// // basic_waitable_timer.hpp // ~~~~~~~~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2014 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_BASIC_WAITABLE_TIMER_HPP #define BOOST_ASIO_BASIC_WAITABLE_TIMER_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include <boost/asio/detail/config.hpp> #include <cstddef> #include <boost/asio/basic_io_object.hpp> #include <boost/asio/detail/handler_type_requirements.hpp> #include <boost/asio/detail/throw_error.hpp> #include <boost/asio/error.hpp> #include <boost/asio/wait_traits.hpp> #include <boost/asio/waitable_timer_service.hpp> #include <boost/asio/detail/push_options.hpp> namespace boost { namespace asio { /// Provides waitable timer functionality. /** * The basic_waitable_timer class template provides the ability to perform a * blocking or asynchronous wait for a timer to expire. * * A waitable timer is always in one of two states: "expired" or "not expired". * If the wait() or async_wait() function is called on an expired timer, the * wait operation will complete immediately. * * Most applications will use one of the boost::asio::steady_timer, * boost::asio::system_timer or boost::asio::high_resolution_timer typedefs. * * @note This waitable timer functionality is for use with the C++11 standard * library's @c <chrono> facility, or with the Boost.Chrono library. * * @par Thread Safety * @e Distinct @e objects: Safe.@n * @e Shared @e objects: Unsafe. * * @par Examples * Performing a blocking wait (C++11): * @code * // Construct a timer without setting an expiry time. * boost::asio::steady_timer timer(io_service); * * // Set an expiry time relative to now. * timer.expires_from_now(std::chrono::seconds(5)); * * // Wait for the timer to expire. * timer.wait(); * @endcode * * @par * Performing an asynchronous wait (C++11): * @code * void handler(const boost::system::error_code& error) * { * if (!error) * { * // Timer expired. * } * } * * ... * * // Construct a timer with an absolute expiry time. * boost::asio::steady_timer timer(io_service, * std::chrono::steady_clock::now() + std::chrono::seconds(60)); * * // Start an asynchronous wait. * timer.async_wait(handler); * @endcode * * @par Changing an active waitable timer's expiry time * * Changing the expiry time of a timer while there are pending asynchronous * waits causes those wait operations to be cancelled. To ensure that the action * associated with the timer is performed only once, use something like this: * used: * * @code * void on_some_event() * { * if (my_timer.expires_from_now(seconds(5)) > 0) * { * // We managed to cancel the timer. Start new asynchronous wait. * my_timer.async_wait(on_timeout); * } * else * { * // Too late, timer has already expired! * } * } * * void on_timeout(const boost::system::error_code& e) * { * if (e != boost::asio::error::operation_aborted) * { * // Timer was not cancelled, take necessary action. * } * } * @endcode * * @li The boost::asio::basic_waitable_timer::expires_from_now() function * cancels any pending asynchronous waits, and returns the number of * asynchronous waits that were cancelled. If it returns 0 then you were too * late and the wait handler has already been executed, or will soon be * executed. If it returns 1 then the wait handler was successfully cancelled. * * @li If a wait handler is cancelled, the boost::system::error_code passed to * it contains the value boost::asio::error::operation_aborted. */ template <typename Clock, typename WaitTraits = boost::asio::wait_traits<Clock>, typename WaitableTimerService = waitable_timer_service<Clock, WaitTraits> > class basic_waitable_timer : public basic_io_object<WaitableTimerService> { public: /// The clock type. typedef Clock clock_type; /// The duration type of the clock. typedef typename clock_type::duration duration; /// The time point type of the clock. typedef typename clock_type::time_point time_point; /// The wait traits type. typedef WaitTraits traits_type; /// Constructor. /** * This constructor creates a timer without setting an expiry time. The * expires_at() or expires_from_now() functions must be called to set an * expiry time before the timer can be waited on. * * @param io_service The io_service object that the timer will use to dispatch * handlers for any asynchronous operations performed on the timer. */ explicit basic_waitable_timer(boost::asio::io_service& io_service) : basic_io_object<WaitableTimerService>(io_service) { } /// Constructor to set a particular expiry time as an absolute time. /** * This constructor creates a timer and sets the expiry time. * * @param io_service The io_service object that the timer will use to dispatch * handlers for any asynchronous operations performed on the timer. * * @param expiry_time The expiry time to be used for the timer, expressed * as an absolute time. */ basic_waitable_timer(boost::asio::io_service& io_service, const time_point& expiry_time) : basic_io_object<WaitableTimerService>(io_service) { boost::system::error_code ec; this->service.expires_at(this->implementation, expiry_time, ec); boost::asio::detail::throw_error(ec, "expires_at"); } /// Constructor to set a particular expiry time relative to now. /** * This constructor creates a timer and sets the expiry time. * * @param io_service The io_service object that the timer will use to dispatch * handlers for any asynchronous operations performed on the timer. * * @param expiry_time The expiry time to be used for the timer, relative to * now. */ basic_waitable_timer(boost::asio::io_service& io_service, const duration& expiry_time) : basic_io_object<WaitableTimerService>(io_service) { boost::system::error_code ec; this->service.expires_from_now(this->implementation, expiry_time, ec); boost::asio::detail::throw_error(ec, "expires_from_now"); } /// Cancel any asynchronous operations that are waiting on the timer. /** * This function forces the completion of any pending asynchronous wait * operations against the timer. The handler for each cancelled operation will * be invoked with the boost::asio::error::operation_aborted error code. * * Cancelling the timer does not change the expiry time. * * @return The number of asynchronous operations that were cancelled. * * @throws boost::system::system_error Thrown on failure. * * @note If the timer has already expired when cancel() is called, then the * handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t cancel() { boost::system::error_code ec; std::size_t s = this->service.cancel(this->implementation, ec); boost::asio::detail::throw_error(ec, "cancel"); return s; } /// Cancel any asynchronous operations that are waiting on the timer. /** * This function forces the completion of any pending asynchronous wait * operations against the timer. The handler for each cancelled operation will * be invoked with the boost::asio::error::operation_aborted error code. * * Cancelling the timer does not change the expiry time. * * @param ec Set to indicate what error occurred, if any. * * @return The number of asynchronous operations that were cancelled. * * @note If the timer has already expired when cancel() is called, then the * handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t cancel(boost::system::error_code& ec) { return this->service.cancel(this->implementation, ec); } /// Cancels one asynchronous operation that is waiting on the timer. /** * This function forces the completion of one pending asynchronous wait * operation against the timer. Handlers are cancelled in FIFO order. The * handler for the cancelled operation will be invoked with the * boost::asio::error::operation_aborted error code. * * Cancelling the timer does not change the expiry time. * * @return The number of asynchronous operations that were cancelled. That is, * either 0 or 1. * * @throws boost::system::system_error Thrown on failure. * * @note If the timer has already expired when cancel_one() is called, then * the handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t cancel_one() { boost::system::error_code ec; std::size_t s = this->service.cancel_one(this->implementation, ec); boost::asio::detail::throw_error(ec, "cancel_one"); return s; } /// Cancels one asynchronous operation that is waiting on the timer. /** * This function forces the completion of one pending asynchronous wait * operation against the timer. Handlers are cancelled in FIFO order. The * handler for the cancelled operation will be invoked with the * boost::asio::error::operation_aborted error code. * * Cancelling the timer does not change the expiry time. * * @param ec Set to indicate what error occurred, if any. * * @return The number of asynchronous operations that were cancelled. That is, * either 0 or 1. * * @note If the timer has already expired when cancel_one() is called, then * the handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t cancel_one(boost::system::error_code& ec) { return this->service.cancel_one(this->implementation, ec); } /// Get the timer's expiry time as an absolute time. /** * This function may be used to obtain the timer's current expiry time. * Whether the timer has expired or not does not affect this value. */ time_point expires_at() const { return this->service.expires_at(this->implementation); } /// Set the timer's expiry time as an absolute time. /** * This function sets the expiry time. Any pending asynchronous wait * operations will be cancelled. The handler for each cancelled operation will * be invoked with the boost::asio::error::operation_aborted error code. * * @param expiry_time The expiry time to be used for the timer. * * @return The number of asynchronous operations that were cancelled. * * @throws boost::system::system_error Thrown on failure. * * @note If the timer has already expired when expires_at() is called, then * the handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t expires_at(const time_point& expiry_time) { boost::system::error_code ec; std::size_t s = this->service.expires_at( this->implementation, expiry_time, ec); boost::asio::detail::throw_error(ec, "expires_at"); return s; } /// Set the timer's expiry time as an absolute time. /** * This function sets the expiry time. Any pending asynchronous wait * operations will be cancelled. The handler for each cancelled operation will * be invoked with the boost::asio::error::operation_aborted error code. * * @param expiry_time The expiry time to be used for the timer. * * @param ec Set to indicate what error occurred, if any. * * @return The number of asynchronous operations that were cancelled. * * @note If the timer has already expired when expires_at() is called, then * the handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t expires_at(const time_point& expiry_time, boost::system::error_code& ec) { return this->service.expires_at(this->implementation, expiry_time, ec); } /// Get the timer's expiry time relative to now. /** * This function may be used to obtain the timer's current expiry time. * Whether the timer has expired or not does not affect this value. */ duration expires_from_now() const { return this->service.expires_from_now(this->implementation); } /// Set the timer's expiry time relative to now. /** * This function sets the expiry time. Any pending asynchronous wait * operations will be cancelled. The handler for each cancelled operation will * be invoked with the boost::asio::error::operation_aborted error code. * * @param expiry_time The expiry time to be used for the timer. * * @return The number of asynchronous operations that were cancelled. * * @throws boost::system::system_error Thrown on failure. * * @note If the timer has already expired when expires_from_now() is called, * then the handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t expires_from_now(const duration& expiry_time) { boost::system::error_code ec; std::size_t s = this->service.expires_from_now( this->implementation, expiry_time, ec); boost::asio::detail::throw_error(ec, "expires_from_now"); return s; } /// Set the timer's expiry time relative to now. /** * This function sets the expiry time. Any pending asynchronous wait * operations will be cancelled. The handler for each cancelled operation will * be invoked with the boost::asio::error::operation_aborted error code. * * @param expiry_time The expiry time to be used for the timer. * * @param ec Set to indicate what error occurred, if any. * * @return The number of asynchronous operations that were cancelled. * * @note If the timer has already expired when expires_from_now() is called, * then the handlers for asynchronous wait operations will: * * @li have already been invoked; or * * @li have been queued for invocation in the near future. * * These handlers can no longer be cancelled, and therefore are passed an * error code that indicates the successful completion of the wait operation. */ std::size_t expires_from_now(const duration& expiry_time, boost::system::error_code& ec) { return this->service.expires_from_now( this->implementation, expiry_time, ec); } /// Perform a blocking wait on the timer. /** * This function is used to wait for the timer to expire. This function * blocks and does not return until the timer has expired. * * @throws boost::system::system_error Thrown on failure. */ void wait() { boost::system::error_code ec; this->service.wait(this->implementation, ec); boost::asio::detail::throw_error(ec, "wait"); } /// Perform a blocking wait on the timer. /** * This function is used to wait for the timer to expire. This function * blocks and does not return until the timer has expired. * * @param ec Set to indicate what error occurred, if any. */ void wait(boost::system::error_code& ec) { this->service.wait(this->implementation, ec); } /// Start an asynchronous wait on the timer. /** * This function may be used to initiate an asynchronous wait against the * timer. It always returns immediately. * * For each call to async_wait(), the supplied handler will be called exactly * once. The handler will be called when: * * @li The timer has expired. * * @li The timer was cancelled, in which case the handler is passed the error * code boost::asio::error::operation_aborted. * * @param handler The handler to be called when the timer expires. Copies * will be made of the handler as required. The function signature of the * handler must be: * @code void handler( * const boost::system::error_code& error // Result of operation. * ); @endcode * Regardless of whether the asynchronous operation completes immediately or * not, the handler will not be invoked from within this function. Invocation * of the handler will be performed in a manner equivalent to using * boost::asio::io_service::post(). */ template <typename WaitHandler> BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler, void (boost::system::error_code)) async_wait(BOOST_ASIO_MOVE_ARG(WaitHandler) handler) { // If you get an error on the following line it means that your handler does // not meet the documented type requirements for a WaitHandler. BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check; return this->service.async_wait(this->implementation, BOOST_ASIO_MOVE_CAST(WaitHandler)(handler)); } }; } // namespace asio } // namespace boost #include <boost/asio/detail/pop_options.hpp> #endif // BOOST_ASIO_BASIC_WAITABLE_TIMER_HPP