203 lines
7.5 KiB
C++
203 lines
7.5 KiB
C++
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//
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// dispatch.hpp
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// ~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2023 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_DISPATCH_HPP
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#define ASIO_DISPATCH_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/async_result.hpp"
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#include "asio/detail/initiate_dispatch.hpp"
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#include "asio/detail/type_traits.hpp"
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#include "asio/execution_context.hpp"
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#include "asio/execution/executor.hpp"
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#include "asio/is_executor.hpp"
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#include "asio/detail/push_options.hpp"
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namespace asio {
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/// Submits a completion token or function object for execution.
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/**
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* This function submits an object for execution using the object's associated
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* executor. The function object may be called from the current thread prior to
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* returning from <tt>dispatch()</tt>. Otherwise, it is queued for execution.
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*
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* @param token The @ref completion_token that will be used to produce a
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* completion handler. The function signature of the completion handler must be:
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* @code void handler(); @endcode
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*
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* @returns This function returns <tt>async_initiate<NullaryToken,
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* void()>(Init{}, token)</tt>, where @c Init is a function object type defined
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* as:
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*
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* @code class Init
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* {
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* public:
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* template <typename CompletionHandler>
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* void operator()(CompletionHandler&& completion_handler) const;
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* }; @endcode
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*
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* The function call operator of @c Init:
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*
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* @li Obtains the handler's associated executor object @c ex of type @c Ex by
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* performing @code auto ex = get_associated_executor(handler); @endcode
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*
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* @li Obtains the handler's associated allocator object @c alloc by performing
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* @code auto alloc = get_associated_allocator(handler); @endcode
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*
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* @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
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* @code prefer(ex, execution::allocator(alloc)).execute(
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* std::forward<CompletionHandler>(completion_handler)); @endcode
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*
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* @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
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* @code ex.dispatch(
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* std::forward<CompletionHandler>(completion_handler),
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* alloc); @endcode
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*
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* @par Completion Signature
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* @code void() @endcode
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*/
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template <ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken>
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ASIO_INITFN_AUTO_RESULT_TYPE_PREFIX(NullaryToken, void()) dispatch(
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ASIO_MOVE_ARG(NullaryToken) token)
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ASIO_INITFN_AUTO_RESULT_TYPE_SUFFIX((
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async_initiate<NullaryToken, void()>(
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declval<detail::initiate_dispatch>(), token)))
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{
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return async_initiate<NullaryToken, void()>(
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detail::initiate_dispatch(), token);
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}
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/// Submits a completion token or function object for execution.
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/**
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* This function submits an object for execution using the specified executor.
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* The function object may be called from the current thread prior to returning
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* from <tt>dispatch()</tt>. Otherwise, it is queued for execution.
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*
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* @param ex The target executor.
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*
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* @param token The @ref completion_token that will be used to produce a
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* completion handler. The function signature of the completion handler must be:
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* @code void handler(); @endcode
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*
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* @returns This function returns <tt>async_initiate<NullaryToken,
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* void()>(Init{ex}, token)</tt>, where @c Init is a function object type
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* defined as:
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*
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* @code class Init
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* {
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* public:
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* using executor_type = Executor;
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* explicit Init(const Executor& ex) : ex_(ex) {}
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* executor_type get_executor() const noexcept { return ex_; }
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* template <typename CompletionHandler>
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* void operator()(CompletionHandler&& completion_handler) const;
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* private:
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* Executor ex_; // exposition only
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* }; @endcode
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*
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* The function call operator of @c Init:
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*
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* @li Obtains the handler's associated executor object @c ex1 of type @c Ex1 by
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* performing @code auto ex1 = get_associated_executor(handler, ex); @endcode
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*
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* @li Obtains the handler's associated allocator object @c alloc by performing
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* @code auto alloc = get_associated_allocator(handler); @endcode
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*
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* @li If <tt>execution::is_executor<Ex1>::value</tt> is true, constructs a
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* function object @c f with a member @c executor_ that is initialised with
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* <tt>prefer(ex1, execution::outstanding_work.tracked)</tt>, a member @c
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* handler_ that is a decay-copy of @c completion_handler, and a function call
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* operator that performs:
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* @code auto a = get_associated_allocator(handler_);
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* prefer(executor_, execution::allocator(a)).execute(std::move(handler_));
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* @endcode
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*
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* @li If <tt>execution::is_executor<Ex1>::value</tt> is false, constructs a
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* function object @c f with a member @c work_ that is initialised with
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* <tt>make_work_guard(ex1)</tt>, a member @c handler_ that is a decay-copy of
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* @c completion_handler, and a function call operator that performs:
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* @code auto a = get_associated_allocator(handler_);
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* work_.get_executor().dispatch(std::move(handler_), a);
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* work_.reset(); @endcode
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*
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* @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
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* @code prefer(ex, execution::allocator(alloc)).execute(std::move(f)); @endcode
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*
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* @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
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* @code ex.dispatch(std::move(f), alloc); @endcode
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*
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* @par Completion Signature
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* @code void() @endcode
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*/
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template <typename Executor,
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ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
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ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(Executor)>
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ASIO_INITFN_AUTO_RESULT_TYPE_PREFIX(NullaryToken, void()) dispatch(
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const Executor& ex,
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ASIO_MOVE_ARG(NullaryToken) token
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ASIO_DEFAULT_COMPLETION_TOKEN(Executor),
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typename constraint<
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execution::is_executor<Executor>::value || is_executor<Executor>::value
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>::type = 0)
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ASIO_INITFN_AUTO_RESULT_TYPE_SUFFIX((
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async_initiate<NullaryToken, void()>(
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declval<detail::initiate_dispatch_with_executor<Executor> >(), token)))
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{
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return async_initiate<NullaryToken, void()>(
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detail::initiate_dispatch_with_executor<Executor>(ex), token);
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}
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/// Submits a completion token or function object for execution.
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/**
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* @param ctx An execution context, from which the target executor is obtained.
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*
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* @param token The @ref completion_token that will be used to produce a
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* completion handler. The function signature of the completion handler must be:
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* @code void handler(); @endcode
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*
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* @returns <tt>dispatch(ctx.get_executor(),
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* forward<NullaryToken>(token))</tt>.
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*
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* @par Completion Signature
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* @code void() @endcode
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*/
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template <typename ExecutionContext,
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ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
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ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
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typename ExecutionContext::executor_type)>
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ASIO_INITFN_AUTO_RESULT_TYPE_PREFIX(NullaryToken, void()) dispatch(
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ExecutionContext& ctx,
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ASIO_MOVE_ARG(NullaryToken) token
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ASIO_DEFAULT_COMPLETION_TOKEN(
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typename ExecutionContext::executor_type),
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typename constraint<is_convertible<
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ExecutionContext&, execution_context&>::value>::type = 0)
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ASIO_INITFN_AUTO_RESULT_TYPE_SUFFIX((
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async_initiate<NullaryToken, void()>(
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declval<detail::initiate_dispatch_with_executor<
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typename ExecutionContext::executor_type> >(), token)))
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{
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return async_initiate<NullaryToken, void()>(
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detail::initiate_dispatch_with_executor<
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typename ExecutionContext::executor_type>(
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ctx.get_executor()), token);
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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_DISPATCH_HPP
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