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 ASIO_DETAIL_COMPLETION_HANDLER_HPP 12 #define ASIO_DETAIL_COMPLETION_HANDLER_HPP 13 14 15 #include "asio/detail/addressof.hpp" 16 #include "asio/detail/config.hpp" 17 #include "asio/detail/fenced_block.hpp" 18 #include "asio/detail/handler_alloc_helpers.hpp" 19 #include "asio/detail/handler_invoke_helpers.hpp" 20 #include "asio/detail/operation.hpp" 21 22 #include "asio/detail/push_options.hpp" 23 24 namespace asio { 25 namespace detail { 26 27 template <typename Handler> 28 class completion_handler : public operation 29 { 30 public: 31 ASIO_DEFINE_HANDLER_PTR(completion_handler); 32 completion_handler(Handler & h)33 completion_handler(Handler& h) 34 : operation(&completion_handler::do_complete), 35 handler_(ASIO_MOVE_CAST(Handler)(h)) 36 { 37 } 38 do_complete(io_service_impl * owner,operation * base,const asio::error_code &,std::size_t)39 static void do_complete(io_service_impl* owner, operation* base, 40 const asio::error_code& /*ec*/, 41 std::size_t /*bytes_transferred*/) 42 { 43 // Take ownership of the handler object. 44 completion_handler* h(static_cast<completion_handler*>(base)); 45 ptr p = { asio::detail::addressof(h->handler_), h, h }; 46 47 ASIO_HANDLER_COMPLETION((h)); 48 49 // Make a copy of the handler so that the memory can be deallocated before 50 // the upcall is made. Even if we're not about to make an upcall, a 51 // sub-object of the handler may be the true owner of the memory associated 52 // with the handler. Consequently, a local copy of the handler is required 53 // to ensure that any owning sub-object remains valid until after we have 54 // deallocated the memory here. 55 Handler handler(ASIO_MOVE_CAST(Handler)(h->handler_)); 56 p.h = asio::detail::addressof(handler); 57 p.reset(); 58 59 // Make the upcall if required. 60 if (owner) 61 { 62 fenced_block b(fenced_block::half); 63 ASIO_HANDLER_INVOCATION_BEGIN(()); 64 asio_handler_invoke_helpers::invoke(handler, handler); 65 ASIO_HANDLER_INVOCATION_END; 66 } 67 } 68 69 private: 70 Handler handler_; 71 }; 72 73 } // namespace detail 74 } // namespace asio 75 76 #include "asio/detail/pop_options.hpp" 77 78 #endif // ASIO_DETAIL_COMPLETION_HANDLER_HPP 79