org.apache.hadoop.io.compress.CompressionInputStream Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.io.compress;
import java.io.IOException;
import java.io.InputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.PositionedReadable;
import org.apache.hadoop.fs.Seekable;
import org.apache.hadoop.fs.statistics.IOStatistics;
import org.apache.hadoop.fs.statistics.IOStatisticsSource;
import org.apache.hadoop.fs.statistics.IOStatisticsSupport;
/**
* A compression input stream.
*
* Implementations are assumed to be buffered. This permits clients to
* reposition the underlying input stream then call {@link #resetState()},
* without having to also synchronize client buffers.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class CompressionInputStream extends InputStream
implements Seekable, IOStatisticsSource {
/**
* The input stream to be compressed.
*/
protected final InputStream in;
protected long maxAvailableData = 0L;
private Decompressor trackedDecompressor;
/**
* Create a compression input stream that reads
* the decompressed bytes from the given stream.
*
* @param in The input stream to be compressed.
* @throws IOException
*/
protected CompressionInputStream(InputStream in) throws IOException {
if (!(in instanceof Seekable) || !(in instanceof PositionedReadable)) {
this.maxAvailableData = in.available();
}
this.in = in;
}
@Override
public void close() throws IOException {
try {
in.close();
} finally {
if (trackedDecompressor != null) {
CodecPool.returnDecompressor(trackedDecompressor);
trackedDecompressor = null;
}
}
}
/**
* Return any IOStatistics provided by the underlying stream.
* @return IO stats from the inner stream.
*/
@Override
public IOStatistics getIOStatistics() {
return IOStatisticsSupport.retrieveIOStatistics(in);
}
/**
* Read bytes from the stream.
* Made abstract to prevent leakage to underlying stream.
*/
@Override
public abstract int read(byte[] b, int off, int len) throws IOException;
/**
* Reset the decompressor to its initial state and discard any buffered data,
* as the underlying stream may have been repositioned.
*/
public abstract void resetState() throws IOException;
/**
* This method returns the current position in the stream.
*
* @return Current position in stream as a long
*/
@Override
public long getPos() throws IOException {
if (!(in instanceof Seekable) || !(in instanceof PositionedReadable)){
//This way of getting the current position will not work for file
//size which can be fit in an int and hence can not be returned by
//available method.
return (this.maxAvailableData - this.in.available());
}
else{
return ((Seekable)this.in).getPos();
}
}
/**
* This method is current not supported.
*
* @throws UnsupportedOperationException
*/
@Override
public void seek(long pos) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
/**
* This method is current not supported.
*
* @throws UnsupportedOperationException
*/
@Override
public boolean seekToNewSource(long targetPos) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
void setTrackedDecompressor(Decompressor decompressor) {
trackedDecompressor = decompressor;
}
}