/**
* 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
*
* 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.apache.hama.examples;
import java.io.IOException;
import java.util.Iterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hama.HamaConfiguration;
import org.apache.hama.bsp.BSP;
import org.apache.hama.bsp.BSPJob;
import org.apache.hama.bsp.BSPPeer;
import org.apache.hama.bsp.Combiner;
import org.apache.hama.bsp.FileOutputFormat;
import org.apache.hama.bsp.NullInputFormat;
import org.apache.hama.bsp.TextOutputFormat;
import org.apache.hama.bsp.sync.SyncException;
public class CombineExample {
private static Path TMP_OUTPUT = new Path("/tmp/combine-"
+ System.currentTimeMillis());
public static class MyBSP extends
BSP<NullWritable, NullWritable, Text, IntWritable, IntWritable> {
public static final Log LOG = LogFactory.getLog(MyBSP.class);
@Override
public void bsp(
BSPPeer<NullWritable, NullWritable, Text, IntWritable, IntWritable> peer)
throws IOException, SyncException, InterruptedException {
for (String peerName : peer.getAllPeerNames()) {
peer.send(peerName, new IntWritable(1));
peer.send(peerName, new IntWritable(2));
peer.send(peerName, new IntWritable(3));
}
peer.sync();
IntWritable received;
while ((received = peer.getCurrentMessage()) != null) {
peer.write(new Text("Sum = "), received);
}
}
}
public static class SumCombiner extends Combiner<IntWritable> {
@Override
public IntWritable combine(Iterable<IntWritable> messages) {
int sum = 0;
Iterator<IntWritable> it = messages.iterator();
while (it.hasNext()) {
sum += it.next().get();
}
return new IntWritable(sum);
}
}
static void printOutput(HamaConfiguration conf) throws IOException {
FileSystem fs = FileSystem.get(conf);
FileStatus[] files = fs.listStatus(TMP_OUTPUT);
for (int i = 0; i < files.length; i++) {
if (files[i].getLen() > 0) {
FSDataInputStream in = fs.open(files[i].getPath());
IOUtils.copyBytes(in, System.out, conf, false);
in.close();
break;
}
}
fs.delete(TMP_OUTPUT, true);
}
public static void main(String[] args) throws InterruptedException,
IOException, ClassNotFoundException {
// BSP job configuration
HamaConfiguration conf = new HamaConfiguration();
BSPJob bsp = new BSPJob(conf, CombineExample.class);
// Set the job name
bsp.setJobName("Combine Example");
bsp.setBspClass(MyBSP.class);
bsp.setCombinerClass(SumCombiner.class);
bsp.setInputFormat(NullInputFormat.class);
bsp.setOutputKeyClass(Text.class);
bsp.setOutputValueClass(IntWritable.class);
bsp.setOutputFormat(TextOutputFormat.class);
FileOutputFormat.setOutputPath(bsp, TMP_OUTPUT);
bsp.setNumBspTask(2);
long startTime = System.currentTimeMillis();
if (bsp.waitForCompletion(true)) {
printOutput(conf);
System.out.println("Job Finished in "
+ (System.currentTimeMillis() - startTime) / 1000.0 + " seconds");
}
}
}