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
019package org.apache.hadoop.mapred;
020
021import java.io.IOException;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025import org.apache.hadoop.util.ReflectionUtils;
026
027/** Default {@link MapRunnable} implementation.*/
028@InterfaceAudience.Public
029@InterfaceStability.Stable
030public class MapRunner<K1, V1, K2, V2>
031    implements MapRunnable<K1, V1, K2, V2> {
032  
033  private Mapper<K1, V1, K2, V2> mapper;
034  private boolean incrProcCount;
035
036  @SuppressWarnings("unchecked")
037  public void configure(JobConf job) {
038    this.mapper = ReflectionUtils.newInstance(job.getMapperClass(), job);
039    //increment processed counter only if skipping feature is enabled
040    this.incrProcCount = SkipBadRecords.getMapperMaxSkipRecords(job)>0 && 
041      SkipBadRecords.getAutoIncrMapperProcCount(job);
042  }
043
044  public void run(RecordReader<K1, V1> input, OutputCollector<K2, V2> output,
045                  Reporter reporter)
046    throws IOException {
047    try {
048      // allocate key & value instances that are re-used for all entries
049      K1 key = input.createKey();
050      V1 value = input.createValue();
051      
052      while (input.next(key, value)) {
053        // map pair to output
054        mapper.map(key, value, output, reporter);
055        if(incrProcCount) {
056          reporter.incrCounter(SkipBadRecords.COUNTER_GROUP, 
057              SkipBadRecords.COUNTER_MAP_PROCESSED_RECORDS, 1);
058        }
059      }
060    } finally {
061      mapper.close();
062    }
063  }
064
065  protected Mapper<K1, V1, K2, V2> getMapper() {
066    return mapper;
067  }
068}