/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* 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.EngineLevelExtensionServicesContext;
import com.espertech.esper.epl.expression.time.ExprTimePeriodEvalDeltaConst;
import com.espertech.esper.epl.expression.time.ExprTimePeriodEvalDeltaResult;
import com.espertech.esper.metrics.instrumentation.InstrumentationHelper;
import com.espertech.esper.schedule.ScheduleHandleCallback;
import com.espertech.esper.util.StopCallback;
import com.espertech.esper.view.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayDeque;
import java.util.Iterator;
/**
* A data view that aggregates events in a stream and releases them in one batch at every specified time interval.
* The view works similar to a time_window but in not continuous.
* The view releases the batched events after the interval as new data to child views. The prior batch if
* not empty is released as old data to child view. The view doesn't release intervals with no old or new data.
* It also does not collect old data published by a parent view.
* <p>
* For example, we want to calculate the average of IBM stock every hour, for the last hour.
* The view accepts 2 parameter combinations.
* (1) A time interval is supplied with a reference point - based on this point the intervals are set.
* (1) A time interval is supplied but no reference point - the reference point is set when the first event arrives.
* <p>
* If there are no events in the current and prior batch, the view will not invoke the update method of child views.
* In that case also, no next callback is scheduled with the scheduling service until the next event arrives.
*/
public class TimeBatchView extends ViewSupport implements CloneableView, StoppableView, StopCallback, DataWindowView {
// View parameters
private final TimeBatchViewFactory timeBatchViewFactory;
protected final AgentInstanceViewFactoryChainContext agentInstanceContext;
protected final ExprTimePeriodEvalDeltaConst timeDeltaComputation;
protected final Long initialReferencePoint;
protected final boolean isForceOutput;
protected final boolean isStartEager;
protected final ViewUpdatedCollection viewUpdatedCollection;
protected final long scheduleSlot;
protected EPStatementHandleCallback handle;
// Current running parameters
protected Long currentReferencePoint;
protected ArrayDeque<EventBean> lastBatch = null;
protected ArrayDeque<EventBean> currentBatch = new ArrayDeque<EventBean>();
protected boolean isCallbackScheduled;
/**
* Constructor.
*
* @param timeDeltaComputation is the number of milliseconds to batch events for
* @param referencePoint is the reference point onto which to base intervals, or null if
* there is no such reference point supplied
* @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
* @param agentInstanceContext context
*/
public TimeBatchView(TimeBatchViewFactory timeBatchViewFactory,
AgentInstanceViewFactoryChainContext agentInstanceContext,
ExprTimePeriodEvalDeltaConst timeDeltaComputation,
Long referencePoint,
boolean forceOutput,
boolean isStartEager,
ViewUpdatedCollection viewUpdatedCollection) {
this.agentInstanceContext = agentInstanceContext;
this.timeBatchViewFactory = timeBatchViewFactory;
this.timeDeltaComputation = timeDeltaComputation;
this.initialReferencePoint = referencePoint;
this.isStartEager = isStartEager;
this.viewUpdatedCollection = viewUpdatedCollection;
this.isForceOutput = forceOutput;
this.scheduleSlot = agentInstanceContext.getStatementContext().getScheduleBucket().allocateSlot();
// schedule the first callback
if (isStartEager) {
if (currentReferencePoint == null) {
currentReferencePoint = agentInstanceContext.getStatementContext().getSchedulingService().getTime();
}
scheduleCallback();
isCallbackScheduled = true;
}
agentInstanceContext.addTerminationCallback(this);
}
public View cloneView() {
return timeBatchViewFactory.makeView(agentInstanceContext);
}
public ExprTimePeriodEvalDeltaConst getTimeDeltaComputation() {
return timeDeltaComputation;
}
/**
* Gets the reference point to use to anchor interval start and end dates to.
*
* @return is the millisecond reference point.
*/
public final Long getInitialReferencePoint() {
return initialReferencePoint;
}
/**
* True for force-output.
*
* @return indicates force-output
*/
public boolean isForceOutput() {
return isForceOutput;
}
/**
* 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 (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().qViewProcessIRStream(this, timeBatchViewFactory.getViewName(), newData, oldData);
}
// we don't care about removed data from a prior view
if ((newData == null) || (newData.length == 0)) {
if (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().aViewProcessIRStream();
}
return;
}
// If we have an empty window about to be filled for the first time, schedule a callback
if (currentBatch.isEmpty()) {
if (currentReferencePoint == null) {
currentReferencePoint = initialReferencePoint;
if (currentReferencePoint == null) {
currentReferencePoint = agentInstanceContext.getStatementContext().getSchedulingService().getTime();
}
}
// Schedule the next callback if there is none currently scheduled
if (!isCallbackScheduled) {
scheduleCallback();
isCallbackScheduled = true;
}
}
// add data points to the timeWindow
for (EventBean newEvent : newData) {
currentBatch.add(newEvent);
}
// We do not update child views, since we batch the events.
if (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().aViewProcessIRStream();
}
}
/**
* This method updates child views and clears the batch of events.
* We schedule a new callback at this time if there were events in the batch.
*/
protected void sendBatch() {
isCallbackScheduled = false;
// 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) {
if (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().qViewIndicate(this, timeBatchViewFactory.getViewName(), newData, oldData);
}
updateChildren(newData, oldData);
if (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().aViewIndicate();
}
}
}
// Only if forceOutput is enabled or
// 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();
isCallbackScheduled = true;
}
lastBatch = currentBatch;
currentBatch = new ArrayDeque<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() +
" initialReferencePoint=" + initialReferencePoint;
}
public void visitView(ViewDataVisitor viewDataVisitor) {
viewDataVisitor.visitPrimary(currentBatch, true, timeBatchViewFactory.getViewName(), null);
viewDataVisitor.visitPrimary(lastBatch, true, timeBatchViewFactory.getViewName(), null);
}
protected void scheduleCallback() {
long current = agentInstanceContext.getStatementContext().getSchedulingService().getTime();
ExprTimePeriodEvalDeltaResult deltaWReference = timeDeltaComputation.deltaAddWReference(current, currentReferencePoint);
long afterTime = deltaWReference.getDelta();
currentReferencePoint = deltaWReference.getLastReference();
ScheduleHandleCallback callback = new ScheduleHandleCallback() {
public void scheduledTrigger(EngineLevelExtensionServicesContext extensionServicesContext) {
if (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().qViewScheduledEval(TimeBatchView.this, timeBatchViewFactory.getViewName());
}
TimeBatchView.this.sendBatch();
if (InstrumentationHelper.ENABLED) {
InstrumentationHelper.get().aViewScheduledEval();
}
}
};
handle = new EPStatementHandleCallback(agentInstanceContext.getEpStatementAgentInstanceHandle(), callback);
agentInstanceContext.getStatementContext().getSchedulingService().add(afterTime, handle, scheduleSlot);
}
public void stopView() {
stopSchedule();
agentInstanceContext.removeTerminationCallback(this);
}
public void stop() {
stopSchedule();
}
public void stopSchedule() {
if (handle != null) {
agentInstanceContext.getStatementContext().getSchedulingService().remove(handle, scheduleSlot);
}
}
public ViewFactory getViewFactory() {
return timeBatchViewFactory;
}
private static final Logger log = LoggerFactory.getLogger(TimeBatchView.class);
}