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Hibernate's core ORM functionality
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or .
*/
package org.hibernate.persister.walking.spi;
import java.util.HashSet;
import java.util.Set;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.loader.PropertyPath;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.persister.collection.QueryableCollection;
import org.hibernate.persister.entity.AbstractEntityPersister;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.type.Type;
import org.jboss.logging.Logger;
/**
* Implements metamodel graph walking. In layman terms, we are walking the graph of the users domain model as
* defined/understood by mapped associations.
*
* Initially grew as a part of the re-implementation of the legacy JoinWalker functionality to instead build LoadPlans.
* But this is really quite simple walking. Interesting events are handled by calling out to
* implementations of {@link AssociationVisitationStrategy} which really provide the real functionality of what we do
* as we walk.
*
* The visitor will walk the entire metamodel graph (the parts reachable from the given root)!!! It is up to the
* provided AssociationVisitationStrategy to tell it when to stop. The walker provides the walking; the strategy
* provides the semantics of what happens at certain points. Its really very similar to parsers and how parsing is
* generally split between syntax and semantics. Walker walks the syntax (associations, identifiers, etc) and when it
* calls out to the strategy the strategy then decides the semantics (literally, the meaning).
*
* The visitor will, however, stop if it sees a "duplicate" AssociationKey. In such a case, the walker would call
* {@link AssociationVisitationStrategy#foundCircularAssociation} and stop walking any further down that graph any
* further.
*
* @author Steve Ebersole
*/
public class MetamodelGraphWalker {
private static final Logger log = Logger.getLogger( MetamodelGraphWalker.class );
/**
* Entry point into walking the model graph of an entity according to its defined metamodel.
*
* @param strategy The semantics strategy
* @param persister The persister describing the entity to start walking from
*/
public static void visitEntity(AssociationVisitationStrategy strategy, EntityPersister persister) {
strategy.start();
try {
new MetamodelGraphWalker( strategy, persister.getFactory() )
.visitEntityDefinition( persister );
}
finally {
strategy.finish();
}
}
/**
* Entry point into walking the model graph of a collection according to its defined metamodel.
*
* @param strategy The semantics strategy
* @param persister The persister describing the collection to start walking from
*/
public static void visitCollection(AssociationVisitationStrategy strategy, CollectionPersister persister) {
strategy.start();
try {
new MetamodelGraphWalker( strategy, persister.getFactory() )
.visitCollectionDefinition( persister );
}
finally {
strategy.finish();
}
}
private final AssociationVisitationStrategy strategy;
private final SessionFactoryImplementor factory;
// todo : add a getDepth() method to PropertyPath
private PropertyPath currentPropertyPath = new PropertyPath();
public MetamodelGraphWalker(AssociationVisitationStrategy strategy, SessionFactoryImplementor factory) {
this.strategy = strategy;
this.factory = factory;
}
private void visitEntityDefinition(EntityDefinition entityDefinition) {
strategy.startingEntity( entityDefinition );
try {
AbstractEntityPersister persister = (AbstractEntityPersister) entityDefinition.getEntityPersister();
visitIdentifierDefinition( entityDefinition.getEntityKeyDefinition() );
visitAttributes( entityDefinition, persister );
}
finally {
strategy.finishingEntity( entityDefinition );
}
}
private void visitIdentifierDefinition(EntityIdentifierDefinition identifierDefinition) {
strategy.startingEntityIdentifier( identifierDefinition );
try {
// to make encapsulated and non-encapsulated composite identifiers work the same here, we "cheat" here a
// little bit and simply walk the attributes of the composite id in both cases.
// this works because the LoadPlans already build the top-level composite for composite ids
if ( identifierDefinition.isEncapsulated() ) {
// in the encapsulated composite id case that means we have a little bit of duplication between here and
// visitCompositeDefinition, but in the spirit of consistently handling composite ids, that is much better
// solution...
final EncapsulatedEntityIdentifierDefinition idAsEncapsulated = (EncapsulatedEntityIdentifierDefinition) identifierDefinition;
final AttributeDefinition idAttr = idAsEncapsulated.getAttributeDefinition();
if ( CompositionDefinition.class.isInstance( idAttr ) ) {
visitCompositeDefinition( (CompositionDefinition) idAttr );
}
}
else {
// NonEncapsulatedEntityIdentifierDefinition itself is defined as a CompositionDefinition
visitCompositeDefinition( (NonEncapsulatedEntityIdentifierDefinition) identifierDefinition );
}
}
finally {
strategy.finishingEntityIdentifier( identifierDefinition );
}
}
private void visitAttributes(AttributeSource attributeSource, AbstractEntityPersister sourcePersister) {
final Iterable attributeDefinitions = attributeSource.getAttributes();
if ( attributeDefinitions == null ) {
return;
}
for ( AttributeDefinition attributeDefinition : attributeDefinitions ) {
visitAttributeDefinition( attributeDefinition, sourcePersister);
}
}
private void visitAttributeDefinition(AttributeDefinition attributeDefinition, AbstractEntityPersister sourcePersister) {
final PropertyPath subPath = currentPropertyPath.append( attributeDefinition.getName() );
log.debug( "Visiting attribute path : " + subPath.getFullPath() );
if ( attributeDefinition.getType().isAssociationType() ) {
final AssociationAttributeDefinition associationAttributeDefinition =
(AssociationAttributeDefinition) attributeDefinition;
final AssociationKey associationKey = associationAttributeDefinition.getAssociationKey();
if ( isDuplicateAssociationKey( associationKey ) ) {
log.debug( "Property path deemed to be circular : " + subPath.getFullPath() );
strategy.foundCircularAssociation( associationAttributeDefinition );
// EARLY EXIT!!!
return;
}
if ( sourcePersister != null ) {
String[] columns = sourcePersister.toColumns(attributeDefinition.getName());
// Empty columns means that the attribute is not resolvable on this persister
if ( columns.length == 0 ) {
return;
}
}
}
boolean continueWalk = strategy.startingAttribute( attributeDefinition );
try {
if ( continueWalk ) {
final PropertyPath old = currentPropertyPath;
currentPropertyPath = subPath;
try {
final Type attributeType = attributeDefinition.getType();
if ( attributeType.isAssociationType() ) {
visitAssociation( (AssociationAttributeDefinition) attributeDefinition );
}
else if ( attributeType.isComponentType() ) {
visitCompositeDefinition( (CompositionDefinition) attributeDefinition );
}
}
finally {
currentPropertyPath = old;
}
}
}
finally {
strategy.finishingAttribute( attributeDefinition );
}
}
private void visitAssociation(AssociationAttributeDefinition attribute) {
// todo : do "too deep" checks; but see note about adding depth to PropertyPath
//
// may also need to better account for "composite fetches" in terms of "depth".
addAssociationKey( attribute.getAssociationKey() );
final AssociationAttributeDefinition.AssociationNature nature = attribute.getAssociationNature();
if ( nature == AssociationAttributeDefinition.AssociationNature.ANY ) {
visitAnyDefinition( attribute.toAnyDefinition() );
}
else if ( nature == AssociationAttributeDefinition.AssociationNature.COLLECTION ) {
visitCollectionDefinition( attribute.toCollectionDefinition() );
}
else {
visitEntityDefinition( attribute.toEntityDefinition() );
}
}
private void visitAnyDefinition(AnyMappingDefinition anyDefinition) {
strategy.foundAny( anyDefinition );
}
private void visitCompositeDefinition(CompositionDefinition compositionDefinition) {
strategy.startingComposite( compositionDefinition );
try {
visitAttributes( compositionDefinition, null );
}
finally {
strategy.finishingComposite( compositionDefinition );
}
}
private void visitCollectionDefinition(CollectionDefinition collectionDefinition) {
strategy.startingCollection( collectionDefinition );
try {
visitCollectionIndex( collectionDefinition );
visitCollectionElements( collectionDefinition );
}
finally {
strategy.finishingCollection( collectionDefinition );
}
}
private void visitCollectionIndex(CollectionDefinition collectionDefinition) {
final CollectionIndexDefinition collectionIndexDefinition = collectionDefinition.getIndexDefinition();
if ( collectionIndexDefinition == null ) {
return;
}
strategy.startingCollectionIndex( collectionIndexDefinition );
try {
log.debug( "Visiting index for collection : " + currentPropertyPath.getFullPath() );
currentPropertyPath = currentPropertyPath.append( "" );
try {
final Type collectionIndexType = collectionIndexDefinition.getType();
if ( collectionIndexType.isAnyType() ) {
visitAnyDefinition( collectionIndexDefinition.toAnyMappingDefinition() );
}
else if ( collectionIndexType.isComponentType() ) {
visitCompositeDefinition( collectionIndexDefinition.toCompositeDefinition() );
}
else if ( collectionIndexType.isAssociationType() ) {
visitEntityDefinition( collectionIndexDefinition.toEntityDefinition() );
}
}
finally {
currentPropertyPath = currentPropertyPath.getParent();
}
}
finally {
strategy.finishingCollectionIndex( collectionIndexDefinition );
}
}
private void visitCollectionElements(CollectionDefinition collectionDefinition) {
final CollectionElementDefinition elementDefinition = collectionDefinition.getElementDefinition();
strategy.startingCollectionElements( elementDefinition );
try {
final Type collectionElementType = elementDefinition.getType();
if ( collectionElementType.isAnyType() ) {
visitAnyDefinition( elementDefinition.toAnyMappingDefinition() );
}
else if ( collectionElementType.isComponentType() ) {
visitCompositeDefinition( elementDefinition.toCompositeElementDefinition() );
}
else if ( collectionElementType.isEntityType() ) {
if ( !collectionDefinition.getCollectionPersister().isOneToMany() ) {
final QueryableCollection queryableCollection = (QueryableCollection) collectionDefinition.getCollectionPersister();
addAssociationKey(
new AssociationKey(
queryableCollection.getTableName(),
queryableCollection.getElementColumnNames()
)
);
}
visitEntityDefinition( elementDefinition.toEntityDefinition() );
}
}
finally {
strategy.finishingCollectionElements( elementDefinition );
}
}
private final Set visitedAssociationKeys = new HashSet();
/**
* Add association key to indicate the association is being visited.
* @param associationKey - the association key.
* @throws WalkingException if the association with the specified association key
* has already been visited.
*/
protected void addAssociationKey(AssociationKey associationKey) {
if ( ! visitedAssociationKeys.add( associationKey ) ) {
throw new WalkingException(
String.format( "Association has already been visited: %s", associationKey )
);
}
strategy.associationKeyRegistered( associationKey );
}
/**
* Has an association with the specified key been visited already?
* @param associationKey - the association key.
* @return true, if the association with the specified association key has already been visited;
* false, otherwise.
*/
protected boolean isDuplicateAssociationKey(AssociationKey associationKey) {
return visitedAssociationKeys.contains( associationKey ) || strategy.isDuplicateAssociationKey( associationKey );
}
}