io.netty.handler.codec.compression

Class LzmaFrameEncoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelOutboundHandlerAdapter

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

io.netty.handler.codec.compression.LzmaFrameEncoder

All Implemented Interfaces:

ChannelHandler, ChannelOutboundHandler

public class LzmaFrameEncoder
extends MessageToByteEncoder<ByteBuf>

Compresses a ByteBuf using the LZMA algorithm. See LZMA and LZMA format or documents in LZMA SDK archive.

Nested Class Summary

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

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
private static int	DEFAULT_LC
private static int	DEFAULT_LP
private static int	DEFAULT_MATCH_FINDER
private static int	DEFAULT_PB
private lzma.sdk.lzma.Encoder	encoder Underlying LZMA encoder in use.
private int	littleEndianDictionarySize Dictionary Size is stored as an unsigned 32-bit little endian integer.
private static InternalLogger	logger
private static int	MAX_FAST_BYTES
private static int	MEDIUM_DICTIONARY_SIZE
private static int	MEDIUM_FAST_BYTES
private static int	MIN_FAST_BYTES
private byte	properties The Properties field contains three properties which are encoded using the following formula:
private static boolean	warningLogged For log warning only once.

Constructor Summary

Constructors

Constructor and Description
LzmaFrameEncoder() Creates LZMA encoder with default settings.
LzmaFrameEncoder(int dictionarySize) Creates LZMA encoder with specified dictionary size and default values of lc = 3, lp = 0, pb = 2.
LzmaFrameEncoder(int lc, int lp, int pb) Creates LZMA encoder with specified lc, lp, pb values and the medium dictionary size of 65536.
LzmaFrameEncoder(int lc, int lp, int pb, int dictionarySize) Creates LZMA encoder with specified lc, lp, pb values and custom dictionary size.
LzmaFrameEncoder(int lc, int lp, int pb, int dictionarySize, boolean endMarkerMode, int numFastBytes) Creates LZMA encoder with specified settings.

Method Summary

Modifier and Type	Method and Description
protected ByteBuf	allocateBuffer(ChannelHandlerContext ctx, ByteBuf in, boolean preferDirect) Allocate a ByteBuf which will be used as argument of #encode(ChannelHandlerContext, I, ByteBuf).
protected void	encode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out) Encode a message into a ByteBuf.
private static int	maxOutputBufferLength(int inputLength) Calculates maximum possible size of output buffer for not compressible data.

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

acceptOutboundMessage, isPreferDirect, write

Methods inherited from class io.netty.channel.ChannelOutboundHandlerAdapter

bind, close, connect, deregister, disconnect, flush, read

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, exceptionCaught, handlerAdded, handlerRemoved, 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, handlerAdded, handlerRemoved

Field Detail

logger

private static final InternalLogger logger

MEDIUM_DICTIONARY_SIZE

private static final int MEDIUM_DICTIONARY_SIZE

See Also:

Constant Field Values

MIN_FAST_BYTES

private static final int MIN_FAST_BYTES

See Also:

Constant Field Values

MEDIUM_FAST_BYTES

private static final int MEDIUM_FAST_BYTES

See Also:

Constant Field Values

MAX_FAST_BYTES

private static final int MAX_FAST_BYTES

See Also:

Constant Field Values

DEFAULT_MATCH_FINDER

private static final int DEFAULT_MATCH_FINDER

See Also:

Constant Field Values

DEFAULT_LC

private static final int DEFAULT_LC

See Also:

Constant Field Values

DEFAULT_LP

private static final int DEFAULT_LP

See Also:

Constant Field Values

DEFAULT_PB

private static final int DEFAULT_PB

See Also:

Constant Field Values

encoder

private final lzma.sdk.lzma.Encoder encoder

Underlying LZMA encoder in use.

properties

private final byte properties

The Properties field contains three properties which are encoded using the following formula:

Properties = (pb * 5 + lp) * 9 + lc

The field consists of

1. the number of literal context bits (lc, [0, 8]);
2. the number of literal position bits (lp, [0, 4]);
3. the number of position bits (pb, [0, 4]).

littleEndianDictionarySize

private final int littleEndianDictionarySize

Dictionary Size is stored as an unsigned 32-bit little endian integer.

warningLogged

private static boolean warningLogged

For log warning only once.

Constructor Detail

LzmaFrameEncoder

public LzmaFrameEncoder()

Creates LZMA encoder with default settings.

LzmaFrameEncoder

public LzmaFrameEncoder(int lc,
                        int lp,
                        int pb)

Creates LZMA encoder with specified lc, lp, pb values and the medium dictionary size of 65536.

LzmaFrameEncoder

public LzmaFrameEncoder(int dictionarySize)

Creates LZMA encoder with specified dictionary size and default values of lc = 3, lp = 0, pb = 2.

LzmaFrameEncoder

public LzmaFrameEncoder(int lc,
                        int lp,
                        int pb,
                        int dictionarySize)

Creates LZMA encoder with specified lc, lp, pb values and custom dictionary size.

LzmaFrameEncoder

public LzmaFrameEncoder(int lc,
                        int lp,
                        int pb,
                        int dictionarySize,
                        boolean endMarkerMode,
                        int numFastBytes)

Creates LZMA encoder with specified settings.

Parameters:

lc - the number of "literal context" bits, available values [0, 8], default value 3.

lp - the number of "literal position" bits, available values [0, 4], default value 0.

pb - the number of "position" bits, available values [0, 4], default value 2.

dictionarySize - available values [0, Integer.MAX_VALUE], default value is 65536.

endMarkerMode - indicates should LzmaFrameEncoder use end of stream marker or not. Note, that LzmaFrameEncoder always sets size of uncompressed data in LZMA header, so EOS marker is unnecessary. But you may use it for better portability. For full description see "LZMA Decoding modes" section of LZMA-Specification.txt in official LZMA SDK.

numFastBytes - available values [5, 273].

Method Detail

encode

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

Description copied from class: MessageToByteEncoder

Encode a message into a ByteBuf. This method will be called for each written message that can be handled by this encoder.

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:

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

allocateBuffer

protected ByteBuf allocateBuffer(ChannelHandlerContext ctx,
                                 ByteBuf in,
                                 boolean preferDirect)
                          throws java.lang.Exception

Description copied from class: MessageToByteEncoder

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

Overrides:

allocateBuffer in class MessageToByteEncoder<ByteBuf>

Throws:

java.lang.Exception

maxOutputBufferLength

private static int maxOutputBufferLength(int inputLength)

Calculates maximum possible size of output buffer for not compressible data.