text: //
  // detail/socket_select_interrupter.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #ifndef ASIO_DETAIL_SOCKET_SELECT_INTERRUPTER_HPP
  #define ASIO_DETAIL_SOCKET_SELECT_INTERRUPTER_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include "asio/detail/config.hpp"
  
  #if !defined(ASIO_WINDOWS_RUNTIME)
  
  #if defined(ASIO_WINDOWS) \
    || defined(__CYGWIN__) \
    || defined(__SYMBIAN32__) \
    || defined(ESP_PLATFORM)
  
  #include "asio/detail/socket_types.hpp"
  
  #include "asio/detail/push_options.hpp"
  
  namespace asio {
  namespace detail {
  
  class socket_select_interrupter
  {
  public:
    // Constructor.
    ASIO_DECL socket_select_interrupter();
  
    // Destructor.
    ASIO_DECL ~socket_select_interrupter();
  
    // Recreate the interrupter's descriptors. Used after a fork.
    ASIO_DECL void recreate();
  
    // Interrupt the select call.
    ASIO_DECL void interrupt();
  
    // Reset the select interrupt. Returns true if the call was interrupted.
    ASIO_DECL bool reset();
  
    // Get the read descriptor to be passed to select.
    socket_type read_descriptor() const
    {
      return read_descriptor_;
    }
  
  private:
    // Open the descriptors. Throws on error.
    ASIO_DECL void open_descriptors();
  
    // Close the descriptors.
    ASIO_DECL void close_descriptors();
  
    // The read end of a connection used to interrupt the select call. This file
    // descriptor is passed to select such that when it is time to stop, a single
    // byte will be written on the other end of the connection and this
    // descriptor will become readable.
    socket_type read_descriptor_;
  
    // The write end of a connection used to interrupt the select call. A single
    // byte may be written to this to wake up the select which is waiting for the
    // other end to become readable.
    socket_type write_descriptor_;
  };
  
  } // namespace detail
  } // namespace asio
  
  #include "asio/detail/pop_options.hpp"
  
  #if defined(ASIO_HEADER_ONLY)
  # include "asio/detail/impl/socket_select_interrupter.ipp"
  #endif // defined(ASIO_HEADER_ONLY)
  
  #endif // defined(ASIO_WINDOWS)
         // || defined(__CYGWIN__)
         // || defined(__SYMBIAN32__)
  
  #endif // !defined(ASIO_WINDOWS_RUNTIME)
  
  #endif // ASIO_DETAIL_SOCKET_SELECT_INTERRUPTER_HPP
  