org.apache.samza.metrics

Class ListGauge<T>

java.lang.Object

org.apache.samza.metrics.ListGauge<T>

All Implemented Interfaces:

Metric

public class ListGauge<T>
extends java.lang.Object
implements Metric

A ListGauge is a Metric that buffers multiple instances of a type T in a list. ListGauges are useful for maintaining, recording, or collecting values over time. For example, a set of specific logging-events (e.g., errors). Eviction is controlled by parameters (maxNumberOfItems and maxStaleness), which are set during instantiation. Eviction happens during element addition or during reads of the ListGauge (getValues). All public methods are thread-safe.

Constructor Summary

Constructors

Constructor and Description
ListGauge(java.lang.String name) Create a new ListGauge that auto evicts upto a max of 100 items and a max-staleness of 60 minutes.
ListGauge(java.lang.String name, int maxNumberOfItems, java.time.Duration maxStaleness) Create a new ListGauge that auto evicts based on the given maxNumberOfItems, maxStaleness, and period parameters.

Method Summary

Modifier and Type	Method and Description
void	add(T value) Add a value to the list.
java.lang.String	getName() Get the name assigned to this ListGauge
java.util.Collection<T>	getValues() Get the Collection of values currently in the list.
void	visit(MetricsVisitor visitor)

Methods inherited from class java.lang.Object

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

Constructor Detail

ListGauge

public ListGauge(java.lang.String name,
                 int maxNumberOfItems,
                 java.time.Duration maxStaleness)

Create a new ListGauge that auto evicts based on the given maxNumberOfItems, maxStaleness, and period parameters.

Parameters:

name - Name to be assigned

maxNumberOfItems - The max number of items that can remain in the listgauge

maxStaleness - The max staleness of items permitted in the listgauge

ListGauge

public ListGauge(java.lang.String name)

Create a new ListGauge that auto evicts upto a max of 100 items and a max-staleness of 60 minutes.

Parameters:

name - Name to be assigned

Method Detail

getName

public java.lang.String getName()

Get the name assigned to this ListGauge

Returns:

the assigned name

getValues

public java.util.Collection<T> getValues()

Get the Collection of values currently in the list.

Returns:

the collection of values

add

public void add(T value)

Add a value to the list. (Timestamp assigned to this value is the current timestamp.)

Parameters:

value - The Gauge value to be added

visit

public void visit(MetricsVisitor visitor)

Specified by:

visit in interface Metric