Chris@16: //
Chris@16: // handler_invoke_hook.hpp
Chris@16: // ~~~~~~~~~~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_HANDLER_INVOKE_HOOK_HPP
Chris@16: #define BOOST_ASIO_HANDLER_INVOKE_HOOK_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/config.hpp>
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: 
Chris@16: /** @defgroup asio_handler_invoke boost::asio::asio_handler_invoke
Chris@16:  *
Chris@16:  * @brief Default invoke function for handlers.
Chris@16:  *
Chris@16:  * Completion handlers for asynchronous operations are invoked by the
Chris@16:  * io_service associated with the corresponding object (e.g. a socket or
Chris@16:  * deadline_timer). Certain guarantees are made on when the handler may be
Chris@16:  * invoked, in particular that a handler can only be invoked from a thread that
Chris@16:  * is currently calling @c run() on the corresponding io_service object.
Chris@16:  * Handlers may subsequently be invoked through other objects (such as
Chris@16:  * io_service::strand objects) that provide additional guarantees.
Chris@16:  *
Chris@16:  * When asynchronous operations are composed from other asynchronous
Chris@16:  * operations, all intermediate handlers should be invoked using the same
Chris@16:  * method as the final handler. This is required to ensure that user-defined
Chris@16:  * objects are not accessed in a way that may violate the guarantees. This
Chris@16:  * hooking function ensures that the invoked method used for the final handler
Chris@16:  * is accessible at each intermediate step.
Chris@16:  *
Chris@16:  * Implement asio_handler_invoke for your own handlers to specify a custom
Chris@16:  * invocation strategy.
Chris@16:  *
Chris@16:  * This default implementation invokes the function object like so:
Chris@16:  * @code function(); @endcode
Chris@16:  * If necessary, the default implementation makes a copy of the function object
Chris@16:  * so that the non-const operator() can be used.
Chris@16:  *
Chris@16:  * @par Example
Chris@16:  * @code
Chris@16:  * class my_handler;
Chris@16:  *
Chris@16:  * template <typename Function>
Chris@16:  * void asio_handler_invoke(Function function, my_handler* context)
Chris@16:  * {
Chris@16:  *   context->strand_.dispatch(function);
Chris@16:  * }
Chris@16:  * @endcode
Chris@16:  */
Chris@16: /*@{*/
Chris@16: 
Chris@16: /// Default handler invocation hook used for non-const function objects.
Chris@16: template <typename Function>
Chris@16: inline void asio_handler_invoke(Function& function, ...)
Chris@16: {
Chris@16:   function();
Chris@16: }
Chris@16: 
Chris@16: /// Default handler invocation hook used for const function objects.
Chris@16: template <typename Function>
Chris@16: inline void asio_handler_invoke(const Function& function, ...)
Chris@16: {
Chris@16:   Function tmp(function);
Chris@16:   tmp();
Chris@16: }
Chris@16: 
Chris@16: /*@}*/
Chris@16: 
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #endif // BOOST_ASIO_HANDLER_INVOKE_HOOK_HPP