1 //
2 // detail/wait_handler.hpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2020 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_WAIT_HANDLER_HPP
12 #define BOOST_ASIO_DETAIL_WAIT_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/config.hpp>
19 #include <boost/asio/detail/bind_handler.hpp>
20 #include <boost/asio/detail/fenced_block.hpp>
21 #include <boost/asio/detail/handler_alloc_helpers.hpp>
22 #include <boost/asio/detail/handler_work.hpp>
23 #include <boost/asio/detail/memory.hpp>
24 #include <boost/asio/detail/wait_op.hpp>
25 
26 #include <boost/asio/detail/push_options.hpp>
27 
28 namespace boost {
29 namespace asio {
30 namespace detail {
31 
32 template <typename Handler, typename IoExecutor>
33 class wait_handler : public wait_op
34 {
35 public:
36   BOOST_ASIO_DEFINE_HANDLER_PTR(wait_handler);
37 
wait_handler(Handler & h,const IoExecutor & io_ex)38   wait_handler(Handler& h, const IoExecutor& io_ex)
39     : wait_op(&wait_handler::do_complete),
40       handler_(BOOST_ASIO_MOVE_CAST(Handler)(h)),
41       work_(handler_, io_ex)
42   {
43   }
44 
do_complete(void * owner,operation * base,const boost::system::error_code &,std::size_t)45   static void do_complete(void* owner, operation* base,
46       const boost::system::error_code& /*ec*/,
47       std::size_t /*bytes_transferred*/)
48   {
49     // Take ownership of the handler object.
50     wait_handler* h(static_cast<wait_handler*>(base));
51     ptr p = { boost::asio::detail::addressof(h->handler_), h, h };
52 
53     BOOST_ASIO_HANDLER_COMPLETION((*h));
54 
55     // Take ownership of the operation's outstanding work.
56     handler_work<Handler, IoExecutor> w(
57         BOOST_ASIO_MOVE_CAST2(handler_work<Handler, IoExecutor>)(
58           h->work_));
59 
60     // Make a copy of the handler so that the memory can be deallocated before
61     // the upcall is made. Even if we're not about to make an upcall, a
62     // sub-object of the handler may be the true owner of the memory associated
63     // with the handler. Consequently, a local copy of the handler is required
64     // to ensure that any owning sub-object remains valid until after we have
65     // deallocated the memory here.
66     detail::binder1<Handler, boost::system::error_code>
67       handler(h->handler_, h->ec_);
68     p.h = boost::asio::detail::addressof(handler.handler_);
69     p.reset();
70 
71     // Make the upcall if required.
72     if (owner)
73     {
74       fenced_block b(fenced_block::half);
75       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
76       w.complete(handler, handler.handler_);
77       BOOST_ASIO_HANDLER_INVOCATION_END;
78     }
79   }
80 
81 private:
82   Handler handler_;
83   handler_work<Handler, IoExecutor> work_;
84 };
85 
86 } // namespace detail
87 } // namespace asio
88 } // namespace boost
89 
90 #include <boost/asio/detail/pop_options.hpp>
91 
92 #endif // BOOST_ASIO_DETAIL_WAIT_HANDLER_HPP
93