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

import java.io.IOException;
import java.util.Map.Entry;
import java.util.NoSuchElementException;

/**
 * Iterates over the entries in a region snapshot. Holds resources that must be freed via
 * {@link #close()}.
 *
 * @param <K> the key type of the snapshot region
 * @param <V> the value type the snapshot region
 *
 * @see SnapshotReader
 *
 * @since GemFire 7.0
 */
public interface SnapshotIterator<K, V> extends AutoCloseable {
  /**
   * Returns true if there are more elements in the iteration.
   *
   * @return true if the iterator has more elements.
   *
   * @throws IOException error reading the snapshot
   * @throws ClassNotFoundException error deserializing the snapshot element
   */
  boolean hasNext() throws IOException, ClassNotFoundException;

  /**
   * Returns the next element in the iteration.
   *
   * @return the next element
   *
   * @throws NoSuchElementException there are no further elements
   * @throws IOException error reading the snapshot
   * @throws ClassNotFoundException error deserializing the snapshot element
   */
  Entry<K, V> next() throws IOException, ClassNotFoundException;

  /**
   * Closes the iterator and its underlying resources.
   *
   * @throws IOException error closing the iterator
   */
  @Override
  void close() throws IOException;
}