net.ontopia.utils
Class CachedIndex<K,E>

java.lang.Object
  net.ontopia.utils.CachedIndex<K,E>

All Implemented Interfaces:

LookupIndexIF<K,E>

public class CachedIndex<K,E>
extends Object
implements LookupIndexIF<K,E>

INTERNAL: A LookupIndexIF which uses another, slower, LookupIndexIF as a fallback and caches the values attached to the most commonly requested keys using an LRU strategy. There is a maximum number of keys that can be stored in the index and the index will automatically prune the less-used keys to avoid the index growing above this maximum size.

Nested Class Summary

class

CachedIndex.Entry<A,B>

Constructor Summary

CachedIndex(LookupIndexIF<K,E> fallback)
Creates an index with the given fallback and default settings.

CachedIndex(LookupIndexIF<K,E> fallback, boolean nulls)
Creates an index with the given fallback, default settings and the specified nulls setting.

CachedIndex(LookupIndexIF<K,E> fallback, int max, int size, boolean nulls)
Creates an index with the given fallback and settings.

Method Summary

E	get(K key)
int	getKeyNumber()
protected void	prune() Removes some of the keys in the cache, keeping only the most frequently requested keys.
E	put(K key, E value)
E	remove(K key)
void	writeReport()

Methods inherited from class java.lang.Object

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

Constructor Detail

CachedIndex

public CachedIndex(LookupIndexIF<K,E> fallback)

Creates an index with the given fallback and default settings.

CachedIndex

public CachedIndex(LookupIndexIF<K,E> fallback,
                   boolean nulls)

Creates an index with the given fallback, default settings and the specified nulls setting.

CachedIndex

public CachedIndex(LookupIndexIF<K,E> fallback,
                   int max,
                   int size,
                   boolean nulls)

Creates an index with the given fallback and settings.

Parameters:

fallback - The index to ask if the value is not found in the cache.

max - The max number of keys to store in the cache (default: 10000).

size - The initial size of the cache.

nulls - Store null values retrieved from fallback.

Method Detail

get

public E get(K key)

Specified by:

get in interface LookupIndexIF<K,E>

put

public E put(K key,
             E value)

Specified by:

put in interface LookupIndexIF<K,E>

remove

public E remove(K key)

Specified by:

remove in interface LookupIndexIF<K,E>

getKeyNumber

public int getKeyNumber()

writeReport

public void writeReport()

prune

protected void prune()

Removes some of the keys in the cache, keeping only the most frequently requested keys.