标准库头文件 <stop_token> (C++20)

 

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语言支持 <cfloat> <climits> <compare> (C++20) <contracts> (C++26) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) 概念 <concepts> (C++20) 诊断 <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) 内存管理 <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) 元编程 <type_traits> (C++11) <ratio> (C++11)

通用工具 <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) 容器 <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <hive> (C++26) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> 迭代器 <iterator> 范围 <generator> (C++23) <ranges> (C++20)

算法 <algorithm> <numeric> 字符串 <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> 文本处理 <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    数值 <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <simd> (C++26) <valarray> 时间 <chrono> (C++11) <ctime> C 兼容性 <ccomplex> (C++11/17/20*) <ciso646> (直到 C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

输入/输出 <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) 并发支持 <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) 执行支持 <execution> (C++17)

 

此头文件是线程支持库的一部分。

类
stop_token (C++20)	用于查询是否已发出 std::jthread 取消请求的接口 (类)
stop_source (C++20)	表示停止一个或多个 std::jthread 的请求的类 (类)
stop_callback (C++20)	用于注册 std::jthread 取消时的回调的接口 (类模板)
never_stop_token (C++26)	提供停止令牌接口，该接口永远不可能停止或请求停止 (类)
inplace_stop_token (C++26)	引用其关联的 std::inplace_stop_source 对象的停止状态的停止令牌 (类)
inplace_stop_source (C++26)	作为停止状态的唯一所有者的 stoppable-source (类)
inplace_stop_callback (C++26)	用于 std::inplace_stop_token 的停止回调 (类模板)
别名模板
stop_callback_for_t (C++26)	获取给定停止令牌类型的回调类型 (别名模板)
概念
stoppable_token (C++26)	指定停止令牌的基本接口，该接口允许查询停止请求以及停止请求是否可能 (概念)
unstoppable_token (C++26)	指定不允许停止的停止令牌 (概念)
标签
nostopstatenostopstate_t (C++20)	用于 stop_source 的标签，指示构造时没有关联的停止状态 (标签)

概要

namespace std {
  // stop token concepts
  template<class CallbackFn, class Token, class Init = CallbackFn>
    concept /*stoppable-callback-for*/ = /* see description */; // exposition only
 
  template<class Token>
    concept stoppable_token = /* see description */;
 
  template<class Token>
    concept unstoppable_token = /* see description */;
 
  template<class Source>
    concept /*stoppable-source*/ = /* see description */; // exposition only
 
  // class stop_token
  class stop_token;
 
  // class stop_source
  class stop_source;
 
  // no-shared-stop-state indicator
  struct nostopstate_t {
    explicit nostopstate_t() = default;
  };
  inline constexpr nostopstate_t nostopstate{};
 
  // class template stop_callback
  template<class Callback>
  class stop_callback;
 
  // class never_stop_token
  class never_stop_token;
 
  // class inplace_stop_token
  class inplace_stop_token;
 
  // class inplace_stop_source
  class inplace_stop_source;
 
  // class template inplace_stop_callback
  template<class CallbackFn>
    class inplace_stop_callback;
 
  template<class T, class CallbackFn>
    using stop_callback_for_t = T::template callback_type<CallbackFn>;
}

停止令牌概念

namespace std {
  template<class CallbackFn, class Token, class Init = CallbackFn>
    concept /*stoppable-callback-for*/ =                         // exposition only
      invocable<CallbackFn> &&
      constructible_from<CallbackFn, Init> &&
      requires { typename stop_callback_for_t<Token, CallbackFn>; } &&
      constructible_from<stop_callback_for_t<Token, CallbackFn>, const Token&, Init>;
 
  template<template<class> class>
    struct /*check-type-alias-exists*/;                          // exposition only
 
  template<class Token>
    concept stoppable_token = 
      requires (const Token tok) {
        typename /*check-type-alias-exists*/<Token::template callback_type>;
        { tok.stop_requested() } noexcept -> same_as<bool>;
        { tok.stop_possible() } noexcept -> same_as<bool>;
        { Token(tok) } noexcept; // see implicit expression variations
      } &&
      copyable<Token> &&
      equality_comparable<Token>;
 
  template<class Token>
    concept unstoppable_token = 
      stoppable_token<Token> &&
      requires (const Token tok) {
        requires bool_constant<(!tok.stop_possible())>::value;
      };
 
  template<class Source>
    concept /*stoppable-source*/ =                               // exposition only
      requires (Source& src, const Source csrc) {
        { csrc.get_token() } -> stoppable_token;
        { csrc.stop_possible() } noexcept -> same_as<bool>;
        { csrc.stop_requested() } noexcept -> same_as<bool>;
        { src.request_stop() } -> same_as<bool>;
      };
}

类 std::stop_token

namespace std {
  class stop_token {
  public:
    template<class CallbackFn>
      using callback_type = stop_callback<CallbackFn>;
 
    // constructors, copy, and assignment
    stop_token() noexcept = default;
 
    // member functions
    void swap(stop_token&) noexcept;
 
    // stop handling
    bool stop_requested() const noexcept;
    bool stop_possible() const noexcept;
 
    friend bool operator==(const stop_token& lhs, const stop_token& rhs) noexcept;
    friend void swap(stop_token& lhs, stop_token& rhs) noexcept;
 
  private:
    shared_ptr</*unspecified*/> stop_state_; // exposition only
  };
}

类 std::stop_source

namespace std {
  class stop_source {
  public:
    // constructors, copy, and assignment
    stop_source();
    explicit stop_source(nostopstate_t) noexcept {}
 
    // member functions
    void swap(stop_source&) noexcept;
 
    // stop handling
    stop_token get_token() const noexcept;
    bool stop_possible() const noexcept;
    bool stop_requested() const noexcept;
    bool request_stop() noexcept;
 
    friend bool
    operator==(const stop_source& lhs, const stop_source& rhs) noexcept;
    friend void swap(stop_source& lhs, stop_source& rhs) noexcept;
 
  private:
    shared_ptr</*unspecified*/> stop_state_; // exposition only
  };
}

类模板 std::stop_callback

namespace std {
  template<class CallbackFn>
  class stop_callback {
  public:
    using callback_type = CallbackFn;
 
    // constructors and destructor
    template<class Init>
    explicit stop_callback(const stop_token& st, Init&& init)
        noexcept(is_nothrow_constructible_v<CallbackFn, Init>);
    template<class Init>
    explicit stop_callback(stop_token&& st, Init&& init)
        noexcept(is_nothrow_constructible_v<CallbackFn, Init>);
    ~stop_callback();
 
    stop_callback(const stop_callback&) = delete;
    stop_callback(stop_callback&&) = delete;
    stop_callback& operator=(const stop_callback&) = delete;
    stop_callback& operator=(stop_callback&&) = delete;
 
  private:
    CallbackFn callback_fn_;      // exposition only
  };
 
  template<class CallbackFn>
  stop_callback(stop_token, CallbackFn) -> stop_callback<CallbackFn>;
}

类模板 std::never_stop_token

namespace std {
  class never_stop_token {
    struct /*callback-type*/ {       // exposition only
      explicit /*callback-type*/(never_stop_token, auto&&) noexcept {}
    };
 
  public:
    template<class>
      using callback_type = /*callback-type*/;
 
    static constexpr bool stop_requested() noexcept { return false; }
    static constexpr bool stop_posible() noexcept { return false; }
 
    bool operator==(const never_stop_token&) const = default;
  };
}

类模板 std::inplace_stop_token

namespace std {
  class inplace_stop_token {
  public:
    template<class CallbackFn>
      using callback_type = inplace_stop_callback<CallbackFn>;
 
    inplace_stop_token() = default;
    bool operator==(const inplace_stop_token&) const = default;
 
    // member functions
    bool stop_requested() const noexcept;
    bool stop_possible() const noexcept;
    void swap(inplace_stop_token&) noexcept;
 
  private:
    const inplace_stop_source* stop_source_ = nullptr; // exposition only
  };
}

类模板 std::inplace_stop_source

namespace std {
  class inplace_stop_source {
    // constructors, assignments, and destructor
    constexpr inplace_stop_source() noexcept;
 
    inplace_stop_source(inplace_stop_source&&) = delete;
    inplace_stop_source(const inplace_stop_source&) = delete;
    inplace_stop_source& operator=(inplace_stop_source&&) = delete;
    inplace_stop_source& operator=(const inplace_stop_source&) = delete;
    ~inplace_stop_source();
 
    // stop handling
    constexpr inplace_stop_token get_token() const noexcept;
    static constexpr bool stop_possible() noexcept { return true; }
    bool stop_requested() const noexcept;
    bool request_stop() noexcept;
  };
}

类模板 std::inplace_stop_callback

namespace std {
  template<class CallbackFn>
  class inplace_stop_callback {
  public:
    using callback_type = CallbackFn;
 
    // constructors and destructor
    template<class Init>
    explicit inplace_stop_callback(inplace_stop_token st, Init&& init)
        noexcept(is_nothrow_constructible_v<CallbackFn, Init>);
    ~inplace_stop_callback();
 
    inplace_stop_callback(const inplace_stop_callback&) = delete;
    inplace_stop_callback(inplace_stop_callback&&) = delete;
    inplace_stop_callback& operator=(const inplace_stop_callback&) = delete;
    inplace_stop_callback& operator=(inplace_stop_callback&&) = delete;
 
  private:
    CallbackFn callback_fn_;      // exposition only
  };
 
  template<class CallbackFn>
  inplace_stop_callback(inplace_stop_token, CallbackFn) 
    -> inplace_stop_callback<CallbackFn>;
}