Class CacheBasedValueHolder
- java.lang.Object
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- org.eclipse.persistence.internal.indirection.DatabaseValueHolder
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- org.eclipse.persistence.internal.indirection.CacheBasedValueHolder
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- All Implemented Interfaces:
Serializable
,Cloneable
,ValueHolderInterface
,WeavedAttributeValueHolderInterface
public class CacheBasedValueHolder extends DatabaseValueHolder
Purpose: In certain cases the contents of a relationship may be retrievable from a cache. This ValueHolder instance provides the mechanism to store a cached relationship and to load that relationship from a cache. This functionality requires that the persistent identities of the targets can be collected as database type foreign key queries are unavailable.
- Since:
- EclipseLink 1.1
- Author:
- gyorke
- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected ForeignReferenceMapping
mapping
protected Object[]
references
protected boolean
shouldAllowInstantiationDeferral
Setting to force the instantiation of the Collection on modification-
Fields inherited from class org.eclipse.persistence.internal.indirection.DatabaseValueHolder
isCoordinatedWithProperty, isInstantiated, row, session, value
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Fields inherited from interface org.eclipse.persistence.indirection.ValueHolderInterface
shouldToStringInstantiate
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Constructor Summary
Constructors Constructor Description CacheBasedValueHolder(Object[] pks, AbstractRecord foreignKeys, AbstractSession session, ForeignReferenceMapping mapping)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Object[]
getCachedPKs()
Object
getValue(UnitOfWorkImpl uow)
Process against the UOW and attempt to load a local copy before going to the shared cache If null is returned then the calling UOW will instantiate as normal.protected Object
instantiate()
Instantiate the object.protected Object
instantiate(AbstractSession localSession)
Object
instantiateForUnitOfWorkValueHolder(UnitOfWorkValueHolder unitOfWorkValueHolder)
Triggers UnitOfWork valueholders directly without triggering the wrapped valueholder (this).boolean
isPessimisticLockingValueHolder()
Answers if this valueholder is a pessimistic locking one.void
setShouldAllowInstantiationDeferral(boolean shouldAllowInstantiationDeferral)
Set if instantiation deferral on modification should be available.boolean
shouldAllowInstantiationDeferral()
INTERNAL: Return if add/remove should trigger instantiation or avoid.-
Methods inherited from class org.eclipse.persistence.internal.indirection.DatabaseValueHolder
clone, getRow, getSession, getValue, getWrappedValueHolder, isCoordinatedWithProperty, isEasilyInstantiated, isInstantiated, isNewlyWeavedValueHolder, isSerializedRemoteUnitOfWorkValueHolder, isTransactionalValueHolder, postInstantiate, privilegedSetValue, releaseWrappedValueHolder, resetFields, setInstantiated, setIsCoordinatedWithProperty, setIsNewlyWeavedValueHolder, setRow, setSession, setUninstantiated, setValue, toString
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Field Detail
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mapping
protected transient ForeignReferenceMapping mapping
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references
protected Object[] references
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shouldAllowInstantiationDeferral
protected boolean shouldAllowInstantiationDeferral
Setting to force the instantiation of the Collection on modification
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Constructor Detail
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CacheBasedValueHolder
public CacheBasedValueHolder(Object[] pks, AbstractRecord foreignKeys, AbstractSession session, ForeignReferenceMapping mapping)
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Method Detail
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getCachedPKs
public Object[] getCachedPKs()
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getValue
public Object getValue(UnitOfWorkImpl uow)
Process against the UOW and attempt to load a local copy before going to the shared cache If null is returned then the calling UOW will instantiate as normal.- Overrides:
getValue
in classDatabaseValueHolder
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instantiate
protected Object instantiate() throws DatabaseException
Description copied from class:DatabaseValueHolder
Instantiate the object.- Specified by:
instantiate
in classDatabaseValueHolder
- Throws:
DatabaseException
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instantiate
protected Object instantiate(AbstractSession localSession) throws DatabaseException
- Throws:
DatabaseException
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instantiateForUnitOfWorkValueHolder
public Object instantiateForUnitOfWorkValueHolder(UnitOfWorkValueHolder unitOfWorkValueHolder)
Triggers UnitOfWork valueholders directly without triggering the wrapped valueholder (this).When in transaction and/or for pessimistic locking the UnitOfWorkValueHolder needs to be triggered directly without triggering the wrapped valueholder. However only the wrapped valueholder knows how to trigger the indirection, i.e. it may be a batchValueHolder, and it stores all the info like the row and the query. Note: This method is not thread-safe. It must be used in a synchronized manner
- Specified by:
instantiateForUnitOfWorkValueHolder
in classDatabaseValueHolder
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isPessimisticLockingValueHolder
public boolean isPessimisticLockingValueHolder()
Description copied from class:DatabaseValueHolder
Answers if this valueholder is a pessimistic locking one. Such valueholders are special in that they can be triggered multiple times by different UnitsOfWork. Each time a lock query will be issued. Hence even if instantiated it may have to be instantiated again, and once instantiated all fields can not be reset. Note: Implementations of this method are not necessarily thread-safe. They must be used in a synchronizaed manner- Specified by:
isPessimisticLockingValueHolder
in classDatabaseValueHolder
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setShouldAllowInstantiationDeferral
public void setShouldAllowInstantiationDeferral(boolean shouldAllowInstantiationDeferral)
Set if instantiation deferral on modification should be available.
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shouldAllowInstantiationDeferral
public boolean shouldAllowInstantiationDeferral()
INTERNAL: Return if add/remove should trigger instantiation or avoid. Current instantiation is avoided is using change tracking.- Specified by:
shouldAllowInstantiationDeferral
in interfaceWeavedAttributeValueHolderInterface
- Overrides:
shouldAllowInstantiationDeferral
in classDatabaseValueHolder
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