org.apache.hadoop.io.compress.CompressionOutputStream 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.OutputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.statistics.IOStatistics;
import org.apache.hadoop.fs.statistics.IOStatisticsSource;
import org.apache.hadoop.fs.statistics.IOStatisticsSupport;
/**
* A compression output stream.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class CompressionOutputStream extends OutputStream
implements IOStatisticsSource {
/**
* The output stream to be compressed.
*/
protected final OutputStream out;
/**
* If non-null, this is the Compressor object that we should call
* CodecPool#returnCompressor on when this stream is closed.
*/
private Compressor trackedCompressor;
/**
* Create a compression output stream that writes
* the compressed bytes to the given stream.
* @param out
*/
protected CompressionOutputStream(OutputStream out) {
this.out = out;
}
void setTrackedCompressor(Compressor compressor) {
trackedCompressor = compressor;
}
@Override
public void close() throws IOException {
try {
finish();
} finally {
try {
out.close();
} finally {
if (trackedCompressor != null) {
CodecPool.returnCompressor(trackedCompressor);
trackedCompressor = null;
}
}
}
}
@Override
public void flush() throws IOException {
out.flush();
}
/**
* Write compressed bytes to the stream.
* Made abstract to prevent leakage to underlying stream.
*/
@Override
public abstract void write(byte[] b, int off, int len) throws IOException;
/**
* Finishes writing compressed data to the output stream
* without closing the underlying stream.
*/
public abstract void finish() throws IOException;
/**
* Reset the compression to the initial state.
* Does not reset the underlying stream.
*/
public abstract void resetState() throws IOException;
/**
* Return any IOStatistics provided by the underlying stream.
* @return IO stats from the inner stream.
*/
@Override
public IOStatistics getIOStatistics() {
return IOStatisticsSupport.retrieveIOStatistics(out);
}
}