io.netty.handler.codec.compression

Class Lz4FrameDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.compression.Lz4FrameDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

public class Lz4FrameDecoder
extends ByteToMessageDecoder

Uncompresses a ByteBuf encoded with the LZ4 format. See original LZ4 Github project 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 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	Lz4FrameDecoder.State Current state of stream.

Nested classes/interfaces inherited from class io.netty.handler.codec.ByteToMessageDecoder

ByteToMessageDecoder.Cumulator

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
private int	blockType Type of current block.
private ByteBufChecksum	checksum Underlying checksum calculator in use.
private int	compressedLength Compressed length of current incoming block.
private int	currentChecksum Checksum value of current incoming block.
private Lz4FrameDecoder.State	currentState
private int	decompressedLength Decompressed length of current incoming block.
private net.jpountz.lz4.LZ4FastDecompressor	decompressor Underlying decompressor in use.

Fields inherited from class io.netty.handler.codec.ByteToMessageDecoder

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Constructor Summary

Constructors

Constructor and Description
Lz4FrameDecoder() Creates the fastest LZ4 decoder.
Lz4FrameDecoder(boolean validateChecksums) Creates a LZ4 decoder with fastest decoder instance available on your machine.
Lz4FrameDecoder(net.jpountz.lz4.LZ4Factory factory, boolean validateChecksums) Creates a new LZ4 decoder with customizable implementation.
Lz4FrameDecoder(net.jpountz.lz4.LZ4Factory factory, java.util.zip.Checksum checksum) Creates a new customizable LZ4 decoder.

Method Summary

Modifier and Type	Method and Description
protected void	decode(ChannelHandlerContext ctx, ByteBuf in, java.util.List<java.lang.Object> out) Decode the from one ByteBuf to an other.
boolean	isClosed() Returns true if and only if the end of the compressed stream has been reached.

Methods inherited from class io.netty.handler.codec.ByteToMessageDecoder

actualReadableBytes, callDecode, channelInactive, channelRead, channelReadComplete, decodeLast, discardSomeReadBytes, handlerRemoved, handlerRemoved0, internalBuffer, isSingleDecode, setCumulator, setDiscardAfterReads, setSingleDecode, userEventTriggered

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.channel.ChannelHandler

handlerAdded

Field Detail

currentState

private Lz4FrameDecoder.State currentState

decompressor

private net.jpountz.lz4.LZ4FastDecompressor decompressor

Underlying decompressor in use.

checksum

private ByteBufChecksum checksum

Underlying checksum calculator in use.

blockType

private int blockType

Type of current block.

compressedLength

private int compressedLength

Compressed length of current incoming block.

decompressedLength

private int decompressedLength

Decompressed length of current incoming block.

currentChecksum

private int currentChecksum

Checksum value of current incoming block.

Constructor Detail

Lz4FrameDecoder

public Lz4FrameDecoder()

Creates the fastest LZ4 decoder. Note that by default, validation of the checksum header in each chunk is DISABLED for performance improvements. If performance is less of an issue, or if you would prefer the safety that checksum validation brings, please use the Lz4FrameDecoder(boolean) constructor with the argument set to true.

Lz4FrameDecoder

public Lz4FrameDecoder(boolean validateChecksums)

Creates a LZ4 decoder with fastest decoder instance available on your machine.

Parameters:

validateChecksums - if true, the checksum field will be validated against the actual uncompressed data, and if the checksums do not match, a suitable DecompressionException will be thrown

Lz4FrameDecoder

public Lz4FrameDecoder(net.jpountz.lz4.LZ4Factory factory,
                       boolean validateChecksums)

Creates a new LZ4 decoder with customizable implementation.

Parameters:

factory - user customizable LZ4Factory instance which may be JNI bindings to the original C implementation, a pure Java implementation or a Java implementation that uses the Unsafe

validateChecksums - if true, the checksum field will be validated against the actual uncompressed data, and if the checksums do not match, a suitable DecompressionException will be thrown. In this case encoder will use xxhash hashing for Java, based on Yann Collet's work available at Github.

Lz4FrameDecoder

public Lz4FrameDecoder(net.jpountz.lz4.LZ4Factory factory,
                       java.util.zip.Checksum checksum)

Creates a new customizable LZ4 decoder.

Parameters:

factory - user customizable LZ4Factory instance which may be JNI bindings to the original C implementation, a pure Java implementation or a Java implementation that uses the Unsafe

checksum - the Checksum instance to use to check data for integrity. You may set null if you do not want to validate checksum of each block

Method Detail

decode

protected void decode(ChannelHandlerContext ctx,
                      ByteBuf in,
                      java.util.List<java.lang.Object> out)
               throws java.lang.Exception

Description copied from class: ByteToMessageDecoder

Decode the from one ByteBuf to an other. This method will be called till either the input ByteBuf has nothing to read when return from this method or till nothing was read from the input ByteBuf.

Specified by:

decode in class ByteToMessageDecoder

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

in - the ByteBuf from which to read data

out - the List to which decoded messages should be added

Throws:

java.lang.Exception - is thrown if an error occurs

isClosed

public boolean isClosed()

Returns true if and only if the end of the compressed stream has been reached.