/**
* 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
*
* http://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.gora.mapreduce;
import java.io.IOException;
import java.io.InputStream;
import org.apache.avro.Schema;
import org.apache.avro.io.BinaryDecoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.gora.avro.PersistentDatumReader;
import org.apache.gora.persistency.Persistent;
import org.apache.gora.util.AvroUtils;
import org.apache.hadoop.io.serializer.Deserializer;
/**
* Hadoop deserializer using {@link PersistentDatumReader}
* with {@link BinaryDecoder}.
*/
public class PersistentDeserializer
implements Deserializer<Persistent> {
private BinaryDecoder decoder;
private Class<? extends Persistent> persistentClass;
private boolean reuseObjects;
private PersistentDatumReader<Persistent> datumReader;
public PersistentDeserializer(Class<? extends Persistent> c, boolean reuseObjects) {
this.persistentClass = c;
this.reuseObjects = reuseObjects;
try {
Schema schema = AvroUtils.getSchema(persistentClass);
datumReader = new PersistentDatumReader<Persistent>(schema, true);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
@Override
public void open(InputStream in) throws IOException {
/* It is very important to use a direct buffer, since Hadoop
* supplies an input stream that is only valid until the end of one
* record serialization. Each time deserialize() is called, the IS
* is advanced to point to the right location, so we should not
* buffer the whole input stream at once.
*/
decoder = new DecoderFactory().configureDirectDecoder(true)
.createBinaryDecoder(in, decoder);
}
@Override
public void close() throws IOException { }
@Override
public Persistent deserialize(Persistent persistent) throws IOException {
return datumReader.read(reuseObjects ? persistent : null, decoder);
}
}