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.hadoop.hbase.io.hfile;
19
20 import java.io.IOException;
21
22 import org.apache.hadoop.fs.FSDataInputStream;
23
24 public class HFileUtil {
25
26 /** guards against NullPointer
27 * utility which tries to seek on the DFSIS and will try an alternative source
28 * if the FSDataInputStream throws an NPE HBASE-17501
29 * @param istream
30 * @param offset
31 * @throws IOException
32 */
33 static public void seekOnMultipleSources(FSDataInputStream istream, long offset) throws IOException {
34 try {
35 // attempt to seek inside of current blockReader
36 istream.seek(offset);
37 } catch (NullPointerException e) {
38 // retry the seek on an alternate copy of the data
39 // this can occur if the blockReader on the DFSInputStream is null
40 istream.seekToNewSource(offset);
41 }
42 }
43 }