com.atlassian.instrumentation

Class CachedExternalValue

java.lang.Object

com.atlassian.instrumentation.CachedExternalValue

All Implemented Interfaces:

ExternalValue

public abstract class CachedExternalValue
extends Object
implements ExternalValue

This class allows values to be computed on as as needed basis and also cache the values for a certain length of time.

For example imagine a value that is the number of users in a system. This may be expensive to compute (lots of database calls maybe) but its still fairly accurate if its only done every 1-5 minutes say.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CachedExternalValue() By default 1 minute is the cache time out value
protected	CachedExternalValue(long cacheTimeout, TimeUnit cacheTimeoutUnits) Creates a CachedExternalValue where the cache time is the values specified.

Method Summary

Modifier and Type	Method and Description
protected abstract long	computeValue() This method is called to compute the value of the ExternalValue
long	getValue()

Methods inherited from class java.lang.Object

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

Constructor Detail

CachedExternalValue

protected CachedExternalValue()

By default 1 minute is the cache time out value

CachedExternalValue

protected CachedExternalValue(long cacheTimeout,
                              TimeUnit cacheTimeoutUnits)

Creates a CachedExternalValue where the cache time is the values specified.

Parameters:

cacheTimeout - the cache time out value

cacheTimeoutUnits - the units of the cache time our value

Method Detail

computeValue

protected abstract long computeValue()

This method is called to compute the value of the ExternalValue

This will be done because the cached value has expired and has since been requested via a call to getValue()

Returns:

the computed value

getValue

public long getValue()

Specified by:

getValue in interface ExternalValue

Returns:

the current value of the external object