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//
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// basic_waitable_timer.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2015 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_BASIC_WAITABLE_TIMER_HPP
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#define BOOST_ASIO_BASIC_WAITABLE_TIMER_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 <cstddef>
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#include <boost/asio/basic_io_object.hpp>
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#include <boost/asio/detail/handler_type_requirements.hpp>
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#include <boost/asio/detail/throw_error.hpp>
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#include <boost/asio/error.hpp>
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#include <boost/asio/wait_traits.hpp>
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#include <boost/asio/waitable_timer_service.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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/// Provides waitable timer functionality.
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/**
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 * The basic_waitable_timer class template provides the ability to perform a
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 * blocking or asynchronous wait for a timer to expire.
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 *
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 * A waitable timer is always in one of two states: "expired" or "not expired".
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 * If the wait() or async_wait() function is called on an expired timer, the
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 * wait operation will complete immediately.
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 *
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 * Most applications will use one of the boost::asio::steady_timer,
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 * boost::asio::system_timer or boost::asio::high_resolution_timer typedefs.
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 *
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 * @note This waitable timer functionality is for use with the C++11 standard
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 * library's @c &lt;chrono&gt; facility, or with the Boost.Chrono library.
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 *
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 * @par Thread Safety
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 * @e Distinct @e objects: Safe.@n
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 * @e Shared @e objects: Unsafe.
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 *
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 * @par Examples
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 * Performing a blocking wait (C++11):
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 * @code
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 * // Construct a timer without setting an expiry time.
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 * boost::asio::steady_timer timer(io_service);
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 *
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 * // Set an expiry time relative to now.
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 * timer.expires_from_now(std::chrono::seconds(5));
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 *
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 * // Wait for the timer to expire.
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 * timer.wait();
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 * @endcode
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 *
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 * @par 
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 * Performing an asynchronous wait (C++11):
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 * @code
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 * void handler(const boost::system::error_code& error)
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 * {
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 *   if (!error)
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 *   {
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 *     // Timer expired.
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 *   }
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 * }
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 *
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 * ...
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 *
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 * // Construct a timer with an absolute expiry time.
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 * boost::asio::steady_timer timer(io_service,
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 *     std::chrono::steady_clock::now() + std::chrono::seconds(60));
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 *
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 * // Start an asynchronous wait.
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 * timer.async_wait(handler);
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 * @endcode
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 *
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 * @par Changing an active waitable timer's expiry time
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 *
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 * Changing the expiry time of a timer while there are pending asynchronous
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 * waits causes those wait operations to be cancelled. To ensure that the action
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 * associated with the timer is performed only once, use something like this:
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 * used:
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 *
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 * @code
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 * void on_some_event()
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 * {
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 *   if (my_timer.expires_from_now(seconds(5)) > 0)
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 *   {
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 *     // We managed to cancel the timer. Start new asynchronous wait.
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 *     my_timer.async_wait(on_timeout);
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 *   }
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 *   else
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 *   {
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 *     // Too late, timer has already expired!
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 *   }
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 * }
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 *
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 * void on_timeout(const boost::system::error_code& e)
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 * {
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 *   if (e != boost::asio::error::operation_aborted)
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 *   {
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 *     // Timer was not cancelled, take necessary action.
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 *   }
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 * }
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 * @endcode
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 *
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 * @li The boost::asio::basic_waitable_timer::expires_from_now() function
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 * cancels any pending asynchronous waits, and returns the number of
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 * asynchronous waits that were cancelled. If it returns 0 then you were too
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 * late and the wait handler has already been executed, or will soon be
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 * executed. If it returns 1 then the wait handler was successfully cancelled.
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 *
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 * @li If a wait handler is cancelled, the boost::system::error_code passed to
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 * it contains the value boost::asio::error::operation_aborted.
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 */
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template <typename Clock,
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    typename WaitTraits = boost::asio::wait_traits<Clock>,
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    typename WaitableTimerService = waitable_timer_service<Clock, WaitTraits> >
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class basic_waitable_timer
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  : public basic_io_object<WaitableTimerService>
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{
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public:
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  /// The clock type.
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  typedef Clock clock_type;
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  /// The duration type of the clock.
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  typedef typename clock_type::duration duration;
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  /// The time point type of the clock.
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  typedef typename clock_type::time_point time_point;
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  /// The wait traits type.
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  typedef WaitTraits traits_type;
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  /// Constructor.
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  /**
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   * This constructor creates a timer without setting an expiry time. The
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   * expires_at() or expires_from_now() functions must be called to set an
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   * expiry time before the timer can be waited on.
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   *
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   * @param io_service The io_service object that the timer will use to dispatch
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   * handlers for any asynchronous operations performed on the timer.
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   */
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  explicit basic_waitable_timer(boost::asio::io_service& io_service)
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    : basic_io_object<WaitableTimerService>(io_service)
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  {
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  }
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  /// Constructor to set a particular expiry time as an absolute time.
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  /**
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   * This constructor creates a timer and sets the expiry time.
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   *
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   * @param io_service The io_service object that the timer will use to dispatch
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   * handlers for any asynchronous operations performed on the timer.
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   *
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   * @param expiry_time The expiry time to be used for the timer, expressed
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   * as an absolute time.
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   */
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  basic_waitable_timer(boost::asio::io_service& io_service,
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      const time_point& expiry_time)
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    : basic_io_object<WaitableTimerService>(io_service)
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  {
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    boost::system::error_code ec;
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    this->service.expires_at(this->implementation, expiry_time, ec);
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    boost::asio::detail::throw_error(ec, "expires_at");
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  }
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  /// Constructor to set a particular expiry time relative to now.
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  /**
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   * This constructor creates a timer and sets the expiry time.
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   *
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   * @param io_service The io_service object that the timer will use to dispatch
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   * handlers for any asynchronous operations performed on the timer.
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   *
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   * @param expiry_time The expiry time to be used for the timer, relative to
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   * now.
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   */
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  basic_waitable_timer(boost::asio::io_service& io_service,
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      const duration& expiry_time)
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    : basic_io_object<WaitableTimerService>(io_service)
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  {
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    boost::system::error_code ec;
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    this->service.expires_from_now(this->implementation, expiry_time, ec);
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    boost::asio::detail::throw_error(ec, "expires_from_now");
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  }
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  /// Cancel any asynchronous operations that are waiting on the timer.
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  /**
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   * This function forces the completion of any pending asynchronous wait
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   * operations against the timer. The handler for each cancelled operation will
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   * be invoked with the boost::asio::error::operation_aborted error code.
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   *
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   * Cancelling the timer does not change the expiry time.
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   *
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   * @return The number of asynchronous operations that were cancelled.
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   *
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   * @throws boost::system::system_error Thrown on failure.
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   *
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   * @note If the timer has already expired when cancel() is called, then the
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   * handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t cancel()
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  {
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    boost::system::error_code ec;
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    std::size_t s = this->service.cancel(this->implementation, ec);
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    boost::asio::detail::throw_error(ec, "cancel");
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    return s;
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  }
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  /// Cancel any asynchronous operations that are waiting on the timer.
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  /**
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   * This function forces the completion of any pending asynchronous wait
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   * operations against the timer. The handler for each cancelled operation will
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   * be invoked with the boost::asio::error::operation_aborted error code.
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   *
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   * Cancelling the timer does not change the expiry time.
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   *
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   * @param ec Set to indicate what error occurred, if any.
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   *
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   * @return The number of asynchronous operations that were cancelled.
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   *
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   * @note If the timer has already expired when cancel() is called, then the
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   * handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t cancel(boost::system::error_code& ec)
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  {
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    return this->service.cancel(this->implementation, ec);
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  }
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  /// Cancels one asynchronous operation that is waiting on the timer.
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  /**
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   * This function forces the completion of one pending asynchronous wait
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   * operation against the timer. Handlers are cancelled in FIFO order. The
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   * handler for the cancelled operation will be invoked with the
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   * boost::asio::error::operation_aborted error code.
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   *
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   * Cancelling the timer does not change the expiry time.
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   *
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   * @return The number of asynchronous operations that were cancelled. That is,
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   * either 0 or 1.
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   *
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   * @throws boost::system::system_error Thrown on failure.
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   *
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   * @note If the timer has already expired when cancel_one() is called, then
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   * the handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t cancel_one()
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  {
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    boost::system::error_code ec;
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    std::size_t s = this->service.cancel_one(this->implementation, ec);
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    boost::asio::detail::throw_error(ec, "cancel_one");
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    return s;
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  }
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  /// Cancels one asynchronous operation that is waiting on the timer.
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  /**
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   * This function forces the completion of one pending asynchronous wait
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   * operation against the timer. Handlers are cancelled in FIFO order. The
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   * handler for the cancelled operation will be invoked with the
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   * boost::asio::error::operation_aborted error code.
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   *
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   * Cancelling the timer does not change the expiry time.
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   *
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   * @param ec Set to indicate what error occurred, if any.
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   *
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   * @return The number of asynchronous operations that were cancelled. That is,
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   * either 0 or 1.
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   *
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   * @note If the timer has already expired when cancel_one() is called, then
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   * the handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t cancel_one(boost::system::error_code& ec)
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  {
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    return this->service.cancel_one(this->implementation, ec);
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  }
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  /// Get the timer's expiry time as an absolute time.
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  /**
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   * This function may be used to obtain the timer's current expiry time.
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   * Whether the timer has expired or not does not affect this value.
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   */
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  time_point expires_at() const
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  {
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    return this->service.expires_at(this->implementation);
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  }
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  /// Set the timer's expiry time as an absolute time.
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  /**
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   * This function sets the expiry time. Any pending asynchronous wait
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   * operations will be cancelled. The handler for each cancelled operation will
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   * be invoked with the boost::asio::error::operation_aborted error code.
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   *
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   * @param expiry_time The expiry time to be used for the timer.
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   *
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   * @return The number of asynchronous operations that were cancelled.
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   *
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   * @throws boost::system::system_error Thrown on failure.
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   *
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   * @note If the timer has already expired when expires_at() is called, then
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   * the handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t expires_at(const time_point& expiry_time)
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  {
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    boost::system::error_code ec;
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    std::size_t s = this->service.expires_at(
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        this->implementation, expiry_time, ec);
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    boost::asio::detail::throw_error(ec, "expires_at");
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    return s;
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  }
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  /// Set the timer's expiry time as an absolute time.
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  /**
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   * This function sets the expiry time. Any pending asynchronous wait
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   * operations will be cancelled. The handler for each cancelled operation will
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   * be invoked with the boost::asio::error::operation_aborted error code.
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   *
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   * @param expiry_time The expiry time to be used for the timer.
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   *
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   * @param ec Set to indicate what error occurred, if any.
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   *
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   * @return The number of asynchronous operations that were cancelled.
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   *
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   * @note If the timer has already expired when expires_at() is called, then
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   * the handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t expires_at(const time_point& expiry_time,
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      boost::system::error_code& ec)
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  {
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    return this->service.expires_at(this->implementation, expiry_time, ec);
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  }
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  /// Get the timer's expiry time relative to now.
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  /**
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   * This function may be used to obtain the timer's current expiry time.
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   * Whether the timer has expired or not does not affect this value.
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   */
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  duration expires_from_now() const
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  {
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    return this->service.expires_from_now(this->implementation);
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  }
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  /// Set the timer's expiry time relative to now.
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  /**
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   * This function sets the expiry time. Any pending asynchronous wait
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   * operations will be cancelled. The handler for each cancelled operation will
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   * be invoked with the boost::asio::error::operation_aborted error code.
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   *
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   * @param expiry_time The expiry time to be used for the timer.
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   *
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   * @return The number of asynchronous operations that were cancelled.
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   *
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   * @throws boost::system::system_error Thrown on failure.
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   *
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   * @note If the timer has already expired when expires_from_now() is called,
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   * then the handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t expires_from_now(const duration& expiry_time)
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  {
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    boost::system::error_code ec;
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    std::size_t s = this->service.expires_from_now(
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        this->implementation, expiry_time, ec);
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    boost::asio::detail::throw_error(ec, "expires_from_now");
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    return s;
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  }
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  /// Set the timer's expiry time relative to now.
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  /**
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   * This function sets the expiry time. Any pending asynchronous wait
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   * operations will be cancelled. The handler for each cancelled operation will
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   * be invoked with the boost::asio::error::operation_aborted error code.
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   *
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   * @param expiry_time The expiry time to be used for the timer.
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   *
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   * @param ec Set to indicate what error occurred, if any.
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   *
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   * @return The number of asynchronous operations that were cancelled.
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   *
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   * @note If the timer has already expired when expires_from_now() is called,
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   * then the handlers for asynchronous wait operations will:
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   *
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   * @li have already been invoked; or
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   *
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   * @li have been queued for invocation in the near future.
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   *
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   * These handlers can no longer be cancelled, and therefore are passed an
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   * error code that indicates the successful completion of the wait operation.
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   */
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  std::size_t expires_from_now(const duration& expiry_time,
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      boost::system::error_code& ec)
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  {
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    return this->service.expires_from_now(
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        this->implementation, expiry_time, ec);
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  }
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  /// Perform a blocking wait on the timer.
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  /**
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   * This function is used to wait for the timer to expire. This function
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   * blocks and does not return until the timer has expired.
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   *
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   * @throws boost::system::system_error Thrown on failure.
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   */
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  void wait()
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  {
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    boost::system::error_code ec;
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    this->service.wait(this->implementation, ec);
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    boost::asio::detail::throw_error(ec, "wait");
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  }
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  /// Perform a blocking wait on the timer.
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  /**
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   * This function is used to wait for the timer to expire. This function
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   * blocks and does not return until the timer has expired.
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   *
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   * @param ec Set to indicate what error occurred, if any.
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   */
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  void wait(boost::system::error_code& ec)
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  {
475
    this->service.wait(this->implementation, ec);
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  }
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478
  /// Start an asynchronous wait on the timer.
479
  /**
480
   * This function may be used to initiate an asynchronous wait against the
481
   * timer. It always returns immediately.
482
   *
483
   * For each call to async_wait(), the supplied handler will be called exactly
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   * once. The handler will be called when:
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   *
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   * @li The timer has expired.
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   *
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   * @li The timer was cancelled, in which case the handler is passed the error
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   * code boost::asio::error::operation_aborted.
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   *
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   * @param handler The handler to be called when the timer expires. Copies
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   * will be made of the handler as required. The function signature of the
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   * handler must be:
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   * @code void handler(
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   *   const boost::system::error_code& error // Result of operation.
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   * ); @endcode
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   * Regardless of whether the asynchronous operation completes immediately or
498
   * not, the handler will not be invoked from within this function. Invocation
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   * of the handler will be performed in a manner equivalent to using
500
   * boost::asio::io_service::post().
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   */
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  template <typename WaitHandler>
503
  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
504
      void (boost::system::error_code))
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  async_wait(BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
506
  {
507
    // If you get an error on the following line it means that your handler does
508
    // not meet the documented type requirements for a WaitHandler.
509
    BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
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    return this->service.async_wait(this->implementation,
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        BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
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  }
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};
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} // namespace asio
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} // namespace boost
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#include <boost/asio/detail/pop_options.hpp>
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#endif // BOOST_ASIO_BASIC_WAITABLE_TIMER_HPP