1 //
2 // detail/reactive_null_buffers_op.hpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10 
11 #ifndef BOOST_ASIO_DETAIL_REACTIVE_NULL_BUFFERS_OP_HPP
12 #define BOOST_ASIO_DETAIL_REACTIVE_NULL_BUFFERS_OP_HPP
13 
14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
15 # pragma once
16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17 
18 #include <boost/asio/detail/config.hpp>
19 #include <boost/asio/detail/addressof.hpp>
20 #include <boost/asio/detail/fenced_block.hpp>
21 #include <boost/asio/detail/handler_alloc_helpers.hpp>
22 #include <boost/asio/detail/handler_invoke_helpers.hpp>
23 #include <boost/asio/detail/reactor_op.hpp>
24 
25 #include <boost/asio/detail/push_options.hpp>
26 
27 namespace boost {
28 namespace asio {
29 namespace detail {
30 
31 template <typename Handler>
32 class reactive_null_buffers_op : public reactor_op
33 {
34 public:
35   BOOST_ASIO_DEFINE_HANDLER_PTR(reactive_null_buffers_op);
36 
reactive_null_buffers_op(Handler & handler)37   reactive_null_buffers_op(Handler& handler)
38     : reactor_op(&reactive_null_buffers_op::do_perform,
39         &reactive_null_buffers_op::do_complete),
40       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
41   {
42   }
43 
do_perform(reactor_op *)44   static bool do_perform(reactor_op*)
45   {
46     return true;
47   }
48 
do_complete(io_service_impl * owner,operation * base,const boost::system::error_code &,std::size_t)49   static void do_complete(io_service_impl* owner, operation* base,
50       const boost::system::error_code& /*ec*/,
51       std::size_t /*bytes_transferred*/)
52   {
53     // Take ownership of the handler object.
54     reactive_null_buffers_op* o(static_cast<reactive_null_buffers_op*>(base));
55     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
56 
57     BOOST_ASIO_HANDLER_COMPLETION((o));
58 
59     // Make a copy of the handler so that the memory can be deallocated before
60     // the upcall is made. Even if we're not about to make an upcall, a
61     // sub-object of the handler may be the true owner of the memory associated
62     // with the handler. Consequently, a local copy of the handler is required
63     // to ensure that any owning sub-object remains valid until after we have
64     // deallocated the memory here.
65     detail::binder2<Handler, boost::system::error_code, std::size_t>
66       handler(o->handler_, o->ec_, o->bytes_transferred_);
67     p.h = boost::asio::detail::addressof(handler.handler_);
68     p.reset();
69 
70     // Make the upcall if required.
71     if (owner)
72     {
73       fenced_block b(fenced_block::half);
74       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
75       boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
76       BOOST_ASIO_HANDLER_INVOCATION_END;
77     }
78   }
79 
80 private:
81   Handler handler_;
82 };
83 
84 } // namespace detail
85 } // namespace asio
86 } // namespace boost
87 
88 #include <boost/asio/detail/pop_options.hpp>
89 
90 #endif // BOOST_ASIO_DETAIL_REACTIVE_NULL_BUFFERS_OP_HPP
91