001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package org.apache.hadoop.mapreduce.lib.aggregate;
020
021 import java.io.IOException;
022 import java.util.ArrayList;
023
024 import org.apache.hadoop.classification.InterfaceAudience;
025 import org.apache.hadoop.classification.InterfaceStability;
026 import org.apache.hadoop.conf.Configuration;
027 import org.apache.hadoop.fs.Path;
028 import org.apache.hadoop.io.Text;
029 import org.apache.hadoop.mapreduce.InputFormat;
030 import org.apache.hadoop.mapreduce.Job;
031 import org.apache.hadoop.mapreduce.MRJobConfig;
032 import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
033 import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
034 import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
035 import org.apache.hadoop.mapreduce.lib.jobcontrol.ControlledJob;
036 import org.apache.hadoop.mapreduce.lib.jobcontrol.JobControl;
037 import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
038 import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
039 import org.apache.hadoop.util.GenericOptionsParser;
040
041 /**
042 * This is the main class for creating a map/reduce job using Aggregate
043 * framework. The Aggregate is a specialization of map/reduce framework,
044 * specializing for performing various simple aggregations.
045 *
046 * Generally speaking, in order to implement an application using Map/Reduce
047 * model, the developer is to implement Map and Reduce functions (and possibly
048 * combine function). However, a lot of applications related to counting and
049 * statistics computing have very similar characteristics. Aggregate abstracts
050 * out the general patterns of these functions and implementing those patterns.
051 * In particular, the package provides generic mapper/redducer/combiner
052 * classes, and a set of built-in value aggregators, and a generic utility
053 * class that helps user create map/reduce jobs using the generic class.
054 * The built-in aggregators include:
055 *
056 * sum over numeric values count the number of distinct values compute the
057 * histogram of values compute the minimum, maximum, media,average, standard
058 * deviation of numeric values
059 *
060 * The developer using Aggregate will need only to provide a plugin class
061 * conforming to the following interface:
062 *
063 * public interface ValueAggregatorDescriptor { public ArrayList<Entry>
064 * generateKeyValPairs(Object key, Object value); public void
065 * configure(Configuration conf); }
066 *
067 * The package also provides a base class, ValueAggregatorBaseDescriptor,
068 * implementing the above interface. The user can extend the base class and
069 * implement generateKeyValPairs accordingly.
070 *
071 * The primary work of generateKeyValPairs is to emit one or more key/value
072 * pairs based on the input key/value pair. The key in an output key/value pair
073 * encode two pieces of information: aggregation type and aggregation id. The
074 * value will be aggregated onto the aggregation id according the aggregation
075 * type.
076 *
077 * This class offers a function to generate a map/reduce job using Aggregate
078 * framework. The function takes the following parameters: input directory spec
079 * input format (text or sequence file) output directory a file specifying the
080 * user plugin class
081 *
082 */
083 @InterfaceAudience.Public
084 @InterfaceStability.Stable
085 public class ValueAggregatorJob {
086
087 public static JobControl createValueAggregatorJobs(String args[],
088 Class<? extends ValueAggregatorDescriptor>[] descriptors)
089 throws IOException {
090
091 JobControl theControl = new JobControl("ValueAggregatorJobs");
092 ArrayList<ControlledJob> dependingJobs = new ArrayList<ControlledJob>();
093 Configuration conf = new Configuration();
094 if (descriptors != null) {
095 conf = setAggregatorDescriptors(descriptors);
096 }
097 Job job = createValueAggregatorJob(conf, args);
098 ControlledJob cjob = new ControlledJob(job, dependingJobs);
099 theControl.addJob(cjob);
100 return theControl;
101 }
102
103 public static JobControl createValueAggregatorJobs(String args[])
104 throws IOException {
105 return createValueAggregatorJobs(args, null);
106 }
107
108 /**
109 * Create an Aggregate based map/reduce job.
110 *
111 * @param conf The configuration for job
112 * @param args the arguments used for job creation. Generic hadoop
113 * arguments are accepted.
114 * @return a Job object ready for submission.
115 *
116 * @throws IOException
117 * @see GenericOptionsParser
118 */
119 public static Job createValueAggregatorJob(Configuration conf, String args[])
120 throws IOException {
121
122 GenericOptionsParser genericParser
123 = new GenericOptionsParser(conf, args);
124 args = genericParser.getRemainingArgs();
125
126 if (args.length < 2) {
127 System.out.println("usage: inputDirs outDir "
128 + "[numOfReducer [textinputformat|seq [specfile [jobName]]]]");
129 GenericOptionsParser.printGenericCommandUsage(System.out);
130 System.exit(2);
131 }
132 String inputDir = args[0];
133 String outputDir = args[1];
134 int numOfReducers = 1;
135 if (args.length > 2) {
136 numOfReducers = Integer.parseInt(args[2]);
137 }
138
139 Class<? extends InputFormat> theInputFormat = null;
140 if (args.length > 3 &&
141 args[3].compareToIgnoreCase("textinputformat") == 0) {
142 theInputFormat = TextInputFormat.class;
143 } else {
144 theInputFormat = SequenceFileInputFormat.class;
145 }
146
147 Path specFile = null;
148
149 if (args.length > 4) {
150 specFile = new Path(args[4]);
151 }
152
153 String jobName = "";
154
155 if (args.length > 5) {
156 jobName = args[5];
157 }
158
159 if (specFile != null) {
160 conf.addResource(specFile);
161 }
162 String userJarFile = conf.get(ValueAggregatorJobBase.USER_JAR);
163 if (userJarFile != null) {
164 conf.set(MRJobConfig.JAR, userJarFile);
165 }
166
167 Job theJob = new Job(conf);
168 if (userJarFile == null) {
169 theJob.setJarByClass(ValueAggregator.class);
170 }
171 theJob.setJobName("ValueAggregatorJob: " + jobName);
172
173 FileInputFormat.addInputPaths(theJob, inputDir);
174
175 theJob.setInputFormatClass(theInputFormat);
176
177 theJob.setMapperClass(ValueAggregatorMapper.class);
178 FileOutputFormat.setOutputPath(theJob, new Path(outputDir));
179 theJob.setOutputFormatClass(TextOutputFormat.class);
180 theJob.setMapOutputKeyClass(Text.class);
181 theJob.setMapOutputValueClass(Text.class);
182 theJob.setOutputKeyClass(Text.class);
183 theJob.setOutputValueClass(Text.class);
184 theJob.setReducerClass(ValueAggregatorReducer.class);
185 theJob.setCombinerClass(ValueAggregatorCombiner.class);
186 theJob.setNumReduceTasks(numOfReducers);
187 return theJob;
188 }
189
190 public static Job createValueAggregatorJob(String args[],
191 Class<? extends ValueAggregatorDescriptor>[] descriptors)
192 throws IOException {
193 return createValueAggregatorJob(
194 setAggregatorDescriptors(descriptors), args);
195 }
196
197 public static Configuration setAggregatorDescriptors(
198 Class<? extends ValueAggregatorDescriptor>[] descriptors) {
199 Configuration conf = new Configuration();
200 conf.setInt(ValueAggregatorJobBase.DESCRIPTOR_NUM, descriptors.length);
201 //specify the aggregator descriptors
202 for(int i=0; i< descriptors.length; i++) {
203 conf.set(ValueAggregatorJobBase.DESCRIPTOR + i,
204 "UserDefined," + descriptors[i].getName());
205 }
206 return conf;
207 }
208
209 /**
210 * create and run an Aggregate based map/reduce job.
211 *
212 * @param args the arguments used for job creation
213 * @throws IOException
214 */
215 public static void main(String args[])
216 throws IOException, InterruptedException, ClassNotFoundException {
217 Job job = ValueAggregatorJob.createValueAggregatorJob(
218 new Configuration(), args);
219 int ret = job.waitForCompletion(true) ? 0 : 1;
220 System.exit(ret);
221 }
222 }