/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.compress;
import java.util.StringTokenizer;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;
import org.h2.api.ErrorCode;
import org.h2.mvstore.DataUtils;
/**
* This is a wrapper class for the Deflater class.
* This algorithm supports the following options:
* <ul>
* <li>l or level: -1 (default), 0 (no compression),
* 1 (best speed), ..., 9 (best compression)
* </li><li>s or strategy: 0 (default),
* 1 (filtered), 2 (huffman only)
* </li></ul>
* See also java.util.zip.Deflater for details.
*/
public class CompressDeflate implements Compressor {
private int level = Deflater.DEFAULT_COMPRESSION;
private int strategy = Deflater.DEFAULT_STRATEGY;
@Override
public void setOptions(String options) {
if (options == null) {
return;
}
try {
StringTokenizer tokenizer = new StringTokenizer(options);
while (tokenizer.hasMoreElements()) {
String option = tokenizer.nextToken();
if ("level".equals(option) || "l".equals(option)) {
level = Integer.parseInt(tokenizer.nextToken());
} else if ("strategy".equals(option) || "s".equals(option)) {
strategy = Integer.parseInt(tokenizer.nextToken());
}
Deflater deflater = new Deflater(level);
deflater.setStrategy(strategy);
}
} catch (Exception e) {
throw DataUtils.newMVStoreException(ErrorCode.UNSUPPORTED_COMPRESSION_OPTIONS_1, options);
}
}
@Override
public int compress(byte[] in, int inPos, int inLen, byte[] out, int outPos) {
Deflater deflater = new Deflater(level);
deflater.setStrategy(strategy);
deflater.setInput(in, inPos, inLen);
deflater.finish();
int compressed = deflater.deflate(out, outPos, out.length - outPos);
if (compressed == 0) {
// the compressed length is 0, meaning compression didn't work
// (sounds like a JDK bug)
// try again, using the default strategy and compression level
strategy = Deflater.DEFAULT_STRATEGY;
level = Deflater.DEFAULT_COMPRESSION;
return compress(in, inPos, inLen, out, outPos);
}
deflater.end();
return outPos + compressed;
}
@Override
public int getAlgorithm() {
return Compressor.DEFLATE;
}
@Override
public void expand(byte[] in, int inPos, int inLen, byte[] out, int outPos,
int outLen) {
Inflater decompresser = new Inflater();
decompresser.setInput(in, inPos, inLen);
decompresser.finished();
try {
int len = decompresser.inflate(out, outPos, outLen);
if (len != outLen) {
throw new DataFormatException(len + " " + outLen);
}
} catch (DataFormatException e) {
throw DataUtils.newMVStoreException(ErrorCode.COMPRESSION_ERROR, e.getMessage(), e);
}
decompresser.end();
}
}