org.apache.avro.mapred.HadoopReducer Maven / Gradle / Ivy
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* 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 extends HadoopReducerBase, NullWritable> {
@Override
@SuppressWarnings("unchecked")
protected AvroReducer getReducer(JobConf conf) {
return ReflectionUtils.newInstance(conf.getClass(AvroJob.REDUCER, AvroReducer.class, AvroReducer.class), conf);
}
private class ReduceCollector extends AvroCollector {
private final AvroWrapper wrapper = new AvroWrapper<>(null);
private OutputCollector, NullWritable> out;
public ReduceCollector(OutputCollector, NullWritable> out) {
this.out = out;
}
@Override
public void collect(OUT datum) throws IOException {
wrapper.datum(datum);
out.collect(wrapper, NullWritable.get());
}
}
@Override
protected AvroCollector getCollector(OutputCollector, NullWritable> collector) {
return new ReduceCollector(collector);
}
}