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.OutputCollector;
  import org.apache.hadoop.util.ReflectionUtils;
  
  /**
   * Bridge between a {@link org.apache.hadoop.mapred.Reducer} and an
   * {@link AvroReducer}.
   */
  class HadoopReducer<K, V, OUT> extends HadoopReducerBase<K, V, OUT, AvroWrapper<OUT>, NullWritable> {
  
    @Override
    @SuppressWarnings("unchecked")
    protected AvroReducer<K, V, OUT> getReducer(JobConf conf) {
      return ReflectionUtils.newInstance(conf.getClass(AvroJob.REDUCER, AvroReducer.class, AvroReducer.class), conf);
    }
  
    private class ReduceCollector extends AvroCollector<OUT> {
      private final AvroWrapper<OUT> wrapper = new AvroWrapper<>(null);
      private OutputCollector<AvroWrapper<OUT>, NullWritable> out;
  
      public ReduceCollector(OutputCollector<AvroWrapper<OUT>, NullWritable> out) {
        this.out = out;
      }
  
      @Override
      public void collect(OUT datum) throws IOException {
        wrapper.datum(datum);
        out.collect(wrapper, NullWritable.get());
      }
    }
  
    @Override
    protected AvroCollector<OUT> getCollector(OutputCollector<AvroWrapper<OUT>, NullWritable> collector) {
      return new ReduceCollector(collector);
    }
  
  }
  