text: //
  // detail/reactive_socket_recvmsg_op.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2020 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_REACTIVE_SOCKET_RECVMSG_OP_HPP
  #define ASIO_DETAIL_REACTIVE_SOCKET_RECVMSG_OP_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include "asio/detail/config.hpp"
  #include "asio/detail/bind_handler.hpp"
  #include "asio/detail/buffer_sequence_adapter.hpp"
  #include "asio/detail/fenced_block.hpp"
  #include "asio/detail/memory.hpp"
  #include "asio/detail/reactor_op.hpp"
  #include "asio/detail/socket_ops.hpp"
  #include "asio/socket_base.hpp"
  
  #include "asio/detail/push_options.hpp"
  
  namespace asio {
  namespace detail {
  
  template <typename MutableBufferSequence>
  class reactive_socket_recvmsg_op_base : public reactor_op
  {
  public:
    reactive_socket_recvmsg_op_base(socket_type socket,
        const MutableBufferSequence& buffers, socket_base::message_flags in_flags,
        socket_base::message_flags& out_flags, func_type complete_func)
      : reactor_op(&reactive_socket_recvmsg_op_base::do_perform, complete_func),
        socket_(socket),
        buffers_(buffers),
        in_flags_(in_flags),
        out_flags_(out_flags)
    {
    }
  
    static status do_perform(reactor_op* base)
    {
      reactive_socket_recvmsg_op_base* o(
          static_cast<reactive_socket_recvmsg_op_base*>(base));
  
      buffer_sequence_adapter<asio::mutable_buffer,
          MutableBufferSequence> bufs(o->buffers_);
  
      status result = socket_ops::non_blocking_recvmsg(o->socket_,
          bufs.buffers(), bufs.count(),
          o->in_flags_, o->out_flags_,
          o->ec_, o->bytes_transferred_) ? done : not_done;
  
      ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_recvmsg",
            o->ec_, o->bytes_transferred_));
  
      return result;
    }
  
  private:
    socket_type socket_;
    MutableBufferSequence buffers_;
    socket_base::message_flags in_flags_;
    socket_base::message_flags& out_flags_;
  };
  
  template <typename MutableBufferSequence, typename Handler, typename IoExecutor>
  class reactive_socket_recvmsg_op :
    public reactive_socket_recvmsg_op_base<MutableBufferSequence>
  {
  public:
    ASIO_DEFINE_HANDLER_PTR(reactive_socket_recvmsg_op);
  
    reactive_socket_recvmsg_op(socket_type socket,
        const MutableBufferSequence& buffers, socket_base::message_flags in_flags,
        socket_base::message_flags& out_flags, Handler& handler,
        const IoExecutor& io_ex)
      : reactive_socket_recvmsg_op_base<MutableBufferSequence>(socket, buffers,
          in_flags, out_flags, &reactive_socket_recvmsg_op::do_complete),
        handler_(ASIO_MOVE_CAST(Handler)(handler)),
        io_executor_(io_ex)
    {
      handler_work<Handler, IoExecutor>::start(handler_, io_executor_);
    }
  
    static void do_complete(void* owner, operation* base,
        const asio::error_code& /*ec*/,
        std::size_t /*bytes_transferred*/)
    {
      // Take ownership of the handler object.
      reactive_socket_recvmsg_op* o(
          static_cast<reactive_socket_recvmsg_op*>(base));
      ptr p = { asio::detail::addressof(o->handler_), o, o };
      handler_work<Handler, IoExecutor> w(o->handler_, o->io_executor_);
  
      ASIO_HANDLER_COMPLETION((*o));
  
      // Make a copy of the handler so that the memory can be deallocated before
      // the upcall is made. Even if we're not about to make an upcall, a
      // sub-object of the handler may be the true owner of the memory associated
      // with the handler. Consequently, a local copy of the handler is required
      // to ensure that any owning sub-object remains valid until after we have
      // deallocated the memory here.
      detail::binder2<Handler, asio::error_code, std::size_t>
        handler(o->handler_, o->ec_, o->bytes_transferred_);
      p.h = asio::detail::addressof(handler.handler_);
      p.reset();
  
      // Make the upcall if required.
      if (owner)
      {
        fenced_block b(fenced_block::half);
        ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
        w.complete(handler, handler.handler_);
        ASIO_HANDLER_INVOCATION_END;
      }
    }
  
  private:
    Handler handler_;
    IoExecutor io_executor_;
  };
  
  } // namespace detail
  } // namespace asio
  
  #include "asio/detail/pop_options.hpp"
  
  #endif // ASIO_DETAIL_REACTIVE_SOCKET_RECVMSG_OP_HPP
  