| /** |
| * 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.fs.slive; |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.io.Text; |
| import org.apache.hadoop.mapred.JobConf; |
| import org.apache.hadoop.mapred.MapReduceBase; |
| import org.apache.hadoop.mapred.OutputCollector; |
| import org.apache.hadoop.mapred.Reducer; |
| import org.apache.hadoop.mapred.Reporter; |
| import org.apache.hadoop.util.StringUtils; |
| |
| /** |
| * The slive reducer which iterates over the given input values and merges them |
| * together into a final output value. |
| */ |
| public class SliveReducer extends MapReduceBase implements |
| Reducer<Text, Text, Text, Text> { |
| |
| private static final Log LOG = LogFactory.getLog(SliveReducer.class); |
| |
| private ConfigExtractor config; |
| |
| /** |
| * Logs to the given reporter and logs to the internal logger at info level |
| * |
| * @param r |
| * the reporter to set status on |
| * @param msg |
| * the message to log |
| */ |
| private void logAndSetStatus(Reporter r, String msg) { |
| r.setStatus(msg); |
| LOG.info(msg); |
| } |
| |
| /** |
| * Fetches the config this object uses |
| * |
| * @return ConfigExtractor |
| */ |
| private ConfigExtractor getConfig() { |
| return config; |
| } |
| |
| /* |
| * (non-Javadoc) |
| * |
| * @see org.apache.hadoop.mapred.Reducer#reduce(java.lang.Object, |
| * java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, |
| * org.apache.hadoop.mapred.Reporter) |
| */ |
| @Override // Reducer |
| public void reduce(Text key, Iterator<Text> values, |
| OutputCollector<Text, Text> output, Reporter reporter) throws IOException { |
| OperationOutput collector = null; |
| int reduceAm = 0; |
| int errorAm = 0; |
| logAndSetStatus(reporter, "Iterating over reduction values for key " + key); |
| while (values.hasNext()) { |
| Text value = values.next(); |
| try { |
| OperationOutput val = new OperationOutput(key, value); |
| if (collector == null) { |
| collector = val; |
| } else { |
| collector = OperationOutput.merge(collector, val); |
| } |
| LOG.info("Combined " + val + " into/with " + collector); |
| ++reduceAm; |
| } catch (Exception e) { |
| ++errorAm; |
| logAndSetStatus(reporter, "Error iterating over reduction input " |
| + value + " due to : " + StringUtils.stringifyException(e)); |
| if (getConfig().shouldExitOnFirstError()) { |
| break; |
| } |
| } |
| } |
| logAndSetStatus(reporter, "Reduced " + reduceAm + " values with " + errorAm |
| + " errors"); |
| if (collector != null) { |
| logAndSetStatus(reporter, "Writing output " + collector.getKey() + " : " |
| + collector.getOutputValue()); |
| output.collect(collector.getKey(), collector.getOutputValue()); |
| } |
| } |
| |
| /* |
| * (non-Javadoc) |
| * |
| * @see |
| * org.apache.hadoop.mapred.MapReduceBase#configure(org.apache.hadoop.mapred |
| * .JobConf) |
| */ |
| @Override // MapReduceBase |
| public void configure(JobConf conf) { |
| config = new ConfigExtractor(conf); |
| ConfigExtractor.dumpOptions(config); |
| } |
| |
| } |