1//
2// detail/completion_handler.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_COMPLETION_HANDLER_HPP
12#define BOOST_ASIO_DETAIL_COMPLETION_HANDLER_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/addressof.hpp>
19#include <boost/asio/detail/config.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/operation.hpp>
24
25#include <boost/asio/detail/push_options.hpp>
26
27namespace boost {
28namespace asio {
29namespace detail {
30
31template <typename Handler>
32class completion_handler : public operation
33{
34public:
35 BOOST_ASIO_DEFINE_HANDLER_PTR(completion_handler);
36
37 completion_handler(Handler& h)
38 : operation(&completion_handler::do_complete),
39 handler_(BOOST_ASIO_MOVE_CAST(Handler)(h))
40 {
41 }
42
43 static void do_complete(io_service_impl* owner, operation* base,
44 const boost::system::error_code& /*ec*/,
45 std::size_t /*bytes_transferred*/)
46 {
47 // Take ownership of the handler object.
48 completion_handler* h(static_cast<completion_handler*>(base));
49 ptr p = { boost::asio::detail::addressof(h->handler_), h, h };
50
51 BOOST_ASIO_HANDLER_COMPLETION((h));
52
53 // Make a copy of the handler so that the memory can be deallocated before
54 // the upcall is made. Even if we're not about to make an upcall, a
55 // sub-object of the handler may be the true owner of the memory associated
56 // with the handler. Consequently, a local copy of the handler is required
57 // to ensure that any owning sub-object remains valid until after we have
58 // deallocated the memory here.
59 Handler handler(BOOST_ASIO_MOVE_CAST(Handler)(h->handler_));
60 p.h = boost::asio::detail::addressof(handler);
61 p.reset();
62
63 // Make the upcall if required.
64 if (owner)
65 {
66 fenced_block b(fenced_block::half);
67 BOOST_ASIO_HANDLER_INVOCATION_BEGIN(());
68 boost_asio_handler_invoke_helpers::invoke(handler, handler);
69 BOOST_ASIO_HANDLER_INVOCATION_END;
70 }
71 }
72
73private:
74 Handler handler_;
75};
76
77} // namespace detail
78} // namespace asio
79} // namespace boost
80
81#include <boost/asio/detail/pop_options.hpp>
82
83#endif // BOOST_ASIO_DETAIL_COMPLETION_HANDLER_HPP
84

source code of boost/boost/asio/detail/completion_handler.hpp