/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008-2011, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.event.internal;
import java.util.Collection;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Set;
import org.hibernate.AssertionFailure;
/**
* EventCache is a Map implementation that can be used by an event
* listener to keep track of entities involved in the operation
* being performed. This implementation allows entities to be added
* to the EventCache before the operation has cascaded to that
* entity.
* <p/>
* There are some restriction;
* <ul>
* <li>the same value cannot be associated with more than one key</li>
* <li>Methods that return collections (e.g., {@link #keySet()},
* {@link #values()}, {@link #entrySet()}) return an
* unnmodifiable view of the collection.</li>
* </ul>
* <p/>
* The following methods can be used by event listeners (and other
* classes) in the same package to add entities to an EventCache
* and indicate if the operation is being performed on the entity:<p/>
* {@link EventCache#put(Object entity, Object copy, boolean isOperatedOn)}
* <p/>
* The following method can be used by event listeners (and other
* classes) in the same package to indicate that the operation is being
* performed on an entity already in the EventCache:
* {@link EventCache#setOperatedOn(Object entity, boolean isOperatedOn)
*
* @author Gail Badner
*/
class EventCache implements Map {
private Map<Object,Object> entityToCopyMap = new IdentityHashMap<Object,Object>(10);
// key is an entity involved with the operation performed by the listener;
// value can be either a copy of the entity or the entity itself
private Map<Object,Object> copyToEntityMap = new IdentityHashMap<Object,Object>( 10 );
// maintains the inverse of the entityToCopyMap for performance reasons.
private Map<Object,Boolean> entityToOperatedOnFlagMap = new IdentityHashMap<Object,Boolean>( 10 );
// key is an entity involved with the operation performed by the listener;
// value is a flag indicating if the listener explicitly operates on the entity
/**
* Clears the EventCache.
*/
public void clear() {
entityToCopyMap.clear();
copyToEntityMap.clear();
entityToOperatedOnFlagMap.clear();
}
/**
* Returns true if this EventCache contains a mapping for the specified entity.
* @param entity must be non-null
* @return true if this EventCache contains a mapping for the specified entity
* @throws NullPointerException if entity is null
*/
public boolean containsKey(Object entity) {
if ( entity == null ) {
throw new NullPointerException( "null entities are not supported by " + getClass().getName() );
}
return entityToCopyMap.containsKey( entity );
}
/**
* Returns true if this EventCache maps an entity to the specified copy.
* @param copy must be non-null
* @return true if this EventCache maps an entity to the specified copy
* @throws NullPointerException if copy is null
*/
public boolean containsValue(Object copy) {
if ( copy == null ) {
throw new NullPointerException( "null copies are not supported by " + getClass().getName() );
}
return copyToEntityMap.containsKey( copy );
}
/**
* Returns an unmodifiable set view of the entity-to-copy mappings contained in this EventCache.
* @return an unmodifiable set view of the entity-to-copy mappings contained in this EventCache
*
* @see {@link Collections#unmodifiableSet(java.util.Set)}
*/
public Set entrySet() {
return Collections.unmodifiableSet( entityToCopyMap.entrySet() );
}
/**
* Returns the copy to which this EventCache maps the specified entity.
* @param entity must be non-null
* @return the copy to which this EventCache maps the specified entity
* @throws NullPointerException if entity is null
*/
public Object get(Object entity) {
if ( entity == null ) {
throw new NullPointerException( "null entities are not supported by " + getClass().getName() );
}
return entityToCopyMap.get( entity );
}
/**
* Returns true if this EventCache contains no entity-copy mappings.
* @return true if this EventCache contains no entity-copy mappings
*/
public boolean isEmpty() {
return entityToCopyMap.isEmpty();
}
/**
* Returns an unmodifiable set view of the entities contained in this EventCache
* @return an unmodifiable set view of the entities contained in this EventCache
*
* @see {@link Collections#unmodifiableSet(java.util.Set)}
*/
public Set keySet() {
return Collections.unmodifiableSet( entityToCopyMap.keySet() );
}
/**
* Associates the specified entity with the specified copy in this EventCache;
* @param entity must be non-null
* @param copy must be non- null and must not be associated with any other entity in this EntityCache.
* @return previous copy associated with specified entity, or null if
* there was no mapping for entity.
* @throws NullPointerException if entity or copy is null
* @throws IllegalStateException if the specified copy is already associated with a different entity.
*/
public Object put(Object entity, Object copy) {
return put( entity, copy, Boolean.FALSE );
}
/**
* Associates the specified entity with the specified copy in this EventCache;
* @param entity must be non-null
* @param copy must be non- null and must not be associated with any other entity in this EntityCache.
* @param isOperatedOn indicates if the operation is performed on the entity.
*
* @return previous copy associated with specified entity, or null if
* there was no mapping for entity.
* @throws NullPointerException if entity or copy is null
* @throws IllegalStateException if the specified copy is already associated with a different entity.
*/
/* package-private */ Object put(Object entity, Object copy, boolean isOperatedOn) {
if ( entity == null || copy == null ) {
throw new NullPointerException( "null entities and copies are not supported by " + getClass().getName() );
}
Object oldCopy = entityToCopyMap.put( entity, copy );
Boolean oldOperatedOn = entityToOperatedOnFlagMap.put( entity, isOperatedOn );
Object oldEntity = copyToEntityMap.put( copy, entity );
if ( oldCopy == null ) {
if ( oldEntity != null ) {
throw new IllegalStateException( "An entity copy was already assigned to a different entity." );
}
if ( oldOperatedOn != null ) {
throw new IllegalStateException( "entityToOperatedOnFlagMap contains an entity, but entityToCopyMap does not." );
}
}
else {
if ( oldCopy != copy ) {
// Replaced an entity copy with a new copy; need to remove the oldCopy from copyToEntityMap
// to synch things up.
Object removedEntity = copyToEntityMap.remove( oldCopy );
if ( removedEntity != entity ) {
throw new IllegalStateException( "An unexpected entity was associated with the old entity copy." );
}
if ( oldEntity != null ) {
throw new IllegalStateException( "A new entity copy is already associated with a different entity." );
}
}
else {
// Replaced an entity copy with the same copy in entityToCopyMap.
// Make sure that copy is associated with the same entity in copyToEntityMap.
if ( oldEntity != entity ) {
throw new IllegalStateException( "An entity copy was associated with a different entity than provided." );
}
}
if ( oldOperatedOn == null ) {
throw new IllegalStateException( "entityToCopyMap contained an entity, but entityToOperatedOnFlagMap did not." );
}
}
return oldCopy;
}
/**
* Copies all of the mappings from the specified map to this EventCache
* @param map keys and values must be non-null
* @throws NullPointerException if any map keys or values are null
*/
public void putAll(Map map) {
for ( Object o : map.entrySet() ) {
Entry entry = (Entry) o;
put( entry.getKey(), entry.getValue() );
}
}
/**
* Removes the mapping for this entity from this EventCache if it is present
* @param entity must be non-null
* @return previous value associated with specified entity, or null if there was no mapping for entity.
* @throws NullPointerException if entity is null
*/
public Object remove(Object entity) {
if ( entity == null ) {
throw new NullPointerException( "null entities are not supported by " + getClass().getName() );
}
Boolean oldOperatedOn = entityToOperatedOnFlagMap.remove( entity );
Object oldCopy = entityToCopyMap.remove( entity );
Object oldEntity = oldCopy != null ? copyToEntityMap.remove( oldCopy ) : null;
if ( oldCopy == null ) {
if ( oldOperatedOn != null ) {
throw new IllegalStateException( "Removed entity from entityToOperatedOnFlagMap, but entityToCopyMap did not contain the entity." );
}
}
else {
if ( oldEntity == null ) {
throw new IllegalStateException( "Removed entity from entityToCopyMap, but copyToEntityMap did not contain the entity." );
}
if ( oldOperatedOn == null ) {
throw new IllegalStateException( "entityToCopyMap contained an entity, but entityToOperatedOnFlagMap did not." );
}
if ( oldEntity != entity ) {
throw new IllegalStateException( "An entity copy was associated with a different entity than provided." );
}
}
return oldCopy;
}
/**
* Returns the number of entity-copy mappings in this EventCache
* @return the number of entity-copy mappings in this EventCache
*/
public int size() {
return entityToCopyMap.size();
}
/**
* Returns an unmodifiable set view of the entity copies contained in this EventCache.
* @return an unmodifiable set view of the entity copies contained in this EventCache
*
* @see {@link Collections#unmodifiableSet(java.util.Set)}
*/
public Collection values() {
return Collections.unmodifiableCollection( entityToCopyMap.values() );
}
/**
* Returns true if the listener is performing the operation on the specified entity.
* @param entity must be non-null
* @return true if the listener is performing the operation on the specified entity.
* @throws NullPointerException if entity is null
*/
public boolean isOperatedOn(Object entity) {
if ( entity == null ) {
throw new NullPointerException( "null entities are not supported by " + getClass().getName() );
}
return entityToOperatedOnFlagMap.get( entity );
}
/**
* Set flag to indicate if the listener is performing the operation on the specified entity.
* @param entity must be non-null and this EventCache must contain a mapping for this entity
* @throws NullPointerException if entity is null
* @throws AssertionFailure if this EventCache does not contain a mapping for the specified entity
*/
/* package-private */ void setOperatedOn(Object entity, boolean isOperatedOn) {
if ( entity == null ) {
throw new NullPointerException( "null entities are not supported by " + getClass().getName() );
}
if ( ! entityToOperatedOnFlagMap.containsKey( entity ) ||
! entityToCopyMap.containsKey( entity ) ) {
throw new AssertionFailure( "called EventCache.setOperatedOn() for entity not found in EventCache" );
}
entityToOperatedOnFlagMap.put( entity, isOperatedOn );
}
/**
* Returns an unmodifiable map view of the copy-entity mappings
* @return an unmodifiable map view of the copy-entity mappings
*
* @see {@link Collections#unmodifiableMap(java.util.Map)}
*/
public Map invertMap() {
return Collections.unmodifiableMap( copyToEntityMap );
}
}