org.eclipse.persistence.internal.identitymaps

Class CacheIdentityMap

java.lang.Object

org.eclipse.persistence.internal.identitymaps.AbstractIdentityMap

org.eclipse.persistence.internal.identitymaps.FullIdentityMap

org.eclipse.persistence.internal.identitymaps.CacheIdentityMap

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, IdentityMap

public class CacheIdentityMap
extends FullIdentityMap

Purpose: A fixed size LRU cache

Using a linked list as well as the map from the superclass a LRU cache is maintained. When a get is executed the LRU list is updated and when a new object is inserted the object at the start of the list is deleted (provided the maxSize has been reached).

Responsibilities:

• Guarantees identity through primary key values
• Keeps the LRU linked list updated.

Since:

TOPLink/Java 1.0

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
CacheIdentityMap(int size, ClassDescriptor descriptor, AbstractSession session, boolean isolated)

Method Summary

Modifier and Type	Method and Description
CacheKey	createCacheKey(java.lang.Object primaryKey, java.lang.Object object, java.lang.Object writeLockValue, long readTime) Create the correct type of CacheKey for this map.
CacheKey	getCacheKey(java.lang.Object primaryKeys, boolean forMerge) Access the object within the table for the given primaryKey.
java.lang.Object	remove(CacheKey key) Remove the LinkedCacheKey from the cache as well as from the linked list.
void	updateMaxSize(int maxSize) INTERNAL: This method will be used to update the max cache size, any objects exceeding the max cache size will be remove from the cache.

Methods inherited from class org.eclipse.persistence.internal.identitymaps.FullIdentityMap

clone, collectLocks, elements, getCacheKeys, getSize, getSize, keys, keys, lazyRelationshipLoaded, put, resetCacheKey

Methods inherited from class org.eclipse.persistence.internal.identitymaps.AbstractIdentityMap

acquireDeferredLock, acquireLock, acquireLockNoWait, acquireLockWithWait, acquireReadLockOnCacheKey, acquireReadLockOnCacheKeyNoWait, containsKey, get, getAllCacheKeysFromIdentityMapWithEntityPK, getAllFromIdentityMapWithEntityPK, getCacheKeyForLock, getDefaultIdentityMapClass, getDescriptor, getDescriptorClass, getMaxSize, getWrapper, getWriteLockValue, release, remove, setDescriptor, setWrapper, setWriteLockValue, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheIdentityMap

public CacheIdentityMap(int size,
                        ClassDescriptor descriptor,
                        AbstractSession session,
                        boolean isolated)

Method Detail

createCacheKey

public CacheKey createCacheKey(java.lang.Object primaryKey,
                               java.lang.Object object,
                               java.lang.Object writeLockValue,
                               long readTime)

Description copied from class: AbstractIdentityMap

Create the correct type of CacheKey for this map.

Overrides:

createCacheKey in class AbstractIdentityMap

getCacheKey

public CacheKey getCacheKey(java.lang.Object primaryKeys,
                            boolean forMerge)

Access the object within the table for the given primaryKey. Move the accessed key to the top of the order keys linked list to maintain LRU.

Specified by:

getCacheKey in interface IdentityMap

Overrides:

getCacheKey in class FullIdentityMap

Parameters:

primaryKeys - is the primary key for the object to search for.

Returns:

the LinkedCacheKey or null if none found for primaryKey

remove

public java.lang.Object remove(CacheKey key)

Remove the LinkedCacheKey from the cache as well as from the linked list.

Specified by:

remove in interface IdentityMap

Overrides:

remove in class FullIdentityMap

Returns:

the LinkedCacheKey to be removed.

updateMaxSize

public void updateMaxSize(int maxSize)

INTERNAL: This method will be used to update the max cache size, any objects exceeding the max cache size will be remove from the cache. Please note that this does not remove the object from the identityMap, except in the case of the CacheIdentityMap.

Specified by:

updateMaxSize in interface IdentityMap

Overrides:

updateMaxSize in class AbstractIdentityMap