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package org.apache.cayenne.access;
import org.apache.cayenne.DataChannelListener;
import org.apache.cayenne.ObjectId;
import org.apache.cayenne.PersistenceState;
import org.apache.cayenne.Persistent;
import org.apache.cayenne.access.ObjectStore.SnapshotEventDecorator;
import org.apache.cayenne.access.event.SnapshotEvent;
import org.apache.cayenne.graph.GraphChangeHandler;
import org.apache.cayenne.graph.GraphDiff;
import org.apache.cayenne.graph.GraphEvent;
import org.apache.cayenne.reflect.AttributeProperty;
import org.apache.cayenne.reflect.ClassDescriptor;
import org.apache.cayenne.reflect.Property;
import org.apache.cayenne.reflect.PropertyVisitor;
import org.apache.cayenne.reflect.ToManyProperty;
import org.apache.cayenne.reflect.ToOneProperty;
import org.apache.cayenne.util.Util;
/**
* A listener of GraphEvents sent by the DataChannel that merges changes to the
* DataContext.
*
* @since 1.2
*/
// TODO: andrus, 11/25/2006 - this logic is the same as the logic in DataRowUtils used to
// merge snapshot changes. Any way to reconclie the two? (in fact DataRowUtils is more
// comprehensive)
class DataContextMergeHandler implements GraphChangeHandler, DataChannelListener {
private boolean active;
private DataContext context;
DataContextMergeHandler(DataContext context) {
this.active = true;
this.context = context;
}
void setActive(boolean active) {
this.active = active;
}
/**
* Returns true if this object is active and an event came from our channel, but did
* not originate in it.
*/
private boolean shouldProcessEvent(GraphEvent e) {
if (!active) {
return false;
}
// this effectively filters out all events that are not coming from peers or
// grandparents...
return e.getSource() == context.getChannel()
&& e.getPostedBy() != context
&& e.getPostedBy() != context.getChannel();
// the first condition (e.getSource() == context.getChannel()) is actually always
// 'true' because of how the listener is registered. Still keep it here as an
// extra safegurad
}
private Property propertyForId(Object nodeId, String propertyName) {
ClassDescriptor descriptor = context.getEntityResolver().getClassDescriptor(
((ObjectId) nodeId).getEntityName());
return descriptor.getProperty(propertyName);
}
// *** GraphEventListener methods
public void graphChanged(GraphEvent event) {
// parent received external change
if (shouldProcessEvent(event)) {
// temp kludge - see TODO in ObjectStore.snapshotsChanged(..)
GraphDiff diff = event.getDiff();
if (diff instanceof SnapshotEventDecorator) {
SnapshotEvent decoratedEvent = ((SnapshotEventDecorator) diff).getEvent();
context.getObjectStore().processSnapshotEvent(decoratedEvent);
}
else {
synchronized (context.getObjectStore()) {
diff.apply(this);
}
}
// repost channel change event for our own children
context.fireDataChannelChanged(event.getPostedBy(), event.getDiff());
}
}
public void graphFlushed(GraphEvent event) {
// peer is committed
if (shouldProcessEvent(event)) {
event.getDiff().apply(this);
// repost as change event for our own children
context.fireDataChannelChanged(event.getPostedBy(), event.getDiff());
}
}
public void graphRolledback(GraphEvent event) {
// TODO: andrus, 3/26/2006 - enable this once all ObjectStore diffs implement
// working undo operation
// if(shouldProcessEvent(e)) {
// event.getDiff().undo(this);
// }
}
// *** GraphChangeHandler methods
public void nodeIdChanged(Object nodeId, Object newId) {
context.getObjectStore().processIdChange(nodeId, newId);
}
public void nodeCreated(Object nodeId) {
// noop
}
public void nodeRemoved(Object nodeId) {
ObjectStore os = context.getObjectStore();
synchronized (os) {
os.processDeletedID(nodeId);
}
}
public void nodePropertyChanged(
Object nodeId,
String property,
Object oldValue,
Object newValue) {
Persistent object = (Persistent) context.getGraphManager().getNode(nodeId);
if (object != null && object.getPersistenceState() != PersistenceState.HOLLOW) {
// do not override local changes....
Property p = propertyForId(nodeId, property);
if (Util.nullSafeEquals(p.readPropertyDirectly(object), oldValue)) {
p.writePropertyDirectly(object, oldValue, newValue);
}
}
}
public void arcCreated(Object nodeId, Object targetNodeId, Object arcId) {
arcChanged(nodeId, targetNodeId, arcId);
}
public void arcDeleted(Object nodeId, Object targetNodeId, Object arcId) {
arcChanged(nodeId, targetNodeId, arcId);
}
// works the same for add and remove as long as we don't get too smart per TODO below.
private void arcChanged(Object nodeId, Object targetNodeId, Object arcId) {
final Persistent source = (Persistent) context.getGraphManager().getNode(nodeId);
if (source != null && source.getPersistenceState() != PersistenceState.HOLLOW) {
final int state = source.getPersistenceState();
Property p = propertyForId(nodeId, arcId.toString());
p.visit(new PropertyVisitor() {
public boolean visitAttribute(AttributeProperty property) {
return false;
}
public boolean visitToMany(ToManyProperty property) {
if (state == PersistenceState.COMMITTED) {
property.invalidate(source);
}
return false;
}
public boolean visitToOne(ToOneProperty property) {
if (state == PersistenceState.COMMITTED) {
property.invalidate(source);
}
// TODO: andrus, 11/25/2006 - handle replacement of clean properties
// of dirty objects. See DataRowUtils for details.
return false;
}
});
}
}
}