org.apache.slider.server.appmaster.web.rest.application.resources

Class CachedContent<T>

java.lang.Object

org.apache.slider.server.appmaster.web.rest.application.resources.CachedContent<T>

Type Parameters:

T - type to return

public class CachedContent<T>
extends Object

A cached resource is one that can be stored and served up, with a refresh only taking place when the expiry happens. The refresh check/refresh is synchronized.

Constructor Summary

Constructors

Constructor and Description
CachedContent(long lifespan, ResourceRefresher<T> refresh)

Method Summary

Methods

Modifier and Type	Method and Description
protected T	forceRefresh() Force a refresh and reset the expiry counter
T	get() Get the value, triggering a refresh if needed
T	getCachedValue() Get the cached value without any expiry check
long	getLifespan() Get the lifespan in millis of the cached value
int	getRefreshCounter()
boolean	maybeRefresh() Maybe refresh the content
protected long	now()
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

CachedContent

public CachedContent(long lifespan,
             ResourceRefresher<T> refresh)

Method Detail

get

public T get()
      throws Exception

Get the value, triggering a refresh if needed

Returns:

the cached or latest value.

Throws:

Exception

getCachedValue

public T getCachedValue()

Get the cached value without any expiry check

Returns:

the last value set. May be null.

getRefreshCounter

public int getRefreshCounter()

getLifespan

public long getLifespan()

Get the lifespan in millis of the cached value

Returns:

the lifespan

maybeRefresh

public boolean maybeRefresh()
                     throws Exception

Maybe refresh the content

Returns:

true if a refresh took place.

Throws:

Exception

now

protected long now()

forceRefresh

protected T forceRefresh()
                  throws Exception

Force a refresh and reset the expiry counter

Returns:

the new value

Throws:

Exception

toString

public String toString()

Overrides:

toString in class Object