libcxx/include/__cxx03/__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___CXX03___STOP_TOKEN_STOP_SOURCE_H
  11 #define _LIBCPP___CXX03___STOP_TOKEN_STOP_SOURCE_H
  12
  13 #include <__cxx03/__config>
  14 #include <__cxx03/__stop_token/intrusive_shared_ptr.h>
  15 #include <__cxx03/__stop_token/stop_state.h>
  16 #include <__cxx03/__stop_token/stop_token.h>
  17 #include <__cxx03/__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 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_STOP_TOKEN) && !defined(_LIBCPP_HAS_NO_THREADS)
  26
  27 struct nostopstate_t {
  28   explicit nostopstate_t() = default;
  29 };
  30
  31 inline constexpr nostopstate_t nostopstate{};
  32
  33 class _LIBCPP_AVAILABILITY_SYNC stop_source {
  34 public:
  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
  83 private:
  84   __intrusive_shared_ptr<__stop_state> __state_;
  85 };
  86
  87 #endif // _LIBCPP_STD_VER >= 20
  88
  89 _LIBCPP_END_NAMESPACE_STD
  90
  91 #endif // _LIBCPP___CXX03___STOP_TOKEN_STOP_SOURCE_H