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/*
* Copyright 2014 The Netty Project
*
* The Netty Project 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 io.netty.handler.codec.compression;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.ChannelPromise;
import io.netty.channel.ChannelPromiseNotifier;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.concurrent.EventExecutor;
import net.jpountz.lz4.LZ4Compressor;
import net.jpountz.lz4.LZ4Exception;
import net.jpountz.lz4.LZ4Factory;
import net.jpountz.xxhash.XXHashFactory;
import java.util.concurrent.TimeUnit;
import java.util.zip.Checksum;
import static io.netty.handler.codec.compression.Lz4Constants.*;
/**
* Compresses a {@link ByteBuf} using the LZ4 format.
*
* See original LZ4 website
* and LZ4 block format
* for full description.
*
* Since the original LZ4 block format does not contains size of compressed block and size of original data
* this encoder uses format like LZ4 Java library
* written by Adrien Grand and approved by Yann Collet (author of original LZ4 library).
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* * Magic * Token * Compressed * Decompressed * Checksum * + * LZ4 compressed *
* * * * length * length * * * block *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*/
public class Lz4FrameEncoder extends MessageToByteEncoder {
/**
* Underlying compressor in use.
*/
private LZ4Compressor compressor;
/**
* Underlying checksum calculator in use.
*/
private Checksum checksum;
/**
* Compression level of current LZ4 encoder (depends on {@link #compressedBlockSize}).
*/
private final int compressionLevel;
/**
* Inner byte buffer for outgoing data.
*/
private byte[] buffer;
/**
* Current length of buffered bytes in {@link #buffer}.
*/
private int currentBlockLength;
/**
* Maximum size of compressed block with header.
*/
private final int compressedBlockSize;
/**
* Indicates if the compressed stream has been finished.
*/
private volatile boolean finished;
/**
* Used to interact with its {@link ChannelPipeline} and other handlers.
*/
private volatile ChannelHandlerContext ctx;
/**
* Creates the fastest LZ4 encoder with default block size (64 KB)
* and xxhash hashing for Java, based on Yann Collet's work available at
* Google Code.
*/
public Lz4FrameEncoder() {
this(false);
}
/**
* Creates a new LZ4 encoder with hight or fast compression, default block size (64 KB)
* and xxhash hashing for Java, based on Yann Collet's work available at
* Google Code.
*
* @param highCompressor if {@code true} codec will use compressor which requires more memory
* and is slower but compresses more efficiently
*/
public Lz4FrameEncoder(boolean highCompressor) {
this(LZ4Factory.fastestInstance(), highCompressor, DEFAULT_BLOCK_SIZE,
XXHashFactory.fastestInstance().newStreamingHash32(DEFAULT_SEED).asChecksum());
}
/**
* Creates a new customizable LZ4 encoder.
*
* @param factory user customizable {@link net.jpountz.lz4.LZ4Factory} instance
* which may be JNI bindings to the original C implementation, a pure Java implementation
* or a Java implementation that uses the {@link sun.misc.Unsafe}
* @param highCompressor if {@code true} codec will use compressor which requires more memory
* and is slower but compresses more efficiently
* @param blockSize the maximum number of bytes to try to compress at once,
* must be >= 64 and <= 32 M
* @param checksum the {@link Checksum} instance to use to check data for integrity
*/
public Lz4FrameEncoder(LZ4Factory factory, boolean highCompressor, int blockSize, Checksum checksum) {
super(false);
if (factory == null) {
throw new NullPointerException("factory");
}
if (checksum == null) {
throw new NullPointerException("checksum");
}
compressor = highCompressor ? factory.highCompressor() : factory.fastCompressor();
this.checksum = checksum;
compressionLevel = compressionLevel(blockSize);
buffer = new byte[blockSize];
currentBlockLength = 0;
compressedBlockSize = HEADER_LENGTH + compressor.maxCompressedLength(blockSize);
finished = false;
}
/**
* Calculates compression level on the basis of block size.
*/
private static int compressionLevel(int blockSize) {
if (blockSize < MIN_BLOCK_SIZE || blockSize > MAX_BLOCK_SIZE) {
throw new IllegalArgumentException(String.format(
"blockSize: %d (expected: %d-%d)", blockSize, MIN_BLOCK_SIZE, MAX_BLOCK_SIZE));
}
int compressionLevel = 32 - Integer.numberOfLeadingZeros(blockSize - 1); // ceil of log2
compressionLevel = Math.max(0, compressionLevel - COMPRESSION_LEVEL_BASE);
return compressionLevel;
}
@Override
protected void encode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out) throws Exception {
if (finished) {
out.writeBytes(in);
return;
}
int length = in.readableBytes();
final byte[] buffer = this.buffer;
final int blockSize = buffer.length;
while (currentBlockLength + length >= blockSize) {
final int tail = blockSize - currentBlockLength;
in.getBytes(in.readerIndex(), buffer, currentBlockLength, tail);
currentBlockLength = blockSize;
flushBufferedData(out);
in.skipBytes(tail);
length -= tail;
}
in.readBytes(buffer, currentBlockLength, length);
currentBlockLength += length;
}
private void flushBufferedData(ByteBuf out) {
int currentBlockLength = this.currentBlockLength;
if (currentBlockLength == 0) {
return;
}
checksum.reset();
checksum.update(buffer, 0, currentBlockLength);
final int check = (int) checksum.getValue();
out.ensureWritable(compressedBlockSize);
final int idx = out.writerIndex();
final byte[] dest = out.array();
final int destOff = out.arrayOffset() + idx;
int compressedLength;
try {
compressedLength = compressor.compress(buffer, 0, currentBlockLength, dest, destOff + HEADER_LENGTH);
} catch (LZ4Exception e) {
throw new CompressionException(e);
}
final int blockType;
if (compressedLength >= currentBlockLength) {
blockType = BLOCK_TYPE_NON_COMPRESSED;
compressedLength = currentBlockLength;
System.arraycopy(buffer, 0, dest, destOff + HEADER_LENGTH, currentBlockLength);
} else {
blockType = BLOCK_TYPE_COMPRESSED;
}
out.setLong(idx, MAGIC_NUMBER);
dest[destOff + TOKEN_OFFSET] = (byte) (blockType | compressionLevel);
writeIntLE(compressedLength, dest, destOff + COMPRESSED_LENGTH_OFFSET);
writeIntLE(currentBlockLength, dest, destOff + DECOMPRESSED_LENGTH_OFFSET);
writeIntLE(check, dest, destOff + CHECKSUM_OFFSET);
out.writerIndex(idx + HEADER_LENGTH + compressedLength);
currentBlockLength = 0;
this.currentBlockLength = currentBlockLength;
}
private ChannelFuture finishEncode(final ChannelHandlerContext ctx, ChannelPromise promise) {
if (finished) {
promise.setSuccess();
return promise;
}
finished = true;
final ByteBuf footer = ctx.alloc().heapBuffer(
compressor.maxCompressedLength(currentBlockLength) + HEADER_LENGTH);
flushBufferedData(footer);
final int idx = footer.writerIndex();
final byte[] dest = footer.array();
final int destOff = footer.arrayOffset() + idx;
footer.setLong(idx, MAGIC_NUMBER);
dest[destOff + TOKEN_OFFSET] = (byte) (BLOCK_TYPE_NON_COMPRESSED | compressionLevel);
writeIntLE(0, dest, destOff + COMPRESSED_LENGTH_OFFSET);
writeIntLE(0, dest, destOff + DECOMPRESSED_LENGTH_OFFSET);
writeIntLE(0, dest, destOff + CHECKSUM_OFFSET);
footer.writerIndex(idx + HEADER_LENGTH);
compressor = null;
checksum = null;
buffer = null;
return ctx.writeAndFlush(footer, promise);
}
/**
* Writes {@code int} value into the byte buffer with little-endian format.
*/
private static void writeIntLE(int i, byte[] buf, int off) {
buf[off++] = (byte) i;
buf[off++] = (byte) (i >>> 8);
buf[off++] = (byte) (i >>> 16);
buf[off] = (byte) (i >>> 24);
}
/**
* Returns {@code true} if and only if the compressed stream has been finished.
*/
public boolean isClosed() {
return finished;
}
/**
* Close this {@link Lz4FrameEncoder} and so finish the encoding.
*
* The returned {@link ChannelFuture} will be notified once the operation completes.
*/
public ChannelFuture close() {
return close(ctx().newPromise());
}
/**
* Close this {@link Lz4FrameEncoder} and so finish the encoding.
* The given {@link ChannelFuture} will be notified once the operation
* completes and will also be returned.
*/
public ChannelFuture close(final ChannelPromise promise) {
ChannelHandlerContext ctx = ctx();
EventExecutor executor = ctx.executor();
if (executor.inEventLoop()) {
return finishEncode(ctx, promise);
} else {
executor.execute(new Runnable() {
@Override
public void run() {
ChannelFuture f = finishEncode(ctx(), promise);
f.addListener(new ChannelPromiseNotifier(promise));
}
});
return promise;
}
}
@Override
public void close(final ChannelHandlerContext ctx, final ChannelPromise promise) throws Exception {
ChannelFuture f = finishEncode(ctx, ctx.newPromise());
f.addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture f) throws Exception {
ctx.close(promise);
}
});
if (!f.isDone()) {
// Ensure the channel is closed even if the write operation completes in time.
ctx.executor().schedule(new Runnable() {
@Override
public void run() {
ctx.close(promise);
}
}, 10, TimeUnit.SECONDS); // FIXME: Magic number
}
}
private ChannelHandlerContext ctx() {
ChannelHandlerContext ctx = this.ctx;
if (ctx == null) {
throw new IllegalStateException("not added to a pipeline");
}
return ctx;
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
this.ctx = ctx;
}
}
