geode-core/src/main/java/org/apache/geode/internal/cache/CachedDeserializable.java

/*
 * 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.geode.internal.cache;

import java.io.DataOutput;
import java.io.IOException;

import org.apache.geode.DataSerializer;
import org.apache.geode.cache.Region;
import org.apache.geode.internal.size.Sizeable;
import org.apache.geode.internal.util.BlobHelper;

/**
 * Provides protocol for getting the deserialized value from a potentially encapsulated object.
 *
 *
 */
public interface CachedDeserializable extends Sizeable {

  /**
   * Returns the raw byte[] that represents this cache value.
   *
   * @return the raw byte[] that represents this cache value
   */
  byte[] getSerializedValue();

  /**
   * Gets a deserialized value for reading. Differs from getDeserializedValue by leaving the value
   * in a form that will optimize future calls.
   *
   * @since GemFire 4.0
   */
  Object getDeserializedForReading();

  /**
   * Gets the string form of the cached object. If an exception is thrown while converting to a
   * string then the exception will be caught and put in the returned string.
   *
   * @return a string that represents the cached object.
   * @since GemFire 6.6
   */
  String getStringForm();

  /**
   * Always makes a copy of the deserialized object and returns it. Leaves the value in a form that
   * will optimize future calls.
   *
   * @param r the region that owns this object or null if no owner
   * @param re the region entry that owns this object or null if no owner
   * @return the deserialized object for this cache value
   */
  Object getDeserializedWritableCopy(Region r, RegionEntry re);

  /**
   * Returns the deserialized object for this cache value.
   *
   * @param r the region that owns this object or null if no owner
   * @param re the region entry that owns this object or null if no owner
   * @return the deserialized object for this cache value
   */
  Object getDeserializedValue(Region r, RegionEntry re);

  /**
   * Return current value regardless of whether it is serialized or deserialized: if it was
   * serialized than it is a byte[], otherwise it is not a byte[].
   */
  Object getValue();

  /**
   * Write out the value contained in this instance to the stream as a byte array (versus serialized
   * form). Anything reading from the stream will have to perform two operations to reconstitute the
   * value: 1) read the byte array off the stream
   * {@link DataSerializer#readByteArray(java.io.DataInput)} 2) de-serialize the byte array using
   * {@link BlobHelper#deserializeBlob(byte[])} into an object. The idea is to delay
   * de-serialization until the last possible moment to provide better parallelism
   *
   * @param out the stream to write on
   */
  void writeValueAsByteArray(DataOutput out) throws IOException;

  /**
   * Sets the serialized value of the Object in the wrapper along with appropriate user bit & valid
   * length. If the Object is already in a serialized form then the byte array is set in the wrapper
   * along with boolean reusable as false
   *
   * @param wrapper object of type BytesAndBitsForCompactor
   */
  void fillSerializedValue(BytesAndBitsForCompactor wrapper, byte userBits);

  /**
   * Return the size of the value, not including the overhead added by this wrapper class.
   */
  int getValueSizeInBytes();

  /**
   * Returns true if the value stored in this memory chunk is a serialized object. Returns false if
   * it is a byte array.
   */
  boolean isSerialized();

  /**
   * Return true if the value uses the java heap; false if not.
   */
  boolean usesHeapForStorage();
}