001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.io.hfile;
019
020import java.io.IOException;
021import org.apache.hadoop.fs.FSDataInputStream;
022import org.apache.yetus.audience.InterfaceAudience;
023
024@InterfaceAudience.Private
025class HFileUtil {
026
027  /**
028   * guards against NullPointer utility which tries to seek on the DFSIS and will try an alternative
029   * source if the FSDataInputStream throws an NPE HBASE-17501 nnn
030   */
031  static public void seekOnMultipleSources(FSDataInputStream istream, long offset)
032    throws IOException {
033    try {
034      // attempt to seek inside of current blockReader
035      istream.seek(offset);
036    } catch (NullPointerException e) {
037      // retry the seek on an alternate copy of the data
038      // this can occur if the blockReader on the DFSInputStream is null
039      istream.seekToNewSource(offset);
040    }
041  }
042}