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package oracle.toplink.essentials.descriptors.changetracking;
import java.util.*;
import oracle.toplink.essentials.internal.sessions.ObjectChangeSet;
import oracle.toplink.essentials.queryframework.*;
import oracle.toplink.essentials.internal.descriptors.*;
import oracle.toplink.essentials.internal.sessions.MergeManager;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
import oracle.toplink.essentials.mappings.*;
import oracle.toplink.essentials.descriptors.DescriptorEvent;
import oracle.toplink.essentials.descriptors.DescriptorEventManager;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
import oracle.toplink.essentials.internal.helper.IdentityHashtable;
/**
* PUBLIC:
* A DeferredChangeDetectionPolicy defers all change detection to the UnitOfWork's
* change detection process. Essentially, the calculateChanges() method will run
* for all objects in a UnitOfWork. This is the default ObjectChangePolicy.
*
* @author Tom Ware
*/
public class DeferredChangeDetectionPolicy implements ObjectChangePolicy, java.io.Serializable {
/**
* INTERNAL:
* calculateChanges creates a change set for a particular object. In DeferredChangeDetectionPolicy
* all mappings will be compared against a backup copy of the object.
* @return oracle.toplink.essentials.changesets.ObjectChangeSet an object change set describing
* the changes to this object
* @param java.lang.Object clone the Object to compute a change set for
* @param java.lang.Object backUp the old version of the object to use for comparison
* @param oracle.toplink.essentials.internal.sessions.UnitOfWorkChangeSet the change set to add changes to
* @param Session the current session
* @param Descriptor the descriptor for this object
* @param shouldRiseEvent indicates whether PreUpdate event should be risen (usually true)
*/
public ObjectChangeSet calculateChanges(Object clone, Object backUp, oracle.toplink.essentials.internal.sessions.UnitOfWorkChangeSet changeSet, AbstractSession session, ClassDescriptor descriptor, boolean shouldRiseEvent) {
boolean isNew = ((backUp == null) || ((((UnitOfWorkImpl)session).isObjectNew(clone)) && (!descriptor.isAggregateDescriptor())));
// PERF: Avoid events if no listeners.
if (descriptor.getEventManager().hasAnyEventListeners() && shouldRiseEvent) {
// The query is built for compatability to old event mechanism.
WriteObjectQuery writeQuery = new WriteObjectQuery(clone.getClass());
writeQuery.setObject(clone);
writeQuery.setBackupClone(backUp);
writeQuery.setSession(session);
writeQuery.setDescriptor(descriptor);
descriptor.getEventManager().executeEvent(new DescriptorEvent(DescriptorEventManager.PreWriteEvent, writeQuery));
if (isNew) {
descriptor.getEventManager().executeEvent(new DescriptorEvent(DescriptorEventManager.PreInsertEvent, writeQuery));
} else {
descriptor.getEventManager().executeEvent(new DescriptorEvent(DescriptorEventManager.PreUpdateEvent, writeQuery));
}
}
ObjectChangeSet changes = createObjectChangeSet(clone, backUp, changeSet, isNew, session, descriptor);
changes.setShouldModifyVersionField((Boolean)((UnitOfWorkImpl)session).getOptimisticReadLockObjects().get(clone));
if (changes.hasChanges() || changes.hasForcedChanges()) {
return changes;
}
return null;
}
/**
* INTERNAL:
* This is a place holder for reseting the listener on one of the subclasses
*/
public void clearChanges(Object object, UnitOfWorkImpl uow, ClassDescriptor descriptor) {
}
/**
* INTERNAL:
* Create ObjectChangeSet
*/
public ObjectChangeSet createObjectChangeSet(Object clone, Object backUp, oracle.toplink.essentials.internal.sessions.UnitOfWorkChangeSet changeSet, boolean isNew, AbstractSession session, ClassDescriptor descriptor) {
return this.createObjectChangeSetThroughComparison(clone, backUp, changeSet, isNew, session, descriptor);
}
/**
* INTERNAL:
* Create ObjectChangeSet
*/
public ObjectChangeSet createObjectChangeSetThroughComparison(Object clone, Object backUp, oracle.toplink.essentials.internal.sessions.UnitOfWorkChangeSet changeSet, boolean isNew, AbstractSession session, ClassDescriptor descriptor) {
ObjectBuilder builder = descriptor.getObjectBuilder();
ObjectChangeSet changes = builder.createObjectChangeSet(clone, changeSet, isNew, session);
// The following code deals with reads that force changes to the flag associated with optimistic locking.
if ((descriptor.usesOptimisticLocking()) && (changes.getPrimaryKeys() != null)) {
changes.setOptimisticLockingPolicyAndInitialWriteLockValue(descriptor.getOptimisticLockingPolicy(), session);
}
// PERF: Avoid synchronized enumerator as is concurrency bottleneck.
Vector mappings = descriptor.getMappings();
int mappingsSize = mappings.size();
for (int index = 0; index < mappingsSize; index++) {
DatabaseMapping mapping = (DatabaseMapping)mappings.get(index);
changes.addChange(mapping.compareForChange(clone, backUp, changes, session));
}
return changes;
}
/**
* INTERNAL:
* This method is used to dissable changetracking temporarily
*/
public void dissableEventProcessing(Object changeTracker){
//no-op
}
/**
* INTERNAL:
* This method is used to enable changetracking temporarily
*/
public void enableEventProcessing(Object changeTracker){
//no-op
}
/**
* INTERNAL:
* Return true if the Object should be compared, false otherwise. In DeferredChangeDetectionPolicy,
* true is always returned since always allow the UnitOfWork to calculate changes.
* @param java.lang.Object object - the object that will be compared
* @param oracle.toplink.essentials.publicinterface.UnitOfWork unitOfWork - the active unitOfWork
* @param oracle.toplink.essentials.publicinterface.Descriptor descriptor - the descriptor for the current object
*/
public boolean shouldCompareForChange(Object object, UnitOfWorkImpl unitOfWork, ClassDescriptor descriptor) {
return true;
}
/**
* INTERNAL:
* Build back up clone. Used if clone is new because listener should not be set.
*/
public Object buildBackupClone(Object clone, ObjectBuilder builder, UnitOfWorkImpl uow) {
return builder.buildBackupClone(clone, uow);
}
/**
* INTERNAL:
* Assign Changelistner to an aggregate object
*/
public void setAggregateChangeListener(Object parent, Object aggregate, UnitOfWorkImpl uow, ClassDescriptor descriptor, String mappingAttribute){
//no-op
}
/**
* INTERNAL:
* Set ChangeListener for the clone
*/
public void setChangeListener(Object clone, UnitOfWorkImpl uow, ClassDescriptor descriptor) {
//no-op
}
/**
* INTERNAL:
* Set the ObjectChangeSet on the Listener, initially used for aggregate support
*/
public void setChangeSetOnListener(ObjectChangeSet objectChangeSet, Object clone){
//no-op
}
/**
* INTERNAL:
* Clear changes in the ChangeListener of the clone
*/
public void updateWithChanges(Object clone, ObjectChangeSet objectChangeSet, UnitOfWorkImpl uow, ClassDescriptor descriptor) {
if (objectChangeSet == null) {
return;
}
Object backupClone = uow.getCloneMapping().get(clone);
if (backupClone != null) {
MergeManager mergeManager = new MergeManager(uow);
mergeManager.setCascadePolicy(MergeManager.NO_CASCADE);
descriptor.getObjectBuilder().mergeChangesIntoObject(backupClone, objectChangeSet, clone, mergeManager);
}
clearChanges(clone, uow, descriptor);
}
/**
* INTERNAL:
* This may cause a property change event to be raised to a listner in the case that a listener exists.
* If there is no listener then this call is a no-op
*/
public void raiseInternalPropertyChangeEvent(Object source, String propertyName, Object oldValue, Object newValue){
//no-op
}
/**
* INTERNAL:
* This method is used to revert an object within the unit of work
* @param cloneMapping may not be the same as whats in the uow
*/
public void revertChanges(Object clone, ClassDescriptor descriptor, UnitOfWorkImpl uow, IdentityHashtable cloneMapping) {
cloneMapping.put(clone, buildBackupClone(clone, descriptor.getObjectBuilder(), uow));
clearChanges(clone, uow, descriptor);
}
/**
* INTERNAL:
* initialize the Policy
*/
public void initialize(AbstractSession session, ClassDescriptor descriptor) {
//do nothing
}
/**
* Used to track instances of the change policies without doing an instance of check
*/
public boolean isDeferredChangeDetectionPolicy(){
return true;
}
/**
* Used to track instances of the change policies without doing an instance of check
*/
public boolean isObjectChangeTrackingPolicy(){
return false;
}
/**
* Used to track instances of the change policies without doing an instance of check
*/
public boolean isAttributeChangeTrackingPolicy(){
return false;
}
}
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