xxhash

This is a native Go implementation of the excellent xxhash* algorithm, an extremely fast non-cryptographic Hash algorithm, working at speeds close to RAM limits.

• The C implementation is (Copyright (c) 2012-2014, Yann Collet)

Install

go get github.com/OneOfOne/xxhash

Features

• On Go 1.7+ the pure go version is faster than CGO for all inputs.
• Supports ChecksumString{32,64} xxhash{32,64}.WriteString, which uses no copies when it can, falls back to copy on appengine.
• The native version falls back to a less optimized version on appengine due to the lack of unsafe.
• Almost as fast as the mostly pure assembly version written by the brilliant cespare, while also supporting seeds.
• To manually toggle the appengine version build with -tags safe.

Benchmark

Core i7-4790 @ 3.60GHz, Linux 4.12.6-1-ARCH (64bit), Go tip (+ff90f4af66 2017-08-19)

➤ go test -bench '64' -count 5 -tags cespare | benchstat /dev/stdin
name                          time/op

# https://github.com/cespare/xxhash
XXSum64Cespare/Func-8          160ns ± 2%
XXSum64Cespare/Struct-8        173ns ± 1%
XXSum64ShortCespare/Func-8    6.78ns ± 1%
XXSum64ShortCespare/Struct-8  19.6ns ± 2%

# this package (default mode, using unsafe)
XXSum64/Func-8                 170ns ± 1%
XXSum64/Struct-8               182ns ± 1%
XXSum64Short/Func-8           13.5ns ± 3%
XXSum64Short/Struct-8         20.4ns ± 0%

# this package (appengine, *not* using unsafe)
XXSum64/Func-8                 241ns ± 5%
XXSum64/Struct-8               243ns ± 6%
XXSum64Short/Func-8           15.2ns ± 2%
XXSum64Short/Struct-8         23.7ns ± 5%

CRC64ISO-8                    1.23µs ± 1%
CRC64ISOString-8              2.71µs ± 4%
CRC64ISOShort-8               22.2ns ± 3%

Fnv64-8                       2.34µs ± 1%
Fnv64Short-8                  74.7ns ± 8%

Usage

	h := xxhash.New64()
	// r, err := os.Open("......")
	// defer f.Close()
	r := strings.NewReader(F)
	io.Copy(h, r)
	fmt.Println("xxhash.Backend:", xxhash.Backend)
	fmt.Println("File checksum:", h.Sum64())

<kbd>playground</kbd>

TODO

• Rewrite the 32bit version to be more optimized.
• General cleanup as the Go inliner gets smarter.

License

This project is released under the Apache v2. license. See LICENSE for more details.