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package oracle.toplink.essentials.internal.identitymaps;

import java.lang.ref.*;

/**
 * 

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 */ public class SoftCacheWeakIdentityMap extends HardCacheWeakIdentityMap { public SoftCacheWeakIdentityMap(int size) { super(size); } /** * Creates a Soft reference if Required * @param object is the domain object to cache. */ public Object buildReference(Object object) { return new SoftReference(object); } /** * Checks if the object is null, or reference's object is null. * @param the object for hard or the reference for soft. */ public boolean hasReference(Object reference) { return (reference != null) && (((SoftReference)reference).get() != null); } }




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