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package oracle.toplink.essentials.internal.indirection;
import java.util.*;
import oracle.toplink.essentials.queryframework.*;
import oracle.toplink.essentials.indirection.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.descriptors.*;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.internal.sessions.AbstractRecord;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
import oracle.toplink.essentials.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:
* 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 relationsip partner trigger the indiretion 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:
* 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) {
if (unitOfWorkIndirectionObject instanceof UnitOfWorkValueHolder) {
ValueHolderInterface valueHolder = ((UnitOfWorkValueHolder)unitOfWorkIndirectionObject).getWrappedValueHolder();
if ((valueHolder != null) && (valueHolder instanceof DatabaseValueHolder)) {
((DatabaseValueHolder)valueHolder).releaseWrappedValueHolder();
}
return valueHolder;
} else {
return unitOfWorkIndirectionObject;
}
}
/**
* 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) {
// Changed for CR 4245. Use a static reference instead of .class
if (ClassConstants.ValueHolderInterface_Class.isAssignableFrom(attribute.getClass())) {
return ((ValueHolderInterface)attribute).getValue();
} else {
return attribute;
}
}
/**
* INTERNAL:
* Iterate over the specified attribute value,
*/
public void iterateOnAttributeValue(DescriptorIterator iterator, Object attributeValue) {
iterator.iterateValueHolderForMapping((ValueHolderInterface)attributeValue, this.getMapping());
}
/**
* 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 inefficent 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 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);
}
}
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