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VertexIdDataIterator xref
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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.giraph.utils;
20  
21  import org.apache.hadoop.io.WritableComparable;
22  
23  /**
24   * Special iterator that reuses vertex ids and data objects so that the
25   * lifetime of the object is only until next() is called.
26   *
27   * Vertex id ownership can be released if desired through
28   * releaseCurrentVertexId().  This optimization allows us to cut down
29   * on the number of objects instantiated and garbage collected.
30   *
31   * @param <I> vertexId type parameter
32   * @param <T> vertexData type parameter
33   */
34  public interface VertexIdDataIterator<I extends WritableComparable, T>
35      extends VertexIdIterator<I> {
36    /**
37     * Get the current data.
38     *
39     * @return Current data
40     */
41    T getCurrentData();
42  
43    /**
44     * Get serialized size of current data
45     *
46     * @return serialized size of data
47     */
48    int getCurrentDataSize();
49  
50    /**
51     * Release the current data object.
52     *
53     * @return Released data object
54     */
55    T releaseCurrentData();
56  }