Package com.j_spaces.map.eviction

Class LFUEvictionStrategy

java.lang.Object

com.j_spaces.map.eviction.AbstractEvictionStrategy

com.j_spaces.map.eviction.LFUEvictionStrategy

All Implemented Interfaces:

EvictionStrategy

public class LFUEvictionStrategy
extends AbstractEvictionStrategy

The heap LFUDA ( Least Frequently Used) policy keeps popular objects in cache regardless of their size and thus optimizes byte hit rate at the expense of hit rate since one large, popular object will prevent many smaller, slightly less popular objects from being cached.

Since:

5.0

Version:

1.0

Author:

Guy Korland

Field Summary

Fields inherited from class com.j_spaces.map.eviction.AbstractEvictionStrategy

_batchSize

Constructor Summary

Constructors

Constructor	Description
LFUEvictionStrategy()

Method Summary

Modifier and Type	Method	Description
void	clear()	Clear EvictionStrategy internal structures only and doesn't clear cache.
CacheEntry	createEntry(Object key, Object value, long ttl, int version)	Creates new CacheEntry for the Cache and probably saves the entry in the internal structures.
void	discardEntry(CacheEntry entry)	Discard an Entry from the EvictionStrategy internal structures.
int	evict(Cache cache)	Evicts batch of CacheEntry from the Cache according to the eviction strategy.
void	touchEntry(CacheEntry entry)	Informs the eviction strategy on a CacheEntry use.

Methods inherited from class com.j_spaces.map.eviction.AbstractEvictionStrategy

setBatchSize

Methods inherited from class java.lang.Object

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

Constructor Details

LFUEvictionStrategy

public LFUEvictionStrategy()

Method Details

clear

public void clear()

Clear EvictionStrategy internal structures only and doesn't clear cache.

discardEntry

public void discardEntry(CacheEntry entry)

Discard an Entry from the EvictionStrategy internal structures.

Parameters:

entry - the entry to discard from the eviction strategy internal structures

evict

public int evict(Cache cache)

Evicts batch of CacheEntry from the Cache according to the eviction strategy.

Parameters:

cache - the cache to be evicted

Returns:

the amount of entries evicted

touchEntry

public void touchEntry(CacheEntry entry)

Informs the eviction strategy on a CacheEntry use.

Parameters:

entry - the touched entry

createEntry

public CacheEntry createEntry(Object key,
 Object value,
 long ttl,
 int version)

Creates new CacheEntry for the Cache and probably saves the entry in the internal structures.

Parameters:

key - the entry key

value - the entry value

ttl - the time to keep the entry in cache

version - the entry version

Returns:

a CacheEntry that holds all the parameters and probably saved in the eviction strategy internal structures