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 */ 018 019package org.apache.hadoop.io.compress; 020 021import java.io.IOException; 022import java.io.InputStream; 023 024import org.apache.hadoop.classification.InterfaceAudience; 025import org.apache.hadoop.classification.InterfaceStability; 026import org.apache.hadoop.fs.PositionedReadable; 027import org.apache.hadoop.fs.Seekable; 028/** 029 * A compression input stream. 030 * 031 * <p>Implementations are assumed to be buffered. This permits clients to 032 * reposition the underlying input stream then call {@link #resetState()}, 033 * without having to also synchronize client buffers. 034 */ 035@InterfaceAudience.Public 036@InterfaceStability.Evolving 037public abstract class CompressionInputStream extends InputStream implements Seekable { 038 /** 039 * The input stream to be compressed. 040 */ 041 protected final InputStream in; 042 protected long maxAvailableData = 0L; 043 044 private Decompressor trackedDecompressor; 045 046 /** 047 * Create a compression input stream that reads 048 * the decompressed bytes from the given stream. 049 * 050 * @param in The input stream to be compressed. 051 * @throws IOException 052 */ 053 protected CompressionInputStream(InputStream in) throws IOException { 054 if (!(in instanceof Seekable) || !(in instanceof PositionedReadable)) { 055 this.maxAvailableData = in.available(); 056 } 057 this.in = in; 058 } 059 060 @Override 061 public void close() throws IOException { 062 in.close(); 063 if (trackedDecompressor != null) { 064 CodecPool.returnDecompressor(trackedDecompressor); 065 trackedDecompressor = null; 066 } 067 } 068 069 /** 070 * Read bytes from the stream. 071 * Made abstract to prevent leakage to underlying stream. 072 */ 073 @Override 074 public abstract int read(byte[] b, int off, int len) throws IOException; 075 076 /** 077 * Reset the decompressor to its initial state and discard any buffered data, 078 * as the underlying stream may have been repositioned. 079 */ 080 public abstract void resetState() throws IOException; 081 082 /** 083 * This method returns the current position in the stream. 084 * 085 * @return Current position in stream as a long 086 */ 087 @Override 088 public long getPos() throws IOException { 089 if (!(in instanceof Seekable) || !(in instanceof PositionedReadable)){ 090 //This way of getting the current position will not work for file 091 //size which can be fit in an int and hence can not be returned by 092 //available method. 093 return (this.maxAvailableData - this.in.available()); 094 } 095 else{ 096 return ((Seekable)this.in).getPos(); 097 } 098 099 } 100 101 /** 102 * This method is current not supported. 103 * 104 * @throws UnsupportedOperationException 105 */ 106 107 @Override 108 public void seek(long pos) throws UnsupportedOperationException { 109 throw new UnsupportedOperationException(); 110 } 111 112 /** 113 * This method is current not supported. 114 * 115 * @throws UnsupportedOperationException 116 */ 117 @Override 118 public boolean seekToNewSource(long targetPos) throws UnsupportedOperationException { 119 throw new UnsupportedOperationException(); 120 } 121 122 void setTrackedDecompressor(Decompressor decompressor) { 123 trackedDecompressor = decompressor; 124 } 125}