整理
This commit is contained in:
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include/boost/asio/post.hpp
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570
include/boost/asio/post.hpp
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//
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// post.hpp
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// ~~~~~~~~
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//
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// Copyright (c) 2003-2025 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 BOOST_ASIO_POST_HPP
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#define BOOST_ASIO_POST_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 <boost/asio/detail/config.hpp>
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#include <boost/asio/async_result.hpp>
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#include <boost/asio/detail/initiate_post.hpp>
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#include <boost/asio/detail/type_traits.hpp>
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#include <boost/asio/execution_context.hpp>
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#include <boost/asio/execution/blocking.hpp>
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#include <boost/asio/execution/executor.hpp>
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#include <boost/asio/is_executor.hpp>
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#include <boost/asio/require.hpp>
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#include <boost/asio/detail/push_options.hpp>
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namespace boost {
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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 is queued for execution, and is never called
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* from the current thread prior to returning from <tt>post()</tt>.
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*
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* The use of @c post(), rather than @ref defer(), indicates the caller's
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* preference that the function object be eagerly 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
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* @code auto ex = get_associated_executor(completion_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(completion_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(
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* require(ex, execution::blocking.never),
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* execution::relationship.fork,
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* execution::allocator(alloc)
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* ).execute(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.post(
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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 <BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken = deferred_t>
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inline auto post(NullaryToken&& token = deferred_t())
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-> decltype(
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async_initiate<NullaryToken, void()>(
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declval<detail::initiate_post>(), token))
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{
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return async_initiate<NullaryToken, void()>(
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detail::initiate_post(), 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 is queued for execution, and is never called from the
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* current thread prior to returning from <tt>post()</tt>.
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*
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* The use of @c post(), rather than @ref defer(), indicates the caller's
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* preference that the function object be eagerly 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
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* @code auto ex1 = get_associated_executor(completion_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(completion_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<Executor>::value</tt> is true, performs
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* @code prefer(
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* require(ex, execution::blocking.never),
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* execution::relationship.fork,
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* execution::allocator(alloc)
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* ).execute(std::move(f)); @endcode
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*
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* @li If <tt>execution::is_executor<Executor>::value</tt> is false, performs
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* @code ex.post(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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BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
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= default_completion_token_t<Executor>>
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inline auto post(const Executor& ex,
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NullaryToken&& token = default_completion_token_t<Executor>(),
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constraint_t<
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(execution::is_executor<Executor>::value
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&& can_require<Executor, execution::blocking_t::never_t>::value)
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|| is_executor<Executor>::value
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> = 0)
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-> decltype(
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async_initiate<NullaryToken, void()>(
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declval<detail::initiate_post_with_executor<Executor>>(),
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token, detail::empty_work_function()))
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{
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return async_initiate<NullaryToken, void()>(
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detail::initiate_post_with_executor<Executor>(ex),
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token, detail::empty_work_function());
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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>post(ctx.get_executor(), 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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BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
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= default_completion_token_t<typename ExecutionContext::executor_type>>
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inline auto post(ExecutionContext& ctx,
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NullaryToken&& token = default_completion_token_t<
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typename ExecutionContext::executor_type>(),
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constraint_t<
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is_convertible<ExecutionContext&, execution_context&>::value
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> = 0)
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-> decltype(
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async_initiate<NullaryToken, void()>(
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declval<detail::initiate_post_with_executor<
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typename ExecutionContext::executor_type>>(),
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token, detail::empty_work_function()))
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{
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return async_initiate<NullaryToken, void()>(
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detail::initiate_post_with_executor<
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typename ExecutionContext::executor_type>(ctx.get_executor()),
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token, detail::empty_work_function());
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}
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/// Submits a function to be run on a specified target executor, and after
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/// completion submits the completion handler.
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/**
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* This function submits a function object for execution on the specified
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* executor. The function object is queued for execution, and is never called
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* from the current thread prior to returning from <tt>post()</tt>. After the
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* submitted function completes, the completion handler is dispatched to run on
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* its associated executor.
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*
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* The use of @c post(), rather than @ref defer(), indicates the caller's
|
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* preference that the function object be eagerly queued for execution.
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*
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* @param function A nullary function to be executed on the target executor.
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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, forward<Function>(function))</tt>, where @c Init is
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* a function object type 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,
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* Function&& function) 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
|
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* @code auto ex1 = get_associated_executor(completion_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(completion_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 wrapper @c f with a member @c executor_ that is initialised
|
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* with <tt>prefer(ex1, execution::outstanding_work.tracked)</tt>, a member @c
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* function_ that is a decay-copy of @c function, a member @c handler_ that is a
|
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* decay-copy of @c completion_handler, and a function call operator that
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* performs:
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* @code std::move(function_)();
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* 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 wrapper @c f with a member @c work_ that is initialised with
|
||||
* <tt>make_work_guard(ex1)</tt>, a member @c function_ that is a decay-copy of
|
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* @c function, a member @c handler_ that is a decay-copy of @c
|
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* completion_handler, and a function call operator that performs:
|
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* @code std::move(function_)();
|
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* 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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*
|
||||
* @li If <tt>execution::is_executor<Executor>::value</tt> is true, performs
|
||||
* @code prefer(
|
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* require(ex, execution::blocking.never),
|
||||
* execution::relationship.fork,
|
||||
* execution::allocator(alloc)
|
||||
* ).execute(std::move(f)); @endcode
|
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*
|
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* @li If <tt>execution::is_executor<Executor>::value</tt> is false, performs
|
||||
* @code ex.post(std::move(f), alloc); @endcode
|
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*
|
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* @note If the function object throws an exception, that exception is allowed
|
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* to propagate to the target executor. The behaviour in this case is dependent
|
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* on the executor. For example, boost::asio::io_context will allow the
|
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* exception to propagate to the caller that runs the @c io_context, whereas
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* boost::asio::thread_pool will call @c std::terminate.
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*
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* @par Example
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* This @c post overload may be used to submit long running work to a thread
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* pool and, once complete, continue execution on an associated completion
|
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* executor, such as a coroutine's associated executor:
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* @code boost::asio::awaitable<void> my_coroutine()
|
||||
* {
|
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* // ...
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*
|
||||
* co_await boost::asio::post(
|
||||
* []{
|
||||
* perform_expensive_computation();
|
||||
* },
|
||||
* my_thread_pool);
|
||||
*
|
||||
* // handle result on the coroutine's associated executor
|
||||
* } @endcode
|
||||
*
|
||||
* @par Completion Signature
|
||||
* @code void() @endcode
|
||||
*/
|
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template <typename Function, typename Executor,
|
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BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
|
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= default_completion_token_t<Executor>>
|
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inline auto post(Function&& function, const Executor& ex,
|
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NullaryToken&& token = default_completion_token_t<Executor>(),
|
||||
constraint_t<
|
||||
is_void<result_of_t<decay_t<Function>()>>::value
|
||||
> = 0,
|
||||
constraint_t<
|
||||
(execution::is_executor<Executor>::value
|
||||
&& can_require<Executor, execution::blocking_t::never_t>::value)
|
||||
|| is_executor<Executor>::value
|
||||
> = 0)
|
||||
-> decltype(
|
||||
async_initiate<NullaryToken, void()>(
|
||||
declval<detail::initiate_post_with_executor<Executor>>(),
|
||||
token, static_cast<Function&&>(function)))
|
||||
{
|
||||
return async_initiate<NullaryToken, void()>(
|
||||
detail::initiate_post_with_executor<Executor>(ex),
|
||||
token, static_cast<Function&&>(function));
|
||||
}
|
||||
|
||||
/// Submits a function to be run on a specified target executor, and passes the
|
||||
/// result to a completion handler.
|
||||
/**
|
||||
* This function submits a function object for execution on the specified
|
||||
* executor. The function object is queued for execution, and is never called
|
||||
* from the current thread prior to returning from <tt>post()</tt>. After the
|
||||
* submitted function completes, the completion handler is dispatched along with
|
||||
* the function's result, to run on its associated executor.
|
||||
*
|
||||
* The use of @c post(), rather than @ref defer(), indicates the caller's
|
||||
* preference that the function object be eagerly queued for execution.
|
||||
*
|
||||
* @param function A nullary function to be executed on the target executor.
|
||||
*
|
||||
* @param ex The target executor.
|
||||
*
|
||||
* @param token The @ref completion_token that will be used to produce a
|
||||
* completion handler. The function signature of the completion handler must be:
|
||||
* @code void handler(decay_t<result_of_t<decay_t<Function>()>>); @endcode
|
||||
*
|
||||
* @returns This function returns <tt>async_initiate<CompletionToken,
|
||||
* void()>(Init{ex}, token)</tt>, where @c Init is a function object type
|
||||
* defined as:
|
||||
*
|
||||
* @code class Init
|
||||
* {
|
||||
* public:
|
||||
* using executor_type = Executor;
|
||||
* explicit Init(const Executor& ex) : ex_(ex) {}
|
||||
* executor_type get_executor() const noexcept { return ex_; }
|
||||
* template <typename CompletionHandler>
|
||||
* void operator()(CompletionHandler&& completion_handler,
|
||||
* Function&& function) const;
|
||||
* private:
|
||||
* Executor ex_; // exposition only
|
||||
* }; @endcode
|
||||
*
|
||||
* The function call operator of @c Init:
|
||||
*
|
||||
* @li Obtains the handler's associated executor object @c ex1 of type @c Ex1 by
|
||||
* performing
|
||||
* @code auto ex1 = get_associated_executor(completion_handler, ex); @endcode
|
||||
*
|
||||
* @li Obtains the handler's associated allocator object @c alloc by performing
|
||||
* @code auto alloc = get_associated_allocator(completion_handler); @endcode
|
||||
*
|
||||
* @li If <tt>execution::is_executor<Ex1>::value</tt> is true, constructs a
|
||||
* function object wrapper @c f with a member @c executor_ that is initialised
|
||||
* with <tt>prefer(ex1, execution::outstanding_work.tracked)</tt>, a member @c
|
||||
* function_ that is a decay-copy of @c function, a member @c handler_ that is a
|
||||
* decay-copy of @c completion_handler, and a function call operator that
|
||||
* performs:
|
||||
* @code auto result = std::move(function_)();
|
||||
* auto a = get_associated_allocator(handler_);
|
||||
* prefer(executor_, execution::allocator(a)).execute(
|
||||
* std::bind(std::move(handler_), std::move(result)));
|
||||
* @endcode
|
||||
*
|
||||
* @li If <tt>execution::is_executor<Ex1>::value</tt> is false, constructs a
|
||||
* function object wrapper @c f with a member @c work_ that is initialised with
|
||||
* <tt>make_work_guard(ex1)</tt>, a member @c function_ that is a decay-copy of
|
||||
* @c function, a member @c handler_ that is a decay-copy of @c
|
||||
* completion_handler, and a function call operator that performs:
|
||||
* @code auto result = std::move(function_)();
|
||||
* auto a = get_associated_allocator(handler_);
|
||||
* work_.get_executor().dispatch(
|
||||
* std::bind(std::move(handler_), std::move(result)), a);
|
||||
* work_.reset(); @endcode
|
||||
*
|
||||
* @li If <tt>execution::is_executor<Executor>::value</tt> is true, performs
|
||||
* @code prefer(
|
||||
* require(ex, execution::blocking.never),
|
||||
* execution::relationship.fork,
|
||||
* execution::allocator(alloc)
|
||||
* ).execute(std::move(f)); @endcode
|
||||
*
|
||||
* @li If <tt>execution::is_executor<Executor>::value</tt> is false, performs
|
||||
* @code ex.post(std::move(f), alloc); @endcode
|
||||
*
|
||||
* @note If the function object throws an exception, that exception is allowed
|
||||
* to propagate to the target executor. The behaviour in this case is dependent
|
||||
* on the executor. For example, boost::asio::io_context will allow the
|
||||
* exception to propagate to the caller that runs the @c io_context, whereas
|
||||
* boost::asio::thread_pool will call @c std::terminate.
|
||||
*
|
||||
* @par Example
|
||||
* This @c post overload may be used to submit long running work to a thread
|
||||
* pool and, once complete, continue execution on an associated completion
|
||||
* executor, such as a coroutine's associated executor:
|
||||
* @code boost::asio::awaitable<void> my_coroutine()
|
||||
* {
|
||||
* // ...
|
||||
*
|
||||
* int result = co_await boost::asio::post(
|
||||
* []{
|
||||
* return perform_expensive_computation();
|
||||
* },
|
||||
* my_thread_pool);
|
||||
*
|
||||
* // handle result on the coroutine's associated executor
|
||||
* } @endcode
|
||||
*
|
||||
* @par Completion Signature
|
||||
* @code void(decay_t<result_of_t<decay_t<Function>()>>) @endcode
|
||||
*/
|
||||
template <typename Function, typename Executor,
|
||||
BOOST_ASIO_COMPLETION_TOKEN_FOR(
|
||||
void(decay_t<result_of_t<decay_t<Function>()>>)) CompletionToken
|
||||
= default_completion_token_t<Executor>>
|
||||
inline auto post(Function&& function, const Executor& ex,
|
||||
CompletionToken&& token = default_completion_token_t<Executor>(),
|
||||
constraint_t<
|
||||
!is_void<result_of_t<decay_t<Function>()>>::value
|
||||
> = 0,
|
||||
constraint_t<
|
||||
(execution::is_executor<Executor>::value
|
||||
&& can_require<Executor, execution::blocking_t::never_t>::value)
|
||||
|| is_executor<Executor>::value
|
||||
> = 0)
|
||||
-> decltype(
|
||||
async_initiate<CompletionToken, void(detail::work_result_t<Function>)>(
|
||||
declval<detail::initiate_post_with_executor<Executor>>(),
|
||||
token, static_cast<Function&&>(function)))
|
||||
{
|
||||
return async_initiate<CompletionToken, void(detail::work_result_t<Function>)>(
|
||||
detail::initiate_post_with_executor<Executor>(ex),
|
||||
token, static_cast<Function&&>(function));
|
||||
}
|
||||
|
||||
/// Submits a function to be run on a specified execution context, and after
|
||||
/// completion submits the completion handler.
|
||||
/**
|
||||
* @param function A nullary function to be executed on the target executor.
|
||||
*
|
||||
* @param ctx An execution context, from which the target executor is obtained.
|
||||
*
|
||||
* @param token The @ref completion_token that will be used to produce a
|
||||
* completion handler. The function signature of the completion handler must be:
|
||||
* @code void handler(); @endcode
|
||||
*
|
||||
* @returns <tt>post(forward<Function>(function), ctx.get_executor(),
|
||||
* forward<NullaryToken>(token))</tt>.
|
||||
*
|
||||
* @note If the function object throws an exception, that exception is allowed
|
||||
* to propagate to the target executor. The behaviour in this case is dependent
|
||||
* on the executor. For example, boost::asio::io_context will allow the
|
||||
* exception to propagate to the caller that runs the @c io_context, whereas
|
||||
* boost::asio::thread_pool will call @c std::terminate.
|
||||
*
|
||||
* @par Completion Signature
|
||||
* @code void() @endcode
|
||||
*/
|
||||
template <typename Function, typename ExecutionContext,
|
||||
BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
|
||||
= default_completion_token_t<typename ExecutionContext::executor_type>>
|
||||
inline auto post(Function&& function, ExecutionContext& ctx,
|
||||
NullaryToken&& token = default_completion_token_t<
|
||||
typename ExecutionContext::executor_type>(),
|
||||
constraint_t<
|
||||
is_void<result_of_t<decay_t<Function>()>>::value
|
||||
> = 0,
|
||||
constraint_t<
|
||||
is_convertible<ExecutionContext&, execution_context&>::value
|
||||
> = 0)
|
||||
-> decltype(
|
||||
async_initiate<NullaryToken, void()>(
|
||||
declval<detail::initiate_post_with_executor<
|
||||
typename ExecutionContext::executor_type>>(),
|
||||
token, static_cast<Function&&>(function)))
|
||||
{
|
||||
return async_initiate<NullaryToken, void()>(
|
||||
detail::initiate_post_with_executor<
|
||||
typename ExecutionContext::executor_type>(ctx.get_executor()),
|
||||
token, static_cast<Function&&>(function));
|
||||
}
|
||||
|
||||
/// Submits a function to be run on a specified execution context, and passes
|
||||
/// the result to a completion handler.
|
||||
/**
|
||||
* @param function A nullary function to be executed on the target executor.
|
||||
*
|
||||
* @param ctx An execution context, from which the target executor is obtained.
|
||||
*
|
||||
* @param token The @ref completion_token that will be used to produce a
|
||||
* completion handler. The function signature of the completion handler must be:
|
||||
* @code void handler(); @endcode
|
||||
*
|
||||
* @returns <tt>post(forward<Function>(function), ctx.get_executor(),
|
||||
* forward<CompletionToken>(token))</tt>.
|
||||
*
|
||||
* @note If the function object throws an exception, that exception is allowed
|
||||
* to propagate to the target executor. The behaviour in this case is dependent
|
||||
* on the executor. For example, boost::asio::io_context will allow the
|
||||
* exception to propagate to the caller that runs the @c io_context, whereas
|
||||
* boost::asio::thread_pool will call @c std::terminate.
|
||||
*
|
||||
* @par Completion Signature
|
||||
* @code void(decay_t<result_of_t<decay_t<Function>()>>) @endcode
|
||||
*/
|
||||
template <typename Function, typename ExecutionContext,
|
||||
BOOST_ASIO_COMPLETION_TOKEN_FOR(
|
||||
void(decay_t<result_of_t<decay_t<Function>()>>)) CompletionToken
|
||||
= default_completion_token_t<typename ExecutionContext::executor_type>>
|
||||
inline auto post(Function&& function, ExecutionContext& ctx,
|
||||
CompletionToken&& token = default_completion_token_t<
|
||||
typename ExecutionContext::executor_type>(),
|
||||
constraint_t<
|
||||
!is_void<result_of_t<decay_t<Function>()>>::value
|
||||
> = 0,
|
||||
constraint_t<
|
||||
is_convertible<ExecutionContext&, execution_context&>::value
|
||||
> = 0)
|
||||
-> decltype(
|
||||
async_initiate<CompletionToken, void(detail::work_result_t<Function>)>(
|
||||
declval<detail::initiate_post_with_executor<
|
||||
typename ExecutionContext::executor_type>>(),
|
||||
token, static_cast<Function&&>(function)))
|
||||
{
|
||||
return async_initiate<CompletionToken, void(detail::work_result_t<Function>)>(
|
||||
detail::initiate_post_with_executor<
|
||||
typename ExecutionContext::executor_type>(ctx.get_executor()),
|
||||
token, static_cast<Function&&>(function));
|
||||
}
|
||||
|
||||
} // namespace asio
|
||||
} // namespace boost
|
||||
|
||||
#include <boost/asio/detail/pop_options.hpp>
|
||||
|
||||
#endif // BOOST_ASIO_POST_HPP
|
||||
Reference in New Issue
Block a user