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 positional reading. */ 026@InterfaceAudience.Public 027@InterfaceStability.Evolving 028public interface PositionedReadable { 029 /** 030 * Read upto the specified number of bytes, from a given 031 * position within a file, and return the number of bytes read. This does not 032 * change the current offset of a file, and is thread-safe. 033 */ 034 public int read(long position, byte[] buffer, int offset, int length) 035 throws IOException; 036 037 /** 038 * Read the specified number of bytes, from a given 039 * position within a file. This does not 040 * change the current offset of a file, and is thread-safe. 041 */ 042 public void readFully(long position, byte[] buffer, int offset, int length) 043 throws IOException; 044 045 /** 046 * Read number of bytes equal to the length of the buffer, from a given 047 * position within a file. This does not 048 * change the current offset of a file, and is thread-safe. 049 */ 050 public void readFully(long position, byte[] buffer) throws IOException; 051}