org.apache.hadoop.hbase.util

Class LossyCounting<T>

java.lang.Object

org.apache.hadoop.hbase.util.LossyCounting<T>

@InterfaceAudience.Private
public class LossyCounting<T>
extends Object

LossyCounting utility, bounded data structure that maintains approximate high frequency elements in data stream. Bucket size is 1 / error rate. (Error rate is 0.02 by default) Lemma If element
does not appear in set, then is frequency is less than e * N (N is total element counts until now.) Based on paper: http://www.vldb.org/conf/2002/S10P03.pdf

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	LossyCounting.LossyCountingListener<T>

Constructor Summary

Constructors

Constructor and Description
LossyCounting(String name, org.apache.hadoop.conf.Configuration conf, LossyCounting.LossyCountingListener<T> listener)
LossyCounting(String name, double errorRate, LossyCounting.LossyCountingListener<T> listener)

Method Summary

Modifier and Type	Method and Description
void	add(T key)
boolean	contains(T key)
long	getBucketSize()
long	getCurrentTerm()
long	getDataSize()
Set<T>	getElements()
Future<?>	getSweepFuture()
void	sweep() sweep low frequency data

Methods inherited from class java.lang.Object

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

Constructor Detail

LossyCounting

public LossyCounting(String name,
                     double errorRate,
                     LossyCounting.LossyCountingListener<T> listener)

LossyCounting

public LossyCounting(String name,
                     org.apache.hadoop.conf.Configuration conf,
                     LossyCounting.LossyCountingListener<T> listener)

Method Detail

add

public void add(T key)

sweep

public void sweep()

sweep low frequency data

getBucketSize

public long getBucketSize()

getDataSize

public long getDataSize()

contains

public boolean contains(T key)

getElements

public Set<T> getElements()

getCurrentTerm

public long getCurrentTerm()

getSweepFuture

public Future<?> getSweepFuture()