org.apache.hadoop.chukwa.datacollection

Class OffsetStatsManager<T>

java.lang.Object

org.apache.hadoop.chukwa.datacollection.OffsetStatsManager<T>

public class OffsetStatsManager<T>
extends Object

Manages stats for multiple objects of type T. T can be any class that is used as a key for offset statistics (i.e. Agent, Collector, etc.). A client would create an instance of this class and call addOffsetDataPoint repeatedly over time. Then calcAverageRate can be called to retrieve the average offset-unit per second over a given time interval.

For a given object T that is actively adding data points, stats are kept for up to 20 minutes.

Care should be taken to always call remove() when old T objects should no longer be tracked.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	OffsetStatsManager.OffsetData

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.log4j.Logger	log

Constructor Summary

Constructors

Constructor and Description
OffsetStatsManager()
OffsetStatsManager(long statsDataTTL)

Method Summary

Methods

Modifier and Type	Method and Description
void	addOffsetDataPoint(T key, long offset, long timestamp) Record that at a given point in time an object key had a given offset.
double	calcAverageRate(T key, long timeIntervalSecs)
void	clear() Remove all objectst that we're tracking stats for.
OffsetStatsManager.OffsetData	mostRecentDataPoint(T key)
OffsetStatsManager.OffsetData	oldestDataPoint(T key)
void	remove(T key) Remove key from the set of objects that we're tracking stats for.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected org.apache.log4j.Logger log

Constructor Detail

OffsetStatsManager

public OffsetStatsManager()

OffsetStatsManager

public OffsetStatsManager(long statsDataTTL)

Method Detail

addOffsetDataPoint

public void addOffsetDataPoint(T key,
                      long offset,
                      long timestamp)

Record that at a given point in time an object key had a given offset.

Parameters:

key - Object to key this data point to

offset - How much of an offset to record

timestamp - The time the offset occured

calcAverageRate

public double calcAverageRate(T key,
                     long timeIntervalSecs)

oldestDataPoint

public OffsetStatsManager.OffsetData oldestDataPoint(T key)

mostRecentDataPoint

public OffsetStatsManager.OffsetData mostRecentDataPoint(T key)

remove

public void remove(T key)

Remove key from the set of objects that we're tracking stats for.

Parameters:

key - key of stats to be removed

clear

public void clear()

Remove all objectst that we're tracking stats for.