geode-core/src/main/java/org/apache/geode/cache/SerializedCacheValue.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.cache;

/**
 * Class <code>SerializedCacheValue</code> represents a serialized cache value. Instances of this
 * class obtained from a region can be put into another region without a copy of this value being
 * made. The two region entries will both have a reference to the same value.
 * <p>
 * If this value originated from a region stored off heap then this object can only be used as long
 * as notification method that obtained it has not returned. For example if your implementation of
 * {@link CacheListener#afterUpdate(EntryEvent)} obtains one by calling
 * {@link EntryEvent#getSerializedOldValue()} then the SerializedCacheValue returned is only valid
 * until your afterUpdate method returns. It is not safe to store instances of this class and use
 * them later when using off heap storage. Attempts to access off-heap data from this event after it
 * has expired will result in an IllegalStateException.
 *
 * @since GemFire 5.5
 */
public interface SerializedCacheValue<V> {

  /**
   * Returns the raw byte[] that represents this cache value.
   *
   * @return the raw byte[] that represents this cache value
   * @throws IllegalStateException if off-heap and called after the method that was passed the
   *         EntryEvent that this serialize value was obtained from returns and this value does not
   *         already have the serialized value.
   */
  byte[] getSerializedValue();

  /**
   * Returns the deserialized object for this cache value.
   *
   * @return the deserialized object for this cache value
   * @throws IllegalStateException if off-heap and called after the method that was passed the
   *         EntryEvent that this serialize value was obtained from returns.
   */
  V getDeserializedValue();
}