Class Lz4XXHash32

java.lang.Object

io.netty.handler.codec.compression.Lz4XXHash32

All Implemented Interfaces:

Checksum

public final class Lz4XXHash32
extends Object

A special-purpose ByteBufChecksum implementation for use with Lz4FrameEncoder and Lz4FrameDecoder. StreamingXXHash32.asChecksum() has a particularly nasty implementation of Checksum.update(int) that allocates a single-element byte array for every invocation. In addition to that, it doesn't implement an overload that accepts a ByteBuffer as an argument. Combined, this means that we can't use ReflectiveByteBufChecksum at all, and can't use SlowByteBufChecksum because of its atrocious performance with direct byte buffers (allocating an array and making a JNI call for every byte checksummed might be considered sub-optimal by some). Block version of xxHash32 (XXHash32), however, does provide XXHash32.hash(ByteBuffer, int) method that is efficient and does exactly what we need, with a caveat that we can only invoke it once before having to reset. This, however, is fine for our purposes, given the way we use it in Lz4FrameEncoder and Lz4FrameDecoder: reset(), followed by one update(), followed by getValue().

Constructor Summary

Constructors

Constructor	Description
Lz4XXHash32(int seed)

Method Summary

Modifier and Type	Method	Description
long	getValue()
void	reset()
void	update(byte[] b, int off, int len)
void	update(int b)
void	update(ByteBuf b, int off, int len)

Methods inherited from class Object

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

Methods inherited from interface Checksum

update, update

Constructor Details

Lz4XXHash32

public Lz4XXHash32(int seed)

Method Details

update

public void update(int b)

update

public void update(byte[] b,
 int off,
 int len)

update

public void update(ByteBuf b,
 int off,
 int len)

See Also:

• Checksum.update(byte[], int, int)

getValue

public long getValue()

reset

public void reset()