Package io.netty.handler.codec.compression

Class Lz4FrameEncoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelOutboundHandlerAdapter

io.netty.handler.codec.MessageToByteEncoder<ByteBuf>

io.netty.handler.codec.compression.Lz4FrameEncoder

All Implemented Interfaces:

ChannelHandler, ChannelOutboundHandler

public class Lz4FrameEncoder
extends MessageToByteEncoder<ByteBuf>

Compresses a ByteBuf using 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/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field	Description
private final int	blockSize
private ByteBuf	buffer	Inner byte buffer for outgoing data.
private final ByteBufChecksum	checksum	Underlying checksum calculator in use.
private final int	compressionLevel	Compression level of current LZ4 encoder (depends on blockSize).
private final net.jpountz.lz4.LZ4Compressor	compressor	Underlying compressor in use.
private ChannelHandlerContext	ctx	Used to interact with its ChannelPipeline and other handlers.
(package private) static final int	DEFAULT_MAX_ENCODE_SIZE
private boolean	finished	Indicates if the compressed stream has been finished.
private final int	maxEncodeSize	Maximum size for any buffer to write encoded (compressed) data into.

Constructor Summary

Constructors

Constructor	Description
Lz4FrameEncoder()	Creates the fastest LZ4 encoder with default block size (64 KB) and xxhash hashing for Java, based on Yann Collet's work available at Github.
Lz4FrameEncoder(boolean highCompressor)	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 Github.
Lz4FrameEncoder(net.jpountz.lz4.LZ4Factory factory, boolean highCompressor, int blockSize, Checksum checksum)	Creates a new customizable LZ4 encoder.
Lz4FrameEncoder(net.jpountz.lz4.LZ4Factory factory, boolean highCompressor, int blockSize, Checksum checksum, int maxEncodeSize)	Creates a new customizable LZ4 encoder.

Method Summary

Modifier and Type	Method	Description
protected ByteBuf	allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg, boolean preferDirect)	Allocate a ByteBuf which will be used as argument of MessageToByteEncoder.encode(ChannelHandlerContext, I, ByteBuf).
private ByteBuf	allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg, boolean preferDirect, boolean allowEmptyReturn)
ChannelFuture	close()	Close this Lz4FrameEncoder and so finish the encoding.
void	close(ChannelHandlerContext ctx, ChannelPromise promise)	Calls ChannelOutboundInvoker.close(ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline.
ChannelFuture	close(ChannelPromise promise)	Close this Lz4FrameEncoder and so finish the encoding.
private static int	compressionLevel(int blockSize)	Calculates compression level on the basis of block size.
private ChannelHandlerContext	ctx()
protected void	encode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out)	Encode a message into a ByteBuf.
private ChannelFuture	finishEncode(ChannelHandlerContext ctx, ChannelPromise promise)
void	flush(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.flush() to forward to the next ChannelOutboundHandler in the ChannelPipeline.
private void	flushBufferedData(ByteBuf out)
(package private) final ByteBuf	getBackingBuffer()
void	handlerAdded(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
void	handlerRemoved(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
boolean	isClosed()	Returns true if and only if the compressed stream has been finished.

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

acceptOutboundMessage, isPreferDirect, write

Methods inherited from class io.netty.channel.ChannelOutboundHandlerAdapter

bind, connect, deregister, disconnect, read

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, exceptionCaught, 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

exceptionCaught

Field Details

DEFAULT_MAX_ENCODE_SIZE

static final int DEFAULT_MAX_ENCODE_SIZE

See Also:

• Constant Field Values

blockSize

private final int blockSize

compressor

private final net.jpountz.lz4.LZ4Compressor compressor

Underlying compressor in use.

checksum

private final ByteBufChecksum checksum

Underlying checksum calculator in use.

compressionLevel

private final int compressionLevel

Compression level of current LZ4 encoder (depends on blockSize).

buffer

private ByteBuf buffer

Inner byte buffer for outgoing data. It's capacity will be blockSize.

maxEncodeSize

private final int maxEncodeSize

Maximum size for any buffer to write encoded (compressed) data into.

finished

private volatile boolean finished

Indicates if the compressed stream has been finished.

ctx

private volatile ChannelHandlerContext ctx

Used to interact with its ChannelPipeline and other handlers.

Constructor Details

Lz4FrameEncoder

public Lz4FrameEncoder()

Creates the fastest LZ4 encoder with default block size (64 KB) and xxhash hashing for Java, based on Yann Collet's work available at Github.

Lz4FrameEncoder

public Lz4FrameEncoder(boolean highCompressor)

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 Github.

Parameters:

highCompressor - if true codec will use compressor which requires more memory and is slower but compresses more efficiently

Lz4FrameEncoder

public Lz4FrameEncoder(net.jpountz.lz4.LZ4Factory factory,
 boolean highCompressor,
 int blockSize,
 Checksum checksum)

Creates a new customizable LZ4 encoder.

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

highCompressor - if true codec will use compressor which requires more memory and is slower but compresses more efficiently

blockSize - the maximum number of bytes to try to compress at once, must be >= 64 and invalid input: '<'= 32 M

checksum - the Checksum instance to use to check data for integrity

Lz4FrameEncoder

public Lz4FrameEncoder(net.jpountz.lz4.LZ4Factory factory,
 boolean highCompressor,
 int blockSize,
 Checksum checksum,
 int maxEncodeSize)

Creates a new customizable LZ4 encoder.

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

highCompressor - if true codec will use compressor which requires more memory and is slower but compresses more efficiently

blockSize - the maximum number of bytes to try to compress at once, must be >= 64 and invalid input: '<'= 32 M

checksum - the Checksum instance to use to check data for integrity

maxEncodeSize - the maximum size for an encode (compressed) buffer

Method Details

compressionLevel

private static int compressionLevel(int blockSize)

Calculates compression level on the basis of block size.

allocateBuffer

protected ByteBuf allocateBuffer(ChannelHandlerContext ctx,
 ByteBuf msg,
 boolean preferDirect)

Description copied from class: MessageToByteEncoder

Allocate a ByteBuf which will be used as argument of MessageToByteEncoder.encode(ChannelHandlerContext, I, ByteBuf). Sub-classes may override this method to return ByteBuf with a perfect matching initialCapacity.

Overrides:

allocateBuffer in class MessageToByteEncoder<ByteBuf>

allocateBuffer

private ByteBuf allocateBuffer(ChannelHandlerContext ctx,
 ByteBuf msg,
 boolean preferDirect,
 boolean allowEmptyReturn)

encode

protected void encode(ChannelHandlerContext ctx,
 ByteBuf in,
 ByteBuf out)
               throws Exception

Encode a message into a ByteBuf. This method will be called for each written message that can be handled by this encoder. Encodes the input buffer into blockSize chunks in the output buffer. Data is only compressed and written once we hit the blockSize; else, it is copied into the backing buffer to await more data.

Specified by:

encode in class MessageToByteEncoder<ByteBuf>

Parameters:

ctx - the ChannelHandlerContext which this MessageToByteEncoder belongs to

in - the message to encode

out - the ByteBuf into which the encoded message will be written

Throws:

Exception - is thrown if an error occurs

flushBufferedData

private void flushBufferedData(ByteBuf out)

flush

public void flush(ChannelHandlerContext ctx)
           throws Exception

Description copied from class: ChannelOutboundHandlerAdapter

Calls ChannelHandlerContext.flush() to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

flush in interface ChannelOutboundHandler

Overrides:

flush in class ChannelOutboundHandlerAdapter

Parameters:

ctx - the ChannelHandlerContext for which the flush operation is made

Throws:

Exception - thrown if an error occurs

finishEncode

private ChannelFuture finishEncode(ChannelHandlerContext ctx,
 ChannelPromise promise)

isClosed

public boolean isClosed()

Returns true if and only if the compressed stream has been finished.

close

public ChannelFuture close()

Close this Lz4FrameEncoder and so finish the encoding. The returned ChannelFuture will be notified once the operation completes.

close

public ChannelFuture close(ChannelPromise promise)

Close this Lz4FrameEncoder and so finish the encoding. The given ChannelFuture will be notified once the operation completes and will also be returned.

close

public void close(ChannelHandlerContext ctx,
 ChannelPromise promise)
           throws Exception

Description copied from class: ChannelOutboundHandlerAdapter

Calls ChannelOutboundInvoker.close(ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

close in interface ChannelOutboundHandler

Overrides:

close in class ChannelOutboundHandlerAdapter

Parameters:

ctx - the ChannelHandlerContext for which the close operation is made

promise - the ChannelPromise to notify once the operation completes

Throws:

Exception - thrown if an error occurs

ctx

private ChannelHandlerContext ctx()

handlerAdded

public void handlerAdded(ChannelHandlerContext ctx)

Description copied from class: ChannelHandlerAdapter

Do nothing by default, sub-classes may override this method.

Specified by:

handlerAdded in interface ChannelHandler

Overrides:

handlerAdded in class ChannelHandlerAdapter

handlerRemoved

public void handlerRemoved(ChannelHandlerContext ctx)
                    throws Exception

Description copied from class: ChannelHandlerAdapter

Do nothing by default, sub-classes may override this method.

Specified by:

handlerRemoved in interface ChannelHandler

Overrides:

handlerRemoved in class ChannelHandlerAdapter

Throws:

Exception

getBackingBuffer

final ByteBuf getBackingBuffer()