package module
Version: v2.1.2 Latest Latest

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Published: Aug 24, 2021 License: MIT Imports: 4 Imported by: 329



Go Reference Test

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

This implementation provides a fast pure-Go implementation and an even faster assembly implementation for amd64.


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.


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

input size purego asm
5 B 979.66 MB/s 1291.17 MB/s
100 B 7475.26 MB/s 7973.40 MB/s
4 KB 17573.46 MB/s 17602.65 MB/s
10 MB 17131.46 MB/s 17142.16 MB/s

These numbers were generated on Ubuntu 18.04 with an Intel i7-8700K CPU using the following commands under Go 1.11.2:

$ go test -tags purego -benchtime 10s -bench '/xxhash,direct,bytes'
$ go test -benchtime 10s -bench '/xxhash,direct,bytes'

Projects using this package



Package xxhash implements the 64-bit variant of xxHash (XXH64) as described at http://cyan4973.github.io/xxHash/.



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func Sum64

func Sum64(b []byte) uint64

Sum64 computes the 64-bit xxHash digest of b.

func Sum64String

func Sum64String(s string) uint64

Sum64String computes the 64-bit xxHash digest of s. It may be faster than Sum64([]byte(s)) by avoiding a copy.


type Digest

type Digest struct {
	// contains filtered or unexported fields

Digest implements hash.Hash64.

func New

func New() *Digest

New creates a new Digest that computes the 64-bit xxHash algorithm.

func (*Digest) BlockSize

func (d *Digest) BlockSize() int

BlockSize always returns 32 bytes.

func (*Digest) MarshalBinary

func (d *Digest) MarshalBinary() ([]byte, error)

MarshalBinary implements the encoding.BinaryMarshaler interface.

func (*Digest) Reset

func (d *Digest) Reset()

Reset clears the Digest's state so that it can be reused.

func (*Digest) Size

func (d *Digest) Size() int

Size always returns 8 bytes.

func (*Digest) Sum

func (d *Digest) Sum(b []byte) []byte

Sum appends the current hash to b and returns the resulting slice.

func (*Digest) Sum64

func (d *Digest) Sum64() uint64

Sum64 returns the current hash.

func (*Digest) UnmarshalBinary

func (d *Digest) UnmarshalBinary(b []byte) error

UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.

func (*Digest) Write

func (d *Digest) Write(b []byte) (n int, err error)

Write adds more data to d. It always returns len(b), nil.

func (*Digest) WriteString

func (d *Digest) WriteString(s string) (n int, err error)

WriteString adds more data to d. It always returns len(s), nil. It may be faster than Write([]byte(s)) by avoiding a copy.


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