content: /*
   * 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
   *
   *     https://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.avro.mapred;
  
  import java.io.IOException;
  
  import org.apache.hadoop.io.NullWritable;
  import org.apache.hadoop.mapred.JobConf;
  import org.apache.hadoop.mapred.MapReduceBase;
  import org.apache.hadoop.mapred.Mapper;
  import org.apache.hadoop.mapred.OutputCollector;
  import org.apache.hadoop.mapred.Reporter;
  import org.apache.hadoop.util.ReflectionUtils;
  
  /**
   * An {@link Mapper} that delegates behaviour of paths to multiple other
   * mappers. Similar to {@link HadoopMapper}, but instantiates map classes in the
   * map() call instead of during configure(), as we rely on the split object to
   * provide us that information.
   *
   * @see {@link AvroMultipleInputs#addInputPath(JobConf, Path, Class, Schema)}
   */
  class DelegatingMapper<IN, OUT, K, V, KO, VO> extends MapReduceBase
      implements Mapper<AvroWrapper<IN>, NullWritable, KO, VO> {
    AvroMapper<IN, OUT> mapper;
    JobConf conf;
    boolean isMapOnly;
    AvroCollector<OUT> out;
  
    @Override
    public void configure(JobConf conf) {
      this.conf = conf;
      this.isMapOnly = conf.getNumReduceTasks() == 0;
    }
  
    @Override
    public void map(AvroWrapper<IN> wrapper, NullWritable value, OutputCollector<KO, VO> collector, Reporter reporter)
        throws IOException {
      if (mapper == null) {
        TaggedInputSplit is = (TaggedInputSplit) reporter.getInputSplit();
        Class<? extends AvroMapper> mapperClass = is.getMapperClass();
        mapper = (AvroMapper<IN, OUT>) ReflectionUtils.newInstance(mapperClass, conf);
      }
      if (out == null)
        out = new MapCollector<OUT, K, V, KO, VO>(collector, isMapOnly);
      mapper.map(wrapper.datum(), out, reporter);
    }
  }
  