org.jboss.cache.eviction
Class BaseEvictionPolicy

java.lang.Object
  org.jboss.cache.eviction.BaseEvictionPolicy

All Implemented Interfaces:

EvictionPolicy

Direct Known Subclasses:

ElementSizePolicy, ExpirationPolicy, FIFOPolicy, LFUPolicy, LRUPolicy, MRUPolicy

public abstract class BaseEvictionPolicy
extends java.lang.Object
implements EvictionPolicy

Base class implementation of EvictionPolicy and TreeCacheListener.

Version:

$Revision: 1.9 $

Author:

Ben Wang 2-2004, Daniel Huang - dhuang@jboss.org

Field Summary

protected CacheSPI

cache_

Constructor Summary

BaseEvictionPolicy()

Method Summary

boolean	canIgnoreEvent(Fqn fqn, NodeEventType eventType) This method will be invoked prior to an event being processed for a node with the specified Fqn.
void	evict(Fqn fqn) Evict the node under given Fqn from cache.
CacheSPI	getCache()
void	setCache(CacheSPI cache) Method called to set the cache in this implementation.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jboss.cache.eviction.EvictionPolicy

getEvictionAlgorithm, getEvictionConfigurationClass

Field Detail

cache_

protected CacheSPI cache_

Constructor Detail

BaseEvictionPolicy

public BaseEvictionPolicy()

Method Detail

evict

public void evict(Fqn fqn)
           throws java.lang.Exception

Evict the node under given Fqn from cache.

Specified by:

evict in interface EvictionPolicy

Parameters:

fqn - The fqn of a node in cache.

Throws:

java.lang.Exception

setCache

public void setCache(CacheSPI cache)

Description copied from interface: EvictionPolicy

Method called to set the cache in this implementation.

Specified by:

setCache in interface EvictionPolicy

Parameters:

cache - the cache to set

getCache

public CacheSPI getCache()

Specified by:

getCache in interface EvictionPolicy

Returns:

the CacheSPI instance this eviction policy is configured to work on.

canIgnoreEvent

public boolean canIgnoreEvent(Fqn fqn,
                              NodeEventType eventType)

Description copied from interface: EvictionPolicy

This method will be invoked prior to an event being processed for a node with the specified Fqn.

This method provides a way to optimize the performance of eviction by signalling that the node associated with the specified Fqn should not be subject to normal eviction processing. It can also be used to filter out certain event types in which the particular eviction algorithm has no interest.

If this method returns false then the event is processed normally and eviction processing for the node continues. As a result, the event will be added to the eviction region's event queue where at some later point the particular algorithm of the eviction policy can use it to decide whether to call EvictionPolicy.evict(Fqn).

If this method returns true, then the event is ignored and will not factor in any subsequent eviction processing.

Specified by:

canIgnoreEvent in interface EvictionPolicy

Parameters:

fqn - The Fqn of the node associated with the event.

eventType - the type of the event

Returns:

true to ignore events of this type for this Fqn, false to process events normally.