org.sf.xrime.algorithms.clique.maximal.WeakNeighborhoodGenerate.java Source code

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Here is the source code for org.sf.xrime.algorithms.clique.maximal.WeakNeighborhoodGenerate.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.clique.maximal;

import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.compress.GzipCodec;
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.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.SequenceFileInputFormat;
import org.apache.hadoop.mapred.SequenceFileOutputFormat;
import org.sf.xrime.ProcessorExecutionException;
import org.sf.xrime.algorithms.GraphAlgorithm;
import org.sf.xrime.algorithms.utils.GraphAlgorithmMapReduceBase;
import org.sf.xrime.model.edge.AdjVertexEdge;
import org.sf.xrime.model.edge.Edge;
import org.sf.xrime.model.vertex.AdjVertex;
import org.sf.xrime.model.vertex.LabeledAdjSetVertex;

/**
 * This algorithm is used to generate weak neighborhood for each vertex in the graph.
 * Take outgoing adjancency lists as the input.
 * @author xue
 */
public class WeakNeighborhoodGenerate extends GraphAlgorithm {
    /**
     * Default constructor.
     */
    public WeakNeighborhoodGenerate() {
        super();
    }

    /**
     * Mapper. Used to find bi-directional arcs between vertexes. 
     * @author xue
     */
    public static class MapClass extends GraphAlgorithmMapReduceBase
            implements Mapper<Text, AdjVertex, Text, LabeledAdjSetVertex> {

        @Override
        public void map(Text key, AdjVertex value, OutputCollector<Text, LabeledAdjSetVertex> output,
                Reporter reporter) throws IOException {
            List<Edge> tos = value.getEdges();
            if (tos.size() == 0)
                return; // This vertex has no outgoing arc.

            // For the remote end of each arc.
            for (int i = 0; i < tos.size(); i++) {
                String to = tos.get(i).getTo();
                // Notify the neighbor about myself.
                LabeledAdjSetVertex notifier = new LabeledAdjSetVertex();
                notifier.setId(to);
                notifier.setStringLabel(ConstantLabels.POTENTIAL_NEIGHBOR, key.toString());
                output.collect(new Text(to), notifier);
            }
            // Make myself shown in reducer.
            LabeledAdjSetVertex myself = new LabeledAdjSetVertex();
            myself.fromAdjVertexTos(value);
            output.collect(key, myself);
        }
    }

    /**
     * Reducer. Settle down the neighborhood of each vertex. 
     * @author xue
     */
    public static class ReduceClass extends GraphAlgorithmMapReduceBase
            implements Reducer<Text, LabeledAdjSetVertex, Text, LabeledAdjSetVertex> {

        @Override
        public void reduce(Text key, Iterator<LabeledAdjSetVertex> values,
                OutputCollector<Text, LabeledAdjSetVertex> output, Reporter reporter) throws IOException {
            HashSet<AdjVertexEdge> neighbors = new HashSet<AdjVertexEdge>();
            while (values.hasNext()) {
                LabeledAdjSetVertex curr_vertex = values.next();
                if (curr_vertex.getStringLabel(ConstantLabels.POTENTIAL_NEIGHBOR) == null) {
                    // No need to do deep clone here.
                    neighbors.addAll(curr_vertex.getOpposites());
                } else {
                    // Neighbors of this direction is also added, since we are interested in weak
                    // neighborhood.
                    String neighbor_id = curr_vertex.getStringLabel(ConstantLabels.POTENTIAL_NEIGHBOR);
                    neighbors.add(new AdjVertexEdge(neighbor_id));
                }
            }

            if (neighbors.size() == 0)
                return; // This vertex has no incoming arcs or outgoing arcs.

            LabeledAdjSetVertex result = new LabeledAdjSetVertex();
            result.setId(key.toString());
            result.setOpposites(neighbors);
            // Collect this.
            output.collect(key, result);
        }
    }

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

        conf.setOutputKeyClass(Text.class);
        conf.setOutputValueClass(LabeledAdjSetVertex.class);
        conf.setMapperClass(MapClass.class);
        // No combiner is permitted, since the logic of reducer depends on the completeness
        // of information.
        conf.setReducerClass(ReduceClass.class);
        // makes the file format suitable for machine processing.
        conf.setInputFormat(SequenceFileInputFormat.class);
        conf.setOutputFormat(SequenceFileOutputFormat.class);
        // Enable compression.
        conf.setCompressMapOutput(true);
        conf.setMapOutputCompressorClass(GzipCodec.class);
        try {
            FileInputFormat.setInputPaths(conf, getSource().getPath());
            FileOutputFormat.setOutputPath(conf, getDestination().getPath());
        } catch (IllegalAccessException e1) {
            throw new ProcessorExecutionException(e1);
        }
        conf.setNumMapTasks(getMapperNum());
        conf.setNumReduceTasks(getReducerNum());

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