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NthHop.java
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NthHop.java
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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* 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 de.jungblut.graph.bsp;
import de.jungblut.graph.bsp.MindistSearch.MindistSearchVertex;
import de.jungblut.graph.bsp.MindistSearch.TabToTextVertexReader;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hama.HamaConfiguration;
import org.apache.hama.bsp.BSPPeer;
import org.apache.hama.bsp.HashPartitioner;
import org.apache.hama.bsp.TextInputFormat;
import org.apache.hama.bsp.TextOutputFormat;
import org.apache.hama.graph.DefaultVertexOutputWriter;
import org.apache.hama.graph.GraphJob;
import org.apache.hama.graph.GraphJobMessage;
import org.apache.hama.graph.Vertex;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
public class NthHop {
public static final String MAX_HOPS_KEY = "graph.max.hops";
public static class NthHopVertex extends
Vertex<Text, NullWritable, HopMessage> {
@Override
public void compute(Iterable<HopMessage> messages) throws IOException {
final int maxHops = getConf().getInt(MAX_HOPS_KEY, 3);
if (getSuperstepCount() == 0L) {
HopMessage msg = new HopMessage();
msg.origin = getVertexID().toString();
msg.hopCounter = 0;
sendMessageToNeighbors(msg);
} else {
for (HopMessage message : messages) {
// fork a new message to not change state somewhere else in case of a
// memory storage.
HopMessage copyMessage = new HopMessage();
copyMessage.origin = message.origin;
copyMessage.hopCounter = message.hopCounter + 1;
if (copyMessage.hopCounter == maxHops) {
getPeer().write(new Text(copyMessage.origin), getVertexID());
voteToHalt();
} else {
sendMessageToNeighbors(copyMessage);
}
}
}
}
}
private static void printUsage() {
System.out.println("Usage: <input> <output> <number of hops> [#tasks]");
System.exit(-1);
}
public static void main(String[] args) throws IOException,
InterruptedException, ClassNotFoundException {
if (args.length < 3) {
printUsage();
}
final int numHops = Integer.parseInt(args[2]);
System.out.println("Number of hops: " + numHops);
HamaConfiguration conf = new HamaConfiguration(new Configuration());
GraphJob job = new GraphJob(conf, MindistSearchVertex.class);
job.setJobName("Nth Hop Search");
job.setVertexClass(NthHopVertex.class);
job.setInputPath(new Path(args[0]));
job.setOutputPath(new Path(args[1]));
// set the defaults
job.setMaxIteration(numHops);
if (args.length == 4) {
job.setNumBspTask(Integer.parseInt(args[3]));
}
job.setVertexIDClass(Text.class);
job.setVertexValueClass(HopMessage.class);
job.setEdgeValueClass(NullWritable.class);
job.setInputKeyClass(LongWritable.class);
job.setInputValueClass(Text.class);
job.setInputFormat(TextInputFormat.class);
job.setVertexInputReaderClass(TabToTextVertexReader.class);
job.setVertexOutputWriterClass(EmptyVertexOutputWriter.class);
job.setPartitioner(HashPartitioner.class);
job.setOutputFormat(TextOutputFormat.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
long startTime = System.currentTimeMillis();
if (job.waitForCompletion(true)) {
System.out.println("Job Finished in "
+ (System.currentTimeMillis() - startTime) / 1000.0 + " seconds");
}
}
public static class EmptyVertexOutputWriter extends
DefaultVertexOutputWriter<Text, NullWritable, HopMessage> {
@Override
public void write(Vertex<Text, NullWritable, HopMessage> vertex,
BSPPeer<Writable, Writable, Text, HopMessage, GraphJobMessage> peer)
throws IOException {
// do nothing, output is handled by the computation itself :)
}
}
public static class HopMessage implements Writable {
String origin;
int hopCounter;
@Override
public void readFields(DataInput in) throws IOException {
origin = in.readUTF();
hopCounter = in.readInt();
}
@Override
public void write(DataOutput out) throws IOException {
out.writeUTF(origin);
out.writeInt(hopCounter);
}
@Override
public String toString() {
return this.origin + " (" + this.hopCounter + ")";
}
}
}