net.jpountz.lz4.LZ4FrameOutputStream Maven / Gradle / Ivy
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package net.jpountz.lz4;
/*
* Licensed 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.
*/
import net.jpountz.util.Utils;
import net.jpountz.xxhash.StreamingXXHash32;
import net.jpountz.xxhash.XXHash32;
import net.jpountz.xxhash.XXHashFactory;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Locale;
/**
* A partial implementation of the v1.5.1 LZ4 Frame format. This class is NOT thread safe.
*
* Not Supported:
* - Dependent blocks
* - Legacy streams
* - Multiple frames (one LZ4FrameOutputStream is one frame)
*
*
* Originally based on kafka's KafkaLZ4BlockOutputStream.
*
* @see LZ4 Framing Format Spec 1.5.1
*/
public class LZ4FrameOutputStream extends FilterOutputStream {
static final int INTEGER_BYTES = Integer.SIZE >>> 3; // or Integer.BYTES in Java 1.8
static final int LONG_BYTES = Long.SIZE >>> 3; // or Long.BYTES in Java 1.8
static final int MAGIC = 0x184D2204;
static final int LZ4_MAX_HEADER_LENGTH =
4 + // magic
1 + // FLG
1 + // BD
8 + // Content Size
1; // HC
static final int LZ4_FRAME_INCOMPRESSIBLE_MASK = 0x80000000;
static final FLG.Bits[] DEFAULT_FEATURES = new FLG.Bits[]{FLG.Bits.BLOCK_INDEPENDENCE};
static final String CLOSED_STREAM = "The stream is already closed";
public static enum BLOCKSIZE {
SIZE_64KB(4), SIZE_256KB(5), SIZE_1MB(6), SIZE_4MB(7);
private final int indicator;
BLOCKSIZE(int indicator) {
this.indicator = indicator;
}
public int getIndicator() {
return this.indicator;
}
public static BLOCKSIZE valueOf(int indicator) {
switch(indicator) {
case 7: return SIZE_4MB;
case 6: return SIZE_1MB;
case 5: return SIZE_256KB;
case 4: return SIZE_64KB;
default: throw new IllegalArgumentException(String.format(Locale.ROOT, "Block size must be 4-7. Cannot use value of [%d]", indicator));
}
}
}
private final LZ4Compressor compressor;
private final XXHash32 checksum;
private final ByteBuffer buffer; // Buffer for uncompressed input data
private final byte[] compressedBuffer; // Only allocated once so it can be reused
private final int maxBlockSize;
private final long knownSize;
private final ByteBuffer intLEBuffer = ByteBuffer.allocate(INTEGER_BYTES).order(ByteOrder.LITTLE_ENDIAN);
private FrameInfo frameInfo = null;
/**
* Creates a new {@link OutputStream} that will compress data of unknown size using the LZ4 algorithm.
*
* @param out the output stream to compress
* @param blockSize the BLOCKSIZE to use
* @param bits a set of features to use
* @throws IOException if an I/O error occurs
*
* @see #LZ4FrameOutputStream(OutputStream, BLOCKSIZE, long, FLG.Bits...)
*/
public LZ4FrameOutputStream(OutputStream out, BLOCKSIZE blockSize, FLG.Bits... bits) throws IOException {
this(out, blockSize, -1L, bits);
}
/**
* Creates a new {@link OutputStream} that will compress data using using fastest instances of {@link LZ4Compressor} and {@link XXHash32}.
*
* @param out the output stream to compress
* @param blockSize the BLOCKSIZE to use
* @param knownSize the size of the uncompressed data. A value less than zero means unknown.
* @param bits a set of features to use
* @throws IOException if an I/O error occurs
*/
public LZ4FrameOutputStream(OutputStream out, BLOCKSIZE blockSize, long knownSize, FLG.Bits... bits) throws IOException {
super(out);
compressor = LZ4Factory.fastestInstance().fastCompressor();
checksum = XXHashFactory.fastestInstance().hash32();
frameInfo = new FrameInfo(new FLG(FLG.DEFAULT_VERSION, bits), new BD(blockSize));
maxBlockSize = frameInfo.getBD().getBlockMaximumSize();
buffer = ByteBuffer.allocate(maxBlockSize).order(ByteOrder.LITTLE_ENDIAN);
compressedBuffer = new byte[compressor.maxCompressedLength(maxBlockSize)];
if (frameInfo.getFLG().isEnabled(FLG.Bits.CONTENT_SIZE) && knownSize < 0) {
throw new IllegalArgumentException("Known size must be greater than zero in order to use the known size feature");
}
this.knownSize = knownSize;
writeHeader();
}
/**
* Creates a new {@link OutputStream} that will compress data using the LZ4 algorithm. The block independence flag is set, and none of the other flags are set.
*
* @param out The stream to compress
* @param blockSize the BLOCKSIZE to use
* @throws IOException if an I/O error occurs
*
* @see #LZ4FrameOutputStream(OutputStream, BLOCKSIZE, FLG.Bits...)
*/
public LZ4FrameOutputStream(OutputStream out, BLOCKSIZE blockSize) throws IOException {
this(out, blockSize, DEFAULT_FEATURES);
}
/**
* Creates a new {@link OutputStream} that will compress data using the LZ4 algorithm with 4-MB blocks.
*
* @param out the output stream to compress
* @throws IOException if an I/O error occurs
*
* @see #LZ4FrameOutputStream(OutputStream, BLOCKSIZE)
*/
public LZ4FrameOutputStream(OutputStream out) throws IOException {
this(out, BLOCKSIZE.SIZE_4MB);
}
/**
* Writes the magic number and frame descriptor to the underlying {@link OutputStream}.
*
* @throws IOException
*/
private void writeHeader() throws IOException {
final ByteBuffer headerBuffer = ByteBuffer.allocate(LZ4_MAX_HEADER_LENGTH).order(ByteOrder.LITTLE_ENDIAN);
headerBuffer.putInt(MAGIC);
headerBuffer.put(frameInfo.getFLG().toByte());
headerBuffer.put(frameInfo.getBD().toByte());
if (frameInfo.isEnabled(FLG.Bits.CONTENT_SIZE)) {
headerBuffer.putLong(knownSize);
}
// compute checksum on all descriptor fields
final int hash = (checksum.hash(headerBuffer.array(), INTEGER_BYTES, headerBuffer.position() - INTEGER_BYTES, 0) >> 8) & 0xFF;
headerBuffer.put((byte) hash);
// write out frame descriptor
out.write(headerBuffer.array(), 0, headerBuffer.position());
}
/**
* Compresses buffered data, optionally computes an XXHash32 checksum, and writes the result to the underlying
* {@link OutputStream}.
*
* @throws IOException
*/
private void writeBlock() throws IOException {
if (buffer.position() == 0) {
return;
}
// Make sure there's no stale data
Arrays.fill(compressedBuffer, (byte) 0);
int compressedLength = compressor.compress(buffer.array(), 0, buffer.position(), compressedBuffer, 0);
final byte[] bufferToWrite;
final int compressMethod;
// Store block uncompressed if compressed length is greater (incompressible)
if (compressedLength >= buffer.position()) {
compressedLength = buffer.position();
bufferToWrite = Arrays.copyOf(buffer.array(), compressedLength);
compressMethod = LZ4_FRAME_INCOMPRESSIBLE_MASK;
} else {
bufferToWrite = compressedBuffer;
compressMethod = 0;
}
// Write content
intLEBuffer.putInt(0, compressedLength | compressMethod);
out.write(intLEBuffer.array());
out.write(bufferToWrite, 0, compressedLength);
// Calculate and write block checksum
if (frameInfo.isEnabled(FLG.Bits.BLOCK_CHECKSUM)) {
intLEBuffer.putInt(0, checksum.hash(bufferToWrite, 0, compressedLength, 0));
out.write(intLEBuffer.array());
}
buffer.rewind();
}
/**
* Similar to the {@link #writeBlock()} method. Writes a 0-length block (without block checksum) to signal the end
* of the block stream.
*
* @throws IOException
*/
private void writeEndMark() throws IOException {
intLEBuffer.putInt(0, 0);
out.write(intLEBuffer.array());
if (frameInfo.isEnabled(FLG.Bits.CONTENT_CHECKSUM)) {
intLEBuffer.putInt(0, frameInfo.currentStreamHash());
out.write(intLEBuffer.array());
}
frameInfo.finish();
}
@Override
public void write(int b) throws IOException {
ensureNotFinished();
if (buffer.position() == maxBlockSize) {
writeBlock();
}
buffer.put((byte) b);
if (frameInfo.isEnabled(FLG.Bits.CONTENT_CHECKSUM)) {
frameInfo.updateStreamHash(new byte[]{(byte) b}, 0, 1);
}
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
if ((off < 0) || (len < 0) || (off + len > b.length)) {
throw new IndexOutOfBoundsException();
}
ensureNotFinished();
// while b will fill the buffer
while (len > buffer.remaining()) {
int sizeWritten = buffer.remaining();
// fill remaining space in buffer
buffer.put(b, off, sizeWritten);
if (frameInfo.isEnabled(FLG.Bits.CONTENT_CHECKSUM)) {
frameInfo.updateStreamHash(b, off, sizeWritten);
}
writeBlock();
// compute new offset and length
off += sizeWritten;
len -= sizeWritten;
}
buffer.put(b, off, len);
if (frameInfo.isEnabled(FLG.Bits.CONTENT_CHECKSUM)) {
frameInfo.updateStreamHash(b, off, len);
}
}
@Override
public void flush() throws IOException {
if (!frameInfo.isFinished()) {
writeBlock();
}
super.flush();
}
/**
* A simple state check to ensure the stream is still open.
*/
private void ensureNotFinished() {
if (frameInfo.isFinished()) {
throw new IllegalStateException(CLOSED_STREAM);
}
}
@Override
public void close() throws IOException {
if (!frameInfo.isFinished()) {
flush();
writeEndMark();
}
super.close();
}
public static class FLG {
private static final int DEFAULT_VERSION = 1;
private final BitSet bitSet;
private final int version;
public enum Bits {
RESERVED_0(0),
RESERVED_1(1),
CONTENT_CHECKSUM(2),
CONTENT_SIZE(3),
BLOCK_CHECKSUM(4),
BLOCK_INDEPENDENCE(5);
private final int position;
Bits(int position) {
this.position = position;
}
}
public FLG(int version, Bits... bits) {
this.bitSet = new BitSet(8);
this.version = version;
if (bits != null) {
for (Bits bit : bits) {
bitSet.set(bit.position);
}
}
validate();
}
private FLG(int version, byte b) {
this.bitSet = BitSet.valueOf(new byte[]{b});
this.version = version;
validate();
}
public static FLG fromByte(byte flg) {
final byte versionMask = (byte)(flg & (3 << 6));
return new FLG(versionMask >>> 6, (byte) (flg ^ versionMask));
}
public byte toByte() {
return (byte)(bitSet.toByteArray()[0] | ((version & 3) << 6));
}
private void validate() {
if (bitSet.get(Bits.RESERVED_0.position)) {
throw new RuntimeException("Reserved0 field must be 0");
}
if (bitSet.get(Bits.RESERVED_1.position)) {
throw new RuntimeException("Reserved1 field must be 0");
}
if (!bitSet.get(Bits.BLOCK_INDEPENDENCE.position)) {
throw new RuntimeException("Dependent block stream is unsupported (BLOCK_INDEPENDENCE must be set)");
}
if (version != DEFAULT_VERSION) {
throw new RuntimeException(String.format(Locale.ROOT, "Version %d is unsupported", version));
}
}
public boolean isEnabled(Bits bit) {
return bitSet.get(bit.position);
}
public int getVersion() {
return version;
}
}
public static class BD {
private static final int RESERVED_MASK = 0x8F;
private final BLOCKSIZE blockSizeValue;
private BD(BLOCKSIZE blockSizeValue) {
this.blockSizeValue = blockSizeValue;
}
public static BD fromByte(byte bd) {
int blockMaximumSize = (bd >>> 4) & 7;
if ((bd & RESERVED_MASK) > 0) {
throw new RuntimeException("Reserved fields must be 0");
}
return new BD(BLOCKSIZE.valueOf(blockMaximumSize));
}
// 2^(2n+8)
public int getBlockMaximumSize() {
return 1 << ((2 * blockSizeValue.getIndicator()) + 8);
}
public byte toByte() {
return (byte) ((blockSizeValue.getIndicator() & 7) << 4);
}
}
static class FrameInfo {
private final FLG flg;
private final BD bd;
private final StreamingXXHash32 streamHash;
private boolean finished = false;
public FrameInfo(FLG flg, BD bd) {
this.flg = flg;
this.bd = bd;
this.streamHash = flg.isEnabled(FLG.Bits.CONTENT_CHECKSUM) ? XXHashFactory.fastestInstance().newStreamingHash32(0) : null;
}
public boolean isEnabled(FLG.Bits bit) {
return flg.isEnabled(bit);
}
public FLG getFLG() {
return this.flg;
}
public BD getBD() {
return this.bd;
}
public void updateStreamHash(byte[] buff, int off, int len) {
this.streamHash.update(buff, off, len);
}
public int currentStreamHash() {
return this.streamHash.getValue();
}
public void finish() {
this.finished = true;
}
public boolean isFinished() {
return this.finished;
}
}
}