Package org.eclipse.persistence.internal.indirection

Class BackupValueHolder

java.lang.Object

org.eclipse.persistence.internal.indirection.DatabaseValueHolder

org.eclipse.persistence.internal.indirection.BackupValueHolder

All Implemented Interfaces:

Serializable, Cloneable, ValueHolderInterface, WeavedAttributeValueHolderInterface

public class BackupValueHolder
extends DatabaseValueHolder

Used as the backup value holder in the unit of work for transparent indirection. This ensure that a reference to the original value holder is held in case the transparent collection or proxy is replace without first instantiating the original.

Since:

10.1.3

Author:

James Sutherland

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected ValueHolderInterface<?>	unitOfWorkValueHolder	Stores the original uow clone's value holder.

Fields inherited from class org.eclipse.persistence.internal.indirection.DatabaseValueHolder

isCoordinatedWithProperty, isInstantiated, row, session, value

Fields inherited from interface org.eclipse.persistence.indirection.ValueHolderInterface

shouldToStringInstantiate

Constructor Summary

Constructors

Constructor	Description
BackupValueHolder(ValueHolderInterface<?> unitOfWorkValueHolder)

Method Summary

Modifier and Type	Method	Description
AbstractRecord	getRow()	Return the row.
AbstractSession	getSession()	Return the session.
ValueHolderInterface<?>	getUnitOfWorkValueHolder()	Return the original uow clone's value holder.
Object	instantiate()	If the original value holder was not instantiated, then first instantiate it to obtain the backup value.
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.

Methods inherited from class org.eclipse.persistence.internal.indirection.DatabaseValueHolder

clone, getValue, getValue, getWrappedValueHolder, isCoordinatedWithProperty, isEasilyInstantiated, isInstantiated, isNewlyWeavedValueHolder, isSerializedRemoteUnitOfWorkValueHolder, isTransactionalValueHolder, postInstantiate, privilegedSetValue, releaseWrappedValueHolder, resetFields, setInstantiated, setIsCoordinatedWithProperty, setIsNewlyWeavedValueHolder, setRow, setSession, setUninstantiated, setValue, shouldAllowInstantiationDeferral, toString

Methods inherited from class java.lang.Object

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

Field Detail

unitOfWorkValueHolder

protected ValueHolderInterface<?> unitOfWorkValueHolder

Stores the original uow clone's value holder.

Constructor Detail

BackupValueHolder

public BackupValueHolder(ValueHolderInterface<?> unitOfWorkValueHolder)

Method Detail

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 class DatabaseValueHolder

instantiateForUnitOfWorkValueHolder

public Object instantiateForUnitOfWorkValueHolder(UnitOfWorkValueHolder unitOfWorkValueHolder)

Description copied from class: DatabaseValueHolder

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: Implementations of this method are not necessarily thread-safe. They must be used in a synchronized manner

Specified by:

instantiateForUnitOfWorkValueHolder in class DatabaseValueHolder

getRow

public AbstractRecord getRow()

Description copied from class: DatabaseValueHolder

Return the row.

Overrides:

getRow in class DatabaseValueHolder

getSession

public AbstractSession getSession()

Description copied from class: DatabaseValueHolder

Return the session.

Overrides:

getSession in class DatabaseValueHolder

instantiate

public Object instantiate()

If the original value holder was not instantiated, then first instantiate it to obtain the backup value.

Specified by:

instantiate in class DatabaseValueHolder

getUnitOfWorkValueHolder

public ValueHolderInterface<?> getUnitOfWorkValueHolder()

Return the original uow clone's value holder.