18
19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20#  pragma GCC system_header
21#endif
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25#if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
26
27struct nostopstate_t {
28  explicit nostopstate_t() = default;
29};
30
31inline constexpr nostopstate_t nostopstate{};
32
33class _LIBCPP_AVAILABILITY_SYNC stop_source {
34public:
35  _LIBCPP_HIDE_FROM_ABI stop_source() : __state_(new __stop_state()) { __state_->__increment_stop_source_counter(); }
36
37  _LIBCPP_HIDE_FROM_ABI explicit stop_source(nostopstate_t) noexcept : __state_(nullptr) {}
38
39  _LIBCPP_HIDE_FROM_ABI stop_source(const stop_source& __other) noexcept : __state_(__other.__state_) {
40    if (__state_) {
41      __state_->__increment_stop_source_counter();
42    }
43  }
44
45  _LIBCPP_HIDE_FROM_ABI stop_source(stop_source&& __other) noexcept = default;
46
47  _LIBCPP_HIDE_FROM_ABI stop_source& operator=(const stop_source& __other) noexcept {
48    // increment `__other` first so that we don't hit 0 in case of self-assignment
49    if (__other.__state_) {
50      __other.__state_->__increment_stop_source_counter();
51    }
52    if (__state_) {
53      __state_->__decrement_stop_source_counter();
54    }
55    __state_ = __other.__state_;
56    return *this;
57  }
58
59  _LIBCPP_HIDE_FROM_ABI stop_source& operator=(stop_source&&) noexcept = default;
60
61  _LIBCPP_HIDE_FROM_ABI ~stop_source() {
62    if (__state_) {
63      __state_->__decrement_stop_source_counter();
64    }
65  }
66
67  _LIBCPP_HIDE_FROM_ABI void swap(stop_source& __other) noexcept { __state_.swap(__other.__state_); }
68
69  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_token get_token() const noexcept { return stop_token(__state_); }
70
71  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool stop_possible() const noexcept { return __state_ != nullptr; }
72
73  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool stop_requested() const noexcept {
74    return __state_ != nullptr && __state_->__stop_requested();
75  }
76
77  _LIBCPP_HIDE_FROM_ABI bool request_stop() noexcept { return __state_ && __state_->__request_stop(); }
78
79  [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend bool operator==(const stop_source&, const stop_source&) noexcept = default;
80
81  _LIBCPP_HIDE_FROM_ABI friend void swap(stop_source& __lhs, stop_source& __rhs) noexcept { __lhs.swap(__rhs); }
82
83private:
84  __intrusive_shared_ptr<__stop_state> __state_;
85};
86
87#endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_THREADS
88
89_LIBCPP_END_NAMESPACE_STD
90
91#endif // _LIBCPP___STOP_TOKEN_STOP_SOURCE_H