libcxx/include/__stop_token/stop_source.h

   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 <__availability>
  14 #include <__config>
  15 #include <__stop_token/intrusive_shared_ptr.h>
  16 #include <__stop_token/stop_state.h>
  17 #include <__stop_token/stop_token.h>
  18 #include <__utility/move.h>
  19
  20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  21 #  pragma GCC system_header
  22 #endif
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 #if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) && !defined(_LIBCPP_HAS_NO_THREADS)
  27
  28 struct nostopstate_t {
  29   explicit nostopstate_t() = default;
  30 };
  31
  32 inline constexpr nostopstate_t nostopstate{};
  33
  34 class _LIBCPP_AVAILABILITY_SYNC stop_source {
  35 public:
  36   _LIBCPP_HIDE_FROM_ABI stop_source() : __state_(new __stop_state()) { __state_->__increment_stop_source_counter(); }
  37
  38   _LIBCPP_HIDE_FROM_ABI explicit stop_source(nostopstate_t) noexcept : __state_(nullptr) {}
  39
  40   _LIBCPP_HIDE_FROM_ABI stop_source(const stop_source& __other) noexcept : __state_(__other.__state_) {
  41     if (__state_) {
  42       __state_->__increment_stop_source_counter();
  43     }
  44   }
  45
  46   _LIBCPP_HIDE_FROM_ABI stop_source(stop_source&& __other) noexcept = default;
  47
  48   _LIBCPP_HIDE_FROM_ABI stop_source& operator=(const stop_source& __other) noexcept {
  49     // increment `__other` first so that we don't hit 0 in case of self-assignment
  50     if (__other.__state_) {
  51       __other.__state_->__increment_stop_source_counter();
  52     }
  53     if (__state_) {
  54       __state_->__decrement_stop_source_counter();
  55     }
  56     __state_ = __other.__state_;
  57     return *this;
  58   }
  59
  60   _LIBCPP_HIDE_FROM_ABI stop_source& operator=(stop_source&&) noexcept = default;
  61
  62   _LIBCPP_HIDE_FROM_ABI ~stop_source() {
  63     if (__state_) {
  64       __state_->__decrement_stop_source_counter();
  65     }
  66   }
  67
  68   _LIBCPP_HIDE_FROM_ABI void swap(stop_source& __other) noexcept { __state_.swap(__other.__state_); }
  69
  70   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI stop_token get_token() const noexcept { return stop_token(__state_); }
  71
  72   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool stop_possible() const noexcept { return __state_ != nullptr; }
  73
  74   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool stop_requested() const noexcept {
  75     return __state_ != nullptr && __state_->__stop_requested();
  76   }
  77
  78   _LIBCPP_HIDE_FROM_ABI bool request_stop() noexcept { return __state_ && __state_->__request_stop(); }
  79
  80   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend bool operator==(const stop_source&, const stop_source&) noexcept = default;
  81
  82   _LIBCPP_HIDE_FROM_ABI friend void swap(stop_source& __lhs, stop_source& __rhs) noexcept { __lhs.swap(__rhs); }
  83
  84 private:
  85   __intrusive_shared_ptr<__stop_state> __state_;
  86 };
  87
  88 #endif // _LIBCPP_STD_VER >= 20
  89
  90 _LIBCPP_END_NAMESPACE_STD
  91
  92 #endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) && !defined(_LIBCPP_HAS_NO_THREADS)