/* 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.preprocess.mapreduce;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
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 com.intel.hadoop.graphbuilder.preprocess.functional.Functional;
import com.intel.hadoop.graphbuilder.preprocess.mapreduce.keyvalue.PairListType;
import com.intel.hadoop.graphbuilder.util.Pair;
/**
* The Reduce functional computes a sufficient statistics on a list of edges,
* and the Apply functional applies it back to each edge in the list.
*
*
* @param <VidType>
*/
public class EdgeTransformReducer<VidType extends WritableComparable<VidType>>
extends MapReduceBase implements Reducer<VidType, PairListType, Text, Text> {
@Override
public void configure(JobConf job) {
super.configure(job);
this.reduceEndPoint = job.getBoolean("reduceEndPoint",
EdgeTransformMR.SOURCE);
try {
this.reduceFunc = (Functional) Class.forName(job.get("ReduceFunc"))
.newInstance();
this.applyFunc = (Functional) Class.forName(job.get("ApplyFunc"))
.newInstance();
this.reduceFunc.configure(job);
this.applyFunc.configure(job);
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void reduce(VidType key, Iterator<PairListType> values,
OutputCollector<Text, Text> out, Reporter reporter) throws IOException {
ArrayList<VidType> vids = new ArrayList<VidType>();
ArrayList<Writable> data = new ArrayList<Writable>();
while (values.hasNext()) {
PairListType list = values.next();
Iterator<Pair<VidType, Writable>> iter = list.iterator();
while (iter.hasNext()) {
Pair<VidType, Writable> pair = iter.next();
vids.add(pair.getL());
data.add(pair.getR());
}
}
// Reduce
Writable r = reduceFunc.base();
for (int i = 1; i < data.size(); i++)
r = reduceFunc.reduce(data.get(i), r);
// Apply
for (int i = 0; i < data.size(); i++) {
Writable res = applyFunc.reduce(data.get(i), r);
// Output
if (reduceEndPoint == EdgeTransformMR.SOURCE)
out.collect(new Text(key.toString()), new Text(vids.get(i).toString()
+ "\t" + res.toString()));
else
out.collect(new Text(vids.get(i).toString()), new Text(key.toString()
+ "\t" + res.toString()));
}
}
private Functional reduceFunc;
private Functional applyFunc;
private boolean reduceEndPoint;
}