Author: omalley
Date: Tue Dec 16 08:51:11 2008
New Revision: 727087
URL: http://svn.apache.org/viewvc?rev=727087&view=rev
Log:
HADOOP-4545 missed a file
Added:
hadoop/core/trunk/src/examples/org/apache/hadoop/examples/SecondarySort.java
Added:
hadoop/core/trunk/src/examples/org/apache/hadoop/examples/SecondarySort.java
URL:
http://svn.apache.org/viewvc/hadoop/core/trunk/src/examples/org/apache/hadoop/examples/SecondarySort.java?rev=727087&view=auto
==============================================================================
---
hadoop/core/trunk/src/examples/org/apache/hadoop/examples/SecondarySort.java
(added)
+++
hadoop/core/trunk/src/examples/org/apache/hadoop/examples/SecondarySort.java
Tue Dec 16 08:51:11 2008
@@ -0,0 +1,239 @@
+/**
+ * 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.hadoop.examples;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.util.StringTokenizer;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.LongWritable;
+import org.apache.hadoop.io.RawComparator;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.WritableComparable;
+import org.apache.hadoop.io.WritableComparator;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.Mapper;
+import org.apache.hadoop.mapreduce.Partitioner;
+import org.apache.hadoop.mapreduce.Reducer;
+import org.apache.hadoop.util.GenericOptionsParser;
+
+/**
+ * This is an example Hadoop Map/Reduce application.
+ * It reads the text input files that must contain two integers per a line.
+ * The output is sorted by the first and second number and grouped on the
+ * first number.
+ *
+ * To run: bin/hadoop jar build/hadoop-examples.jar secondarysort
+ * <i>in-dir</i> <i>out-dir</i>
+ */
+public class SecondarySort {
+
+ /**
+ * Define a pair of integers that are writable.
+ * They are serialized in a byte comparable format.
+ */
+ public static class IntPair
+ implements WritableComparable<IntPair> {
+ private int first = 0;
+ private int second = 0;
+
+ /**
+ * Set the left and right values.
+ */
+ public void set(int left, int right) {
+ first = left;
+ second = right;
+ }
+ public int getFirst() {
+ return first;
+ }
+ public int getSecond() {
+ return second;
+ }
+ /**
+ * Read the two integers.
+ * Encoded as: MIN_VALUE -> 0, 0 -> -MIN_VALUE, MAX_VALUE-> -1
+ */
+ @Override
+ public void readFields(DataInput in) throws IOException {
+ first = in.readInt() + Integer.MIN_VALUE;
+ second = in.readInt() + Integer.MIN_VALUE;
+ }
+ @Override
+ public void write(DataOutput out) throws IOException {
+ out.writeInt(first - Integer.MIN_VALUE);
+ out.writeInt(second - Integer.MIN_VALUE);
+ }
+ @Override
+ public int hashCode() {
+ return first * 157 + second;
+ }
+ @Override
+ public boolean equals(Object right) {
+ if (right instanceof IntPair) {
+ IntPair r = (IntPair) right;
+ return r.first == first && r.second == second;
+ } else {
+ return false;
+ }
+ }
+ /** A Comparator that compares serialized IntPair. */
+ public static class Comparator extends WritableComparator {
+ public Comparator() {
+ super(IntPair.class);
+ }
+
+ public int compare(byte[] b1, int s1, int l1,
+ byte[] b2, int s2, int l2) {
+ return compareBytes(b1, s1, l1, b2, s2, l2);
+ }
+ }
+
+ static { // register this comparator
+ WritableComparator.define(IntPair.class, new Comparator());
+ }
+
+ @Override
+ public int compareTo(IntPair o) {
+ if (first != o.first) {
+ return first < o.first ? -1 : 1;
+ } else if (second != o.second) {
+ return second < o.second ? -1 : 1;
+ } else {
+ return 0;
+ }
+ }
+ }
+
+ /**
+ * Partition based on the first part of the pair.
+ */
+ public static class FirstPartitioner extends
Partitioner<IntPair,IntWritable>{
+ @Override
+ public int getPartition(IntPair key, IntWritable value,
+ int numPartitions) {
+ return Math.abs(key.getFirst() * 127) % numPartitions;
+ }
+ }
+
+ /**
+ * Compare only the first part of the pair, so that reduce is called once
+ * for each value of the first part.
+ */
+ public static class FirstGroupingComparator
+ implements RawComparator<IntPair> {
+ @Override
+ public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
+ return WritableComparator.compareBytes(b1, s1, Integer.SIZE/8,
+ b2, s2, Integer.SIZE/8);
+ }
+
+ @Override
+ public int compare(IntPair o1, IntPair o2) {
+ int l = o1.getFirst();
+ int r = o2.getFirst();
+ return l == r ? 0 : (l < r ? -1 : 1);
+ }
+ }
+
+ /**
+ * Read two integers from each line and generate a key, value pair
+ * as ((left, right), right).
+ */
+ public static class MapClass
+ extends Mapper<LongWritable, Text, IntPair, IntWritable> {
+
+ private final IntPair key = new IntPair();
+ private final IntWritable value = new IntWritable();
+
+ @Override
+ public void map(LongWritable inKey, Text inValue,
+ Context context) throws IOException, InterruptedException {
+ StringTokenizer itr = new StringTokenizer(inValue.toString());
+ int left = 0;
+ int right = 0;
+ if (itr.hasMoreTokens()) {
+ left = Integer.parseInt(itr.nextToken());
+ if (itr.hasMoreTokens()) {
+ right = Integer.parseInt(itr.nextToken());
+ }
+ key.set(left, right);
+ value.set(right);
+ context.write(key, value);
+ }
+ }
+ }
+
+ /**
+ * A reducer class that just emits the sum of the input values.
+ */
+ public static class Reduce
+ extends Reducer<IntPair, IntWritable, Text, IntWritable> {
+ private static final Text SEPARATOR =
+ new Text("------------------------------------------------");
+ private final Text first = new Text();
+
+ @Override
+ public void reduce(IntPair key, Iterable<IntWritable> values,
+ Context context
+ ) throws IOException, InterruptedException {
+ context.write(SEPARATOR, null);
+ first.set(Integer.toString(key.getFirst()));
+ for(IntWritable value: values) {
+ context.write(first, value);
+ }
+ }
+ }
+
+ public static void main(String[] args) throws Exception {
+ Configuration conf = new Configuration();
+ String[] otherArgs = new GenericOptionsParser(conf,
args).getRemainingArgs();
+ if (otherArgs.length != 2) {
+ System.err.println("Usage: secondarysrot <in> <out>");
+ System.exit(2);
+ }
+ Job job = new Job(conf, "secondary sort");
+ job.setJarByClass(SecondarySort.class);
+ job.setMapperClass(MapClass.class);
+ job.setReducerClass(Reduce.class);
+
+ // group and partition by the first int in the pair
+ job.setPartitionerClass(FirstPartitioner.class);
+ job.setGroupingComparatorClass(FirstGroupingComparator.class);
+
+ // the map output is IntPair, IntWritable
+ job.setMapOutputKeyClass(IntPair.class);
+ job.setMapOutputValueClass(IntWritable.class);
+
+ // the reduce output is Text, IntWritable
+ job.setOutputKeyClass(Text.class);
+ job.setOutputValueClass(IntWritable.class);
+
+ FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
+ FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
+ System.exit(job.waitForCompletion() ? 0 : 1);
+ }
+
+}
