org.apache.commons.jcs.engine.memory.lru

Class LRUMemoryCache<K,V>

java.lang.Object

org.apache.commons.jcs.engine.memory.AbstractMemoryCache<K,V>

org.apache.commons.jcs.engine.memory.AbstractDoubleLinkedListMemoryCache<K,V>

org.apache.commons.jcs.engine.memory.lru.LRUMemoryCache<K,V>

All Implemented Interfaces:

IMemoryCache<K,V>

public class LRUMemoryCache<K,V>
extends AbstractDoubleLinkedListMemoryCache<K,V>

A fast reference management system. The least recently used items move to the end of the list and get spooled to disk if the cache hub is configured to use a disk cache. Most of the cache bottlenecks are in IO. There are no io bottlenecks here, it's all about processing power.

Even though there are only a few adjustments necessary to maintain the double linked list, we might want to find a more efficient memory manager for large cache regions.

The LRUMemoryCache is most efficient when the first element is selected. The smaller the region, the better the chance that this will be the case. < .04 ms per put, p3 866, 1/10 of that per get

Field Summary

Fields inherited from class org.apache.commons.jcs.engine.memory.AbstractDoubleLinkedListMemoryCache

list

Fields inherited from class org.apache.commons.jcs.engine.memory.AbstractMemoryCache

chunkSize, hitCnt, lock, map, missCnt, putCnt

Constructor Summary

Constructors

Constructor and Description
LRUMemoryCache()

Method Summary

Modifier and Type	Method and Description
protected void	adjustListForGet(MemoryElementDescriptor<K,V> me) Makes the item the first in the list.
protected MemoryElementDescriptor<K,V>	adjustListForUpdate(ICacheElement<K,V> ce) Puts an item to the cache.

Methods inherited from class org.apache.commons.jcs.engine.memory.AbstractDoubleLinkedListMemoryCache

addFirst, addLast, createMap, freeElements, get, getKeySet, getStatistics, initialize, remove, removeAll, update

Methods inherited from class org.apache.commons.jcs.engine.memory.AbstractMemoryCache

dispose, dumpMap, getCacheAttributes, getCacheName, getCompositeCache, getMultiple, getQuiet, getSize, getStatus, setCacheAttributes, waterfal

Methods inherited from class java.lang.Object

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

Constructor Detail

LRUMemoryCache

public LRUMemoryCache()

Method Detail

adjustListForUpdate

protected MemoryElementDescriptor<K,V> adjustListForUpdate(ICacheElement<K,V> ce)
                                                    throws IOException

Puts an item to the cache. Removes any pre-existing entries of the same key from the linked list and adds this one first.

Specified by:

adjustListForUpdate in class AbstractDoubleLinkedListMemoryCache<K,V>

Parameters:

ce - The cache element, or entry wrapper

Returns:

MemoryElementDescriptor the new node

Throws:

IOException

adjustListForGet

protected void adjustListForGet(MemoryElementDescriptor<K,V> me)

Makes the item the first in the list.

Specified by:

adjustListForGet in class AbstractDoubleLinkedListMemoryCache<K,V>

Parameters:

me -