| /** |
| * 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; |
| |
| import java.io.IOException; |
| |
| import java.util.Iterator; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.mapred.Reducer; |
| import org.apache.hadoop.mapred.OutputCollector; |
| import org.apache.hadoop.mapred.Reporter; |
| import org.apache.hadoop.mapred.MapReduceBase; |
| |
| /** |
| * Performs no reduction, writing all input values directly to the output. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class IdentityReducer<K, V> |
| extends MapReduceBase implements Reducer<K, V, K, V> { |
| |
| /** Writes all keys and values directly to output. */ |
| public void reduce(K key, Iterator<V> values, |
| OutputCollector<K, V> output, Reporter reporter) |
| throws IOException { |
| while (values.hasNext()) { |
| output.collect(key, values.next()); |
| } |
| } |
| |
| } |
