Java tutorial
/* * chombo: Hadoop Map Reduce utility * Author: Pranab Ghosh * * 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 org.chombo.mr; import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.NullWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.FileSplit; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.chombo.util.SecondarySort; import org.chombo.util.Tuple; import org.chombo.util.Utility; /** * Modifies a record set by excluding certain records or by including certain records. * The record identifier field values are provided through a second set of files * @author pranab * */ public class RecordSetModifier extends Configured implements Tool { @Override public int run(String[] args) throws Exception { Job job = new Job(getConf()); String jobName = "record set modifier MR"; job.setJobName(jobName); job.setJarByClass(RecordSetModifier.class); FileInputFormat.addInputPaths(job, args[0]); FileOutputFormat.setOutputPath(job, new Path(args[1])); job.setMapperClass(RecordSetModifier.ModifierMapper.class); job.setReducerClass(RecordSetModifier.ModifierReducer.class); job.setMapOutputKeyClass(Tuple.class); job.setMapOutputValueClass(Tuple.class); job.setOutputKeyClass(NullWritable.class); job.setOutputValueClass(Text.class); job.setGroupingComparatorClass(SecondarySort.TuplePairGroupComprator.class); job.setPartitionerClass(SecondarySort.TuplePairPartitioner.class); Utility.setConfiguration(job.getConfiguration()); int numReducer = job.getConfiguration().getInt("rsm.num.reducer", -1); numReducer = -1 == numReducer ? job.getConfiguration().getInt("num.reducer", 1) : numReducer; job.setNumReduceTasks(numReducer); int status = job.waitForCompletion(true) ? 0 : 1; return status; } /** * @author pranab * */ public static class ModifierMapper extends Mapper<LongWritable, Text, Tuple, Tuple> { private String fieldDelimRegex; private String[] items; private Tuple keyOut = new Tuple(); private Tuple valOut = new Tuple(); private boolean isRecIdFileSplit; private int idFieldOrdinal; private static final int FIELD_VALUE_ORDINAL = 0; /* (non-Javadoc) * @see org.apache.hadoop.mapreduce.Mapper#setup(org.apache.hadoop.mapreduce.Mapper.Context) */ protected void setup(Context context) throws IOException, InterruptedException { Configuration config = context.getConfiguration(); fieldDelimRegex = config.get("field.delim.regex", ","); String recordIdentifierFilePrefix = config.get("record.identifier.file.prefix", "recid"); isRecIdFileSplit = ((FileSplit) context.getInputSplit()).getPath().getName() .startsWith(recordIdentifierFilePrefix); idFieldOrdinal = config.getInt("id.field.ordinal", -1); } /* (non-Javadoc) * @see org.apache.hadoop.mapreduce.Mapper#map(KEYIN, VALUEIN, org.apache.hadoop.mapreduce.Mapper.Context) */ @Override protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { items = value.toString().split(fieldDelimRegex); keyOut.initialize(); valOut.initialize(); if (isRecIdFileSplit) { //record identifier keyOut.add(items[FIELD_VALUE_ORDINAL], 0); valOut.add(0); } else { //actual records keyOut.add(items[idFieldOrdinal], 1); valOut.add(1, value.toString()); } context.write(keyOut, valOut); } } /** * @author pranab * */ public static class ModifierReducer extends Reducer<Tuple, Tuple, NullWritable, Text> { private String fieldDelim; private Text valOut = new Text(); private boolean toBeExcuded; private boolean toBeFiletred; /* (non-Javadoc) * @see org.apache.hadoop.mapreduce.Reducer#setup(org.apache.hadoop.mapreduce.Reducer.Context) */ protected void setup(Context context) throws IOException, InterruptedException { Configuration config = context.getConfiguration(); fieldDelim = config.get("field.delim", ","); toBeExcuded = config.getBoolean("exclude.rec", true); } /* (non-Javadoc) * @see org.apache.hadoop.mapreduce.Reducer#reduce(KEYIN, java.lang.Iterable, org.apache.hadoop.mapreduce.Reducer.Context) */ protected void reduce(Tuple key, Iterable<Tuple> values, Context context) throws IOException, InterruptedException { toBeFiletred = false; for (Tuple value : values) { int type = value.getInt(0); if (0 == type) { toBeFiletred = true; } else { if (toBeFiletred && !toBeExcuded || !toBeFiletred && toBeExcuded) { valOut.set(value.getString(1)); context.write(NullWritable.get(), valOut); } } } } } /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { int exitCode = ToolRunner.run(new RecordSetModifier(), args); System.exit(exitCode); } }