org.eclipse.persistence.internal.indirection.IndirectionPolicy Maven / Gradle / Ivy
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/*
* Copyright (c) 1998, 2019 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.internal.indirection;
import java.io.Serializable;
import java.util.Map;
import org.eclipse.persistence.exceptions.DescriptorException;
import org.eclipse.persistence.exceptions.IntegrityChecker;
import org.eclipse.persistence.indirection.ValueHolderInterface;
import org.eclipse.persistence.internal.descriptors.DescriptorIterator;
import org.eclipse.persistence.internal.identitymaps.CacheKey;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.internal.sessions.MergeManager;
import org.eclipse.persistence.internal.sessions.UnitOfWorkImpl;
import org.eclipse.persistence.internal.sessions.remote.RemoteValueHolder;
import org.eclipse.persistence.mappings.CollectionMapping;
import org.eclipse.persistence.mappings.DatabaseMapping;
import org.eclipse.persistence.mappings.ForeignReferenceMapping;
import org.eclipse.persistence.mappings.ObjectReferenceMapping;
import org.eclipse.persistence.mappings.foundation.AbstractTransformationMapping;
import org.eclipse.persistence.queries.ObjectLevelReadQuery;
import org.eclipse.persistence.queries.ReadObjectQuery;
import org.eclipse.persistence.queries.ReadQuery;
import org.eclipse.persistence.sessions.remote.DistributedSession;
/**
* Purpose
:
* An IndirectionPolicy acts as a 'rules' holder that determines
* the behavior of a ForeignReferenceMapping (or TransformationMapping)
* with respect to indirection, or lack thereof.
*
*
Description
:
* IndirectionPolicy is an abstract class that defines the protocol to be implemented by
* subclasses so that the assorted DatabaseMappings can use an assortment of
* indirection policies:
* - no indirection policy (read everything from database)
*
- basic indirection policy (use ValueHolders)
*
- transparent indirection policy (collections only)
*
- proxy indirection policy (transparent 1:1 indirection using JDK 1.3's
Proxy)
*
*
*
*
Responsibilities
:
*
* - instantiate the various IndirectionPolicies
*
*
*
* @see ForeignReferenceMapping
* @author Mike Norman
* @since TOPLink/Java 2.5
*/
public abstract class IndirectionPolicy implements Cloneable, Serializable {
protected DatabaseMapping mapping;
/**
* INTERNAL:
* Construct a new indirection policy.
*/
public IndirectionPolicy() {
super();
}
/**
* INTERNAL:
* Return a backup clone of the attribute.
*/
public Object backupCloneAttribute(Object attributeValue, Object clone, Object backup, UnitOfWorkImpl unitOfWork) {
return this.mapping.buildBackupCloneForPartObject(attributeValue, clone, backup, unitOfWork);
}
/**
* INTERNAL
* Return true if the refresh should refresh on this mapping or not.
*/
protected ReadObjectQuery buildCascadeQuery(MergeManager mergeManager) {
ReadObjectQuery query = new ReadObjectQuery();
if (this.mapping.getReferenceDescriptor() != null) {
query.setReferenceClass(this.mapping.getReferenceDescriptor().getJavaClass());
}
if (mergeManager.shouldCascadeAllParts()) {
query.cascadeAllParts();
query.refreshIdentityMapResult();
}
if (mergeManager.shouldCascadePrivateParts() && getForeignReferenceMapping().isPrivateOwned()) {
query.cascadePrivateParts();
query.refreshIdentityMapResult();
}
return query;
}
/**
* 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 abstract Object buildIndirectObject(ValueHolderInterface valueHolder);
/**
* INTERNAL:
* Clones itself.
*/
@Override
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
/**
* 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 abstract Object cloneAttribute(Object attributeValue, Object original, CacheKey cacheKey, Object clone, Integer refreshCascade, AbstractSession cloningSession, boolean buildDirectlyFromRow);
/**
* 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 Object extractPrimaryKeyForReferenceObject(Object referenceObject, AbstractSession session) {
return getOneToOneMapping().extractPrimaryKeysFromRealReferenceObject(referenceObject, session);
}
/**
* 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 abstract AbstractRecord extractReferenceRow(Object referenceObject);
/**
* 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 abstract void fixObjectReferences(Object object, Map objectDescriptors, Map processedObjects, ObjectLevelReadQuery query, DistributedSession session);
/**
* INTERNAL:
* Reduce casting clutter....
*/
protected CollectionMapping getCollectionMapping() {
return (CollectionMapping)this.mapping;
}
/**
* INTERNAL:
* Reduce casting clutter....
*/
protected ForeignReferenceMapping getForeignReferenceMapping() {
return (ForeignReferenceMapping)this.mapping;
}
/**
* INTERNAL:
* Return the database mapping that uses the indirection policy.
*/
public DatabaseMapping getMapping() {
return mapping;
}
/**
* INTERNAL:
* Reduce casting clutter....
*/
protected ObjectReferenceMapping getOneToOneMapping() {
return (ObjectReferenceMapping)this.mapping;
}
/**
* INTERNAL:
* Return the original indirection object for a unit of work indirection object.
*/
public abstract Object getOriginalIndirectionObject(Object unitOfWorkIndirectionObject, AbstractSession session);
/**
* INTERNAL:
* Return the original indirection object for a unit of work indirection object.
*/
public Object getOriginalIndirectionObjectForMerge(Object unitOfWorkIndirectionObject, AbstractSession session){
return getOriginalIndirectionObject(unitOfWorkIndirectionObject, session);
}
/**
* 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 abstract Object getOriginalValueHolder(Object unitOfWorkIndirectionObject, AbstractSession session);
/**
* INTERNAL:
* Return the "real" attribute value, as opposed to any wrapper.
* This will trigger the wrapper to instantiate the value.
*/
public abstract Object getRealAttributeValueFromObject(Object object, Object attribute);
/**
* INTERNAL:
* Trigger the instantiation of the value.
*/
public void instantiateObject(Object object, Object attribute) {
getRealAttributeValueFromObject(object, attribute);
}
/**
* INTERNAL:
* Reduce casting clutter....
*/
protected AbstractTransformationMapping getTransformationMapping() {
return (AbstractTransformationMapping)this.mapping;
}
/**
* INTERNAL:
* Extract and return the appropriate value from the
* specified remote value holder.
*/
public abstract Object getValueFromRemoteValueHolder(RemoteValueHolder remoteValueHolder);
/**
* INTERNAL:
* The method validateAttributeOfInstantiatedObject(Object attributeValue) fixes the value of the attributeValue
* in cases where it is null and indirection requires that it contain some specific data structure. Return whether this will happen.
* This method is used to help determine if indirection has been triggered
* @param attributeValue
* @return
* @see validateAttributeOfInstantiatedObject(Object attributeValue)
*/
public boolean isAttributeValueFullyBuilt(Object attributeValue){
return true;
}
/**
* INTERNAL:
* Initialize the indirection policy (Do nothing by default)
*/
public void initialize() {
}
/**
* INTERNAL:
*/
public boolean isWeavedObjectBasicIndirectionPolicy() {
return false;
}
/**
* INTERNAL:
* Iterate over the specified attribute value,
* heeding the settings in the iterator.
*/
public void iterateOnAttributeValue(DescriptorIterator iterator, Object attributeValue) {
if (attributeValue != null) {
this.mapping.iterateOnRealAttributeValue(iterator, attributeValue);
}
}
/**
* INTERNAL
* Replace the client value holder with the server value holder,
* after copying some of the settings from the client value holder.
*/
protected void mergeClientIntoServerValueHolder(RemoteValueHolder serverValueHolder, MergeManager mergeManager) {
serverValueHolder.setMapping(this.mapping);
serverValueHolder.setSession(mergeManager.getSession());
if (this.mapping.isForeignReferenceMapping()) {
ObjectLevelReadQuery query = buildCascadeQuery(mergeManager);
serverValueHolder.setQuery(query);
}
}
/**
* INTERNAL
* Replace the client value holder with the server value holder,
* after copying some of the settings from the client value holder.
*/
public abstract void mergeRemoteValueHolder(Object clientSideDomainObject, Object serverSideDomainObject, MergeManager mergeManager);
/**
* 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.
*/
public abstract Object nullValueFromRow();
/**
* INTERNAL:
* Return whether the specified object is instantiated.
*/
public abstract boolean objectIsInstantiated(Object object);
/**
* INTERNAL:
* Return whether the specified object can be instantiated without database access.
*/
public abstract boolean objectIsEasilyInstantiated(Object object);
/**
* INTERNAL:
* Return whether the specified object is instantiated, or if it has changes.
*/
public boolean objectIsInstantiatedOrChanged(Object object) {
return objectIsInstantiated(object);
}
/**
* INTERNAL:
* set the database mapping that uses the indirection policy.
*/
public void setMapping(DatabaseMapping mapping) {
this.mapping = mapping;
}
/**
* INTERNAL:
* Set the value of the appropriate attribute of target to attributeValue.
* In this case, simply place the value inside the target.
*/
public void setRealAttributeValueInObject(Object target, Object attributeValue) {
this.mapping.setAttributeValueInObject(target, attributeValue);
}
/**
* INTERNAL:
* Same functionality as setRealAttributeValueInObject(Object target, Object attributeValue) but allows
* overridden behavior for IndirectionPolicies that track changes
* @param target
* @param attributeValue
* @param allowChangeTracking
*/
public void setRealAttributeValueInObject(Object target, Object attributeValue, boolean allowChangeTracking) {
setRealAttributeValueInObject(target, attributeValue);
}
/**
* INTERNAL:
* set the source object into QueryBasedValueHolder.
* Used only by transparent indirection.
*/
public void setSourceObject(Object sourceObject, Object attributeValue) {
}
/**
* ADVANCED:
* This method will only change the behavior of TransparentIndirectionPolicy.
*
* IndirectList and IndirectSet can be configured not to instantiate the list from the
* database when you add and remove from them. IndirectList defaults to this behavior. When
* Set to true, the collection associated with this TransparentIndirection will be setup so as
* not to instantiate for adds and removes. The weakness of this setting for an IndirectSet is
* that when the set is not instantiated, if a duplicate element is added, it will not be
* detected until commit time.
*
*/
public void setUseLazyInstantiation(Boolean useLazyInstantiation) {
}
/**
* ADVANCED:
* Returns false unless this is a transparent indirection policy
*
* IndirectList and IndirectSet can be configured not to instantiate the list from the
* database when you add and remove from them. IndirectList defaults to this behavior. When
* Set to true, the collection associated with this TransparentIndirection will be setup so as
* not to instantiate for adds and removes. The weakness of this setting for an IndirectSet is
* that when the set is not instantiated, if a duplicate element is added, it will not be
* detected until commit time.
*/
public Boolean shouldUseLazyInstantiation() {
return false;
}
/**
* Reset the wrapper used to store the value.
* This is only required if a wrapper is used.
*/
public void reset(Object target) {
// Nothing by default.
}
/**
* INTERNAL:
* Return whether the indirection policy actually uses indirection.
* The default is true.
*/
public boolean usesIndirection() {
return true;
}
/**
* INTERNAL:
* Return whether the indirection policy uses transparent indirection.
* The default is false.
*/
public boolean usesTransparentIndirection(){
return false;
}
/**
* INTERNAL:
* Verify that the value of the attribute within an instantiated object
* is of the appropriate type for the indirection policy.
* If it is incorrect, throw an exception.
* If the value is null return a new indirection object to be used for the attribute.
*/
public Object validateAttributeOfInstantiatedObject(Object attributeValue) throws DescriptorException {
return attributeValue;
}
/**
* INTERNAL:
* Verify that the container policy is compatible with the
* indirection policy. If it is incorrect, add an exception to the
* integrity checker.
*/
public void validateContainerPolicy(IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Verify that attributeType is correct for the
* indirection policy. If it is incorrect, add an exception to the
* integrity checker.
*/
public void validateDeclaredAttributeType(Class attributeType, IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Verify that attributeType is an appropriate collection type for the
* indirection policy. If it is incorrect, add an exception to the integrity checker.
*/
public void validateDeclaredAttributeTypeForCollection(Class attributeType, IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Verify that getter returnType is correct for the
* indirection policy. If it is incorrect, add an exception
* to the integrity checker.
*/
public void validateGetMethodReturnType(Class returnType, IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Verify that getter returnType is an appropriate collection type for the
* indirection policy. If it is incorrect, add an exception to the integrity checker.
*/
public void validateGetMethodReturnTypeForCollection(Class returnType, IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Verify that setter parameterType is correct for the
* indirection policy. If it is incorrect, add an exception
* to the integrity checker.
*/
public void validateSetMethodParameterType(Class parameterType, IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Verify that setter parameterType is an appropriate collection type for the
* indirection policy. If it is incorrect, add an exception to the integrity checker.
*/
public void validateSetMethodParameterTypeForCollection(Class parameterType, IntegrityChecker checker) throws DescriptorException {
// by default, do nothing
}
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the batchQuery.
*/
public abstract Object valueFromBatchQuery(ReadQuery batchQuery, AbstractRecord row, ObjectLevelReadQuery originalQuery, CacheKey parentCacheKey);
/**
* 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.
*/
public abstract Object valueFromMethod(Object object, AbstractRecord row, AbstractSession session);
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the query.
*/
public abstract Object valueFromQuery(ReadQuery query, AbstractRecord row, Object sourceObject, AbstractSession session);
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the query.
*/
public abstract Object valueFromQuery(ReadQuery query, AbstractRecord row, AbstractSession session);
/**
* INTERNAL:
* Return the value to be stored in the object's attribute.
* This value is determined by the row.
*/
public abstract Object valueFromRow(Object object);
}