org.apache.hadoop.io.compress.CompressionCodec 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 java.io.OutputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
/**
* This class encapsulates a streaming compression/decompression pair.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface CompressionCodec {
/**
* Create a {@link CompressionOutputStream} that will write to the given
* {@link OutputStream}.
*
* @param out the location for the final output stream
* @return a stream the user can write uncompressed data to have it compressed
* @throws IOException
*/
CompressionOutputStream createOutputStream(OutputStream out)
throws IOException;
/**
* Create a {@link CompressionOutputStream} that will write to the given
* {@link OutputStream} with the given {@link Compressor}.
*
* @param out the location for the final output stream
* @param compressor compressor to use
* @return a stream the user can write uncompressed data to have it compressed
* @throws IOException
*/
CompressionOutputStream createOutputStream(OutputStream out,
Compressor compressor)
throws IOException;
/**
* Get the type of {@link Compressor} needed by this {@link CompressionCodec}.
*
* @return the type of compressor needed by this codec.
*/
Class getCompressorType();
/**
* Create a new {@link Compressor} for use by this {@link CompressionCodec}.
*
* @return a new compressor for use by this codec
*/
Compressor createCompressor();
/**
* Create a {@link CompressionInputStream} that will read from the given
* input stream.
*
* @param in the stream to read compressed bytes from
* @return a stream to read uncompressed bytes from
* @throws IOException
*/
CompressionInputStream createInputStream(InputStream in) throws IOException;
/**
* Create a {@link CompressionInputStream} that will read from the given
* {@link InputStream} with the given {@link Decompressor}.
*
* @param in the stream to read compressed bytes from
* @param decompressor decompressor to use
* @return a stream to read uncompressed bytes from
* @throws IOException
*/
CompressionInputStream createInputStream(InputStream in,
Decompressor decompressor)
throws IOException;
/**
* Get the type of {@link Decompressor} needed by this {@link CompressionCodec}.
*
* @return the type of decompressor needed by this codec.
*/
Class getDecompressorType();
/**
* Create a new {@link Decompressor} for use by this {@link CompressionCodec}.
*
* @return a new decompressor for use by this codec
*/
Decompressor createDecompressor();
/**
* Get the default filename extension for this kind of compression.
* @return the extension including the '.'
*/
String getDefaultExtension();
static class Util {
/**
* Create an output stream with a codec taken from the global CodecPool.
*
* @param codec The codec to use to create the output stream.
* @param conf The configuration to use if we need to create a new codec.
* @param out The output stream to wrap.
* @return The new output stream
* @throws IOException
*/
static CompressionOutputStream createOutputStreamWithCodecPool(
CompressionCodec codec, Configuration conf, OutputStream out)
throws IOException {
Compressor compressor = CodecPool.getCompressor(codec, conf);
CompressionOutputStream stream = null;
try {
stream = codec.createOutputStream(out, compressor);
} finally {
if (stream == null) {
CodecPool.returnCompressor(compressor);
} else {
stream.setTrackedCompressor(compressor);
}
}
return stream;
}
/**
* Create an input stream with a codec taken from the global CodecPool.
*
* @param codec The codec to use to create the input stream.
* @param conf The configuration to use if we need to create a new codec.
* @param in The input stream to wrap.
* @return The new input stream
* @throws IOException
*/
static CompressionInputStream createInputStreamWithCodecPool(
CompressionCodec codec, Configuration conf, InputStream in)
throws IOException {
Decompressor decompressor = CodecPool.getDecompressor(codec);
CompressionInputStream stream = null;
try {
stream = codec.createInputStream(in, decompressor);
} finally {
if (stream == null) {
CodecPool.returnDecompressor(decompressor);
} else {
stream.setTrackedDecompressor(decompressor);
}
}
return stream;
}
}
}