LRUCachePolicy (JBoss/Common API) - JBoss 3.2.7 common API Documentation 英文版文档

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org.jboss.util
Class LRUCachePolicy

java.lang.Object
  org.jboss.util.LRUCachePolicy

All Implemented Interfaces:: CachePolicy

public class LRUCachePolicy
extends Object
implements CachePolicy

Implementation of a Least Recently Used cache policy.

Version:: $Revision: 1.4.2.4 $
Author:: Simone Bordet

Nested Class Summary

static class LRUCachePolicy.LRUCacheEntry
          Double linked cell used as entry in the cache list.

class LRUCachePolicy.LRUList
          Double queued list used to store cache entries.

Field Summary

protected LRUCachePolicy.LRUList m_list
          The linked list used to implement the LRU algorithm

protected HashMap m_map
          The map holding the cached objects

protected int m_maxCapacity
          The maximum capacity of this cache

protected int m_minCapacity
          The minimum capacity of this cache

Constructor Summary

LRUCachePolicy()
          Creates a LRU cache policy object with zero cache capacity.

LRUCachePolicy(int min, int max)
          Creates a LRU cache policy object with the specified minimum and maximum capacity.

Method Summary

protected void ageOut(LRUCachePolicy.LRUCacheEntry entry)
          Callback method called when the cache algorithm ages out of the cache the given entry.

protected void cacheMiss()
          Callback method called when a cache miss happens.

void create()
          Initializes the cache, creating all required objects and initializing their values.

protected LRUCachePolicy.LRUCacheEntry createCacheEntry(Object key, Object value)
          Factory method for cache entries

protected LRUCachePolicy.LRUList createList()
          Factory method for the linked list used by this cache implementation.

void destroy()
          Destroys the cache that is now unusable.

void flush()
          Flushes the cached objects from the cache.

Object get(Object key)
          Returns the object paired with the specified key if it's present in the cache, otherwise must return null.

void insert(Object key, Object o)
          Inserts the specified object into the cache following the implemented policy.

Object peek(Object key)
          Returns the object paired with the specified key if it's present in the cache, otherwise must return null.

void remove(Object key)
          Remove the cached object paired with the specified key.

int size()
          Get the size of the cache.

void start()
          Starts this cache that is now ready to be used.

void stop()
          Stops this cache thus flush()ing all cached objects.

Methods inherited from class java.lang.Object

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

Field Detail

m_map

protected HashMap m_map

The map holding the cached objects

m_list

protected LRUCachePolicy.LRUList m_list

The linked list used to implement the LRU algorithm

m_maxCapacity

protected int m_maxCapacity

The maximum capacity of this cache

m_minCapacity

protected int m_minCapacity

The minimum capacity of this cache

Constructor Detail

LRUCachePolicy

public LRUCachePolicy()

Creates a LRU cache policy object with zero cache capacity.
See Also:: create()

LRUCachePolicy

public LRUCachePolicy(int min,
                      int max)

Creates a LRU cache policy object with the specified minimum and maximum capacity.
See Also:: create()

Method Detail

create

public void create()

Initializes the cache, creating all required objects and initializing their values.

Specified by:: create in interface CachePolicy

See Also:: start(), destroy()

start

public void start()

Starts this cache that is now ready to be used.

Specified by:: start in interface CachePolicy

See Also:: create(), stop()

stop

public void stop()

Stops this cache thus flush()ing all cached objects.
After this method is called, a call to start() will restart the cache.

Specified by:: stop in interface CachePolicy

See Also:: start(), destroy()

destroy

public void destroy()

Destroys the cache that is now unusable.
To have it working again it must be re-create()ed and re-start()ed.

Specified by:: destroy in interface CachePolicy

See Also:: create()