IntervalTimer.java

package org.rzo.netty.ahessian.timeout;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import org.jboss.netty.util.Timeout;
import org.jboss.netty.util.Timer;
import org.jboss.netty.util.TimerTask;

public class IntervalTimer
{
	private final Timer _timer;
	private final TimerTask _task;
	private volatile Timeout _timeout;
	private final long _interval;
	private volatile String _name = "?";
	private final Lock _lock = new ReentrantLock();
	
	public IntervalTimer(final Timer timer, final TimerTask task, final long interval)
	{
		_timer = timer;
		_task = new TimerTask()
		{

			public void run(Timeout timeout) throws Exception
			{
				_lock.lock();
				try
				{
				if (!timeout.equals(getTimeout()))
				{
					//System.out.println("other timeout -> ignore");
					return;
				}
				//System.out.println(new Date()+" timer called " + _name+"/"+_interval);
				try
				{
				task.run(timeout);
				}
				catch (Throwable ex)
				{
					ex.printStackTrace();
				}
				if (getTimeout() != null)
					setTimeout(_timer.newTimeout(this, interval, TimeUnit.MILLISECONDS));
				}
				finally
				{
					_lock.unlock();
				}
	
			}
			
		};
		_interval = interval;
	}
	
	synchronized public void start()
	{
		_lock.lock();
		try
		{
		if (_timeout != null)
			return;
		//System.out.println("starting timer "+_name);
		setTimeout(_timer.newTimeout(_task, _interval, TimeUnit.MILLISECONDS));
		}
		catch (Exception ex)
		{
			ex.printStackTrace();
		}
		finally
		{
			_lock.unlock();
		}
	}
	
	synchronized public void stop()
	{
		_lock.lock();
		try
		{
		if (getTimeout() == null)
			return;
		//System.out.println("stopping timer "+_name);
		getTimeout().cancel();
		setTimeout(null);
		}
		catch (Exception ex)
		{
			ex.printStackTrace();
		}
		finally
		{
			_lock.unlock();
		}
	}
	
	synchronized public boolean isActive()
	{
		return _timeout != null;
	}
	
	public long getInterval()
	{
		return _interval;
	}

	public void setName(String name)
	{
		_name = name;
	}
	
	private Timeout getTimeout()
	{
		return _timeout;
	}
	
	private void setTimeout(Timeout timeout)
	{
		_timeout = timeout;
	}

}