| /** |
| * 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.mapred.lib.aggregate; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.io.Text; |
| import org.apache.hadoop.mapred.FileInputFormat; |
| import org.apache.hadoop.mapred.FileOutputFormat; |
| import org.apache.hadoop.mapred.InputFormat; |
| import org.apache.hadoop.mapred.JobClient; |
| import org.apache.hadoop.mapred.JobConf; |
| import org.apache.hadoop.mapred.SequenceFileInputFormat; |
| import org.apache.hadoop.mapred.TextInputFormat; |
| import org.apache.hadoop.mapred.TextOutputFormat; |
| import org.apache.hadoop.mapred.jobcontrol.Job; |
| import org.apache.hadoop.mapred.jobcontrol.JobControl; |
| import org.apache.hadoop.util.GenericOptionsParser; |
| |
| /** |
| * This is the main class for creating a map/reduce job using Aggregate |
| * framework. The Aggregate is a specialization of map/reduce framework, |
| * specilizing for performing various simple aggregations. |
| * |
| * Generally speaking, in order to implement an application using Map/Reduce |
| * model, the developer is to implement Map and Reduce functions (and possibly |
| * combine function). However, a lot of applications related to counting and |
| * statistics computing have very similar characteristics. Aggregate abstracts |
| * out the general patterns of these functions and implementing those patterns. |
| * In particular, the package provides generic mapper/redducer/combiner classes, |
| * and a set of built-in value aggregators, and a generic utility class that |
| * helps user create map/reduce jobs using the generic class. The built-in |
| * aggregators include: |
| * |
| * sum over numeric values count the number of distinct values compute the |
| * histogram of values compute the minimum, maximum, media,average, standard |
| * deviation of numeric values |
| * |
| * The developer using Aggregate will need only to provide a plugin class |
| * conforming to the following interface: |
| * |
| * public interface ValueAggregatorDescriptor { public ArrayList<Entry> |
| * generateKeyValPairs(Object key, Object value); public void |
| * configure(JobConfjob); } |
| * |
| * The package also provides a base class, ValueAggregatorBaseDescriptor, |
| * implementing the above interface. The user can extend the base class and |
| * implement generateKeyValPairs accordingly. |
| * |
| * The primary work of generateKeyValPairs is to emit one or more key/value |
| * pairs based on the input key/value pair. The key in an output key/value pair |
| * encode two pieces of information: aggregation type and aggregation id. The |
| * value will be aggregated onto the aggregation id according the aggregation |
| * type. |
| * |
| * This class offers a function to generate a map/reduce job using Aggregate |
| * framework. The function takes the following parameters: input directory spec |
| * input format (text or sequence file) output directory a file specifying the |
| * user plugin class |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class ValueAggregatorJob { |
| |
| public static JobControl createValueAggregatorJobs(String args[] |
| , Class<? extends ValueAggregatorDescriptor>[] descriptors) throws IOException { |
| |
| JobControl theControl = new JobControl("ValueAggregatorJobs"); |
| ArrayList<Job> dependingJobs = new ArrayList<Job>(); |
| JobConf aJobConf = createValueAggregatorJob(args); |
| if(descriptors != null) |
| setAggregatorDescriptors(aJobConf, descriptors); |
| Job aJob = new Job(aJobConf, dependingJobs); |
| theControl.addJob(aJob); |
| return theControl; |
| } |
| |
| public static JobControl createValueAggregatorJobs(String args[]) throws IOException { |
| return createValueAggregatorJobs(args, null); |
| } |
| |
| /** |
| * Create an Aggregate based map/reduce job. |
| * |
| * @param args the arguments used for job creation. Generic hadoop |
| * arguments are accepted. |
| * @return a JobConf object ready for submission. |
| * |
| * @throws IOException |
| * @see GenericOptionsParser |
| */ |
| public static JobConf createValueAggregatorJob(String args[]) |
| throws IOException { |
| |
| Configuration conf = new Configuration(); |
| |
| GenericOptionsParser genericParser |
| = new GenericOptionsParser(conf, args); |
| args = genericParser.getRemainingArgs(); |
| |
| if (args.length < 2) { |
| System.out.println("usage: inputDirs outDir " |
| + "[numOfReducer [textinputformat|seq [specfile [jobName]]]]"); |
| GenericOptionsParser.printGenericCommandUsage(System.out); |
| System.exit(1); |
| } |
| String inputDir = args[0]; |
| String outputDir = args[1]; |
| int numOfReducers = 1; |
| if (args.length > 2) { |
| numOfReducers = Integer.parseInt(args[2]); |
| } |
| |
| Class<? extends InputFormat> theInputFormat = |
| TextInputFormat.class; |
| if (args.length > 3 && |
| args[3].compareToIgnoreCase("textinputformat") == 0) { |
| theInputFormat = TextInputFormat.class; |
| } else { |
| theInputFormat = SequenceFileInputFormat.class; |
| } |
| |
| Path specFile = null; |
| |
| if (args.length > 4) { |
| specFile = new Path(args[4]); |
| } |
| |
| String jobName = ""; |
| |
| if (args.length > 5) { |
| jobName = args[5]; |
| } |
| |
| JobConf theJob = new JobConf(conf); |
| if (specFile != null) { |
| theJob.addResource(specFile); |
| } |
| String userJarFile = theJob.get("user.jar.file"); |
| if (userJarFile == null) { |
| theJob.setJarByClass(ValueAggregator.class); |
| } else { |
| theJob.setJar(userJarFile); |
| } |
| theJob.setJobName("ValueAggregatorJob: " + jobName); |
| |
| FileInputFormat.addInputPaths(theJob, inputDir); |
| |
| theJob.setInputFormat(theInputFormat); |
| |
| theJob.setMapperClass(ValueAggregatorMapper.class); |
| FileOutputFormat.setOutputPath(theJob, new Path(outputDir)); |
| theJob.setOutputFormat(TextOutputFormat.class); |
| theJob.setMapOutputKeyClass(Text.class); |
| theJob.setMapOutputValueClass(Text.class); |
| theJob.setOutputKeyClass(Text.class); |
| theJob.setOutputValueClass(Text.class); |
| theJob.setReducerClass(ValueAggregatorReducer.class); |
| theJob.setCombinerClass(ValueAggregatorCombiner.class); |
| theJob.setNumMapTasks(1); |
| theJob.setNumReduceTasks(numOfReducers); |
| return theJob; |
| } |
| |
| public static JobConf createValueAggregatorJob(String args[] |
| , Class<? extends ValueAggregatorDescriptor>[] descriptors) |
| throws IOException { |
| JobConf job = createValueAggregatorJob(args); |
| setAggregatorDescriptors(job, descriptors); |
| return job; |
| } |
| |
| public static void setAggregatorDescriptors(JobConf job |
| , Class<? extends ValueAggregatorDescriptor>[] descriptors) { |
| job.setInt("aggregator.descriptor.num", descriptors.length); |
| //specify the aggregator descriptors |
| for(int i=0; i< descriptors.length; i++) { |
| job.set("aggregator.descriptor." + i, "UserDefined," + descriptors[i].getName()); |
| } |
| } |
| |
| /** |
| * create and run an Aggregate based map/reduce job. |
| * |
| * @param args the arguments used for job creation |
| * @throws IOException |
| */ |
| public static void main(String args[]) throws IOException { |
| JobConf job = ValueAggregatorJob.createValueAggregatorJob(args); |
| JobClient.runJob(job); |
| } |
| } |