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편집 파일: strand.hpp

// // strand.hpp // ~~~~~~~~~~ // // Copyright (c) 2003-2024 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_STRAND_HPP #define BOOST_ASIO_STRAND_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/detail/strand_executor_service.hpp> #include <boost/asio/detail/type_traits.hpp> #include <boost/asio/execution/blocking.hpp> #include <boost/asio/execution/executor.hpp> #include <boost/asio/is_executor.hpp> #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { /// Provides serialised function invocation for any executor type. template <typename Executor> class strand { public: /// The type of the underlying executor. typedef Executor inner_executor_type; /// Default constructor. /** * This constructor is only valid if the underlying executor type is default * constructible. */ strand() : executor_(), impl_(strand::create_implementation(executor_)) { } /// Construct a strand for the specified executor. template <typename Executor1> explicit strand(const Executor1& e, constraint_t< conditional_t< !is_same<Executor1, strand>::value, is_convertible<Executor1, Executor>, false_type >::value > = 0) : executor_(e), impl_(strand::create_implementation(executor_)) { } /// Copy constructor. strand(const strand& other) noexcept : executor_(other.executor_), impl_(other.impl_) { } /// Converting constructor. /** * This constructor is only valid if the @c OtherExecutor type is convertible * to @c Executor. */ template <class OtherExecutor> strand( const strand<OtherExecutor>& other) noexcept : executor_(other.executor_), impl_(other.impl_) { } /// Assignment operator. strand& operator=(const strand& other) noexcept { executor_ = other.executor_; impl_ = other.impl_; return *this; } /// Converting assignment operator. /** * This assignment operator is only valid if the @c OtherExecutor type is * convertible to @c Executor. */ template <class OtherExecutor> strand& operator=( const strand<OtherExecutor>& other) noexcept { executor_ = other.executor_; impl_ = other.impl_; return *this; } /// Move constructor. strand(strand&& other) noexcept : executor_(static_cast<Executor&&>(other.executor_)), impl_(static_cast<implementation_type&&>(other.impl_)) { } /// Converting move constructor. /** * This constructor is only valid if the @c OtherExecutor type is convertible * to @c Executor. */ template <class OtherExecutor> strand(strand<OtherExecutor>&& other) noexcept : executor_(static_cast<OtherExecutor&&>(other.executor_)), impl_(static_cast<implementation_type&&>(other.impl_)) { } /// Move assignment operator. strand& operator=(strand&& other) noexcept { executor_ = static_cast<Executor&&>(other.executor_); impl_ = static_cast<implementation_type&&>(other.impl_); return *this; } /// Converting move assignment operator. /** * This assignment operator is only valid if the @c OtherExecutor type is * convertible to @c Executor. */ template <class OtherExecutor> strand& operator=(strand<OtherExecutor>&& other) noexcept { executor_ = static_cast<OtherExecutor&&>(other.executor_); impl_ = static_cast<implementation_type&&>(other.impl_); return *this; } /// Destructor. ~strand() noexcept { } /// Obtain the underlying executor. inner_executor_type get_inner_executor() const noexcept { return executor_; } /// Forward a query to the underlying executor. /** * Do not call this function directly. It is intended for use with the * boost::asio::query customisation point. * * For example: * @code boost::asio::strand<my_executor_type> ex = ...; * if (boost::asio::query(ex, boost::asio::execution::blocking) * == boost::asio::execution::blocking.never) * ... @endcode */ template <typename Property> constraint_t< can_query<const Executor&, Property>::value, conditional_t< is_convertible<Property, execution::blocking_t>::value, execution::blocking_t, query_result_t<const Executor&, Property> > > query(const Property& p) const noexcept(is_nothrow_query<const Executor&, Property>::value) { return this->query_helper( is_convertible<Property, execution::blocking_t>(), p); } /// Forward a requirement to the underlying executor. /** * Do not call this function directly. It is intended for use with the * boost::asio::require customisation point. * * For example: * @code boost::asio::strand<my_executor_type> ex1 = ...; * auto ex2 = boost::asio::require(ex1, * boost::asio::execution::blocking.never); @endcode */ template <typename Property> constraint_t< can_require<const Executor&, Property>::value && !is_convertible<Property, execution::blocking_t::always_t>::value, strand<decay_t<require_result_t<const Executor&, Property>>> > require(const Property& p) const noexcept(is_nothrow_require<const Executor&, Property>::value) { return strand<decay_t<require_result_t<const Executor&, Property>>>( boost::asio::require(executor_, p), impl_); } /// Forward a preference to the underlying executor. /** * Do not call this function directly. It is intended for use with the * boost::asio::prefer customisation point. * * For example: * @code boost::asio::strand<my_executor_type> ex1 = ...; * auto ex2 = boost::asio::prefer(ex1, * boost::asio::execution::blocking.never); @endcode */ template <typename Property> constraint_t< can_prefer<const Executor&, Property>::value && !is_convertible<Property, execution::blocking_t::always_t>::value, strand<decay_t<prefer_result_t<const Executor&, Property>>> > prefer(const Property& p) const noexcept(is_nothrow_prefer<const Executor&, Property>::value) { return strand<decay_t<prefer_result_t<const Executor&, Property>>>( boost::asio::prefer(executor_, p), impl_); } #if !defined(BOOST_ASIO_NO_TS_EXECUTORS) /// Obtain the underlying execution context. execution_context& context() const noexcept { return executor_.context(); } /// Inform the strand that it has some outstanding work to do. /** * The strand delegates this call to its underlying executor. */ void on_work_started() const noexcept { executor_.on_work_started(); } /// Inform the strand that some work is no longer outstanding. /** * The strand delegates this call to its underlying executor. */ void on_work_finished() const noexcept { executor_.on_work_finished(); } #endif // !defined(BOOST_ASIO_NO_TS_EXECUTORS) /// Request the strand to invoke the given function object. /** * This function is used to ask the strand to execute the given function * object on its underlying executor. The function object will be executed * according to the properties of the underlying executor. * * @param f The function object to be called. The executor will make * a copy of the handler object as required. The function signature of the * function object must be: @code void function(); @endcode */ template <typename Function> constraint_t< traits::execute_member<const Executor&, Function>::is_valid, void > execute(Function&& f) const { detail::strand_executor_service::execute(impl_, executor_, static_cast<Function&&>(f)); } #if !defined(BOOST_ASIO_NO_TS_EXECUTORS) /// Request the strand to invoke the given function object. /** * This function is used to ask the strand to execute the given function * object on its underlying executor. The function object will be executed * inside this function if the strand is not otherwise busy and if the * underlying executor's @c dispatch() function is also able to execute the * function before returning. * * @param f The function object to be called. The executor will make * a copy of the handler object as required. The function signature of the * function object must be: @code void function(); @endcode * * @param a An allocator that may be used by the executor to allocate the * internal storage needed for function invocation. */ template <typename Function, typename Allocator> void dispatch(Function&& f, const Allocator& a) const { detail::strand_executor_service::dispatch(impl_, executor_, static_cast<Function&&>(f), a); } /// Request the strand to invoke the given function object. /** * This function is used to ask the executor to execute the given function * object. The function object will never be executed inside this function. * Instead, it will be scheduled by the underlying executor's defer function. * * @param f The function object to be called. The executor will make * a copy of the handler object as required. The function signature of the * function object must be: @code void function(); @endcode * * @param a An allocator that may be used by the executor to allocate the * internal storage needed for function invocation. */ template <typename Function, typename Allocator> void post(Function&& f, const Allocator& a) const { detail::strand_executor_service::post(impl_, executor_, static_cast<Function&&>(f), a); } /// Request the strand to invoke the given function object. /** * This function is used to ask the executor to execute the given function * object. The function object will never be executed inside this function. * Instead, it will be scheduled by the underlying executor's defer function. * * @param f The function object to be called. The executor will make * a copy of the handler object as required. The function signature of the * function object must be: @code void function(); @endcode * * @param a An allocator that may be used by the executor to allocate the * internal storage needed for function invocation. */ template <typename Function, typename Allocator> void defer(Function&& f, const Allocator& a) const { detail::strand_executor_service::defer(impl_, executor_, static_cast<Function&&>(f), a); } #endif // !defined(BOOST_ASIO_NO_TS_EXECUTORS) /// Determine whether the strand is running in the current thread. /** * @return @c true if the current thread is executing a function that was * submitted to the strand using post(), dispatch() or defer(). Otherwise * returns @c false. */ bool running_in_this_thread() const noexcept { return detail::strand_executor_service::running_in_this_thread(impl_); } /// Compare two strands for equality. /** * Two strands are equal if they refer to the same ordered, non-concurrent * state. */ friend bool operator==(const strand& a, const strand& b) noexcept { return a.impl_ == b.impl_; } /// Compare two strands for inequality. /** * Two strands are equal if they refer to the same ordered, non-concurrent * state. */ friend bool operator!=(const strand& a, const strand& b) noexcept { return a.impl_ != b.impl_; } #if defined(GENERATING_DOCUMENTATION) private: #endif // defined(GENERATING_DOCUMENTATION) typedef detail::strand_executor_service::implementation_type implementation_type; template <typename InnerExecutor> static implementation_type create_implementation(const InnerExecutor& ex, constraint_t< can_query<InnerExecutor, execution::context_t>::value > = 0) { return use_service<detail::strand_executor_service>( boost::asio::query(ex, execution::context)).create_implementation(); } template <typename InnerExecutor> static implementation_type create_implementation(const InnerExecutor& ex, constraint_t< !can_query<InnerExecutor, execution::context_t>::value > = 0) { return use_service<detail::strand_executor_service>( ex.context()).create_implementation(); } strand(const Executor& ex, const implementation_type& impl) : executor_(ex), impl_(impl) { } template <typename Property> query_result_t<const Executor&, Property> query_helper( false_type, const Property& property) const { return boost::asio::query(executor_, property); } template <typename Property> execution::blocking_t query_helper(true_type, const Property& property) const { execution::blocking_t result = boost::asio::query(executor_, property); return result == execution::blocking.always ? execution::blocking.possibly : result; } Executor executor_; implementation_type impl_; }; /** @defgroup make_strand boost::asio::make_strand * * @brief The boost::asio::make_strand function creates a @ref strand object for * an executor or execution context. */ /*@{*/ /// Create a @ref strand object for an executor. /** * @param ex An executor. * * @returns A strand constructed with the specified executor. */ template <typename Executor> inline strand<Executor> make_strand(const Executor& ex, constraint_t< is_executor<Executor>::value || execution::is_executor<Executor>::value > = 0) { return strand<Executor>(ex); } /// Create a @ref strand object for an execution context. /** * @param ctx An execution context, from which an executor will be obtained. * * @returns A strand constructed with the execution context's executor, obtained * by performing <tt>ctx.get_executor()</tt>. */ template <typename ExecutionContext> inline strand<typename ExecutionContext::executor_type> make_strand(ExecutionContext& ctx, constraint_t< is_convertible<ExecutionContext&, execution_context&>::value > = 0) { return strand<typename ExecutionContext::executor_type>(ctx.get_executor()); } /*@}*/ #if !defined(GENERATING_DOCUMENTATION) namespace traits { #if !defined(BOOST_ASIO_HAS_DEDUCED_EQUALITY_COMPARABLE_TRAIT) template <typename Executor> struct equality_comparable<strand<Executor>> { static constexpr bool is_valid = true; static constexpr bool is_noexcept = true; }; #endif // !defined(BOOST_ASIO_HAS_DEDUCED_EQUALITY_COMPARABLE_TRAIT) #if !defined(BOOST_ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT) template <typename Executor, typename Function> struct execute_member<strand<Executor>, Function, enable_if_t< traits::execute_member<const Executor&, Function>::is_valid >> { static constexpr bool is_valid = true; static constexpr bool is_noexcept = false; typedef void result_type; }; #endif // !defined(BOOST_ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT) #if !defined(BOOST_ASIO_HAS_DEDUCED_QUERY_MEMBER_TRAIT) template <typename Executor, typename Property> struct query_member<strand<Executor>, Property, enable_if_t< can_query<const Executor&, Property>::value >> { static constexpr bool is_valid = true; static constexpr bool is_noexcept = is_nothrow_query<Executor, Property>::value; typedef conditional_t< is_convertible<Property, execution::blocking_t>::value, execution::blocking_t, query_result_t<Executor, Property>> result_type; }; #endif // !defined(BOOST_ASIO_HAS_DEDUCED_QUERY_MEMBER_TRAIT) #if !defined(BOOST_ASIO_HAS_DEDUCED_REQUIRE_MEMBER_TRAIT) template <typename Executor, typename Property> struct require_member<strand<Executor>, Property, enable_if_t< can_require<const Executor&, Property>::value && !is_convertible<Property, execution::blocking_t::always_t>::value >> { static constexpr bool is_valid = true; static constexpr bool is_noexcept = is_nothrow_require<Executor, Property>::value; typedef strand<decay_t<require_result_t<Executor, Property>>> result_type; }; #endif // !defined(BOOST_ASIO_HAS_DEDUCED_REQUIRE_MEMBER_TRAIT) #if !defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT) template <typename Executor, typename Property> struct prefer_member<strand<Executor>, Property, enable_if_t< can_prefer<const Executor&, Property>::value && !is_convertible<Property, execution::blocking_t::always_t>::value >> { static constexpr bool is_valid = true; static constexpr bool is_noexcept = is_nothrow_prefer<Executor, Property>::value; typedef strand<decay_t<prefer_result_t<Executor, Property>>> result_type; }; #endif // !defined(BOOST_ASIO_HAS_DEDUCED_PREFER_MEMBER_TRAIT) } // namespace traits #endif // !defined(GENERATING_DOCUMENTATION) } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> // If both io_context.hpp and strand.hpp have been included, automatically // include the header file needed for the io_context::strand class. #if !defined(BOOST_ASIO_NO_EXTENSIONS) # if defined(BOOST_ASIO_IO_CONTEXT_HPP) # include <boost/asio/io_context_strand.hpp> # endif // defined(BOOST_ASIO_IO_CONTEXT_HPP) #endif // !defined(BOOST_ASIO_NO_EXTENSIONS) #endif // BOOST_ASIO_STRAND_HPP