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// Copyright (C) 2011-2020 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef ASIOLINK_INTERVAL_TIMER_H
#define ASIOLINK_INTERVAL_TIMER_H 1
#include <boost/shared_ptr.hpp>
#include <functional>
#include <asiolink/io_service.h>
namespace isc {
namespace asiolink {
class IntervalTimerImpl;
/// \brief The \c IntervalTimer class is a wrapper for the ASIO
/// \c boost::asio::deadline_timer class.
///
/// This class is implemented to use \c boost::asio::deadline_timer as interval
/// timer.
///
/// \c setup() sets a timer to expire on (now + interval), a call back
/// function, and an interval mode.
///
/// \c IntervalTimerImpl::callback() is called by the timer when it expires.
///
/// The function calls the call back function set by \c setup() and if the
/// the interval mode indicates a repeating interval, will reschedule the
/// timer to expire in (now + interval) milliseconds.
///
/// The type of call back function is \c void(void).
///
/// The call back function will not be called if the instance of this class is
/// destroyed before the timer is expired.
///
/// Sample code:
/// \code
/// void function_to_call_back() {
/// // this function will be called periodically
/// }
/// int interval_in_milliseconds = 1000;
/// IOService io_service;
///
/// IntervalTimer intervalTimer(io_service);
/// intervalTimer.setup(function_to_call_back, interval_in_milliseconds);
/// io_service.run();
/// \endcode
class IntervalTimer {
public:
/// \name The type of timer callback function
typedef std::function<void()> Callback;
/// \brief Defines possible timer modes used to setup a timer.
/// - REPEATING - Timer will reschedule itself after each expiration
/// - ONE_SHOT - Timer will expire after one interval and not reschedule.
enum Mode
{
REPEATING,
ONE_SHOT
};
///
/// \name Constructors and Destructor
///
/// Note: The copy constructor and the assignment operator are
/// intentionally defined as private, making this class non-copyable.
//@{
private:
IntervalTimer(const IntervalTimer& source);
IntervalTimer& operator=(const IntervalTimer& source);
public:
/// \brief The constructor with \c IOService.
///
/// This constructor may throw a standard exception if
/// memory allocation fails inside the method.
/// This constructor may also throw \c boost::system::system_error.
///
/// \param io_service A smart pointer to an instance of IOService
IntervalTimer(const IOServicePtr& io_service);
/// \brief The destructor.
///
/// This destructor never throws an exception.
///
/// On the destruction of this class the timer will be canceled
/// inside \c boost::asio::deadline_timer.
~IntervalTimer();
//@}
/// \brief Register timer callback function and interval.
///
/// This function sets callback function and interval in milliseconds.
/// Timer will actually start after calling \c IOService::run().
///
/// \param cbfunc A reference to a function \c void(void) to call back
/// when the timer is expired (should not be an empty functor)
/// \param interval Interval in milliseconds (greater than 0)
/// \param mode Determines if the timer will automatically reschedule after
/// each expiration (the default) or behave as a one-shot which will run
/// for a single interval and not reschedule.
///
/// Note: IntervalTimer will not pass \c boost::system::error_code to
/// call back function. In case the timer is canceled, the function
/// will not be called.
///
/// \throw isc::InvalidParameter cbfunc is empty
/// \throw isc::BadValue interval is less than or equal to 0
/// \throw isc::Unexpected internal runtime error
void setup(const Callback& cbfunc, const long interval,
const Mode& mode = REPEATING);
/// Cancel the timer.
///
/// If the timer has been set up, this method cancels any asynchronous
/// events waiting on the timer and stops the timer itself.
/// If the timer has already been canceled, this method effectively does
/// nothing.
///
/// This method never throws an exception.
void cancel();
/// Return the timer interval.
///
/// This method returns the timer interval in milliseconds if it's running;
/// if the timer has been canceled it returns 0.
///
/// This method never throws an exception.
long getInterval() const;
private:
boost::shared_ptr<IntervalTimerImpl> impl_;
};
typedef boost::shared_ptr<isc::asiolink::IntervalTimer> IntervalTimerPtr;
} // namespace asiolink
} // namespace isc
#endif // ASIOLINK_INTERVAL_TIMER_H
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