Source code

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,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.examples.suspend;
020
021import org.apache.hadoop.io.Writable;
022import org.apache.reef.wake.remote.Codec;
023import org.apache.reef.wake.remote.exception.RemoteRuntimeException;
024
025import java.io.*;
026import java.util.logging.Level;
027import java.util.logging.Logger;
028
029/**
030 * Codec for Hadoop Writable object serialization.
031 *
032 * @param <T> Class derived from Hadoop Writable.
033 */
034public class ObjectWritableCodec<T extends Writable> implements Codec<T> {
035
036  /**
037   * Standard Java logger.
038   */
039  private static final Logger LOG = Logger.getLogger(ObjectWritableCodec.class.getName());
040
041  /**
042   * we need it to invoke the class constructor.
043   */
044  private final Class<? extends T> writableClass;
045
046  /**
047   * Create a new codec for Hadoop Writables.
048   *
049   * @param clazz we need it to invoke the class constructor.
050   */
051  public ObjectWritableCodec(final Class<? extends T> clazz) {
052    this.writableClass = clazz;
053  }
054
055  /**
056   * Encodes Hadoop Writable object into a byte array.
057   *
058   * @param writable the object to encode.
059   * @return serialized object as byte array.
060   * @throws RemoteRuntimeException if serialization fails.
061   */
062  @Override
063  public byte[] encode(final T writable) {
064    try (final ByteArrayOutputStream bos = new ByteArrayOutputStream();
065         final DataOutputStream dos = new DataOutputStream(bos)) {
066      writable.write(dos);
067      return bos.toByteArray();
068    } catch (final IOException ex) {
069      LOG.log(Level.SEVERE, "Cannot encode object " + writable, ex);
070      throw new RemoteRuntimeException(ex);
071    }
072  }
073
074  /**
075   * Decode Hadoop Writable object from a byte array.
076   *
077   * @param buffer serialized version of the Writable object (as a byte array).
078   * @return a Writable object.
079   * @throws RemoteRuntimeException if deserialization fails.
080   */
081  @Override
082  public T decode(final byte[] buffer) {
083    try (final ByteArrayInputStream bis = new ByteArrayInputStream(buffer);
084         final DataInputStream dis = new DataInputStream(bis)) {
085      final T writable = this.writableClass.newInstance();
086      writable.readFields(dis);
087      return writable;
088    } catch (final IOException | InstantiationException | IllegalAccessException ex) {
089      LOG.log(Level.SEVERE, "Cannot decode class " + this.writableClass, ex);
090      throw new RemoteRuntimeException(ex);
091    }
092  }
093}