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/**
026 *  Stream that permits seeking.
027 */
028@InterfaceAudience.Public
029@InterfaceStability.Evolving
030public interface Seekable {
031  /**
032   * Seek to the given offset from the start of the file.
033   * The next read() will be from that location.  Can't
034   * seek past the end of the file.
035   */
036  void seek(long pos) throws IOException;
037  
038  /**
039   * Return the current offset from the start of the file
040   */
041  long getPos() throws IOException;
042
043  /**
044   * Seeks a different copy of the data.  Returns true if 
045   * found a new source, false otherwise.
046   */
047  @InterfaceAudience.Private
048  boolean seekToNewSource(long targetPos) throws IOException;
049}