NAME
Digest::xxHash - xxHash Implementation For Perl
SYNOPSIS
use Digest::xxHash qw[xxhash xxhash_hex];
my $hash = xxhash( $data, $seed );
my $hex = xxhash_hex( $data, $seed );
# OO remix!
my $digest = Digest::xxHash->new( $seed );
$digest->add( $data );
$digest->add( $more_data );
my $xxhash = $digest->digest( );
my $xxhex = $digest->digest_hex( );
DESCRIPTION
This module provides both a functional and an OO interface to xxHash
functions. xxHash is an extremely fast (and likely very weak) algorithm
that claims to work at speeds close to RAM limits.
FUNCTIONAL INTERFACE
These functions are easy to use but aren't very flexible.
$h = xxhash( $data, $seed )
Calculates a 32 bit hash.
$h = xxhash_hex( $data, $seed )
Calculates a 32 bit hash and returns it as a hex string.
OO INTERFACE
The OO interface is a lot more flexible but less succinct.
$d = Digest::xxHash->new( $seed )
Returns a new Digest::xxHash object. This is a simple constructor.
$d->add( $data )
Adds data to the spool that will eventually be hashed. You may call this
as many times as needed.
$d->reset( )
This will reset the data added to the object. This is great if you want
to hash several pieces of data with the same seed.
$h = $d->digest( )
Calculates a 32 bit hash of the data added to the object.
$h = $d->digest_hex( )
Calculates a 32 bit hash of the data added to the object and returns it
as a hex string.
SPEED
The strength of xxHash isn't very well documented but it's fast.
According to the xxhash project's website, when run in a single thread
on a 32bit Windows 7 box with a 3GHz Core 2 Duo processor, xxhash looks
a little like:
Name Speed Q.Score Author
xxHash 5.4 GB/s 10
MumurHash 3a 2.7 GB/s 10 Austin Appleby
SpookyHash 2.0 GB/s 10 Bob Jenkins
SBox 1.4 GB/s 9 Bret Mulvey
Lookup3 1.2 GB/s 9 Bob Jenkins
CityHash64 1.05 GB/s 10 Pike & Alakuijala
FNV 0.55 GB/s 5 Fowler, Noll, Vo
CRC32 0.43 GB/s 9
MD5-32 0.33 GB/s 10 Ronald L. Rivest
SHA1-32 0.28 GB/s 10
Q.Score is a measure of "quality" of the hash function. It depends on
successfully passing SMHasher test set. 10 is a perfect score. Hash
functions with a Q.score < 5 are not listed in this table.
LICENSE
xxxHash is covered by the BSD license.
I don't actually care about the wrapper I've written.
AUTHOR
Sanko Robinson <
[email protected]>
xxHash by Yann Collet.
