Class blocking_t

3rd/asio-1.24.0/include/asio/execution/blocking.hpp:44–178

A property to describe what guarantees an executor makes about the blocking behaviour of their execution functions.

/// A property to describe what guarantees an executor makes about the blocking
/// behaviour of their execution functions.
struct blocking_t
{
  /// The blocking_t property applies to executors, senders, and schedulers.
  template <typename T>
  static constexpr bool is_applicable_property_v =
    is_executor_v<T> || is_sender_v<T> || is_scheduler_v<T>;

  /// The top-level blocking_t property cannot be required.
  static constexpr bool is_requirable = false;

  /// The top-level blocking_t property cannot be preferred.
  static constexpr bool is_preferable = false;

  /// The type returned by queries against an @c any_executor.
  typedef blocking_t polymorphic_query_result_type;

  /// A sub-property that indicates that invocation of an executor's execution
  /// function may block pending completion of one or more invocations of the
  /// submitted function object.
  struct possibly_t
  {
    /// The blocking_t::possibly_t property applies to executors, senders, and
    /// schedulers.
    template <typename T>
    static constexpr bool is_applicable_property_v =
      is_executor_v<T> || is_sender_v<T> || is_scheduler_v<T>;

    /// The blocking_t::possibly_t property can be required.
    static constexpr bool is_requirable = true;

    /// The blocking_t::possibly_t property can be preferred.
    static constexpr bool is_preferable = true;

    /// The type returned by queries against an @c any_executor.
    typedef blocking_t polymorphic_query_result_type;

    /// Default constructor.
    constexpr possibly_t();

    /// Get the value associated with a property object.
    /**
     * @returns possibly_t();
     */
    static constexpr blocking_t value();
  };

  /// A sub-property that indicates that invocation of an executor's execution
  /// function shall block until completion of all invocations of the submitted
  /// function object.
  struct always_t
  {
    /// The blocking_t::always_t property applies to executors, senders, and
    /// schedulers.
    template <typename T>
    static constexpr bool is_applicable_property_v =
      is_executor_v<T> || is_sender_v<T> || is_scheduler_v<T>;

    /// The blocking_t::always_t property can be required.