ceph/src/boost/boost/asio/detail/completion_handler.hpp

   1 //
   2 // detail/completion_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_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/config.hpp>
  19 #include <boost/asio/detail/fenced_block.hpp>
  20 #include <boost/asio/detail/handler_alloc_helpers.hpp>
  21 #include <boost/asio/detail/handler_work.hpp>
  22 #include <boost/asio/detail/memory.hpp>
  23 #include <boost/asio/detail/operation.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, typename IoExecutor>
  32 class completion_handler : public operation
  33 {
  34 public:
  35   BOOST_ASIO_DEFINE_HANDLER_PTR(completion_handler);
  36
  37   completion_handler(Handler& h, const IoExecutor& io_ex)
  38     : operation(&completion_handler::do_complete),
  39       handler_(BOOST_ASIO_MOVE_CAST(Handler)(h)),
  40       work_(handler_, io_ex)
  41   {
  42   }
  43
  44   static void do_complete(void* owner, operation* base,
  45       const boost::system::error_code& /*ec*/,
  46       std::size_t /*bytes_transferred*/)
  47   {
  48     // Take ownership of the handler object.
  49     completion_handler* h(static_cast<completion_handler*>(base));
  50     ptr p = { boost::asio::detail::addressof(h->handler_), h, h };
  51
  52     BOOST_ASIO_HANDLER_COMPLETION((*h));
  53
  54     // Take ownership of the operation's outstanding work.
  55     handler_work<Handler, IoExecutor> w(
  56         BOOST_ASIO_MOVE_CAST2(handler_work<Handler, IoExecutor>)(
  57           h->work_));
  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     Handler handler(BOOST_ASIO_MOVE_CAST(Handler)(h->handler_));
  66     p.h = boost::asio::detail::addressof(handler);
  67     p.reset();
  68
  69     // Make the upcall if required.
  70     if (owner)
  71     {
  72       fenced_block b(fenced_block::half);
  73       BOOST_ASIO_HANDLER_INVOCATION_BEGIN(());
  74       w.complete(handler, handler);
  75       BOOST_ASIO_HANDLER_INVOCATION_END;
  76     }
  77   }
  78
  79 private:
  80   Handler handler_;
  81   handler_work<Handler, IoExecutor> work_;
  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_COMPLETION_HANDLER_HPP