org.sf.xrime.algorithms.partitions.connected.strongly.PropagationConvergenceTest.java Source code

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Here is the source code for org.sf.xrime.algorithms.partitions.connected.strongly.PropagationConvergenceTest.java

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/*
 * Copyright (C) IBM Corp. 2009.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package org.sf.xrime.algorithms.partitions.connected.strongly;

import java.io.IOException;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.SequenceFileInputFormat;
import org.sf.xrime.ProcessorExecutionException;
import org.sf.xrime.algorithms.GraphAlgorithm;
import org.sf.xrime.algorithms.utils.GraphAlgorithmMapReduceBase;
import org.sf.xrime.model.vertex.LabeledAdjBiSetVertex;

/**
 * This is used to check for convergence of label propagation. We count the number of forward and
 * backward labels settled down. If this number does not change, the label propagation converges.
 * @author xue
 *
 */
public class PropagationConvergenceTest extends GraphAlgorithm {
    /**
     * Key used to accumulate propagated label number.
     */
    public static final String KEY_LABEL_NUM = "key_label_num";

    /**
     * Default constructor.
     */
    public PropagationConvergenceTest() {
        super();
    }

    /**
     * Mapper. Check the forward/backward label number of each vertex. (Please recall that
     * we only propagate a single label at a time.) No reducer is needed. We only emit
     * key-value pairs when the label exists, as a result, the map output records number
     * is the number we want. We eliminate the overhead of transfering map output to reducer,
     * and the overhead of reading from reduce output HDFS file.
     * @author xue
     */
    public static class MapClass extends GraphAlgorithmMapReduceBase
            implements Mapper<Text, LabeledAdjBiSetVertex, Text, IntWritable> {

        @Override
        public void map(Text key, LabeledAdjBiSetVertex value, OutputCollector<Text, IntWritable> output,
                Reporter reporter) throws IOException {
            if (value.getStringLabel(ConstantLabels.BACKWARD_LABEL) != null)
                output.collect(new Text(KEY_LABEL_NUM), new IntWritable(1));
            if (value.getStringLabel(ConstantLabels.FORWARD_LABEL) != null)
                output.collect(new Text(KEY_LABEL_NUM), new IntWritable(1));
        }
    }

    @Override
    public void execute() throws ProcessorExecutionException {
        JobConf conf = new JobConf(context, PropagationConvergenceTest.class);
        conf.setJobName("PropagationConvergenceTest");

        // the keys are vertex identifiers (strings)
        conf.setOutputKeyClass(Text.class);
        // the values are integers (Writable)
        conf.setOutputValueClass(IntWritable.class);
        conf.setMapperClass(MapClass.class);
        // makes the file format suitable for machine processing.
        conf.setInputFormat(SequenceFileInputFormat.class);
        try {
            FileInputFormat.setInputPaths(conf, getSource().getPath());
            FileOutputFormat.setOutputPath(conf, getDestination().getPath());
        } catch (IllegalAccessException e1) {
            throw new ProcessorExecutionException(e1);
        }
        conf.setNumMapTasks(getMapperNum());
        conf.setNumReduceTasks(0);

        try {
            this.runningJob = JobClient.runJob(conf);
        } catch (IOException e) {
            throw new ProcessorExecutionException(e);
        }
    }
}