boulder/vendor/github.com/cespare/xxhash/v2

xxhash

xxhash is a Go implementation of the 64-bit xxHash algorithm, XXH64. This is a high-quality hashing algorithm that is much faster than anything in the Go standard library.

This package provides a straightforward API:

func Sum64(b []byte) uint64
func Sum64String(s string) uint64
type Digest struct{ ... }
    func New() *Digest

The Digest type implements hash.Hash64. Its key methods are:

func (*Digest) Write([]byte) (int, error)
func (*Digest) WriteString(string) (int, error)
func (*Digest) Sum64() uint64

The package is written with optimized pure Go and also contains even faster assembly implementations for amd64 and arm64. If desired, the purego build tag opts into using the Go code even on those architectures.

Compatibility

This package is in a module and the latest code is in version 2 of the module. You need a version of Go with at least "minimal module compatibility" to use github.com/cespare/xxhash/v2:

• 1.9.7+ for Go 1.9
• 1.10.3+ for Go 1.10
• Go 1.11 or later

I recommend using the latest release of Go.

Benchmarks

Here are some quick benchmarks comparing the pure-Go and assembly implementations of Sum64.

input size	purego	asm
4 B	1.3 GB/s	1.2 GB/s
16 B	2.9 GB/s	3.5 GB/s
100 B	6.9 GB/s	8.1 GB/s
4 KB	11.7 GB/s	16.7 GB/s
10 MB	12.0 GB/s	17.3 GB/s

These numbers were generated on Ubuntu 20.04 with an Intel Xeon Platinum 8252C CPU using the following commands under Go 1.19.2:

benchstat <(go test -tags purego -benchtime 500ms -count 15 -bench 'Sum64$')
benchstat <(go test -benchtime 500ms -count 15 -bench 'Sum64$')

Projects using this package

• InfluxDB
• Prometheus
• VictoriaMetrics
• FreeCache
• FastCache
• Ristretto
• Badger