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- //
- // basic_deadline_timer.hpp
- // ~~~~~~~~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2019 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 ASIO_BASIC_DEADLINE_TIMER_HPP
- #define ASIO_BASIC_DEADLINE_TIMER_HPP
-
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
- #include "asio/detail/config.hpp"
-
- #if defined(ASIO_HAS_BOOST_DATE_TIME) \
- || defined(GENERATING_DOCUMENTATION)
-
- #include <cstddef>
- #include "asio/detail/deadline_timer_service.hpp"
- #include "asio/detail/handler_type_requirements.hpp"
- #include "asio/detail/io_object_impl.hpp"
- #include "asio/detail/non_const_lvalue.hpp"
- #include "asio/detail/throw_error.hpp"
- #include "asio/error.hpp"
- #include "asio/execution_context.hpp"
- #include "asio/executor.hpp"
- #include "asio/time_traits.hpp"
-
- #include "asio/detail/push_options.hpp"
-
- namespace asio {
-
- /// Provides waitable timer functionality.
- /**
- * The basic_deadline_timer class template provides the ability to perform a
- * blocking or asynchronous wait for a timer to expire.
- *
- * A deadline 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 the asio::deadline_timer typedef.
- *
- * @par Thread Safety
- * @e Distinct @e objects: Safe.@n
- * @e Shared @e objects: Unsafe.
- *
- * @par Examples
- * Performing a blocking wait:
- * @code
- * // Construct a timer without setting an expiry time.
- * asio::deadline_timer timer(my_context);
- *
- * // Set an expiry time relative to now.
- * timer.expires_from_now(boost::posix_time::seconds(5));
- *
- * // Wait for the timer to expire.
- * timer.wait();
- * @endcode
- *
- * @par
- * Performing an asynchronous wait:
- * @code
- * void handler(const asio::error_code& error)
- * {
- * if (!error)
- * {
- * // Timer expired.
- * }
- * }
- *
- * ...
- *
- * // Construct a timer with an absolute expiry time.
- * asio::deadline_timer timer(my_context,
- * boost::posix_time::time_from_string("2005-12-07 23:59:59.000"));
- *
- * // Start an asynchronous wait.
- * timer.async_wait(handler);
- * @endcode
- *
- * @par Changing an active deadline_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 asio::error_code& e)
- * {
- * if (e != asio::error::operation_aborted)
- * {
- * // Timer was not cancelled, take necessary action.
- * }
- * }
- * @endcode
- *
- * @li The asio::basic_deadline_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 asio::error_code passed to
- * it contains the value asio::error::operation_aborted.
- */
- template <typename Time,
- typename TimeTraits = asio::time_traits<Time>,
- typename Executor = executor>
- class basic_deadline_timer
- {
- public:
- /// The type of the executor associated with the object.
- typedef Executor executor_type;
-
- /// The time traits type.
- typedef TimeTraits traits_type;
-
- /// The time type.
- typedef typename traits_type::time_type time_type;
-
- /// The duration type.
- typedef typename traits_type::duration_type duration_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 ex The I/O executor that the timer will use, by default, to
- * dispatch handlers for any asynchronous operations performed on the timer.
- */
- explicit basic_deadline_timer(const executor_type& ex)
- : impl_(ex)
- {
- }
-
- /// 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 context An execution context which provides the I/O executor that
- * the timer will use, by default, to dispatch handlers for any asynchronous
- * operations performed on the timer.
- */
- template <typename ExecutionContext>
- explicit basic_deadline_timer(ExecutionContext& context,
- typename enable_if<
- is_convertible<ExecutionContext&, execution_context&>::value
- >::type* = 0)
- : impl_(context)
- {
- }
-
- /// Constructor to set a particular expiry time as an absolute time.
- /**
- * This constructor creates a timer and sets the expiry time.
- *
- * @param ex The I/O executor that the timer will use, by default, 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_deadline_timer(const executor_type& ex, const time_type& expiry_time)
- : impl_(ex)
- {
- asio::error_code ec;
- impl_.get_service().expires_at(impl_.get_implementation(), expiry_time, ec);
- asio::detail::throw_error(ec, "expires_at");
- }
-
- /// Constructor to set a particular expiry time as an absolute time.
- /**
- * This constructor creates a timer and sets the expiry time.
- *
- * @param context An execution context which provides the I/O executor that
- * the timer will use, by default, 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.
- */
- template <typename ExecutionContext>
- basic_deadline_timer(ExecutionContext& context, const time_type& expiry_time,
- typename enable_if<
- is_convertible<ExecutionContext&, execution_context&>::value
- >::type* = 0)
- : impl_(context)
- {
- asio::error_code ec;
- impl_.get_service().expires_at(impl_.get_implementation(), expiry_time, ec);
- 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 ex The I/O executor that the timer will use, by default, 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_deadline_timer(const executor_type& ex,
- const duration_type& expiry_time)
- : impl_(ex)
- {
- asio::error_code ec;
- impl_.get_service().expires_from_now(
- impl_.get_implementation(), expiry_time, ec);
- asio::detail::throw_error(ec, "expires_from_now");
- }
-
- /// Constructor to set a particular expiry time relative to now.
- /**
- * This constructor creates a timer and sets the expiry time.
- *
- * @param context An execution context which provides the I/O executor that
- * the timer will use, by default, 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.
- */
- template <typename ExecutionContext>
- basic_deadline_timer(ExecutionContext& context,
- const duration_type& expiry_time,
- typename enable_if<
- is_convertible<ExecutionContext&, execution_context&>::value
- >::type* = 0)
- : impl_(context)
- {
- asio::error_code ec;
- impl_.get_service().expires_from_now(
- impl_.get_implementation(), expiry_time, ec);
- asio::detail::throw_error(ec, "expires_from_now");
- }
-
- #if defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
- /// Move-construct a basic_deadline_timer from another.
- /**
- * This constructor moves a timer from one object to another.
- *
- * @param other The other basic_deadline_timer object from which the move will
- * occur.
- *
- * @note Following the move, the moved-from object is in the same state as if
- * constructed using the @c basic_deadline_timer(const executor_type&)
- * constructor.
- */
- basic_deadline_timer(basic_deadline_timer&& other)
- : impl_(std::move(other.impl_))
- {
- }
-
- /// Move-assign a basic_deadline_timer from another.
- /**
- * This assignment operator moves a timer from one object to another. Cancels
- * any outstanding asynchronous operations associated with the target object.
- *
- * @param other The other basic_deadline_timer object from which the move will
- * occur.
- *
- * @note Following the move, the moved-from object is in the same state as if
- * constructed using the @c basic_deadline_timer(const executor_type&)
- * constructor.
- */
- basic_deadline_timer& operator=(basic_deadline_timer&& other)
- {
- impl_ = std::move(other.impl_);
- return *this;
- }
- #endif // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
-
- /// Destroys the timer.
- /**
- * This function destroys the timer, cancelling any outstanding asynchronous
- * wait operations associated with the timer as if by calling @c cancel.
- */
- ~basic_deadline_timer()
- {
- }
-
- /// Get the executor associated with the object.
- executor_type get_executor() ASIO_NOEXCEPT
- {
- return impl_.get_executor();
- }
-
- /// 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 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 asio::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()
- {
- asio::error_code ec;
- std::size_t s = impl_.get_service().cancel(impl_.get_implementation(), ec);
- 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 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(asio::error_code& ec)
- {
- return impl_.get_service().cancel(impl_.get_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
- * 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 asio::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()
- {
- asio::error_code ec;
- std::size_t s = impl_.get_service().cancel_one(
- impl_.get_implementation(), ec);
- 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
- * 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(asio::error_code& ec)
- {
- return impl_.get_service().cancel_one(impl_.get_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_type expires_at() const
- {
- return impl_.get_service().expires_at(impl_.get_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 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 asio::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_type& expiry_time)
- {
- asio::error_code ec;
- std::size_t s = impl_.get_service().expires_at(
- impl_.get_implementation(), expiry_time, ec);
- 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 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_type& expiry_time,
- asio::error_code& ec)
- {
- return impl_.get_service().expires_at(
- impl_.get_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_type expires_from_now() const
- {
- return impl_.get_service().expires_from_now(impl_.get_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 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 asio::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_type& expiry_time)
- {
- asio::error_code ec;
- std::size_t s = impl_.get_service().expires_from_now(
- impl_.get_implementation(), expiry_time, ec);
- 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 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_type& expiry_time,
- asio::error_code& ec)
- {
- return impl_.get_service().expires_from_now(
- impl_.get_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 asio::system_error Thrown on failure.
- */
- void wait()
- {
- asio::error_code ec;
- impl_.get_service().wait(impl_.get_implementation(), ec);
- 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(asio::error_code& ec)
- {
- impl_.get_service().wait(impl_.get_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 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 asio::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. On
- * immediate completion, invocation of the handler will be performed in a
- * manner equivalent to using asio::post().
- */
- template <typename WaitHandler>
- ASIO_INITFN_RESULT_TYPE(WaitHandler,
- void (asio::error_code))
- async_wait(ASIO_MOVE_ARG(WaitHandler) handler)
- {
- return async_initiate<WaitHandler, void (asio::error_code)>(
- initiate_async_wait(), handler, this);
- }
-
- private:
- // Disallow copying and assignment.
- basic_deadline_timer(const basic_deadline_timer&) ASIO_DELETED;
- basic_deadline_timer& operator=(
- const basic_deadline_timer&) ASIO_DELETED;
-
- struct initiate_async_wait
- {
- template <typename WaitHandler>
- void operator()(ASIO_MOVE_ARG(WaitHandler) handler,
- basic_deadline_timer* self) const
- {
- // If you get an error on the following line it means that your handler
- // does not meet the documented type requirements for a WaitHandler.
- ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
-
- detail::non_const_lvalue<WaitHandler> handler2(handler);
- self->impl_.get_service().async_wait(
- self->impl_.get_implementation(), handler2.value,
- self->impl_.get_implementation_executor());
- }
- };
-
- detail::io_object_impl<
- detail::deadline_timer_service<TimeTraits>, Executor> impl_;
- };
-
- } // namespace asio
-
- #include "asio/detail/pop_options.hpp"
-
- #endif // defined(ASIO_HAS_BOOST_DATE_TIME)
- // || defined(GENERATING_DOCUMENTATION)
-
- #endif // ASIO_BASIC_DEADLINE_TIMER_HPP
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