com.espertech.esper.epl.agg.aggregator

Class AggregatorNth

java.lang.Object

com.espertech.esper.epl.agg.aggregator.AggregatorNth

All Implemented Interfaces:

AggregationMethod

Direct Known Subclasses:

AggregatorNthFilter

public class AggregatorNth
extends Object
implements AggregationMethod

Aggregator to return the Nth oldest element to enter, with N=1 the most recent value is returned. If N is larger than the enter minus leave size, null is returned. A maximum N historical values are stored, so it can be safely used to compare recent values in large views without incurring excessive overhead.

Field Summary

Fields

Modifier and Type	Field and Description
protected Object[]	circularBuffer
protected int	currentBufferElementPointer
protected long	numDataPoints
protected int	sizeBuf

Constructor Summary

Constructors

Constructor and Description
AggregatorNth(int sizeBuf) Ctor.

Method Summary

Modifier and Type	Method and Description
void	clear() Clear out the collection.
void	enter(Object value) Apply the value as entering aggregation (entering window).
protected void	enterValues(Object[] arr)
Object[]	getCircularBuffer()
int	getCurrentBufferElementPointer()
long	getNumDataPoints()
int	getSizeBuf()
Object	getValue() Returns the current value held.
void	leave(Object value) Apply the value as leaving aggregation (leaving window).
void	setCircularBuffer(Object[] circularBuffer)
void	setCurrentBufferElementPointer(int currentBufferElementPointer)
void	setNumDataPoints(long numDataPoints)

Methods inherited from class java.lang.Object

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

Field Detail

sizeBuf

protected final int sizeBuf

circularBuffer

protected Object[] circularBuffer

currentBufferElementPointer

protected int currentBufferElementPointer

numDataPoints

protected long numDataPoints

Constructor Detail

AggregatorNth

public AggregatorNth(int sizeBuf)

Ctor.

Parameters:

sizeBuf - size

Method Detail

enter

public void enter(Object value)

Description copied from interface: AggregationMethod

Apply the value as entering aggregation (entering window).

The value can be null since 'null' values may be counted as unique separate values.

Specified by:

enter in interface AggregationMethod

Parameters:

value - to add to aggregate

leave

public void leave(Object value)

Description copied from interface: AggregationMethod

Apply the value as leaving aggregation (leaving window).

The value can be null since 'null' values may be counted as unique separate values.

Specified by:

leave in interface AggregationMethod

Parameters:

value - to remove from aggregate

getValue

public Object getValue()

Description copied from interface: AggregationMethod

Returns the current value held.

Specified by:

getValue in interface AggregationMethod

Returns:

current value

clear

public void clear()

Description copied from interface: AggregationMethod

Clear out the collection.

Specified by:

clear in interface AggregationMethod

enterValues

protected void enterValues(Object[] arr)

getSizeBuf

public int getSizeBuf()

getCircularBuffer

public Object[] getCircularBuffer()

setCircularBuffer

public void setCircularBuffer(Object[] circularBuffer)

getCurrentBufferElementPointer

public int getCurrentBufferElementPointer()

setCurrentBufferElementPointer

public void setCurrentBufferElementPointer(int currentBufferElementPointer)

getNumDataPoints

public long getNumDataPoints()

setNumDataPoints

public void setNumDataPoints(long numDataPoints)