tikhomirov@530: /*
tikhomirov@530:  * Copyright (c) 2013 TMate Software Ltd
tikhomirov@530:  *  
tikhomirov@530:  * This program is free software; you can redistribute it and/or modify
tikhomirov@530:  * it under the terms of the GNU General Public License as published by
tikhomirov@530:  * the Free Software Foundation; version 2 of the License.
tikhomirov@530:  *
tikhomirov@530:  * This program is distributed in the hope that it will be useful,
tikhomirov@530:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
tikhomirov@530:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
tikhomirov@530:  * GNU General Public License for more details.
tikhomirov@530:  *
tikhomirov@530:  * For information on how to redistribute this software under
tikhomirov@530:  * the terms of a license other than GNU General Public License
tikhomirov@530:  * contact TMate Software at support@hg4j.com
tikhomirov@530:  */
tikhomirov@530: package org.tmatesoft.hg.internal;
tikhomirov@530: 
tikhomirov@530: import java.io.IOException;
tikhomirov@530: import java.io.OutputStream;
tikhomirov@530: import java.util.zip.Deflater;
tikhomirov@530: import java.util.zip.DeflaterOutputStream;
tikhomirov@530: 
tikhomirov@530: /**
tikhomirov@530:  * 
tikhomirov@530:  * @author Artem Tikhomirov
tikhomirov@530:  * @author TMate Software Ltd.
tikhomirov@530:  */
tikhomirov@530: public class RevlogCompressor {
tikhomirov@530: 	private final Deflater zip;
tikhomirov@530: 	private byte[] sourceData;
tikhomirov@530: 	private int compressedLenEstimate;
tikhomirov@530: 	
tikhomirov@530: 	public RevlogCompressor() {
tikhomirov@530: 		zip = new Deflater();
tikhomirov@530: 	}
tikhomirov@530: 
tikhomirov@530: 	public void reset(byte[] source) {
tikhomirov@530: 		sourceData = source;
tikhomirov@530: 		compressedLenEstimate = -1;
tikhomirov@530: 	}
tikhomirov@530: 	
tikhomirov@530: 	public int writeCompressedData(OutputStream out) throws IOException {
tikhomirov@530: 		zip.reset();
tikhomirov@530: 		DeflaterOutputStream dos = new DeflaterOutputStream(out, zip, Math.min(2048, sourceData.length));
tikhomirov@530: 		dos.write(sourceData);
tikhomirov@530: 		dos.finish();
tikhomirov@530: 		return zip.getTotalOut();
tikhomirov@530: 	}
tikhomirov@530: 
tikhomirov@530: 	public int getCompressedLengthEstimate() {
tikhomirov@530: 		if (compressedLenEstimate != -1) {
tikhomirov@530: 			return compressedLenEstimate;
tikhomirov@530: 		}
tikhomirov@530: 		zip.reset();
tikhomirov@530: 		int rv = 0;
tikhomirov@530: 		// from DeflaterOutputStream:
tikhomirov@530: 		byte[] buffer = new byte[Math.min(2048, sourceData.length)];
tikhomirov@530:         for (int i = 0, stride = buffer.length; i < sourceData.length; i+= stride) {
tikhomirov@530:             zip.setInput(sourceData, i, Math.min(stride, sourceData.length - i));
tikhomirov@530:             while (!zip.needsInput()) {
tikhomirov@530:             	rv += zip.deflate(buffer, 0, buffer.length);
tikhomirov@530:             }
tikhomirov@530:         }
tikhomirov@530:         zip.finish();
tikhomirov@530:         while (!zip.finished()) {
tikhomirov@530:         	rv += zip.deflate(buffer, 0, buffer.length);
tikhomirov@530:         }
tikhomirov@530:         return compressedLenEstimate = rv;
tikhomirov@530: 	}
tikhomirov@530: }