AvroBinaryDelta.java

/*
 * Copyright 2014-2016 CyberVision, Inc.
 *
 * Licensed 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.kaaproject.kaa.server.common.core.algorithms.delta;

import static org.kaaproject.kaa.server.common.core.algorithms.CommonConstants.DELTA;

import org.apache.avro.Schema;
import org.apache.avro.generic.GenericArray;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.kaaproject.kaa.common.avro.GenericAvroConverter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;


/**
 * The Class AvroBinaryDelta.
 *
 * @author Yaroslav Zeygerman
 */
public final class AvroBinaryDelta implements RawBinaryDelta {

  /**
   * The Constant LOG.
   */
  private static final Logger LOG = LoggerFactory.getLogger(AvroBinaryDelta.class);

  /**
   * The Constant serialVersionUID.
   */
  private static final long serialVersionUID = 4311409282997230034L;

  /**
   * The schema.
   */
  private transient Schema schema;

  /**
   * The delta queue.
   */
  private transient Queue<GenericRecord> deltaQueue;

  /**
   * The serialized data.
   */
  private byte[] serializedData;

  /**
   * Instantiates a new avro binary delta during deserialization.
   */
  public AvroBinaryDelta() {
    super();
    this.deltaQueue = new LinkedList<GenericRecord>();
  }

  /**
   * Instantiates a new avro binary delta.
   *
   * @param schema the schema
   */
  public AvroBinaryDelta(Schema schema) {
    this();
    this.schema = schema;
  }

  /**
   * Adds the delta.
   *
   * @param delta the delta
   */
  public synchronized void addDelta(GenericRecord delta) {
    deltaQueue.offer(delta);
  }

  /*
   * (non-Javadoc)
   *
   * @see
   * org.kaaproject.kaa.server.operations.service.delta.RawBinaryDelta#getData()
   */
  @Override
  public synchronized byte[] getData() throws IOException {
    if (deltaQueue != null && !deltaQueue.isEmpty()) {
      GenericArray deltaArray = new GenericData.Array(deltaQueue.size(),
          schema);
      while (!deltaQueue.isEmpty()) {
        GenericRecord deltaT = new GenericData.Record(
            schema.getElementType());
        deltaT.put(DELTA, deltaQueue.poll());
        deltaArray.add(deltaT);
      }
      GenericAvroConverter<GenericArray> converter = new GenericAvroConverter<>(schema);
      serializedData = converter.encode(deltaArray);
      if (LOG.isTraceEnabled()) {
        LOG.trace("Delta array: {}", deltaArray.toString());
      }
    }
    return serializedData != null ? Arrays.copyOf(serializedData,
        serializedData.length) : null;
  }

  /*
   * (non-Javadoc)
   *
   * @see
   * org.kaaproject.kaa.server.operations.service.delta.RawBinaryDelta#hasChanges
   * ()
   */
  @Override
  public synchronized boolean hasChanges() {
    return serializedData != null || !(deltaQueue == null || deltaQueue.isEmpty());
  }

  /*
   * (non-Javadoc)
   *
   * @see java.lang.Object#hashCode()
   */
  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + Arrays.hashCode(serializedData);
    return result;
  }

  /*
   * (non-Javadoc)
   *
   * @see java.lang.Object#equals(java.lang.Object)
   */
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (getClass() != obj.getClass()) {
      return false;
    }
    AvroBinaryDelta other = (AvroBinaryDelta) obj;
    if (!Arrays.equals(serializedData, other.serializedData)) {
      return false;
    }
    return true;
  }

}