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85 lines
2.6 KiB
85 lines
2.6 KiB
// |
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// handler_invoke_hook.hpp |
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// ~~~~~~~~~~~~~~~~~~~~~~~ |
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// |
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// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See accompanying |
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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// |
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#ifndef ASIO_HANDLER_INVOKE_HOOK_HPP |
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#define ASIO_HANDLER_INVOKE_HOOK_HPP |
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#if defined(_MSC_VER) && (_MSC_VER >= 1200) |
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# pragma once |
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
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#include "asio/detail/config.hpp" |
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#include "asio/detail/push_options.hpp" |
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namespace asio { |
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/** @defgroup asio_handler_invoke asio::asio_handler_invoke |
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* |
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* @brief Default invoke function for handlers. |
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* |
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* Completion handlers for asynchronous operations are invoked by the |
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* io_context associated with the corresponding object (e.g. a socket or |
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* deadline_timer). Certain guarantees are made on when the handler may be |
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* invoked, in particular that a handler can only be invoked from a thread that |
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* is currently calling @c run() on the corresponding io_context object. |
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* Handlers may subsequently be invoked through other objects (such as |
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* io_context::strand objects) that provide additional guarantees. |
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* |
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* When asynchronous operations are composed from other asynchronous |
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* operations, all intermediate handlers should be invoked using the same |
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* method as the final handler. This is required to ensure that user-defined |
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* objects are not accessed in a way that may violate the guarantees. This |
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* hooking function ensures that the invoked method used for the final handler |
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* is accessible at each intermediate step. |
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* |
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* Implement asio_handler_invoke for your own handlers to specify a custom |
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* invocation strategy. |
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* |
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* This default implementation invokes the function object like so: |
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* @code function(); @endcode |
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* If necessary, the default implementation makes a copy of the function object |
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* so that the non-const operator() can be used. |
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* |
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* @par Example |
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* @code |
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* class my_handler; |
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* |
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* template <typename Function> |
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* void asio_handler_invoke(Function function, my_handler* context) |
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* { |
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* context->strand_.dispatch(function); |
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* } |
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* @endcode |
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*/ |
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/*@{*/ |
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/// Default handler invocation hook used for non-const function objects. |
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template <typename Function> |
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inline void asio_handler_invoke(Function& function, ...) |
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{ |
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function(); |
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} |
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/// Default handler invocation hook used for const function objects. |
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template <typename Function> |
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inline void asio_handler_invoke(const Function& function, ...) |
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{ |
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Function tmp(function); |
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tmp(); |
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} |
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/*@}*/ |
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} // namespace asio |
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#include "asio/detail/pop_options.hpp" |
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#endif // ASIO_HANDLER_INVOKE_HOOK_HPP
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