/*
* Cloud9: A MapReduce Library for Hadoop
*
* 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 edu.umd.cloud9.webgraph;
import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
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.apache.hadoop.mapred.lib.IdentityMapper;
import org.apache.log4j.Logger;
import edu.umd.cloud9.io.array.ArrayListWritable;
import edu.umd.cloud9.util.PowerTool;
import edu.umd.cloud9.util.array.ArrayListOfInts;
import edu.umd.cloud9.webgraph.data.AnchorText;
import edu.umd.cloud9.webgraph.data.AnchorTextConstants;
/**
*
* @author Nima Asadi
*
*/
public class BuildReverseWebGraph extends PowerTool {
private static final Logger LOG = Logger.getLogger(BuildReverseWebGraph.class);
public static class Reduce extends MapReduceBase implements
Reducer<Text, ArrayListWritable<AnchorText>, IntWritable,
ArrayListWritable<AnchorText>> {
private static final IntWritable keyWord = new IntWritable();
private static final ArrayListWritable<AnchorText> arrayList =
new ArrayListWritable<AnchorText>();
private static final ArrayListOfInts docnos = new ArrayListOfInts();
private static ArrayListWritable<AnchorText> packet;
private static boolean pushed;
private int indegree;
public void reduce(Text key, Iterator<ArrayListWritable<AnchorText>> values,
OutputCollector<IntWritable, ArrayListWritable<AnchorText>> output,
Reporter reporter) throws IOException {
docnos.clear();
arrayList.clear();
indegree = 0;
while(values.hasNext()) {
packet = values.next();
for(AnchorText data : packet) {
//docno field data
if(data.isDocnoField()) {
//in theory, there must be only one "docno" packet.
//Unless there are duplicate pages.
for(int docno: data) {
docnos.add(docno);
}
continue;
}
pushed = false;
indegree += data.getSize();
for(int i = 0; i < arrayList.size(); i++) {
if(arrayList.get(i).equalsIgnoreSources(data)) {
arrayList.get(i).addDocumentsFrom(data);
pushed = true;
break;
}
}
if(!pushed) {
arrayList.add(data.clone());
}
}
}
arrayList.add(new AnchorText(AnchorTextConstants.Type.IN_DEGREE.val,
null, indegree));
arrayList.add(new AnchorText(AnchorTextConstants.Type.URL_FIELD.val,
key.toString()));
Collections.sort(arrayList);
//if there was no document number detected,
//this record would not be emitted.
for(int docno : docnos) {
keyWord.set(docno);
output.collect(keyWord, arrayList);
}
}
}
public static final String[] RequiredParameters = {
"Cloud9.InputPath",
"Cloud9.OutputPath",
"Cloud9.Mappers",
"Cloud9.Reducers"
};
public String[] getRequiredParameters() {
return RequiredParameters;
}
public BuildReverseWebGraph(Configuration conf) {
super(conf);
}
public int runTool() throws Exception {
JobConf conf = new JobConf(getConf(), BuildReverseWebGraph.class);
FileSystem fs = FileSystem.get(conf);
int numMappers = conf.getInt("Cloud9.Mappers", 1);
int numReducers = conf.getInt("Cloud9.Reducers", 200);
String inputPath = conf.get("Cloud9.InputPath");
String outputPath = conf.get("Cloud9.OutputPath");
conf.setJobName("ReverseWebGraph");
conf.set("mapred.child.java.opts", "-Xmx2048m");
conf.setInt("mapred.task.timeout", 60000000);
conf.set("mapreduce.map.memory.mb", "2048");
conf.set("mapreduce.map.java.opts", "-Xmx2048m");
conf.set("mapreduce.reduce.memory.mb", "2048");
conf.set("mapreduce.reduce.java.opts", "-Xmx2048m");
conf.set("mapreduce.task.timeout", "60000000");
conf.setNumMapTasks(numMappers);
conf.setNumReduceTasks(numReducers);
conf.setMapperClass(IdentityMapper.class);
conf.setReducerClass(Reduce.class);
conf.setOutputKeyClass(IntWritable.class);
conf.setOutputValueClass(ArrayListWritable.class);
conf.setMapOutputKeyClass(Text.class);
conf.setMapOutputValueClass(ArrayListWritable.class);
conf.setInputFormat(SequenceFileInputFormat.class);
conf.setOutputFormat(SequenceFileOutputFormat.class);
SequenceFileOutputFormat.setCompressOutput(conf, true);
SequenceFileOutputFormat.setOutputCompressionType(conf,
SequenceFile.CompressionType.BLOCK);
SequenceFileInputFormat.setInputPaths(conf, inputPath);
FileOutputFormat.setOutputPath(conf, new Path(outputPath));
LOG.info("BuildReverseWebGraph");
LOG.info(" - input path: " + inputPath);
LOG.info(" - output path: " + outputPath);
if(!fs.exists(new Path(outputPath))) {
JobClient.runJob(conf);
} else {
LOG.info(outputPath + " already exists! Skipping this step...");
}
return 0;
}
}