/**
* 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.avro.file;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterOutputStream;
/**
* Implements DEFLATE (RFC1951) compression and decompression.
*
* Note that there is a distinction between RFC1951 (deflate)
* and RFC1950 (zlib). zlib adds an extra 2-byte header
* at the front, and a 4-byte checksum at the end. The
* code here, by passing "true" as the "nowrap" option to
* {@link Inflater} and {@link Deflater}, is using
* RFC1951.
*/
class DeflateCodec extends Codec {
static class Option extends CodecFactory {
private int compressionLevel;
Option(int compressionLevel) {
this.compressionLevel = compressionLevel;
}
@Override
protected Codec createInstance() {
return new DeflateCodec(compressionLevel);
}
}
private ByteArrayOutputStream outputBuffer;
private Deflater deflater;
private Inflater inflater;
//currently only do 'nowrap' -- RFC 1951, not zlib
private boolean nowrap = true;
private int compressionLevel;
public DeflateCodec(int compressionLevel) {
this.compressionLevel = compressionLevel;
}
@Override
String getName() {
return DataFileConstants.DEFLATE_CODEC;
}
@Override
ByteBuffer compress(ByteBuffer data) throws IOException {
ByteArrayOutputStream baos = getOutputBuffer(data.remaining());
DeflaterOutputStream ios = new DeflaterOutputStream(baos, getDeflater());
writeAndClose(data, ios);
ByteBuffer result = ByteBuffer.wrap(baos.toByteArray());
return result;
}
@Override
ByteBuffer decompress(ByteBuffer data) throws IOException {
ByteArrayOutputStream baos = getOutputBuffer(data.remaining());
InflaterOutputStream ios = new InflaterOutputStream(baos, getInflater());
writeAndClose(data, ios);
ByteBuffer result = ByteBuffer.wrap(baos.toByteArray());
return result;
}
private void writeAndClose(ByteBuffer data, OutputStream to) throws IOException {
byte[] input = data.array();
int offset = data.arrayOffset() + data.position();
int length = data.remaining();
try {
to.write(input, offset, length);
} finally {
to.close();
}
}
// get and initialize the inflater for use.
private Inflater getInflater() {
if (null == inflater) {
inflater = new Inflater(nowrap);
}
inflater.reset();
return inflater;
}
// get and initialize the deflater for use.
private Deflater getDeflater() {
if (null == deflater) {
deflater = new Deflater(compressionLevel, nowrap);
}
deflater.reset();
return deflater;
}
// get and initialize the output buffer for use.
private ByteArrayOutputStream getOutputBuffer(int suggestedLength) {
if (null == outputBuffer) {
outputBuffer = new ByteArrayOutputStream(suggestedLength);
}
outputBuffer.reset();
return outputBuffer;
}
@Override
public int hashCode() {
return nowrap ? 0 : 1;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (getClass() != obj.getClass())
return false;
DeflateCodec other = (DeflateCodec)obj;
return (this.nowrap == other.nowrap);
}
@Override
public String toString() {
return getName() + "-" + compressionLevel;
}
}