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 package org.apache.giraph.utils;
19
20 import java.io.IOException;
21 import org.apache.hadoop.io.Writable;
22
23 /**
24 * The objects provided by this iterator have lifetimes only until next() is
25 * called. In that sense, the object provided is only a representative object.
26 *
27 * @param <T> Type that extends Writable that will be iterated
28 */
29 public abstract class RepresentativeByteStructIterator<T extends
30 Writable> extends ByteStructIterator<T> {
31 /** Representative writable */
32 private final T representativeWritable = createWritable();
33
34 /**
35 * Wrap ExtendedDataInput in ByteArrayIterator
36 *
37 * @param extendedDataInput ExtendedDataInput
38 */
39 public RepresentativeByteStructIterator(ExtendedDataInput extendedDataInput) {
40 super(extendedDataInput);
41 }
42
43 @Override
44 public T next() {
45 try {
46 representativeWritable.readFields(extendedDataInput);
47 } catch (IOException e) {
48 throw new IllegalStateException("next: readFields got IOException", e);
49 }
50 return representativeWritable;
51 }
52 }