- All Implemented Interfaces:
public class LFUAlgorithm
- extends BaseSortedEvictionAlgorithm
Least Frequently Used algorithm for cache eviction.
Note that this algorithm is not thread-safe.
This algorithm relies on maxNodes and minNodes to operate correctly.
Eviction takes place using Least Frequently Used algorithm. A node A
that is used less than a node B is evicted sooner.
The minNodes property defines a threshold for eviction. If minNodes = 100,
the LFUAlgorithm will not evict the cache to anything less than 100 elements
still left in cache. The maxNodes property defines the maximum number of nodes
the cache will accept before eviction. maxNodes = 0 means that this region is
unbounded. minNodes = 0 means that the eviction queue will attempt to bring
the cache of this region to 0 elements (evict all elements) whenever it is run.
This algorithm uses a sorted eviction queue. The eviction queue is sorted in
ascending order based on the number of times a node is visited. The more frequently
a node is visited, the less likely it will be evicted.
- $Revision: 7168 $
- Daniel Huang - firstname.lastname@example.org 10/2005
|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, processRemovedElement, processRemovedNodes, processUnmarkInUseNodes, processVisitedNodes, resetEvictionQueue, setEvictionActionPolicy, toString
protected boolean shouldEvictNode(NodeEntry ne)
- Description copied from class:
- This method will check whether the given node should be evicted or not.
- Specified by:
shouldEvictNode in class
ne - NodeEntry to test eviction for.
- True if the given node should be evicted. False if the given node should not be evicted.
protected EvictionQueue setupEvictionQueue()
- Will create a LFUQueue to be used as the underlying eviction queue.
- Specified by:
setupEvictionQueue in class
- The created LFUQueue.
- See Also:
protected void prune()
prune in class
public Class<? extends EvictionAlgorithmConfig> getConfigurationClass()
- Description copied from interface:
- This is a helper so that the XML parser will be able to select and use the correct
class corresponding to this EvictionAlgorithm. E.g., the
FIFOAlgorithm would return
- a class that is used to configure this EvictionAlgorithm.
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