net.sf.ehcache.store
Class MemoryStore

java.lang.Object
  net.sf.ehcache.store.MemoryStore

All Implemented Interfaces:

Store

public class MemoryStore

extends java.lang.Object

implements Store

An implementation of a MemoryStore.

This uses LinkedHashMap as its backing map. It uses the LinkedHashMap LRU feature. LRU for this implementation means least recently accessed.

Version:

$Id: MemoryStore.java,v 1.23 2005/03/20 01:38:48 gregluck Exp $

Author:

Greg Luck

Nested Class Summary

class	MemoryStore.SpoolingLinkedHashMap An extension of LinkedHashMap which overrides MemoryStore.SpoolingLinkedHashMap.removeEldestEntry(java.util.Map.Entry) to persist cache entries to the auxiliary cache before they are removed.
class	MemoryStore.SpoolingLRUMap A Map implementation that delegates to Apache Commons LRUMap.

Field Summary

Fields inherited from interface net.sf.ehcache.store.Store

CACHE_HUB, DISK_CACHE, STATUS_ALIVE, STATUS_DISPOSED, STATUS_ERROR, STATUS_UNINITIALISED

Constructor Summary

MemoryStore(Cache cache, DiskStore diskStore)
Constructor for the MemoryStore object The backing LinkedHashMap is created with LRU by access order.

Method Summary

void	dispose() Prepares for shutdown.
Element	get(java.io.Serializable key) Gets an item from the cache The last access time in Element is updated.
Cache	getCache() Gets the cache that the MemoryStore is used by
int	getCacheType() Returns the cache type.
java.lang.Object[]	getKeyArray() Gets an Array of the keys for all elements in the memory cache Does not check for expired entries
java.lang.String	getName() Returns the cache name.
Element	getQuiet(java.io.Serializable key) Gets an item from the cache, without updating Element statistics The last access time in Element is updated.
int	getSize() Returns the current cache size.
long	getSizeInBytes() Measures the size of the memory store by measuring the serialized size of all elements.
int	getStatus() Gets the status of the MemoryStore.
java.util.Map	loadMapInstance() Tries to load a LinkedHashMap (JDK1.4) and then tries to load an LRUMap.
void	put(Element element) Puts an item in the cache.
boolean	remove(java.io.Serializable key) Removes an item from the cache.
void	removeAll() Remove all of the elements from the cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryStore

public MemoryStore(Cache cache,
                   DiskStore diskStore)

Constructor for the MemoryStore object The backing LinkedHashMap is created with LRU by access order.

Method Detail

loadMapInstance

public java.util.Map loadMapInstance()
                              throws CacheException

Tries to load a LinkedHashMap (JDK1.4) and then tries to load an LRUMap.

This way applications running JDK1.4 do not have a dependency on Apache commons-collections.

Returns:

a Map, being either LinkedHashMap or

Throws:

CacheException

put

public void put(Element element)

Puts an item in the cache. Note that this automatically results in MemoryStore.SpoolingLinkedHashMap.removeEldestEntry(java.util.Map.Entry) being called.

Specified by:

put in interface Store

Parameters:

element - the element to add

removeAll

public void removeAll()

Remove all of the elements from the cache.

Specified by:

removeAll in interface Store

get

public Element get(java.io.Serializable key)

Gets an item from the cache

The last access time in Element is updated.

Specified by:

get in interface Store

Parameters:

key - the cache key

Returns:

the element, or null if there was no match for the key

getQuiet

public Element getQuiet(java.io.Serializable key)

Gets an item from the cache, without updating Element statistics

The last access time in Element is updated.

Parameters:

key - the cache key

Returns:

the element, or null if there was no match for the key

remove

public boolean remove(java.io.Serializable key)

Removes an item from the cache.

Specified by:

remove in interface Store

Parameters:

key - the key, usually a String

Returns:

true if at least one object was removed.

getKeyArray

public java.lang.Object[] getKeyArray()

Gets an Array of the keys for all elements in the memory cache

Does not check for expired entries

Returns:

An Object[]

getSize

public int getSize()

Returns the current cache size.

Specified by:

getSize in interface Store

Returns:

The size value

getCache

public Cache getCache()

Gets the cache that the MemoryStore is used by

getStatus

public int getStatus()

Gets the status of the MemoryStore. Can be Store.STATUS_ALIVE or Store.STATUS_ERROR

Specified by:

getStatus in interface Store

getCacheType

public int getCacheType()

Returns the cache type.

Specified by:

getCacheType in interface Store

Returns:

The cacheType value

getName

public java.lang.String getName()

Returns the cache name.

Specified by:

getName in interface Store

dispose

public void dispose()

Prepares for shutdown.

Specified by:

dispose in interface Store

getSizeInBytes

public long getSizeInBytes()
                    throws CacheException

Measures the size of the memory store by measuring the serialized size of all elements.

Warning: This method can be very expensive to run. Allow approximately 1 second per 1MB of entries. Running this method could create liveness problems because the object lock is held for a long period

Returns:

the size, in bytes

Throws:

CacheException