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.fs;
019
020import java.io.*;
021
022import org.apache.hadoop.classification.InterfaceAudience;
023import org.apache.hadoop.classification.InterfaceStability;
024
025/** Stream that permits seeking. */
026@InterfaceAudience.Public
027@InterfaceStability.Evolving
028public interface Seekable {
029  /**
030   * Seek to the given offset from the start of the file.
031   * The next read() will be from that location.  Can't
032   * seek past the end of the file.
033   */
034  void seek(long pos) throws IOException;
035  
036  /**
037   * Return the current offset from the start of the file
038   */
039  long getPos() throws IOException;
040
041  /**
042   * Seeks a different copy of the data.  Returns true if 
043   * found a new source, false otherwise.
044   */
045  @InterfaceAudience.Private
046  boolean seekToNewSource(long targetPos) throws IOException;
047}