c8841bc9de
Motivation: LZ4 compression codec provides sending and receiving data encoded by very fast LZ4 algorithm. Modifications: - Added `lz4` library which implements LZ4 algorithm. - Implemented Lz4FramedEncoder which extends MessageToByteEncoder and provides compression of outgoing messages. - Added tests to verify the Lz4FramedEncoder and how it can compress data for the next uncompression using the original library. - Implemented Lz4FramedDecoder which extends ByteToMessageDecoder and provides uncompression of incoming messages. - Added tests to verify the Lz4FramedDecoder and how it can uncompress data after compression using the original library. - Added integration tests for Lz4FramedEncoder/Decoder. Result: Full LZ4 compression codec which can compress/uncompress data using LZ4 algorithm.
334 lines
12 KiB
Java
334 lines
12 KiB
Java
/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.compression;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelFuture;
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import io.netty.channel.ChannelFutureListener;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.ChannelPipeline;
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import io.netty.channel.ChannelPromise;
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import io.netty.channel.ChannelPromiseNotifier;
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import io.netty.handler.codec.MessageToByteEncoder;
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import io.netty.util.concurrent.EventExecutor;
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import net.jpountz.lz4.LZ4Compressor;
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import net.jpountz.lz4.LZ4Exception;
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import net.jpountz.lz4.LZ4Factory;
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import net.jpountz.xxhash.XXHashFactory;
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import java.util.concurrent.TimeUnit;
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import java.util.zip.Checksum;
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import static io.netty.handler.codec.compression.Lz4Constants.*;
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/**
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* Compresses a {@link ByteBuf} using the LZ4 format.
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*
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* See original <a href="http://code.google.com/p/lz4/">LZ4 website</a>
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* and <a href="http://fastcompression.blogspot.ru/2011/05/lz4-explained.html">LZ4 block format</a>
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* for full description.
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*
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* Since the original LZ4 block format does not contains size of compressed block and size of original data
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* this encoder uses format like <a href="https://github.com/idelpivnitskiy/lz4-java">LZ4 Java</a> library
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* written by Adrien Grand and approved by Yann Collet (author of original LZ4 library).
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*
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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* * Magic * Token * Compressed * Decompressed * Checksum * + * LZ4 compressed *
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* * * * length * length * * * block *
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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*/
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public class Lz4FrameEncoder extends MessageToByteEncoder<ByteBuf> {
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/**
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* Underlying compressor in use.
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*/
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private LZ4Compressor compressor;
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/**
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* Underlying checksum calculator in use.
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*/
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private Checksum checksum;
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/**
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* Compression level of current LZ4 encoder (depends on {@link #compressedBlockSize}).
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*/
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private final int compressionLevel;
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/**
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* Inner byte buffer for outgoing data.
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*/
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private byte[] buffer;
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/**
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* Current length of buffered bytes in {@link #buffer}.
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*/
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private int currentBlockLength;
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/**
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* Maximum size of compressed block with header.
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*/
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private final int compressedBlockSize;
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/**
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* Indicates if the compressed stream has been finished.
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*/
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private volatile boolean finished;
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/**
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* Used to interact with its {@link ChannelPipeline} and other handlers.
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*/
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private volatile ChannelHandlerContext ctx;
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/**
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* Creates the fastest LZ4 encoder with default block size (64 KB)
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* and xxhash hashing for Java, based on Yann Collet's work available at
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* <a href="http://code.google.com/p/xxhash/">Google Code</a>.
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*/
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public Lz4FrameEncoder() {
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this(false);
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}
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/**
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* Creates a new LZ4 encoder with hight or fast compression, default block size (64 KB)
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* and xxhash hashing for Java, based on Yann Collet's work available at
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* <a href="http://code.google.com/p/xxhash/">Google Code</a>.
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*
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* @param highCompressor if {@code true} codec will use compressor which requires more memory
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* and is slower but compresses more efficiently
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*/
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public Lz4FrameEncoder(boolean highCompressor) {
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this(LZ4Factory.fastestInstance(), highCompressor, DEFAULT_BLOCK_SIZE,
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XXHashFactory.fastestInstance().newStreamingHash32(DEFAULT_SEED).asChecksum());
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}
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/**
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* Creates a new customizable LZ4 encoder.
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*
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* @param factory user customizable {@link net.jpountz.lz4.LZ4Factory} instance
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* which may be JNI bindings to the original C implementation, a pure Java implementation
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* or a Java implementation that uses the {@link sun.misc.Unsafe}
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* @param highCompressor if {@code true} codec will use compressor which requires more memory
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* and is slower but compresses more efficiently
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* @param blockSize the maximum number of bytes to try to compress at once,
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* must be >= 64 and <= 32 M
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* @param checksum the {@link Checksum} instance to use to check data for integrity
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*/
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public Lz4FrameEncoder(LZ4Factory factory, boolean highCompressor, int blockSize, Checksum checksum) {
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super(false);
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if (factory == null) {
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throw new NullPointerException("factory");
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}
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if (checksum == null) {
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throw new NullPointerException("checksum");
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}
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compressor = highCompressor ? factory.highCompressor() : factory.fastCompressor();
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this.checksum = checksum;
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compressionLevel = compressionLevel(blockSize);
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buffer = new byte[blockSize];
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currentBlockLength = 0;
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compressedBlockSize = HEADER_LENGTH + compressor.maxCompressedLength(blockSize);
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finished = false;
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}
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/**
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* Calculates compression level on the basis of block size.
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*/
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private static int compressionLevel(int blockSize) {
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if (blockSize < MIN_BLOCK_SIZE || blockSize > MAX_BLOCK_SIZE) {
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throw new IllegalArgumentException(String.format(
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"blockSize: %d (expected: %d-%d)", blockSize, MIN_BLOCK_SIZE, MAX_BLOCK_SIZE));
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}
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int compressionLevel = 32 - Integer.numberOfLeadingZeros(blockSize - 1); // ceil of log2
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compressionLevel = Math.max(0, compressionLevel - COMPRESSION_LEVEL_BASE);
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return compressionLevel;
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}
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@Override
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protected void encode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out) throws Exception {
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if (finished) {
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out.writeBytes(in);
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return;
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}
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int length = in.readableBytes();
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final byte[] buffer = this.buffer;
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final int blockSize = buffer.length;
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while (currentBlockLength + length >= blockSize) {
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final int tail = blockSize - currentBlockLength;
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in.getBytes(in.readerIndex(), buffer, currentBlockLength, tail);
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currentBlockLength = blockSize;
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flushBufferedData(out);
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in.skipBytes(tail);
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length -= tail;
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}
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in.readBytes(buffer, currentBlockLength, length);
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currentBlockLength += length;
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}
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private void flushBufferedData(ByteBuf out) {
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int currentBlockLength = this.currentBlockLength;
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if (currentBlockLength == 0) {
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return;
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}
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checksum.reset();
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checksum.update(buffer, 0, currentBlockLength);
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final int check = (int) checksum.getValue();
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out.ensureWritable(compressedBlockSize);
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final int idx = out.writerIndex();
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final byte[] dest = out.array();
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final int destOff = out.arrayOffset() + idx;
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int compressedLength;
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try {
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compressedLength = compressor.compress(buffer, 0, currentBlockLength, dest, destOff + HEADER_LENGTH);
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} catch (LZ4Exception e) {
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throw new CompressionException(e);
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}
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final int blockType;
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if (compressedLength >= currentBlockLength) {
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blockType = BLOCK_TYPE_NON_COMPRESSED;
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compressedLength = currentBlockLength;
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System.arraycopy(buffer, 0, dest, destOff + HEADER_LENGTH, currentBlockLength);
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} else {
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blockType = BLOCK_TYPE_COMPRESSED;
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}
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out.setLong(idx, MAGIC_NUMBER);
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dest[destOff + TOKEN_OFFSET] = (byte) (blockType | compressionLevel);
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writeIntLE(compressedLength, dest, destOff + COMPRESSED_LENGTH_OFFSET);
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writeIntLE(currentBlockLength, dest, destOff + DECOMPRESSED_LENGTH_OFFSET);
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writeIntLE(check, dest, destOff + CHECKSUM_OFFSET);
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out.writerIndex(idx + HEADER_LENGTH + compressedLength);
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currentBlockLength = 0;
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this.currentBlockLength = currentBlockLength;
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}
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private ChannelFuture finishEncode(final ChannelHandlerContext ctx, ChannelPromise promise) {
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if (finished) {
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promise.setSuccess();
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return promise;
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}
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finished = true;
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final ByteBuf footer = ctx.alloc().heapBuffer(
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compressor.maxCompressedLength(currentBlockLength) + HEADER_LENGTH);
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flushBufferedData(footer);
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final int idx = footer.writerIndex();
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final byte[] dest = footer.array();
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final int destOff = footer.arrayOffset() + idx;
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footer.setLong(idx, MAGIC_NUMBER);
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dest[destOff + TOKEN_OFFSET] = (byte) (BLOCK_TYPE_NON_COMPRESSED | compressionLevel);
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writeIntLE(0, dest, destOff + COMPRESSED_LENGTH_OFFSET);
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writeIntLE(0, dest, destOff + DECOMPRESSED_LENGTH_OFFSET);
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writeIntLE(0, dest, destOff + CHECKSUM_OFFSET);
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footer.writerIndex(idx + HEADER_LENGTH);
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compressor = null;
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checksum = null;
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buffer = null;
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return ctx.writeAndFlush(footer, promise);
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}
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/**
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* Writes {@code int} value into the byte buffer with little-endian format.
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*/
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private static void writeIntLE(int i, byte[] buf, int off) {
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buf[off++] = (byte) i;
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buf[off++] = (byte) (i >>> 8);
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buf[off++] = (byte) (i >>> 16);
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buf[off] = (byte) (i >>> 24);
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}
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/**
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* Returns {@code true} if and only if the compressed stream has been finished.
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*/
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public boolean isClosed() {
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return finished;
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}
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/**
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* Close this {@link Lz4FrameEncoder} and so finish the encoding.
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*
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* The returned {@link ChannelFuture} will be notified once the operation completes.
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*/
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public ChannelFuture close() {
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return close(ctx().newPromise());
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}
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/**
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* Close this {@link Lz4FrameEncoder} and so finish the encoding.
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* The given {@link ChannelFuture} will be notified once the operation
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* completes and will also be returned.
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*/
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public ChannelFuture close(final ChannelPromise promise) {
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ChannelHandlerContext ctx = ctx();
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EventExecutor executor = ctx.executor();
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if (executor.inEventLoop()) {
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return finishEncode(ctx, promise);
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} else {
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executor.execute(new Runnable() {
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@Override
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public void run() {
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ChannelFuture f = finishEncode(ctx(), promise);
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f.addListener(new ChannelPromiseNotifier(promise));
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}
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});
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return promise;
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}
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}
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@Override
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public void close(final ChannelHandlerContext ctx, final ChannelPromise promise) throws Exception {
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ChannelFuture f = finishEncode(ctx, ctx.newPromise());
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f.addListener(new ChannelFutureListener() {
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@Override
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public void operationComplete(ChannelFuture f) throws Exception {
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ctx.close(promise);
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}
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});
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if (!f.isDone()) {
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// Ensure the channel is closed even if the write operation completes in time.
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ctx.executor().schedule(new Runnable() {
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@Override
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public void run() {
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ctx.close(promise);
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}
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}, 10, TimeUnit.SECONDS); // FIXME: Magic number
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}
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}
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private ChannelHandlerContext ctx() {
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ChannelHandlerContext ctx = this.ctx;
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if (ctx == null) {
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throw new IllegalStateException("not added to a pipeline");
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}
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return ctx;
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}
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@Override
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public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
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this.ctx = ctx;
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}
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}
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