asio/detail/reactive_null_buffers_op.hpp

0001 //
0002 // detail/reactive_null_buffers_op.hpp
0003 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 //
0010
0011 #ifndef BOOST_ASIO_DETAIL_REACTIVE_NULL_BUFFERS_OP_HPP
0012 #define BOOST_ASIO_DETAIL_REACTIVE_NULL_BUFFERS_OP_HPP
0013
0014 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0015 # pragma once
0016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0017
0018 #include <boost/asio/detail/config.hpp>
0019 #include <boost/asio/detail/bind_handler.hpp>
0020 #include <boost/asio/detail/fenced_block.hpp>
0021 #include <boost/asio/detail/handler_alloc_helpers.hpp>
0022 #include <boost/asio/detail/handler_work.hpp>
0023 #include <boost/asio/detail/memory.hpp>
0024 #include <boost/asio/detail/reactor_op.hpp>
0025
0026 #include <boost/asio/detail/push_options.hpp>
0027
0028 namespace boost {
0029 namespace asio {
0030 namespace detail {
0031
0032 template <typename Handler, typename IoExecutor>
0033 class reactive_null_buffers_op : public reactor_op
0034 {
0035 public:
0036   typedef Handler handler_type;
0037   typedef IoExecutor io_executor_type;
0038
0039   BOOST_ASIO_DEFINE_HANDLER_PTR(reactive_null_buffers_op);
0040
0041   reactive_null_buffers_op(const boost::system::error_code& success_ec,
0042       Handler& handler, const IoExecutor& io_ex)
0043     : reactor_op(success_ec, &reactive_null_buffers_op::do_perform,
0044         &reactive_null_buffers_op::do_complete),
0045       handler_(static_cast<Handler&&>(handler)),
0046       work_(handler_, io_ex)
0047   {
0048   }
0049
0050   static status do_perform(reactor_op*)
0051   {
0052     return done;
0053   }
0054
0055   static void do_complete(void* owner, operation* base,
0056       const boost::system::error_code& /*ec*/,
0057       std::size_t /*bytes_transferred*/)
0058   {
0059     // Take ownership of the handler object.
0060     BOOST_ASIO_ASSUME(base != 0);
0061     reactive_null_buffers_op* o(static_cast<reactive_null_buffers_op*>(base));
0062     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
0063
0064     BOOST_ASIO_HANDLER_COMPLETION((*o));
0065
0066     // Take ownership of the operation's outstanding work.
0067     handler_work<Handler, IoExecutor> w(
0068         static_cast<handler_work<Handler, IoExecutor>&&>(
0069           o->work_));
0070
0071     // Make a copy of the handler so that the memory can be deallocated before
0072     // the upcall is made. Even if we're not about to make an upcall, a
0073     // sub-object of the handler may be the true owner of the memory associated
0074     // with the handler. Consequently, a local copy of the handler is required
0075     // to ensure that any owning sub-object remains valid until after we have
0076     // deallocated the memory here.
0077     detail::binder2<Handler, boost::system::error_code, std::size_t>
0078       handler(o->handler_, o->ec_, o->bytes_transferred_);
0079     p.h = boost::asio::detail::addressof(handler.handler_);
0080     p.reset();
0081
0082     // Make the upcall if required.
0083     if (owner)
0084     {
0085       fenced_block b(fenced_block::half);
0086       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
0087       w.complete(handler, handler.handler_);
0088       BOOST_ASIO_HANDLER_INVOCATION_END;
0089     }
0090   }
0091
0092   static void do_immediate(operation* base, bool, const void* io_ex)
0093   {
0094     // Take ownership of the handler object.
0095     BOOST_ASIO_ASSUME(base != 0);
0096     reactive_null_buffers_op* o(static_cast<reactive_null_buffers_op*>(base));
0097     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
0098
0099     BOOST_ASIO_HANDLER_COMPLETION((*o));
0100
0101     // Take ownership of the operation's outstanding work.
0102     immediate_handler_work<Handler, IoExecutor> w(
0103         static_cast<handler_work<Handler, IoExecutor>&&>(
0104           o->work_));
0105
0106     // Make a copy of the handler so that the memory can be deallocated before
0107     // the upcall is made. Even if we're not about to make an upcall, a
0108     // sub-object of the handler may be the true owner of the memory associated
0109     // with the handler. Consequently, a local copy of the handler is required
0110     // to ensure that any owning sub-object remains valid until after we have
0111     // deallocated the memory here.
0112     detail::binder2<Handler, boost::system::error_code, std::size_t>
0113       handler(o->handler_, o->ec_, o->bytes_transferred_);
0114     p.h = boost::asio::detail::addressof(handler.handler_);
0115     p.reset();
0116
0117     BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
0118     w.complete(handler, handler.handler_, io_ex);
0119     BOOST_ASIO_HANDLER_INVOCATION_END;
0120   }
0121
0122 private:
0123   Handler handler_;
0124   handler_work<Handler, IoExecutor> work_;
0125 };
0126
0127 } // namespace detail
0128 } // namespace asio
0129 } // namespace boost
0130
0131 #include <boost/asio/detail/pop_options.hpp>
0132
0133 #endif // BOOST_ASIO_DETAIL_REACTIVE_NULL_BUFFERS_OP_HPP