/**************************************************************************************
* 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.TimeWindow;
import com.espertech.esper.collection.ViewUpdatedCollection;
import com.espertech.esper.core.context.util.AgentInstanceViewFactoryChainContext;
import com.espertech.esper.core.service.EPStatementHandleCallback;
import com.espertech.esper.core.service.ExtensionServicesContext;
import com.espertech.esper.schedule.ScheduleAdjustmentCallback;
import com.espertech.esper.schedule.ScheduleHandleCallback;
import com.espertech.esper.schedule.ScheduleSlot;
import com.espertech.esper.util.StopCallback;
import com.espertech.esper.view.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.util.ArrayDeque;
import java.util.Iterator;
/**
* This view is a moving timeWindow extending the specified amount of milliseconds into the past.
* The view bases the timeWindow on the time obtained from the scheduling service.
* All incoming events receive a timestamp and are placed in a sorted map by timestamp.
* The view does not care about old data published by the parent view to this view.
*
* Events leave or expire from the time timeWindow by means of a scheduled callback registered with the
* scheduling service. Thus child views receive updates containing old data only asynchronously
* as the system-time-based timeWindow moves on. However child views receive updates containing new data
* as soon as the new data arrives.
*/
public class TimeWindowView extends ViewSupport implements CloneableView, DataWindowView, ScheduleAdjustmentCallback, StoppableView, StopCallback
{
private final TimeWindowViewFactory timeWindowViewFactory;
private final long millisecondsBeforeExpiry;
protected final TimeWindow timeWindow;
private final ViewUpdatedCollection viewUpdatedCollection;
protected final AgentInstanceViewFactoryChainContext agentInstanceContext;
private final ScheduleSlot scheduleSlot;
private final EPStatementHandleCallback handle;
/**
* Constructor.
* @param millisecondsBeforeExpiry is the number of milliseconds before events gets pushed
* out of the timeWindow as oldData in the update method.
* @param viewUpdatedCollection is a collection the view must update when receiving events
* @param timeWindowViewFactory for copying the view in a group-by
*/
public TimeWindowView(AgentInstanceViewFactoryChainContext agentInstanceContext, TimeWindowViewFactory timeWindowViewFactory, long millisecondsBeforeExpiry, ViewUpdatedCollection viewUpdatedCollection)
{
this.agentInstanceContext = agentInstanceContext;
this.timeWindowViewFactory = timeWindowViewFactory;
this.millisecondsBeforeExpiry = millisecondsBeforeExpiry;
this.viewUpdatedCollection = viewUpdatedCollection;
this.scheduleSlot = agentInstanceContext.getStatementContext().getScheduleBucket().allocateSlot();
this.timeWindow = new TimeWindow(agentInstanceContext.isRemoveStream());
ScheduleHandleCallback callback = new ScheduleHandleCallback() {
public void scheduledTrigger(ExtensionServicesContext extensionServicesContext)
{
TimeWindowView.this.expire();
}
};
this.handle = new EPStatementHandleCallback(agentInstanceContext.getEpStatementAgentInstanceHandle(), callback);
agentInstanceContext.getStatementContext().getScheduleAdjustmentService().addCallback(this);
agentInstanceContext.addTerminationCallback(this);
}
public void adjust(long delta)
{
timeWindow.adjust(delta);
}
public View cloneView()
{
return timeWindowViewFactory.makeView(agentInstanceContext);
}
/**
* Returns the size of the time window in millisecond.
* @return size of window
*/
public final long getMillisecondsBeforeExpiry()
{
return millisecondsBeforeExpiry;
}
/**
* 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()
{
return parent.getEventType();
}
public final void update(EventBean[] newData, EventBean[] oldData)
{
long timestamp = agentInstanceContext.getStatementContext().getSchedulingService().getTime();
if (oldData != null)
{
for (int i = 0; i < oldData.length; i++)
{
timeWindow.remove(oldData[i]);
}
}
// we don't care about removed data from a prior view
if ((newData != null) && (newData.length > 0))
{
// If we have an empty window about to be filled for the first time, schedule a callback
// for now plus millisecondsBeforeExpiry
if (timeWindow.isEmpty())
{
scheduleCallback(millisecondsBeforeExpiry);
}
// add data points to the timeWindow
for (int i = 0; i < newData.length; i++)
{
timeWindow.add(timestamp, newData[i]);
}
if (viewUpdatedCollection != null)
{
viewUpdatedCollection.update(newData, null);
}
}
// update child views
if (this.hasViews())
{
updateChildren(newData, oldData);
}
}
/**
* This method removes (expires) objects from the window and schedules a new callback for the
* time when the next oldest message would expire from the window.
*/
protected final void expire()
{
long expireBeforeTimestamp = agentInstanceContext.getStatementContext().getSchedulingService().getTime() - millisecondsBeforeExpiry + 1;
// Remove from the timeWindow any events that have an older or timestamp then the given timestamp
// The window extends from X to (X - millisecondsBeforeExpiry + 1)
ArrayDeque<EventBean> expired = timeWindow.expireEvents(expireBeforeTimestamp);
// If there are child views, fireStatementStopped update method
if (this.hasViews())
{
if ((expired != null) && (!expired.isEmpty()))
{
EventBean[] oldEvents = expired.toArray(new EventBean[expired.size()]);
if (viewUpdatedCollection != null)
{
viewUpdatedCollection.update(null, oldEvents);
}
updateChildren(null, oldEvents);
}
}
scheduleExpiryCallback();
}
protected void scheduleExpiryCallback() {
// If we still have events in the window, schedule new callback
if (timeWindow.isEmpty())
{
return;
}
Long oldestTimestamp = timeWindow.getOldestTimestamp();
long currentTimestamp = agentInstanceContext.getStatementContext().getSchedulingService().getTime();
long scheduleMillisec = millisecondsBeforeExpiry - (currentTimestamp - oldestTimestamp);
scheduleCallback(scheduleMillisec);
}
private void scheduleCallback(long msecAfterCurrentTime)
{
agentInstanceContext.getStatementContext().getSchedulingService().add(msecAfterCurrentTime, handle, scheduleSlot);
}
public final Iterator<EventBean> iterator()
{
return timeWindow.iterator();
}
public final String toString()
{
return this.getClass().getName() +
" millisecondsBeforeExpiry=" + millisecondsBeforeExpiry;
}
/**
* Returns true if the window is empty, or false if not empty.
* @return true if empty
*/
public boolean isEmpty()
{
return timeWindow.isEmpty();
}
public void stopView() {
stopSchedule();
agentInstanceContext.removeTerminationCallback(this);
}
public void stop() {
stopSchedule();
}
public void stopSchedule() {
if (handle != null) {
agentInstanceContext.getStatementContext().getSchedulingService().remove(handle, scheduleSlot);
}
agentInstanceContext.getStatementContext().getScheduleAdjustmentService().removeCallback(this);
}
private static final Log log = LogFactory.getLog(TimeWindowView.class);
}