com.espertech.esper.view.window

Class TimeBatchView

java.lang.Object

com.espertech.esper.view.ViewSupport

com.espertech.esper.view.window.TimeBatchView

All Implemented Interfaces:

StopCallback, CloneableView, DataWindowView, EventCollection, GroupableView, StoppableView, View, Viewable, ViewDataVisitable, Iterable<EventBean>

public class TimeBatchView
extends ViewSupport
implements CloneableView, StoppableView, StopCallback, DataWindowView

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.

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.

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.

Field Summary

Fields

Modifier and Type	Field and Description
protected AgentInstanceViewFactoryChainContext	agentInstanceContext
protected ArrayDeque<EventBean>	currentBatch
protected Long	currentReferencePoint
protected EPStatementHandleCallback	handle
protected Long	initialReferencePoint
protected boolean	isCallbackScheduled
protected boolean	isForceOutput
protected boolean	isStartEager
protected ArrayDeque<EventBean>	lastBatch
protected long	scheduleSlot
protected ExprTimePeriodEvalDeltaConst	timeDeltaComputation
protected ViewUpdatedCollection	viewUpdatedCollection

Fields inherited from class com.espertech.esper.view.ViewSupport

EMPTY_VIEW_ARRAY, parent

Constructor Summary

Constructors

Constructor and Description
TimeBatchView(TimeBatchViewFactory timeBatchViewFactory, AgentInstanceViewFactoryChainContext agentInstanceContext, ExprTimePeriodEvalDeltaConst timeDeltaComputation, Long referencePoint, boolean forceOutput, boolean isStartEager, ViewUpdatedCollection viewUpdatedCollection) Constructor.

Method Summary

Modifier and Type	Method and Description
View	cloneView() Duplicates the view.
EventType	getEventType() Provides metadata information about the type of object the event collection contains.
Long	getInitialReferencePoint() Gets the reference point to use to anchor interval start and end dates to.
ExprTimePeriodEvalDeltaConst	getTimeDeltaComputation()
ViewFactory	getViewFactory()
boolean	isEmpty() Returns true if the window is empty, or false if not empty.
boolean	isForceOutput() True for force-output.
boolean	isStartEager() True for start-eager.
Iterator<EventBean>	iterator() Allows iteration through all elements in this event collection.
protected void	scheduleCallback()
protected void	sendBatch() This method updates child views and clears the batch of events.
void	stop() Stops the underlying resources.
void	stopSchedule()
void	stopView()
String	toString()
void	update(EventBean[] newData, EventBean[] oldData) Notify that data has been added or removed from the Viewable parent.
void	visitView(ViewDataVisitor viewDataVisitor)

Methods inherited from class com.espertech.esper.view.ViewSupport

addView, addView, dumpChildViews, dumpUpdateParams, dumpUpdateParams, findDescendent, findViewIndex, getParent, getViews, hasViews, removeAllViews, removeView, removeView, setParent, updateChildren, updateChildren

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.espertech.esper.view.View

getParent, setParent

Methods inherited from interface com.espertech.esper.view.Viewable

addView, getViews, hasViews, removeAllViews, removeView

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

agentInstanceContext

protected final AgentInstanceViewFactoryChainContext agentInstanceContext

timeDeltaComputation

protected final ExprTimePeriodEvalDeltaConst timeDeltaComputation

initialReferencePoint

protected final Long initialReferencePoint

isForceOutput

protected final boolean isForceOutput

isStartEager

protected final boolean isStartEager

viewUpdatedCollection

protected final ViewUpdatedCollection viewUpdatedCollection

scheduleSlot

protected final long scheduleSlot

handle

protected EPStatementHandleCallback handle

currentReferencePoint

protected Long currentReferencePoint

lastBatch

protected ArrayDeque<EventBean> lastBatch

currentBatch

protected ArrayDeque<EventBean> currentBatch

isCallbackScheduled

protected boolean isCallbackScheduled

Constructor Detail

TimeBatchView

public TimeBatchView(TimeBatchViewFactory timeBatchViewFactory,
                     AgentInstanceViewFactoryChainContext agentInstanceContext,
                     ExprTimePeriodEvalDeltaConst timeDeltaComputation,
                     Long referencePoint,
                     boolean forceOutput,
                     boolean isStartEager,
                     ViewUpdatedCollection viewUpdatedCollection)

Constructor.

Parameters:

timeDeltaComputation - is the number of milliseconds to batch events for

referencePoint - is the reference point onto which to base intervals, or null if there is no such reference point supplied

viewUpdatedCollection - is a collection that the view must update when receiving events

timeBatchViewFactory - for copying this view in a group-by

forceOutput - is true if the batch should produce empty output if there is no value to output following time intervals

isStartEager - is true for start-eager

agentInstanceContext - context

Method Detail

cloneView

public View cloneView()

Description copied from interface: CloneableView

Duplicates the view.

Expected to return a same view in initialized state for grouping.

Specified by:

cloneView in interface CloneableView

Returns:

cloned view

getTimeDeltaComputation

public ExprTimePeriodEvalDeltaConst getTimeDeltaComputation()

getInitialReferencePoint

public final Long getInitialReferencePoint()

Gets the reference point to use to anchor interval start and end dates to.

Returns:

is the millisecond reference point.

isForceOutput

public boolean isForceOutput()

True for force-output.

Returns:

indicates force-output

isStartEager

public boolean isStartEager()

True for start-eager.

Returns:

indicates start-eager

getEventType

public final EventType getEventType()

Description copied from interface: EventCollection

Provides metadata information about the type of object the event collection contains.

Specified by:

getEventType in interface EventCollection

Returns:

metadata for the objects in the collection

update

public void update(EventBean[] newData,
                   EventBean[] oldData)

Description copied from interface: View

Notify that data has been added or removed from the Viewable parent. The last object in the newData array of objects would be the newest object added to the parent view. The first object of the oldData array of objects would be the oldest object removed from the parent view.

If the call to update contains new (inserted) data, then the first argument will be a non-empty list and the second will be empty. Similarly, if the call is a notification of deleted data, then the first argument will be empty and the second will be non-empty. Either the newData or oldData will be non-null. This method won't be called with both arguments being null, but either one could be null. The same is true for zero-length arrays. Either newData or oldData will be non-empty. If both are non-empty, then the update is a modification notification.

When update() is called on a view by the parent object, the data in newData will be in the collection of the parent, and its data structures will be arranged to reflect that. The data in oldData will not be in the parent's data structures, and any access to the parent will indicate that that data is no longer there.

Specified by:

update in interface View

Parameters:

newData - is the new data that has been added to the parent view

oldData - is the old data that has been removed from the parent view

sendBatch

protected void sendBatch()

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.

isEmpty

public boolean isEmpty()

Returns true if the window is empty, or false if not empty.

Returns:

true if empty

iterator

public final Iterator<EventBean> iterator()

Description copied from interface: EventCollection

Allows iteration through all elements in this event collection. The iterator will return the elements in the collection in their natural order, or, if there is no natural ordering, in some unpredictable order.

Specified by:

iterator in interface EventCollection

Specified by:

iterator in interface Iterable<EventBean>

Returns:

an iterator which will go through all current elements in the collection.

toString

public final String toString()

Overrides:

toString in class Object

visitView

public void visitView(ViewDataVisitor viewDataVisitor)

Specified by:

visitView in interface ViewDataVisitable

scheduleCallback

protected void scheduleCallback()

stopView

public void stopView()

stop

public void stop()

Description copied from interface: StopCallback

Stops the underlying resources.

Specified by:

stop in interface StopCallback

stopSchedule

public void stopSchedule()

getViewFactory

public ViewFactory getViewFactory()

Specified by:

getViewFactory in interface GroupableView