/**************************************************************************************
* 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.core.service.EPStatementHandleCallback;
import com.espertech.esper.core.service.ExtensionServicesContext;
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.ArrayList;
import java.util.Iterator;
/**
* A data view that aggregates events in a stream and releases them in one batch if either one of these
* conditions is reached, whichever comes first: One, a time interval passes. Two, a given number of events collected.
* <p>
* The view releases the batched events after the interval or number of events as new data to child views. The prior batch if
* not empty is released as old data to child view. The view DOES release intervals with no old or new data.
* It does not collect old data published by a parent view.
* If there are no events in the current and prior batch, the view WILL invoke the update method of child views.
* <p>
* The view starts the first interval when the view is created.
*/
public class TimeLengthBatchView extends ViewSupport implements CloneableView, StoppableView, StopCallback, DataWindowView {
private static final Log log = LogFactory.getLog(TimeLengthBatchView.class);
// View parameters
private final TimeLengthBatchViewFactory timeLengthBatchViewFactory;
protected final AgentInstanceViewFactoryChainContext agentInstanceContext;
protected final long msecIntervalSize;
protected final long numberOfEvents;
protected final boolean isForceOutput;
protected final boolean isStartEager;
protected final ViewUpdatedCollection viewUpdatedCollection;
protected final ScheduleSlot scheduleSlot;
// Current running parameters
protected ArrayList<EventBean> lastBatch = null;
protected ArrayList<EventBean> currentBatch = new ArrayList<EventBean>();
protected Long callbackScheduledTime;
protected EPStatementHandleCallback handle;
/**
* Constructor.
* @param msecIntervalSize is the number of milliseconds to batch events for
* @param numberOfEvents is the event count before the batch fires off
* @param viewUpdatedCollection is a collection that the view must update when receiving events
* @param timeBatchViewFactory for copying this view in a group-by
* @param forceOutput is true if the batch should produce empty output if there is no value to output following time intervals
* @param isStartEager is true for start-eager
*/
public TimeLengthBatchView(TimeLengthBatchViewFactory timeBatchViewFactory,
AgentInstanceViewFactoryChainContext agentInstanceContext,
long msecIntervalSize,
long numberOfEvents,
boolean forceOutput,
boolean isStartEager,
ViewUpdatedCollection viewUpdatedCollection)
{
this.agentInstanceContext = agentInstanceContext;
this.timeLengthBatchViewFactory = timeBatchViewFactory;
this.msecIntervalSize = msecIntervalSize;
this.numberOfEvents = numberOfEvents;
this.isStartEager = isStartEager;
this.viewUpdatedCollection = viewUpdatedCollection;
this.isForceOutput = forceOutput;
this.scheduleSlot = agentInstanceContext.getStatementContext().getScheduleBucket().allocateSlot();
// schedule the first callback
if (isStartEager)
{
scheduleCallback(0);
}
agentInstanceContext.addTerminationCallback(this);
}
public View cloneView()
{
return timeLengthBatchViewFactory.makeView(agentInstanceContext);
}
/**
* Returns the interval size in milliseconds.
* @return batch size
*/
public final long getMsecIntervalSize()
{
return msecIntervalSize;
}
/**
* True for force-output.
* @return indicates force-output
*/
public boolean isForceOutput()
{
return isForceOutput;
}
/**
* Returns the length of the batch.
* @return maximum number of events allowed before window gets flushed
*/
public long getNumberOfEvents()
{
return numberOfEvents;
}
/**
* True for start-eager.
* @return indicates start-eager
*/
public boolean isStartEager()
{
return isStartEager;
}
public final EventType getEventType()
{
return parent.getEventType();
}
public void update(EventBean[] newData, EventBean[] oldData)
{
if (oldData != null)
{
for (int i = 0; i < oldData.length; i++)
{
if (currentBatch.remove(oldData[i])) {
internalHandleRemoved(oldData[i]);
}
}
}
// we don't care about removed data from a prior view
if ((newData == null) || (newData.length == 0))
{
return;
}
// Add data points
for (EventBean newEvent : newData) {
currentBatch.add(newEvent);
internalHandleAdded(newEvent);
}
// We are done unless we went over the boundary
if (currentBatch.size() < numberOfEvents)
{
// Schedule a callback if there is none scheduled
if (callbackScheduledTime == null)
{
scheduleCallback(0);
}
return;
}
// send a batch of events
sendBatch(false);
}
public void internalHandleAdded(EventBean newEvent) {
// no action required
}
public void internalHandleRemoved(EventBean eventBean) {
// no action required
}
/**
* This method updates child views and clears the batch of events.
* We cancel and old callback and schedule a new callback at this time if there were events in the batch.
* @param isFromSchedule true if invoked from a schedule, false if not
*/
protected void sendBatch(boolean isFromSchedule)
{
// No more callbacks scheduled if called from a schedule
if (isFromSchedule)
{
callbackScheduledTime = null;
}
else
{
// Remove schedule if called from on overflow due to number of events
if (callbackScheduledTime != null)
{
agentInstanceContext.getStatementContext().getSchedulingService().remove(handle, scheduleSlot);
callbackScheduledTime = null;
}
}
// If there are child views and the batch was filled, fireStatementStopped update method
if (this.hasViews())
{
// Convert to object arrays
EventBean[] newData = null;
EventBean[] oldData = null;
if (!currentBatch.isEmpty())
{
newData = currentBatch.toArray(new EventBean[currentBatch.size()]);
}
if ((lastBatch != null) && (!lastBatch.isEmpty()))
{
oldData = lastBatch.toArray(new EventBean[lastBatch.size()]);
}
// Post new data (current batch) and old data (prior batch)
if (viewUpdatedCollection != null)
{
viewUpdatedCollection.update(newData, oldData);
}
if ((newData != null) || (oldData != null) || (isForceOutput))
{
updateChildren(newData, oldData);
}
}
// Only if there have been any events in this or the last interval do we schedule a callback,
// such as to not waste resources when no events arrive.
if (((!currentBatch.isEmpty()) || ((lastBatch != null) && (!lastBatch.isEmpty())))
||
(isForceOutput))
{
scheduleCallback(0);
}
// Flush and roll
lastBatch = currentBatch;
currentBatch = new ArrayList<EventBean>();
}
/**
* Returns true if the window is empty, or false if not empty.
* @return true if empty
*/
public boolean isEmpty()
{
if (lastBatch != null)
{
if (!lastBatch.isEmpty())
{
return false;
}
}
return currentBatch.isEmpty();
}
public final Iterator<EventBean> iterator()
{
return currentBatch.iterator();
}
public final String toString()
{
return this.getClass().getName() +
" msecIntervalSize=" + msecIntervalSize +
" numberOfEvents=" + numberOfEvents;
}
protected void scheduleCallback(long delta)
{
ScheduleHandleCallback callback = new ScheduleHandleCallback() {
public void scheduledTrigger(ExtensionServicesContext extensionServicesContext)
{
TimeLengthBatchView.this.sendBatch(true);
}
};
handle = new EPStatementHandleCallback(agentInstanceContext.getEpStatementAgentInstanceHandle(), callback);
agentInstanceContext.getStatementContext().getSchedulingService().add(msecIntervalSize - delta, handle, scheduleSlot);
callbackScheduledTime = agentInstanceContext.getStatementContext().getSchedulingService().getTime() - delta;
}
public void stopView() {
stopSchedule();
agentInstanceContext.removeTerminationCallback(this);
}
public void stop() {
stopSchedule();
}
public void stopSchedule() {
if (handle != null) {
agentInstanceContext.getStatementContext().getSchedulingService().remove(handle, scheduleSlot);
}
}
}