oracle.toplink.essentials.internal.identitymaps

Class SoftCacheWeakIdentityMap

java.lang.Object

oracle.toplink.essentials.internal.identitymaps.IdentityMap

oracle.toplink.essentials.internal.identitymaps.FullIdentityMap

oracle.toplink.essentials.internal.identitymaps.WeakIdentityMap

oracle.toplink.essentials.internal.identitymaps.HardCacheWeakIdentityMap

oracle.toplink.essentials.internal.identitymaps.SoftCacheWeakIdentityMap

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class SoftCacheWeakIdentityMap
extends HardCacheWeakIdentityMap

Purpose: A weak cache is identical to the weak identity map, however the weak can be a performance problem for some types of apps because it can cause too much garbage collection of objects read causing them to be re-read and re-built (this defeats the purpose of the cache). The weak cache solves this through also holding a fixed number of objects is memory to improve caching.

Responsibilities:

• Guarantees identity
• Allows garbage collection
• Increases performance through maintaining a fixed size cache of MRU objects when memory is available
• The default size of the reference cache is half the max size

Since:

TOPLink/Java 1.2

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class oracle.toplink.essentials.internal.identitymaps.HardCacheWeakIdentityMap

HardCacheWeakIdentityMap.ReferenceCacheKey

Field Summary

Fields inherited from class oracle.toplink.essentials.internal.identitymaps.HardCacheWeakIdentityMap

referenceCache

Fields inherited from class oracle.toplink.essentials.internal.identitymaps.WeakIdentityMap

cleanupCount, cleanupSize

Fields inherited from class oracle.toplink.essentials.internal.identitymaps.FullIdentityMap

cacheKeys

Fields inherited from class oracle.toplink.essentials.internal.identitymaps.IdentityMap

maxSize, searchKey

Constructor Summary

Constructors

Constructor and Description
SoftCacheWeakIdentityMap(int size)

Method Summary

Modifier and Type	Method and Description
java.lang.Object	buildReference(java.lang.Object object) Creates a Soft reference if Required
boolean	hasReference(java.lang.Object reference) Checks if the object is null, or reference's object is null.

Methods inherited from class oracle.toplink.essentials.internal.identitymaps.HardCacheWeakIdentityMap

createCacheKey, getReferenceCache, put, remove, updateMaxSize

Methods inherited from class oracle.toplink.essentials.internal.identitymaps.WeakIdentityMap

cleanupDeadCacheKeys, getCleanupCount, getCleanupSize, setCleanupCount, setCleanupSize

Methods inherited from class oracle.toplink.essentials.internal.identitymaps.FullIdentityMap

clone, collectLocks, elements, getCacheKey, getCacheKeys, getSize, getSize, keys, put, resetCacheKey, resetCacheKey, setCacheKeys

Methods inherited from class oracle.toplink.essentials.internal.identitymaps.IdentityMap

acquireDeferredLock, acquireLock, acquireLockNoWait, acquireReadLockOnCacheKey, acquireReadLockOnCacheKeyNoWait, containsKey, createCacheKey, get, getCacheKey, getCacheKeyWithReadLock, getDefaultIdentityMapClass, getMaxSize, getSearchKey, getWrapper, getWriteLockValue, initialize, remove, setMaxSize, setSearchKey, setWrapper, setWriteLockValue, toString, updateCacheKey

Methods inherited from class java.lang.Object

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

Constructor Detail

SoftCacheWeakIdentityMap

public SoftCacheWeakIdentityMap(int size)

Method Detail

buildReference

public java.lang.Object buildReference(java.lang.Object object)

Creates a Soft reference if Required

Overrides:

buildReference in class HardCacheWeakIdentityMap

Parameters:

object - is the domain object to cache.

hasReference

public boolean hasReference(java.lang.Object reference)

Checks if the object is null, or reference's object is null.

Overrides:

hasReference in class HardCacheWeakIdentityMap

Parameters:

the - object for hard or the reference for soft.