001    /*
002     * Copyright 2011 Christian Kumpe http://kumpe.de/christian/java
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *     http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package de.kumpe.hadooptimizer.impl;
017    
018    import java.util.Collection;
019    
020    import org.apache.commons.logging.Log;
021    import org.apache.commons.logging.LogFactory;
022    
023    import de.kumpe.hadooptimizer.EvaluationResult;
024    import de.kumpe.hadooptimizer.Halter;
025    import de.kumpe.hadooptimizer.Stoppable;
026    
027    /**
028     * This {@link Halter}'s {@link #halt(Collection)} will always return false,
029     * thus never halt.
030     * 
031     * @param <I>
032     *            the individuals' type
033     * 
034     * @author <a href="http://kumpe.de/christian/java">Christian Kumpe</a>
035     */
036    public final class NeverHalter<I> implements Halter<I>, Stoppable {
037            private static final long serialVersionUID = 1L;
038            private static final Log log = LogFactory.getLog(NeverHalter.class);
039    
040            private volatile boolean stop = false;
041    
042            public NeverHalter() {
043                    if (log.isDebugEnabled()) {
044                            log.debug("Constructing new NeverHalter.");
045                    }
046            }
047    
048            @Override
049            public boolean halt(final Collection<EvaluationResult<I>> evaluationResults) {
050                    return stop;
051            }
052    
053            @Override
054            public void stop() {
055                    stop = true;
056            }
057    
058            @Override
059            public String toString() {
060                    return "NeverHalter []";
061            }
062    }