org.onemind.commons.java.datastructure
Class LookupCache

java.lang.Object
  org.onemind.commons.java.datastructure.LookupCache

Direct Known Subclasses:

ClassLookupCache

public abstract class LookupCache

extends java.lang.Object

A lookup cache implements simple lookup caching algorithm for looking up things. The derived class simply implement the produce(Object key) method which is assumed an expensive operation and the results will be cached by the lookup cache implementation. There's no public method on lookup cache, the developer should provide application specific lookup interface.

Version:

$Id: LookupCache.java,v 1.4 2004/09/30 13:26:26 thlee Exp $ $Name: $

Author:

TiongHiang Lee (thlee@onemindsoft.org)

Constructor Summary

LookupCache()
{@inheritDoc}

LookupCache(boolean doNegCache)
{@inheritDoc}

Method Summary

protected void	clearNegCache() Clear all the negative cache
protected boolean	isInCache(java.lang.Object o) Test if the key is in cache
protected boolean	isInNegCache(java.lang.Object o) Get whether the object is in negative cache
protected java.lang.Object	lookup(java.lang.Object key) The main lookup method.
protected abstract java.lang.Object	produce(java.lang.Object key) Produce the object given the key.
protected void	setDoNegativeCache(boolean b) Turn on/off the negative cache

Methods inherited from class java.lang.Object

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

Constructor Detail

LookupCache

public LookupCache()

{@inheritDoc}

LookupCache

public LookupCache(boolean doNegCache)

{@inheritDoc}

Parameters:

doNegCache - whether to do negative caching

Method Detail

lookup

protected final java.lang.Object lookup(java.lang.Object key)

The main lookup method. The developer should provide another application specific method that call this method to return what the application wants

Parameters:

key - the key

Returns:

the object or null

produce

protected abstract java.lang.Object produce(java.lang.Object key)

Produce the object given the key. This is assumed to be an expensive operation and it will be called by the lookup method. The result will be cached by the lookup method and negative result also will be cached to if the doNegCache is turned on.

Parameters:

key - the key

Returns:

the result or null if no result

setDoNegativeCache

protected void setDoNegativeCache(boolean b)

Turn on/off the negative cache

Parameters:

b - true to turn on the neg cache

isInNegCache

protected boolean isInNegCache(java.lang.Object o)

Get whether the object is in negative cache

Parameters:

o - the object

Returns:

true if is in negative cache

isInCache

protected boolean isInCache(java.lang.Object o)

Test if the key is in cache

Parameters:

o - the object

Returns:

true if is in cache

clearNegCache

protected void clearNegCache()

Clear all the negative cache