203 lines
7.6 KiB
C++
Executable File
203 lines
7.6 KiB
C++
Executable File
//
|
|
// defer.hpp
|
|
// ~~~~~~~~~
|
|
//
|
|
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
|
|
//
|
|
// Distributed under the Boost Software License, Version 1.0. (See accompanying
|
|
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
//
|
|
|
|
#ifndef BOOST_ASIO_DEFER_HPP
|
|
#define BOOST_ASIO_DEFER_HPP
|
|
|
|
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
|
|
# pragma once
|
|
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
|
|
|
|
#include <boost/asio/detail/config.hpp>
|
|
#include <boost/asio/async_result.hpp>
|
|
#include <boost/asio/detail/type_traits.hpp>
|
|
#include <boost/asio/execution_context.hpp>
|
|
#include <boost/asio/execution/executor.hpp>
|
|
#include <boost/asio/is_executor.hpp>
|
|
|
|
#include <boost/asio/detail/push_options.hpp>
|
|
|
|
namespace boost {
|
|
namespace asio {
|
|
|
|
/// Submits a completion token or function object for execution.
|
|
/**
|
|
* This function submits an object for execution using the object's associated
|
|
* executor. The function object is queued for execution, and is never called
|
|
* from the current thread prior to returning from <tt>defer()</tt>.
|
|
*
|
|
* The use of @c defer(), rather than @ref post(), indicates the caller's
|
|
* preference that the executor defer the queueing of the function object. This
|
|
* may allow the executor to optimise queueing for cases when the function
|
|
* object represents a continuation of the current call context.
|
|
*
|
|
* @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 This function returns <tt>async_initiate<NullaryToken,
|
|
* void()>(Init{}, token)</tt>, where @c Init is a function object type defined
|
|
* as:
|
|
*
|
|
* @code class Init
|
|
* {
|
|
* public:
|
|
* template <typename CompletionHandler>
|
|
* void operator()(CompletionHandler&& completion_handler) const;
|
|
* }; @endcode
|
|
*
|
|
* The function call operator of @c Init:
|
|
*
|
|
* @li Obtains the handler's associated executor object @c ex of type @c Ex by
|
|
* performing @code auto ex = get_associated_executor(handler); @endcode
|
|
*
|
|
* @li Obtains the handler's associated allocator object @c alloc by performing
|
|
* @code auto alloc = get_associated_allocator(handler); @endcode
|
|
*
|
|
* @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
|
|
* @code execution::execute(
|
|
* prefer(
|
|
* require(ex, execution::blocking.never),
|
|
* execution::relationship.continuation,
|
|
* execution::allocator(alloc)),
|
|
* std::forward<CompletionHandler>(completion_handler)); @endcode
|
|
*
|
|
* @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
|
|
* @code ex.defer(
|
|
* std::forward<CompletionHandler>(completion_handler),
|
|
* alloc); @endcode
|
|
*
|
|
* @par Completion Signature
|
|
* @code void() @endcode
|
|
*/
|
|
template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken>
|
|
BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(NullaryToken, void()) defer(
|
|
BOOST_ASIO_MOVE_ARG(NullaryToken) token);
|
|
|
|
/// Submits a completion token or function object for execution.
|
|
/**
|
|
* This function submits an object for execution using the specified executor.
|
|
* The function object is queued for execution, and is never called from the
|
|
* current thread prior to returning from <tt>defer()</tt>.
|
|
*
|
|
* The use of @c defer(), rather than @ref post(), indicates the caller's
|
|
* preference that the executor defer the queueing of the function object. This
|
|
* may allow the executor to optimise queueing for cases when the function
|
|
* object represents a continuation of the current call context.
|
|
*
|
|
* @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(); @endcode
|
|
*
|
|
* @returns This function returns <tt>async_initiate<NullaryToken,
|
|
* 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) 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(handler, ex); @endcode
|
|
*
|
|
* @li Obtains the handler's associated allocator object @c alloc by performing
|
|
* @code auto alloc = get_associated_allocator(handler); @endcode
|
|
*
|
|
* @li If <tt>execution::is_executor<Ex1>::value</tt> is true, constructs a
|
|
* function object @c f with a member @c executor_ that is initialised with
|
|
* <tt>prefer(ex1, execution::outstanding_work.tracked)</tt>, a member @c
|
|
* handler_ that is a decay-copy of @c completion_handler, and a function call
|
|
* operator that performs:
|
|
* @code auto a = get_associated_allocator(handler_);
|
|
* execution::execute(
|
|
* prefer(executor_,
|
|
* execution::blocking.possibly,
|
|
* execution::allocator(a)),
|
|
* std::move(handler_)); @endcode
|
|
*
|
|
* @li If <tt>execution::is_executor<Ex1>::value</tt> is false, constructs a
|
|
* function object @c f with a member @c work_ that is initialised with
|
|
* <tt>make_work_guard(ex1)</tt>, a member @c handler_ that is a decay-copy of
|
|
* @c completion_handler, and a function call operator that performs:
|
|
* @code auto a = get_associated_allocator(handler_);
|
|
* work_.get_executor().dispatch(std::move(handler_), a);
|
|
* work_.reset(); @endcode
|
|
*
|
|
* @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
|
|
* @code execution::execute(
|
|
* prefer(
|
|
* require(ex, execution::blocking.never),
|
|
* execution::relationship.continuation,
|
|
* execution::allocator(alloc)),
|
|
* std::move(f)); @endcode
|
|
*
|
|
* @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
|
|
* @code ex.defer(std::move(f), alloc); @endcode
|
|
*
|
|
* @par Completion Signature
|
|
* @code void() @endcode
|
|
*/
|
|
template <typename Executor,
|
|
BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
|
|
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(Executor)>
|
|
BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(NullaryToken, void()) defer(
|
|
const Executor& ex,
|
|
BOOST_ASIO_MOVE_ARG(NullaryToken) token
|
|
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(Executor),
|
|
typename constraint<
|
|
execution::is_executor<Executor>::value || is_executor<Executor>::value
|
|
>::type = 0);
|
|
|
|
/// Submits a completion token or function object for execution.
|
|
/**
|
|
* @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>defer(ctx.get_executor(), forward<NullaryToken>(token))</tt>.
|
|
*
|
|
* @par Completion Signature
|
|
* @code void() @endcode
|
|
*/
|
|
template <typename ExecutionContext,
|
|
BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
|
|
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
|
|
typename ExecutionContext::executor_type)>
|
|
BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(NullaryToken, void()) defer(
|
|
ExecutionContext& ctx,
|
|
BOOST_ASIO_MOVE_ARG(NullaryToken) token
|
|
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
|
|
typename ExecutionContext::executor_type),
|
|
typename constraint<is_convertible<
|
|
ExecutionContext&, execution_context&>::value>::type = 0);
|
|
|
|
} // namespace asio
|
|
} // namespace boost
|
|
|
|
#include <boost/asio/detail/pop_options.hpp>
|
|
|
|
#include <boost/asio/impl/defer.hpp>
|
|
|
|
#endif // BOOST_ASIO_DEFER_HPP
|