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.hadoop;
017    
018    import java.io.IOException;
019    
020    import org.apache.hadoop.io.DoubleWritable;
021    import org.apache.hadoop.mapreduce.Mapper;
022    
023    /**
024     * A {@link Mapper} which mutates and evaluates given individuals and outputs
025     * evaluation/mutant pairs.
026     * 
027     * @param <I>
028     *            the individuals' type
029     * 
030     * @author <a href="http://kumpe.de/christian/java">Christian Kumpe</a>
031     */
032    public final class MutateAndEvaluateChildMapper<I> extends
033                    MapperWithOptimizerConfiguration<I> {
034            @Override
035            protected void map(final DoubleWritable key, final I value,
036                            final Context context) throws IOException, InterruptedException {
037                    context.getCounter(HadoOptimizerBase.COUNTER_GROUP,
038                                    "MutateAndEvaluateChildMapper reads").increment(1);
039    
040                    // mutation
041                    final I mutant = configuration.getMutator().mutate(value);
042                    // evaluation
043                    final double evaluation = configuration.getEvaluator().evaluate(mutant);
044    
045                    context.getCounter(HadoOptimizerBase.COUNTER_GROUP,
046                                    "MutateAndEvaluateChildMapper writes").increment(1);
047    
048                    context.write(new DoubleWritable(evaluation), mutant);
049            }
050    }