/* Copyright (C) 2012 Intel Corporation.
* All rights reserved.
*
* 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.
*
* For more about this software visit:
* http://www.01.org/GraphBuilder
*/
package com.intel.hadoop.graphbuilder.idnormalize.mapreduce;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
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.log4j.Logger;
import com.intel.hadoop.graphbuilder.graph.Vertex;
import com.intel.hadoop.graphbuilder.parser.FieldParser;
import com.intel.hadoop.graphbuilder.parser.GraphParser;
/**
* Reducer class reduce the (baseid, List<(vid, vdata)>) into a dictionary
* (lvid, vid), and a new vertex data file (lvid, vdata), where lvid = baseid +
* vid.index * splitsize; Because the splitsize is fixed for all mapper using
* option {@code mapred.line.input.format.linespermap} in the {@code JobConf},
* this guarantee all vids are mapped into [0, ..., |V|-1]. The assumption is
* that the input should not contain any duplicate vertex ids.
*
*/
public class HashIdReducer extends MapReduceBase implements
Reducer<IntWritable, Text, Text, Text> {
private static final Logger LOG = Logger.getLogger(HashIdReducer.class);
@Override
public void configure(JobConf job) {
super.configure(job);
splitsize = job.getInt("mapred.line.input.format.linespermap", 600000);
try {
this.graphparser = (GraphParser) Class.forName(job.get("GraphParser"))
.newInstance();
this.vidparser = (FieldParser) Class.forName(job.get("VidParser"))
.newInstance();
this.vdataparser = (FieldParser) Class.forName(job.get("VdataParser"))
.newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
@Override
public void reduce(IntWritable key, Iterator<Text> iter,
OutputCollector<Text, Text> out, Reporter reporter) throws IOException {
long baseid = key.get();
int split = 0;
while (iter.hasNext()) {
Vertex v = graphparser.parseVertex(iter.next().toString(), vidparser,
vdataparser);
long newId = baseid + splitsize * split;
out.collect(new Text("vidmap"), new Text(newId + "\t" + v.vid()));
out.collect(new Text("vdata"), new Text("!" + newId + "\t"
+ v.vdata().toString()));
split++;
}
}
private int splitsize;
private GraphParser graphparser;
private FieldParser vidparser;
private FieldParser vdataparser;
}