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 27 namespace boost { 28 namespace asio { 29 namespace detail { 30 31 template <typename Handler> 32 class completion_handler : public operation 33 { 34 public: 35 BOOST_ASIO_DEFINE_HANDLER_PTR(completion_handler); 36 completion_handler(Handler & h)37 completion_handler(Handler& h) 38 : operation(&completion_handler::do_complete), 39 handler_(BOOST_ASIO_MOVE_CAST(Handler)(h)) 40 { 41 } 42 do_complete(io_service_impl * owner,operation * base,const boost::system::error_code &,std::size_t)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 73 private: 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