org.jboss.cache.eviction
Class MRUAlgorithm

java.lang.Object
  org.jboss.cache.eviction.BaseEvictionAlgorithm
      org.jboss.cache.eviction.MRUAlgorithm

All Implemented Interfaces:

EvictionAlgorithm

public class MRUAlgorithm
extends BaseEvictionAlgorithm

Most Recently Used Algorithm.

This algorithm will evict the most recently used cache entries from cache.

Note: None of the Eviction classes are thread safe. It is assumed that an individual instance of an EvictionPolicy/ EvictionAlgorithm/EvictionQueue/EvictionConfiguration are only operated on by one thread at any given time.

Version:

$Revision: 7168 $

Author:

Daniel Huang (dhuang@jboss.org)

Field Summary

Fields inherited from class org.jboss.cache.eviction.BaseEvictionAlgorithm

allowTombstones, cache, configuration, evictionActionPolicy, evictionAlgorithmConfig, evictionQueue, recycleQueue, regionFqn

Constructor Summary

MRUAlgorithm()

Method Summary

Class<? extends EvictionAlgorithmConfig>	getConfigurationClass() This is a helper so that the XML parser will be able to select and use the correct EvictionAlgorithmConfig implementation class corresponding to this EvictionAlgorithm.
protected void	processVisitedNodes(EvictionEvent evictedEventNode) Visit a node in cache.
protected EvictionQueue	setupEvictionQueue() This method will create an EvictionQueue implementation and prepare it for use.
protected boolean	shouldEvictNode(NodeEntry ne) This method will check whether the given node should be evicted or not.

Methods inherited from class org.jboss.cache.eviction.BaseEvictionAlgorithm

assignToRegion, canIgnoreEvent, emptyRecycleQueue, evict, evictCacheNode, getEvictionActionPolicy, getEvictionAlgorithmConfig, getEvictionQueue, getNextInQueue, initialize, isNodeInUseAndNotTimedOut, isYoungerThanMinimumTimeToLive, process, processAddedElement, processAddedNodes, processAddedNodes, processMarkInUseNodes, processQueues, processRemovedElement, processRemovedNodes, processUnmarkInUseNodes, prune, resetEvictionQueue, setEvictionActionPolicy, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

MRUAlgorithm

public MRUAlgorithm()

Method Detail

setupEvictionQueue

protected EvictionQueue setupEvictionQueue()
                                    throws EvictionException

Description copied from class: BaseEvictionAlgorithm

This method will create an EvictionQueue implementation and prepare it for use.

Specified by:

setupEvictionQueue in class BaseEvictionAlgorithm

Returns:

The created EvictionQueue to be used as the eviction queue for this algorithm.

Throws:

EvictionException - if there are problems

See Also:

EvictionQueue

shouldEvictNode

protected boolean shouldEvictNode(NodeEntry ne)

Description copied from class: BaseEvictionAlgorithm

This method will check whether the given node should be evicted or not.

Specified by:

shouldEvictNode in class BaseEvictionAlgorithm

Parameters:

ne - NodeEntry to test eviction for.

Returns:

True if the given node should be evicted. False if the given node should not be evicted.

processVisitedNodes

protected void processVisitedNodes(EvictionEvent evictedEventNode)
                            throws EvictionException

Description copied from class: BaseEvictionAlgorithm

Visit a node in cache.

This method will update the numVisits and modifiedTimestamp properties of the Node. These properties are used as statistics to determine eviction (LRU, LFU, MRU, etc..)

*Note* that this method updates Node Entries by reference and does not put them back into the queue. For some sorted collections, a remove, and a re-add is required to maintain the sorted order of the elements.

Overrides:

processVisitedNodes in class BaseEvictionAlgorithm

Throws:

EvictionException

getConfigurationClass

public Class<? extends EvictionAlgorithmConfig> getConfigurationClass()

Description copied from interface: EvictionAlgorithm

This is a helper so that the XML parser will be able to select and use the correct EvictionAlgorithmConfig implementation class corresponding to this EvictionAlgorithm. E.g., the FIFOAlgorithm would return FIFOAlgorithmConfig.class.

Returns:

a class that is used to configure this EvictionAlgorithm.