/*******************************************************************************
* Copyright (c) 1998, 2009 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.indirection;
import java.util.*;
import org.eclipse.persistence.queries.*;
import org.eclipse.persistence.sessions.remote.RemoteSession;
import org.eclipse.persistence.indirection.*;
import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.internal.descriptors.*;
import org.eclipse.persistence.internal.helper.*;
import org.eclipse.persistence.internal.sessions.remote.RemoteSessionController;
import org.eclipse.persistence.internal.sessions.remote.RemoteUnitOfWork;
import org.eclipse.persistence.internal.sessions.remote.RemoteValueHolder;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.internal.sessions.MergeManager;
import org.eclipse.persistence.internal.sessions.UnitOfWorkImpl;
import org.eclipse.persistence.internal.sessions.AbstractSession;
/**
* <h2>Purpose</h2>:
* BasicIndirectionPolicy implements the behavior necessary for a
* a ForeignReferenceMapping (or TransformationMapping) to
* use ValueHolders to delay the reading of objects from the database
* until they are actually needed.
*
* @see ForeignReferenceMapping
* @author Mike Norman
* @since TOPLink/Java 2.5
*/
public class BasicIndirectionPolicy extends IndirectionPolicy {
/**
* INTERNAL:
* Construct a new indirection policy.
*/
public BasicIndirectionPolicy() {
super();
}
/**
* INTERNAL:
* Return a backup clone of the attribute.
*/
public Object backupCloneAttribute(Object attributeValue, Object clone, Object backup, UnitOfWorkImpl unitOfWork) {
//no need to check if the attribute is a valueholder because closeAttribute
// should always be called first
ValueHolderInterface valueHolder = (ValueHolderInterface)attributeValue;// cast the value
ValueHolder result = new ValueHolder();
// delay instantiation until absolutely necessary
if ((!(valueHolder instanceof UnitOfWorkValueHolder)) || valueHolder.isInstantiated()) {
result.setValue(super.backupCloneAttribute(valueHolder.getValue(), clone, backup, unitOfWork));
} else {
((UnitOfWorkValueHolder)valueHolder).setBackupValueHolder(result);
}
return result;
}
/**
* INTERNAL: This method can be used when an Indirection Object is required
* to be built from a provided ValueHolderInterface object. This may be used
* for custom value holder types. Certain policies like the
* TransparentIndirectionPolicy may wrap the valueholder in another object.
*/
public Object buildIndirectObject(ValueHolderInterface valueHolder){
return valueHolder;
}
/**
* INTERNAL:
* Return a clone of the attribute.
* @param buildDirectlyFromRow indicates that we are building the clone
* directly from a row as opposed to building the original from the
* row, putting it in the shared cache, and then cloning the original.
*/
public Object cloneAttribute(Object attributeValue, Object original, Object clone, UnitOfWorkImpl unitOfWork, boolean buildDirectlyFromRow) {
ValueHolderInterface valueHolder = (ValueHolderInterface) attributeValue;
ValueHolderInterface result;
if (!buildDirectlyFromRow && unitOfWork.isOriginalNewObject(original)) {
// CR#3156435 Throw a meaningful exception if a serialized/dead value holder is detected.
// This can occur if an existing serialized object is attempt to be registered as new.
if ((valueHolder instanceof DatabaseValueHolder)
&& (! ((DatabaseValueHolder) valueHolder).isInstantiated())
&& (((DatabaseValueHolder) valueHolder).getSession() == null)
&& (! ((DatabaseValueHolder) valueHolder).isSerializedRemoteUnitOfWorkValueHolder())) {
throw DescriptorException.attemptToRegisterDeadIndirection(original, getMapping());
}
if (this.getMapping().getRelationshipPartner() == null) {
result = new ValueHolder();
result.setValue(this.getMapping().buildCloneForPartObject(valueHolder.getValue(), original, clone, unitOfWork, false));
} else {
//if I have a relationship partner trigger the indirection so that the value will be inserted
// because of this call the entire tree should be recursively cloned
AbstractRecord row = null;
if (valueHolder instanceof DatabaseValueHolder) {
row = ((DatabaseValueHolder)valueHolder).getRow();
}
result = this.getMapping().createUnitOfWorkValueHolder(valueHolder, original, clone, row, unitOfWork, buildDirectlyFromRow);
Object newObject = this.getMapping().buildCloneForPartObject(valueHolder.getValue(), original, clone, unitOfWork, false);
((UnitOfWorkValueHolder)result).privilegedSetValue(newObject);
((UnitOfWorkValueHolder)result).setInstantiated();
}
} else {
AbstractRecord row = null;
if (valueHolder instanceof DatabaseValueHolder) {
row = ((DatabaseValueHolder)valueHolder).getRow();
}
result = this.getMapping().createUnitOfWorkValueHolder(valueHolder, original, clone, row, unitOfWork, buildDirectlyFromRow);
}
return result;
}
/**
* INTERNAL:
* Return the primary key for the reference object (i.e. the object
* object referenced by domainObject and specified by mapping).
* This key will be used by a RemoteValueHolder.
*/
public Vector extractPrimaryKeyForReferenceObject(Object referenceObject, AbstractSession session) {
if (this.objectIsInstantiated(referenceObject)) {
return super.extractPrimaryKeyForReferenceObject(((ValueHolderInterface)referenceObject).getValue(), session);
} else {
return this.getOneToOneMapping().extractPrimaryKeysForReferenceObjectFromRow(this.extractReferenceRow(referenceObject));
}
}
/**
* INTERNAL:
* Return the reference row for the reference object.
* This allows the new row to be built without instantiating
* the reference object.
* Return null if the object has already been instantiated.
*/
public AbstractRecord extractReferenceRow(Object referenceObject) {
if (this.objectIsInstantiated(referenceObject)) {
return null;
} else {
return ((DatabaseValueHolder)referenceObject).getRow();
}
}
/**
* INTERNAL:
* An object has been serialized from the server to the client.
* Replace the transient attributes of the remote value holders
* with client-side objects.
*/
public void fixObjectReferences(Object object, Map objectDescriptors, Map processedObjects, ObjectLevelReadQuery query, RemoteSession session) {
Object attributeValue = this.getMapping().getAttributeValueFromObject(object);
//bug 4147755 if it is not a Remote Valueholder then treat as if there was no VH...
if (attributeValue instanceof RemoteValueHolder){
RemoteValueHolder rvh = (RemoteValueHolder)this.getMapping().getAttributeValueFromObject(object);
rvh.setSession(session);
rvh.setMapping(this.getMapping());
if ((!query.shouldMaintainCache()) && ((!query.shouldCascadeParts()) || (query.shouldCascadePrivateParts() && (!getMapping().isPrivateOwned())))) {
rvh.setQuery(null);
} else {
rvh.setQuery(query);
}
// set to uninstantiated since no objects are serialized past remote value holders
rvh.setUninstantiated();
}else{
this.getMapping().fixRealObjectReferences(object, objectDescriptors, processedObjects, query, session);
}
}
/**
* INTERNAL:
* Return the original indirection object for a unit of work indirection object.
* This is used when building a new object from the unit of work when the original fell out of the cache.
*/
public Object getOriginalIndirectionObject(Object unitOfWorkIndirectionObject, AbstractSession session) {
return this.getOriginalValueHolder(unitOfWorkIndirectionObject, session);
}
/**
* INTERNAL:
* Return the original indirection object for a unit of work indirection object.
*/
public Object getOriginalIndirectionObjectForMerge(Object unitOfWorkIndirectionObject, AbstractSession session) {
DatabaseValueHolder holder = (DatabaseValueHolder)getOriginalIndirectionObject(unitOfWorkIndirectionObject, session);
if (holder != null && holder.getSession()!= null){
holder.setSession(session);
}
return holder;
}
/**
* INTERNAL: Return the original valueHolder object. Access to the
* underlying valueholder may be required when serializing the valueholder
* or converting the valueHolder to another type.
*/
public Object getOriginalValueHolder(Object unitOfWorkIndirectionObject, AbstractSession session) {
if (unitOfWorkIndirectionObject instanceof UnitOfWorkValueHolder) {
ValueHolderInterface valueHolder = ((UnitOfWorkValueHolder) unitOfWorkIndirectionObject).getWrappedValueHolder();
if ((valueHolder == null) && session.isRemoteUnitOfWork()) {
// For remote session the original value holder is transient,
// so the value must be found in the registry or created.
RemoteSessionController controller = ((RemoteUnitOfWork) session).getParentSessionController();
Object id = ((UnitOfWorkValueHolder) unitOfWorkIndirectionObject).getWrappedValueHolderRemoteID();
if (id == null) {
// Must build a new value holder.
Object object = ((UnitOfWorkValueHolder) unitOfWorkIndirectionObject).getSourceObject();
AbstractRecord row = getMapping().getDescriptor().getObjectBuilder().buildRow(object, session);
ReadObjectQuery query = new ReadObjectQuery();
query.setSession(((RemoteUnitOfWork) session).getParent());
valueHolder = (ValueHolderInterface) getMapping().valueFromRow(row, null, query);
} else {
valueHolder = (ValueHolderInterface) controller.getRemoteValueHolders().get(id);
}
}
if ((valueHolder != null) && (valueHolder instanceof DatabaseValueHolder)) {
((DatabaseValueHolder) valueHolder).releaseWrappedValueHolder();
}
return valueHolder;
} else {
return unitOfWorkIndirectionObject;
}
}
/**
* Reset the wrapper used to store the value.
*/
public void reset(Object target) {
getMapping().setAttributeValueInObject(target, new ValueHolder());
}
/**
* INTERNAL:
* Return the "real" attribute value, as opposed to any wrapper.
* This will trigger the wrapper to instantiate the value.
*/
public Object getRealAttributeValueFromObject(Object object, Object attribute) {
if (attribute instanceof ValueHolderInterface) {
return ((ValueHolderInterface)attribute).getValue();
} else {
return attribute;
}
}
/**
* INTERNAL:
* Extract and return the appropriate value from the
* specified remote value holder.
*/
public Object getValueFromRemoteValueHolder(RemoteValueHolder remoteValueHolder) {
return remoteValueHolder.getValue();
}
/**
* INTERNAL:
* Iterate over the specified attribute value,
*/
public void iterateOnAttributeValue(DescriptorIterator iterator, Object attributeValue) {
iterator.iterateValueHolderForMapping((ValueHolderInterface)attributeValue, this.getMapping());
}
/**
* INTERNAL
* Replace the client value holder with the server value holder,
* after copying some of the settings from the client value holder.
*/
public void mergeRemoteValueHolder(Object clientSideDomainObject, Object serverSideDomainObject, MergeManager mergeManager) {
// This will always be a remote value holder coming from the server,
RemoteValueHolder serverValueHolder = (RemoteValueHolder)getMapping().getAttributeValueFromObject(serverSideDomainObject);
mergeClientIntoServerValueHolder(serverValueHolder, mergeManager);
getMapping().setAttributeValueInObject(clientSideDomainObject, serverValueHolder);
}
/**
* INTERNAL:
* Return the null value of the appropriate attribute. That is, the
* field from the database is NULL, return what should be
* placed in the object's attribute as a result.
* In this case, return an empty ValueHolder.
*/
public Object nullValueFromRow() {
return new ValueHolder();
}
/**
* INTERNAL:
* Return whether the specified object is instantiated.
*/
public boolean objectIsInstantiated(Object object) {
return ((ValueHolderInterface)object).isInstantiated();
}
/**
* INTERNAL:
* Set the value of the appropriate attribute of target to attributeValue.
* In this case, place the value inside the target's ValueHolder.
*/
public void setRealAttributeValueInObject(Object target, Object attributeValue) {
ValueHolderInterface holder = (ValueHolderInterface)this.getMapping().getAttributeValueFromObject(target);
if (holder == null) {
holder = new ValueHolder(attributeValue);
} else {
holder.setValue(attributeValue);
}
super.setRealAttributeValueInObject(target, holder);
}
/**
* INTERNAL:
* Return whether the type is appropriate for the indirection policy.
* In this case, the attribute type MUST be ValueHolderInterface.
*/
protected boolean typeIsValid(Class attributeType) {
return attributeType == ClassConstants.ValueHolderInterface_Class ||
attributeType == ClassConstants.WeavedAttributeValueHolderInterface_Class;
}
/**
* INTERNAL:
* Verify that the value of the attribute within an instantiated object
* is of the appropriate type for the indirection policy.
* In this case, the attribute must be non-null and it must be a
* ValueHolderInterface.
* If the value is null return a new indirection object to be used for the attribute.
*/
public Object validateAttributeOfInstantiatedObject(Object attributeValue) {
// PERF: If the value is null, create a new value holder instance for the attribute value,
// this allows for indirection attributes to not be instantiated in the constructor as they
// are typically replaced when reading or cloning so is very inefficient to initialize.
if (attributeValue == null) {
return new ValueHolder();
}
if (!(attributeValue instanceof ValueHolderInterface)) {
throw DescriptorException.valueHolderInstantiationMismatch(attributeValue, this.getMapping());
}
return attributeValue;
}
/**
* INTERNAL:
* Verify that attributeType is correct for the
* indirection policy. If it is incorrect, add an exception to the
* integrity checker.
* In this case, the attribute type MUST be ValueHolderInterface.
*/
public void validateDeclaredAttributeType(Class attributeType, IntegrityChecker checker) throws DescriptorException {
super.validateDeclaredAttributeType(attributeType, checker);
if (!this.typeIsValid(attributeType)) {
checker.handleError(DescriptorException.attributeAndMappingWithIndirectionMismatch(this.getMapping()));
}
}
/**
* INTERNAL:
* Verify that getter returnType is correct for the
* indirection policy. If it is incorrect, add an exception
* to the integrity checker.
* In this case, the return type MUST be ValueHolderInterface.
*/
public void validateGetMethodReturnType(Class returnType, IntegrityChecker checker) throws DescriptorException {
super.validateGetMethodReturnType(returnType, checker);
if (!this.typeIsValid(returnType)) {
checker.handleError(DescriptorException.returnAndMappingWithIndirectionMismatch(this.getMapping()));
}
}
/**
* INTERNAL:
* Verify that setter parameterType is correct for the
* indirection policy. If it is incorrect, add an exception
* to the integrity checker.
* In this case, the parameter type MUST be ValueHolderInterface.
*/
public void validateSetMethodParameterType(Class parameterType, IntegrityChecker checker) throws DescriptorException {
super.validateSetMethodParameterType(parameterType, checker);
if (!this.typeIsValid(parameterType)) {
checker.handleError(DescriptorException.parameterAndMappingWithIndirectionMismatch(this.getMapping()));
}
}
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the batchQuery.
* In this case, wrap the query in a ValueHolder for later invocation.
*/
public Object valueFromBatchQuery(ReadQuery batchQuery, AbstractRecord row, ObjectLevelReadQuery originalQuery) {
return new BatchValueHolder(batchQuery, row, this.getForeignReferenceMapping(), originalQuery);
}
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by invoking the appropriate
* method on the object and passing it the row and session.
* In this case, wrap the row in a ValueHolder for later use.
*/
public Object valueFromMethod(Object object, AbstractRecord row, AbstractSession session) {
return new TransformerBasedValueHolder(this.getTransformationMapping().getAttributeTransformer(), object, row, session);
}
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the query.
* In this case, wrap the query in a ValueHolder for later invocation.
*/
public Object valueFromQuery(ReadQuery query, AbstractRecord row, AbstractSession session) {
return new QueryBasedValueHolder(query, row, session);
}
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the row.
* In this case, simply wrap the object in a ValueHolder.
*/
public Object valueFromRow(Object object) {
return new ValueHolder(object);
}
}