source: XMLIO_V2/external/src/POCO/Foundation.save/Poco/Timer.h @ 80

//
// Timer.h
//
// $Id: //poco/1.3/Foundation/include/Poco/Timer.h#6 $
//
// Library: Foundation
// Package: Threading
// Module:  Timer
//
// Definition of the Timer and related classes.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_Timer_INCLUDED
#define Foundation_Timer_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Runnable.h"
#include "Poco/Mutex.h"
#include "Poco/Event.h"
#include "Poco/Thread.h"
#include "Poco/Timestamp.h"


namespace Poco {


class AbstractTimerCallback;
class ThreadPool;


class Foundation_API Timer: protected Runnable
        /// This class implements a thread-based timer.
        /// A timer starts a thread that first waits for a given start interval.
        /// Once that interval expires, the timer callback is called repeatedly
        /// in the given periodic interval. If the interval is 0, the timer is only
        /// called once.
        /// The timer callback method can stop the timer by setting the 
        /// timer's periodic interval to 0.
        ///
        /// The timer callback runs in its own thread, so multithreading
        /// issues (proper synchronization) have to be considered when writing 
        /// the callback method.
        ///
        /// The exact interval at which the callback is called depends on many 
        /// factors like operating system, CPU performance and system load and
        /// may differ from the specified interval.
        ///
        /// The time needed to execute the timer callback is not included
        /// in the interval between invocations. For example, if the interval
        /// is 500 milliseconds, and the callback needs 400 milliseconds to
        /// execute, the callback function is nevertheless called every 500
        /// milliseconds. If the callback takes longer to execute than the
        /// interval, the callback function will be immediately called again
        /// once it returns.
        ///
        /// The timer thread is taken from a thread pool, so
        /// there is a limit to the number of available concurrent timers.
{
public:
        Timer(long startInterval = 0, long periodicInterval = 0);
                /// Creates a new timer object. StartInterval and periodicInterval
                /// are given in milliseconds. If a periodicInterval of zero is 
                /// specified, the callback will only be called once, after the
                /// startInterval expires.
                /// To start the timer, call the Start() method.

        virtual ~Timer();
                /// Stops and destroys the timer.

        void start(const AbstractTimerCallback& method);
                /// Starts the timer.
                /// Create the TimerCallback as follows:
                ///     TimerCallback<MyClass> callback(*this, &MyClass::onTimer);
                ///     timer.start(callback);
                ///
                /// The timer thread is taken from the global default thread pool.

        void start(const AbstractTimerCallback& method, Thread::Priority priority);
                /// Starts the timer in a thread with the given priority.
                /// Create the TimerCallback as follows:
                ///     TimerCallback<MyClass> callback(*this, &MyClass::onTimer);
                ///     timer.start(callback);
                ///
                /// The timer thread is taken from the global default thread pool.

        void start(const AbstractTimerCallback& method, ThreadPool& threadPool);
                /// Starts the timer.
                /// Create the TimerCallback as follows:
                ///     TimerCallback<MyClass> callback(*this, &MyClass::onTimer);
                ///     timer.start(callback);

        void start(const AbstractTimerCallback& method, Thread::Priority priority, ThreadPool& threadPool);
                /// Starts the timer in a thread with the given priority.
                /// Create the TimerCallback as follows:
                ///     TimerCallback<MyClass> callback(*this, &MyClass::onTimer);
                ///     timer.start(callback);
                
        void stop();
                /// Stops the timer. If the callback method is currently running
                /// it will be allowed to finish first.
                /// WARNING: Never call this method from within the callback method,
                /// as a deadlock would result. To stop the timer from within the
                /// callback method, call restart(0).

        void restart();
                /// Restarts the periodic interval. If the callback method is already running,
                /// nothing will happen.

        void restart(long milliseconds);
                /// Sets a new periodic interval and restarts the timer.
                /// An interval of 0 will stop the timer.

        long getStartInterval() const;
                /// Returns the start interval.

        void setStartInterval(long milliseconds);
                /// Sets the start interval. Will only be 
                /// effective before start() is called.

        long getPeriodicInterval() const;
                /// Returns the periodic interval.

        void setPeriodicInterval(long milliseconds);
                /// Sets the periodic interval. If the timer is already running
                /// the new interval will be effective when the current interval
                /// expires.

protected:
        void run();

private:
        volatile long _startInterval;
        volatile long _periodicInterval;
        Event         _wakeUp;
        Event         _done;
        AbstractTimerCallback* _pCallback;
        Timestamp              _nextInvocation;
        mutable FastMutex      _mutex;
        
        Timer(const Timer&);
        Timer& operator = (const Timer&);
};


class Foundation_API AbstractTimerCallback
        /// This is the base class for all instantiations of
        /// the TimerCallback template.
{
public:
        AbstractTimerCallback();
        AbstractTimerCallback(const AbstractTimerCallback& callback);
        virtual ~AbstractTimerCallback();
        
        AbstractTimerCallback& operator = (const AbstractTimerCallback& callback);

        virtual void invoke(Timer& timer) const = 0;
        virtual AbstractTimerCallback* clone() const = 0;
};


template <class C> 
class TimerCallback: public AbstractTimerCallback
        /// This template class implements an adapter that sits between
        /// a Timer and an object's method invoked by the timer.
        /// It is quite similar in concept to the RunnableAdapter, but provides 
        /// some Timer specific additional methods.
        /// See the Timer class for information on how
        /// to use this template class.
{
public:
        typedef void (C::*Callback)(Timer&);

        TimerCallback(C& object, Callback method): _pObject(&object), _method(method)
        {
        }

        TimerCallback(const TimerCallback& callback): _pObject(callback._pObject), _method(callback._method)
        {
        }

        ~TimerCallback()
        {
        }

        TimerCallback& operator = (const TimerCallback& callback)
        {
                if (&callback != this)
                {
                        _pObject = callback._pObject;
                        _method  = callback._method;
                }
                return *this;
        }

        void invoke(Timer& timer) const
        {
                (_pObject->*_method)(timer);
        }

        AbstractTimerCallback* clone() const
        {
                return new TimerCallback(*this);
        }

private:
        TimerCallback();

        C*       _pObject;
        Callback _method;
};


} // namespace Poco


#endif // Foundation_Timer_INCLUDED