Package org.apache.hadoop.fs.impl

Class WeakRefMetricsSource

java.lang.Object

org.apache.hadoop.fs.impl.WeakRefMetricsSource

All Implemented Interfaces:

MetricsSource

@Private
public class WeakRefMetricsSource
extends java.lang.Object
implements MetricsSource

A weak referenced metrics source which avoids hanging on to large objects if somehow they don't get fully closed/cleaned up. The JVM may clean up all objects which are only weakly referenced whenever it does a GC, even if there is no memory pressure. To avoid these refs being removed, always keep a strong reference around somewhere.

Constructor Summary

Constructors

Constructor	Description
WeakRefMetricsSource(java.lang.String name, MetricsSource source)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	getMetrics(MetricsCollector collector, boolean all)	If the weak reference is non null, update the metrics.
java.lang.String	getName()	Name to know when unregistering.
MetricsSource	getSource()	Get the source, will be null if the reference has been GC'd
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

WeakRefMetricsSource

public WeakRefMetricsSource(java.lang.String name,
                            MetricsSource source)

Constructor.

Parameters:

name - Name to know when unregistering.

source - metrics source

Method Detail

getMetrics

public void getMetrics(MetricsCollector collector,
                       boolean all)

If the weak reference is non null, update the metrics.

Specified by:

getMetrics in interface MetricsSource

Parameters:

collector - to contain the resulting metrics snapshot

all - if true, return all metrics even if unchanged.

getName

public java.lang.String getName()

Name to know when unregistering.

Returns:

the name passed in during construction.

getSource

public MetricsSource getSource()

Get the source, will be null if the reference has been GC'd

Returns:

the source reference

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object