001    /*
002     * JBoss DNA (http://www.jboss.org/dna)
003     * See the COPYRIGHT.txt file distributed with this work for information
004     * regarding copyright ownership.  Some portions may be licensed
005     * to Red Hat, Inc. under one or more contributor license agreements.
006     * See the AUTHORS.txt file in the distribution for a full listing of 
007     * individual contributors. 
008     *
009     * JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA
010     * is licensed to you under the terms of the GNU Lesser General Public License as
011     * published by the Free Software Foundation; either version 2.1 of
012     * the License, or (at your option) any later version.
013     *
014     * JBoss DNA is distributed in the hope that it will be useful,
015     * but WITHOUT ANY WARRANTY; without even the implied warranty of
016     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
017     * Lesser General Public License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this software; if not, write to the Free
021     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
022     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
023     */
024    package org.jboss.dna.connector.federation.contribution;
025    
026    import net.jcip.annotations.Immutable;
027    import org.jboss.dna.graph.Location;
028    import org.jboss.dna.graph.property.DateTime;
029    
030    /**
031     * A source contribution that is empty. In other words, the source has no contribution to make.
032     * <p>
033     * Note that this is different than an unknown contribution, which may occur when a source is added to a federated repository
034     * after the contributions have already been determined for nodes. In this case, the new source's contribution for a node is not
035     * known and must be determined.
036     * </p>
037     * 
038     * @author Randall Hauch
039     */
040    @Immutable
041    public class EmptyContribution extends Contribution {
042    
043        /**
044         * This is the first version of this class. See the documentation of MergePlan.serialVersionUID.
045         */
046        private static final long serialVersionUID = 1L;
047    
048        /**
049         * Create a contribution for the source with the supplied name.
050         * 
051         * @param sourceName the name of the source, which may not be null or blank
052         * @param workspaceName the name of the workspace, which may not be null or blank
053         * @param expirationTime the time (in UTC) after which this contribution should be considered expired, or null if there is no
054         *        expiration time
055         */
056        public EmptyContribution( String sourceName,
057                                  String workspaceName,
058                                  DateTime expirationTime ) {
059            super(sourceName, workspaceName, expirationTime);
060            if (ContributionStatistics.RECORD) ContributionStatistics.record(0, 0);
061        }
062    
063        /**
064         * {@inheritDoc}
065         * 
066         * @see org.jboss.dna.connector.federation.contribution.Contribution#getLocationInSource()
067         */
068        @Override
069        public Location getLocationInSource() {
070            return null;
071        }
072    
073        /**
074         * {@inheritDoc}
075         * 
076         * @see org.jboss.dna.connector.federation.contribution.Contribution#isEmpty()
077         */
078        @Override
079        public boolean isEmpty() {
080            return true;
081        }
082    
083        /**
084         * {@inheritDoc}
085         */
086        @Override
087        public boolean equals( Object obj ) {
088            if (obj == this) return true;
089            if (obj instanceof EmptyContribution) {
090                EmptyContribution that = (EmptyContribution)obj;
091                if (!this.getSourceName().equals(that.getSourceName())) return false;
092                if (!this.getWorkspaceName().equals(that.getWorkspaceName())) return false;
093                return true;
094            }
095            return false;
096        }
097    }