Package org.eclipse.persistence.internal.sessions.remote

Class RemoteValueHolder

java.lang.Object

org.eclipse.persistence.internal.indirection.DatabaseValueHolder

org.eclipse.persistence.internal.sessions.remote.RemoteValueHolder

All Implemented Interfaces:

Externalizable, Serializable, Cloneable, ValueHolderInterface, WeavedAttributeValueHolderInterface

public class RemoteValueHolder
extends DatabaseValueHolder
implements Externalizable

Remote value holders can be invoked locally and remotely. In both situations the associated indirect object is invoked.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected ObjID	id
protected DatabaseMapping	mapping
protected ObjectLevelReadQuery	query
protected Object	serverIndirectionObject
protected Object	targetObjectPrimaryKeys
protected ValueHolderInterface<Object>	wrappedServerValueHolder

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
RemoteValueHolder()
RemoteValueHolder(ObjID id)

Method Summary

Modifier and Type	Method	Description
protected boolean	canDoCacheCheck()	If the reference object is mapped thru one to one mapping and the object derives its primary key value from this relationship then remote value holder has a primary key row for.
boolean	equals(Object object)	Only the id is checked for equality check.
void	finalize()	This method is used to remove the RemoteValueHolder from the dispatcher on Garbage collection from the client
ObjID	getID()	Return the unique id.
DatabaseMapping	getMapping()	Return the associated mapping.
protected Object	getObjectFromCache()	Get object from the cache if there is one.
ObjectLevelReadQuery	getQuery()	Return the associated query.
Object	getServerIndirectionObject()	Return the object on the server that holds on to the remote value holder.
protected Object	getTargetObjectPrimaryKeys()	Get target object primary key row.
ValueHolderInterface<Object>	getWrappedServerValueHolder()	Return the original value holder.
int	hashCode()	Return the hashcode for id, because it is unqiue.
Object	instantiate()	Return the object.
Object	instantiateForUnitOfWorkValueHolder(UnitOfWorkValueHolder unitOfWorkValueHolder)	Triggers UnitOfWork valueholders directly without triggering the wrapped valueholder (this).
boolean	isEasilyInstantiated()	INTERNAL: Answers if this valueholder is easy to instantiate.
boolean	isPessimisticLockingValueHolder()	INTERNAL: Answers if this valueholder is a pessimistic locking one.
void	readExternal(ObjectInput in)	Override the default serialization for a remote valueholder so as not to serialize the value Note: Changed for bug 3145211.
protected void	setID(ObjID anID)	Set the unique id.
void	setMapping(DatabaseMapping mapping)	Set mapping
void	setQuery(ObjectLevelReadQuery query)	Set the query.
void	setServerIndirectionObject(Object serverIndirectionObject)	Set the object on the server that holds on to the remote value holder.
void	setTargetObjectPrimaryKeys(Object primaryKeys)	Set target object primary keys.
void	setValue(Object theValue)	Set the object.
void	setWrappedServerValueHolder(ValueHolderInterface wrappedServerValueHolder)	Set the original value holder.
void	writeExternal(ObjectOutput out)	Override the default serialization for a remote valueholder so as not to serialize the value Note: Changed for bug 3145211.

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

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

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

id

protected ObjID id

targetObjectPrimaryKeys

protected Object targetObjectPrimaryKeys

mapping

protected transient DatabaseMapping mapping

query

protected transient ObjectLevelReadQuery query

wrappedServerValueHolder

protected transient ValueHolderInterface<Object> wrappedServerValueHolder

serverIndirectionObject

protected transient Object serverIndirectionObject

Constructor Detail

RemoteValueHolder

public RemoteValueHolder()

RemoteValueHolder

public RemoteValueHolder(ObjID id)

Method Detail

canDoCacheCheck

protected boolean canDoCacheCheck()

If the reference object is mapped thru one to one mapping and the object derives its primary key value from this relationship then remote value holder has a primary key row for.

equals

public boolean equals(Object object)

Only the id is checked for equality check.

Overrides:

equals in class Object

finalize

public void finalize()

This method is used to remove the RemoteValueHolder from the dispatcher on Garbage collection from the client

Overrides:

finalize in class Object

getID

public ObjID getID()

Return the unique id.

getMapping

public DatabaseMapping getMapping()

Return the associated mapping.

getObjectFromCache

protected Object getObjectFromCache()

Get object from the cache if there is one.

getQuery

public ObjectLevelReadQuery getQuery()

Return the associated query.

getServerIndirectionObject

public Object getServerIndirectionObject()

Return the object on the server that holds on to the remote value holder. Currently used only by TransparentIndirection so we can get back to the original IndirectContainer.

getTargetObjectPrimaryKeys

protected Object getTargetObjectPrimaryKeys()

Get target object primary key row.

getWrappedServerValueHolder

public ValueHolderInterface<Object> getWrappedServerValueHolder()

Return the original value holder. This is null on the client side because it is tagged transient. This is how we know whether the remote value holder is being invoked on the client or on the server.

hashCode

public int hashCode()

Return the hashcode for id, because it is unqiue.

Overrides:

hashCode in class Object

instantiate

public Object instantiate()

Return the object.

Specified by:

instantiate in class DatabaseValueHolder

isEasilyInstantiated

public boolean isEasilyInstantiated()

INTERNAL: Answers if this valueholder is easy to instantiate.

Overrides:

isEasilyInstantiated in class DatabaseValueHolder

Returns:

true if getValue() won't trigger a database read.

isPessimisticLockingValueHolder

public boolean isPessimisticLockingValueHolder()

INTERNAL: 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 instantatiated all fields can not be reset. Note: This method is not thread-safe. It must be used in a synchronizaed manner

Specified by:

isPessimisticLockingValueHolder in class DatabaseValueHolder

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 synchronizaed manner

Specified by:

instantiateForUnitOfWorkValueHolder in class DatabaseValueHolder

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

Override the default serialization for a remote valueholder so as not to serialize the value Note: Changed for bug 3145211. We used to use the java.io.Serializable interface, but need to convert to Externalizable interface to avoid sending extra data through the superclass's serialization

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException

setID

protected void setID(ObjID anID)

Set the unique id.

setMapping

public void setMapping(DatabaseMapping mapping)

Set mapping

setQuery

public void setQuery(ObjectLevelReadQuery query)

Set the query.

setServerIndirectionObject

public void setServerIndirectionObject(Object serverIndirectionObject)

Set the object on the server that holds on to the remote value holder. Currently used only by TransparentIndirection so we can get back to the original IndirectContainer.

setTargetObjectPrimaryKeys

public void setTargetObjectPrimaryKeys(Object primaryKeys)

Set target object primary keys.

setValue

public void setValue(Object theValue)

Set the object.

Specified by:

setValue in interface ValueHolderInterface

Overrides:

setValue in class DatabaseValueHolder

setWrappedServerValueHolder

public void setWrappedServerValueHolder(ValueHolderInterface wrappedServerValueHolder)

Set the original value holder.

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Override the default serialization for a remote valueholder so as not to serialize the value Note: Changed for bug 3145211. We used to use the java.io.Serializable interface, but need to convert to Externalizable interface to avoid sending extra data through the superclass's serialization

Specified by:

writeExternal in interface Externalizable

Throws:

IOException