/*
* JBoss, Home of Professional Open Source.
* Copyright 2000 - 2008, Red Hat Middleware LLC, and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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 software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.cache.commands.read;
import org.jboss.cache.Fqn;
import org.jboss.cache.InternalNode;
import org.jboss.cache.InvocationContext;
import org.jboss.cache.NodeSPI;
import org.jboss.cache.commands.Visitor;
import org.jboss.cache.mvcc.ReadCommittedNode;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* This command retrieves the names of children for a specific Fqn, as defined by {@link org.jboss.cache.Node#getChildrenNames()}
* <p/>
* This is the equivalent of the old MethodCallDefinitions.getChildrenNamesMethodLocal method call from 2.1.x.
* <p/>
*
* @author Mircea.Markus@jboss.com
* @since 2.2.0
*/
public class GetChildrenNamesCommand extends AbstractDataCommand
{
public static final int METHOD_ID = 23;
public GetChildrenNamesCommand()
{
}
public GetChildrenNamesCommand(Fqn fqn)
{
this.fqn = fqn;
}
/**
* Retrieves the names of children for a specific Fqn.
*
* @param ctx invocation context
* @return a Set<Object> of child names, for a given Fqn, or null if the Fqn refers to a node that does not exist.
*/
@SuppressWarnings("unchecked")
public Object perform(InvocationContext ctx)
{
ReadCommittedNode n = (ReadCommittedNode) (fqn == null ? null : ctx.lookUpNode(fqn));
if (n == null || n.isDeleted()) return null;
Map<Object, InternalNode<?, ?>> childrenMap = n.getDelegationTarget().getChildrenMap();
Collection<InternalNode> children = (Collection<InternalNode>) (childrenMap.isEmpty() ? Collections.emptySet() : childrenMap.values());
return getCorrectedChildNames(children, ctx);
}
/**
* Cleans the collection of children passed in to extract child names into a Set. This implementation provides
* additional filtering such as removing known deleted children and adding known created ones.
*
* @param children children set. Must not be null.
* @param ctx invocation context
* @return a set of valid children names.
*/
private Set<Object> getCorrectedChildNames(Collection<InternalNode> children, InvocationContext ctx)
{
Set<Object> childNames = new HashSet<Object>();
for (InternalNode realChild : children)
{
Fqn childFqn = realChild.getFqn();
NodeSPI childNode = ctx.lookUpNode(childFqn);
// deletion flag should be checked on what we get from the ctx.
// if childNode is null then it hasn't been removed in the current scope and hence should be included in this list.
if (childNode == null || !childNode.isDeleted()) childNames.add(childFqn.getLastElement());
}
// now check for any *new* children added.
for (Map.Entry<Fqn, NodeSPI> n : ctx.getLookedUpNodes().entrySet())
{
Fqn childFqn = n.getKey();
if (childFqn.isDirectChildOf(fqn))
{
ReadCommittedNode childNode = (ReadCommittedNode) n.getValue();
if (childNode.isCreated()) childNames.add(childFqn.getLastElement());
}
}
return childNames;
}
public Object acceptVisitor(InvocationContext ctx, Visitor visitor) throws Throwable
{
return visitor.visitGetChildrenNamesCommand(ctx, this);
}
public int getCommandId()
{
return METHOD_ID;
}
}