/**************************************************************************************
* Copyright (C) 2008 EsperTech, Inc. All rights reserved. *
* http://esper.codehaus.org *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
**************************************************************************************/
package com.espertech.esper.view.window;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.collection.ViewUpdatedCollection;
import com.espertech.esper.core.context.util.AgentInstanceViewFactoryChainContext;
import com.espertech.esper.view.CloneableView;
import com.espertech.esper.view.DataWindowView;
import com.espertech.esper.view.View;
import com.espertech.esper.view.ViewSupport;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Iterator;
/**
* This view is a moving window extending the specified number of elements into the past.
*/
public class LengthWindowView extends ViewSupport implements DataWindowView, CloneableView
{
protected final AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext;
private final LengthWindowViewFactory lengthWindowViewFactory;
private final int size;
private final ViewUpdatedCollection viewUpdatedCollection;
protected final ArrayDeque<EventBean> events = new ArrayDeque<EventBean>();
/**
* Constructor creates a moving window extending the specified number of elements into the past.
* @param size is the specified number of elements into the past
* @param viewUpdatedCollection is a collection that the view must update when receiving events
* @param lengthWindowViewFactory for copying this view in a group-by
*/
public LengthWindowView(AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext, LengthWindowViewFactory lengthWindowViewFactory, int size, ViewUpdatedCollection viewUpdatedCollection)
{
if (size < 1)
{
throw new IllegalArgumentException("Illegal argument for size of length window");
}
this.agentInstanceViewFactoryContext = agentInstanceViewFactoryContext;
this.lengthWindowViewFactory = lengthWindowViewFactory;
this.size = size;
this.viewUpdatedCollection = viewUpdatedCollection;
}
public View cloneView()
{
return lengthWindowViewFactory.makeView(agentInstanceViewFactoryContext);
}
/**
* Returns true if the window is empty, or false if not empty.
* @return true if empty
*/
public boolean isEmpty()
{
return events.isEmpty();
}
/**
* Returns the size of the length window.
* @return size of length window
*/
public final int getSize()
{
return size;
}
/**
* Returns the (optional) collection handling random access to window contents for prior or previous events.
* @return buffer for events
*/
public ViewUpdatedCollection getViewUpdatedCollection()
{
return viewUpdatedCollection;
}
public final EventType getEventType()
{
// The event type is the parent view's event type
return parent.getEventType();
}
public final void update(EventBean[] newData, EventBean[] oldData)
{
// add data points to the window
// we don't care about removed data from a prior view
if (newData != null)
{
for (EventBean event : newData) {
events.add(event);
}
}
// Check for any events that get pushed out of the window
int expiredCount = events.size() - size;
EventBean[] expiredArr = null;
if (expiredCount > 0)
{
expiredArr = new EventBean[expiredCount];
for (int i = 0; i < expiredCount; i++)
{
expiredArr[i] = events.removeFirst();
}
}
// update event buffer for access by expressions, if any
if (viewUpdatedCollection != null)
{
viewUpdatedCollection.update(newData, expiredArr);
}
// If there are child views, call update method
if (this.hasViews())
{
updateChildren(newData, expiredArr);
}
}
public final Iterator<EventBean> iterator()
{
return events.iterator();
}
public final String toString()
{
return this.getClass().getName() + " size=" + size;
}
}