1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 package org.apache.hadoop.mapred;
20
21 import java.io.IOException;
22
23 import org.apache.hadoop.io.Writable;
24 import org.apache.hadoop.io.WritableComparable;
25 import org.apache.hadoop.util.ReflectionUtils;
26
27 /** Default {@link MapRunnable} implementation.*/
28 public class MapRunner implements MapRunnable {
29 private Mapper mapper;
30
31 public void configure(JobConf job) {
32 this.mapper = (Mapper)ReflectionUtils.newInstance(job.getMapperClass(),
33 job);
34 }
35
36 public void run(RecordReader input, OutputCollector output,
37 Reporter reporter)
38 throws IOException {
39 try {
40 // allocate key & value instances that are re-used for all entries
41 WritableComparable key = input.createKey();
42 Writable value = input.createValue();
43
44 while (input.next(key, value)) {
45 // map pair to output
46 mapper.map(key, value, output, reporter);
47 }
48 } finally {
49 mapper.close();
50 }
51 }
52
53 }
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