cascadingaction.java

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//$Id: CascadingAction.java 10458 2006-09-06 14:07:22Z epbernard $
package org.hibernate.engine;

import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.LockMode;
import org.hibernate.ReplicationMode;
import org.hibernate.TransientObjectException;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.collection.PersistentCollection;
import org.hibernate.event.EventSource;
import org.hibernate.type.CollectionType;
import org.hibernate.type.Type;
import org.hibernate.type.EntityType;

/**
 * A session action that may be cascaded from parent entity to its children
 *
 * @author Gavin King
 */
public abstract class CascadingAction {

	private static final Log log = LogFactory.getLog( CascadingAction.class );


	// the CascadingAction contract ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	/**
	 * protected constructor
	 */
	CascadingAction() {
	}

	/**
	 * Cascade the action to the child object.
	 *
	 * @param session The session within which the cascade is occuring.
	 * @param child The child to which cascading should be performed.
	 * @param entityName The child's entity name
	 * @param anything Anything ;)  Typically some form of cascade-local cache
	 * which is specific to each CascadingAction type
	 * @param isCascadeDeleteEnabled Are cascading deletes enabled.
	 * @throws HibernateException
	 */
	public abstract void cascade(
			EventSource session,
			Object child,
			String entityName,
			Object anything,
			boolean isCascadeDeleteEnabled) throws HibernateException;

	/**
	 * Given a collection, get an iterator of the children upon which the
	 * current cascading action should be visited.
	 *
	 * @param session The session within which the cascade is occuring.
	 * @param collectionType The mapping type of the collection.
	 * @param collection The collection instance.
	 * @return The children iterator.
	 */
	public abstract Iterator getCascadableChildrenIterator(
			EventSource session,
			CollectionType collectionType,
			Object collection);

	/**
	 * Does this action potentially extrapolate to orphan deletes?
	 *
	 * @return True if this action can lead to deletions of orphans.
	 */
	public abstract boolean deleteOrphans();


	/**
	 * Does the specified cascading action require verification of no cascade validity?
	 *
	 * @return True if this action requires no-cascade verification; false otherwise.
	 */
	public boolean requiresNoCascadeChecking() {
		return false;
	}

	/**
	 * Called (in the case of {@link #requiresNoCascadeChecking} returning true) to validate
	 * that no cascade on the given property is considered a valid semantic.
	 *
	 * @param session The session witin which the cascade is occurring.
	 * @param child The property value
	 * @param parent The property value owner
	 * @param persister The entity persister for the owner
	 * @param propertyIndex The index of the property within the owner.
	 */
	public void noCascade(EventSource session, Object child, Object parent, EntityPersister persister, int propertyIndex) {
	}

	/**
	 * Should this action be performed (or noCascade consulted) in the case of lazy properties.
	 */
	public boolean performOnLazyProperty() {
		return true;
	}


	// the CascadingAction implementations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	/**
	 * @see org.hibernate.Session#delete(Object)
	 */
	public static final CascadingAction DELETE = new CascadingAction() {
		public void cascade(EventSource session, Object child, String entityName, Object anything, boolean isCascadeDeleteEnabled)
		throws HibernateException {
			if ( log.isTraceEnabled() ) {
				log.trace("cascading to delete: " + entityName);
			}
			session.delete( entityName, child, isCascadeDeleteEnabled, ( Set ) anything );
		}
		public Iterator getCascadableChildrenIterator(EventSource session, CollectionType collectionType, Object collection) {
			// delete does cascade to uninitialized collections
			return CascadingAction.getAllElementsIterator(session, collectionType, collection);
		}
		public boolean deleteOrphans() {
			// orphans should be deleted during delete
			return true;
		}
		public String toString() {
			return "ACTION_DELETE";
		}
	};

	/**
	 * @see org.hibernate.Session#lock(Object, LockMode)
	 */
	public static final CascadingAction LOCK = new CascadingAction() {
		public void cascade(EventSource session, Object child, String entityName, Object anything, boolean isCascadeDeleteEnabled)
		throws HibernateException {
			if ( log.isTraceEnabled() ) {
				log.trace( "cascading to lock: " + entityName );
			}
			session.lock( entityName, child, LockMode.NONE/*(LockMode) anything*/ );
		}
		public Iterator getCascadableChildrenIterator(EventSource session, CollectionType collectionType, Object collection) {
			// lock doesn't cascade to uninitialized collections
			return getLoadedElementsIterator(session, collectionType, collection);
		}
		public boolean deleteOrphans() {
			//TODO: should orphans really be deleted during lock???
			return false;
		}
		public String toString() {
			return "ACTION_LOCK";
		}
	};

	/**
	 * @see org.hibernate.Session#refresh(Object)
	 */
	public static final CascadingAction REFRESH = new CascadingAction() {
		public void cascade(EventSource session, Object child, String entityName, Object anything, boolean isCascadeDeleteEnabled)
		throws HibernateException {
			if ( log.isTraceEnabled() ) {
				log.trace( "cascading to refresh: " + entityName );
			}
			session.refresh( child, (Map) anything );
		}
		public Iterator getCascadableChildrenIterator(EventSource session, CollectionType collectionType, Object collection) {
			// refresh doesn't cascade to uninitialized collections
			return getLoadedElementsIterator(session, collectionType, collection);
		}
		public boolean deleteOrphans() {
			return false;
		}
		public String toString() {
			return "ACTION_REFRESH";
		}
	};

	/**
	 * @see org.hibernate.Session#evict(Object)
	 */
	public static final CascadingAction EVICT = new CascadingAction() {
		public void cascade(EventSource session, Object child, String entityName, Object anything, boolean isCascadeDeleteEnabled)
		throws HibernateException {
			if ( log.isTraceEnabled() ) {
				log.trace( "cascading to evict: " + entityName );
			}
			session.evict(child);
		}
		public Iterator getCascadableChildrenIterator(EventSource session, CollectionType collectionType, Object collection) {
			// evicts don't cascade to uninitialized collections
			return getLoadedElementsIterator(session, collectionType, collection);
		}
		public boolean deleteOrphans() {
			return false;
		}
		public boolean performOnLazyProperty() {
			return false;
		}
		public String toString() {
			return "ACTION_EVICT";
		}
	};

	/**
	 * @see org.hibernate.Session#saveOrUpdate(Object)
	 */
	public static final CascadingAction SAVE_UPDATE = new CascadingAction() {
		public void cascade(EventSource session, Object child, String entityName, Object anything, boolean isCascadeDeleteEnabled)
		throws HibernateException {
			if ( log.isTraceEnabled() ) {
				log.trace( "cascading to saveOrUpdate: " + entityName );
			}
			session.saveOrUpdate(entityName, child);
		}