Package com.codahale.metrics

Class CachedGauge<T>

java.lang.Object

com.codahale.metrics.CachedGauge<T>

Type Parameters:

T - the type of the gauge's value

All Implemented Interfaces:

Gauge<T>, Metric

public abstract class CachedGauge<T>
extends Object
implements Gauge<T>

A Gauge implementation which caches its value for a period of time.

Field Summary

Fields

Modifier and Type	Field	Description
private final Clock	clock
private final AtomicLong	reloadAt
private final long	timeoutNS
private T	value

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	CachedGauge(long timeout, TimeUnit timeoutUnit)	Creates a new cached gauge with the given timeout period.
protected	CachedGauge(Clock clock, long timeout, TimeUnit timeoutUnit)	Creates a new cached gauge with the given clock and timeout period.

Method Summary

Modifier and Type	Method	Description
T	getValue()	Returns the metric's current value.
protected abstract T	loadValue()	Loads the value and returns it.
private boolean	shouldLoad()

Methods inherited from class java.lang.Object

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

Field Details

clock

private final Clock clock

reloadAt

private final AtomicLong reloadAt

timeoutNS

private final long timeoutNS

value

private volatile T value

Constructor Details

CachedGauge

protected CachedGauge(long timeout,
 TimeUnit timeoutUnit)

Creates a new cached gauge with the given timeout period.

Parameters:

timeout - the timeout

timeoutUnit - the unit of timeout

CachedGauge

protected CachedGauge(Clock clock,
 long timeout,
 TimeUnit timeoutUnit)

Creates a new cached gauge with the given clock and timeout period.

Parameters:

clock - the clock used to calculate the timeout

timeout - the timeout

timeoutUnit - the unit of timeout

Method Details

loadValue

protected abstract T loadValue()

Loads the value and returns it.

Returns:

the new value

getValue

public T getValue()

Description copied from interface: Gauge

Returns the metric's current value.

Specified by:

getValue in interface Gauge<T>

Returns:

the metric's current value

shouldLoad

private boolean shouldLoad()