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https://github.com/featurebasedb/featurebase.git
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95 lines
2.6 KiB
Go
95 lines
2.6 KiB
Go
// Copyright 2022 Molecula Corp. (DBA FeatureBase).
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// SPDX-License-Identifier: Apache-2.0
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package hash
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import (
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cryptorand "crypto/rand"
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"encoding/binary"
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"fmt"
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"sync"
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"github.com/zeebo/blake3"
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"golang.org/x/mod/sumdb/dirhash"
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)
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// Blake3Hasher is a thread/goroutine safe way to
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// obtain a blake3 cryptographic hash of input []byte.
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// Reference https://github.com/BLAKE3-team/BLAKE3
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// suggests it is 6x faster than BLAKE2B.
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// The Go github.com/zeebo/blake3 version is
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// AVX2 and SSE4.1 accelerated.
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type Blake3Hasher struct {
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hasher *blake3.Hasher
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hasherMu sync.Mutex
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}
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// NewBlake3Hasher returns a new Blake3Hasher.
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func NewBlake3Hasher() *Blake3Hasher {
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return &Blake3Hasher{
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hasher: blake3.New(),
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}
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}
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// CryptoHash writes the blake3 cryptographic hash of
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// input into buffer and returns it.
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// Like the standard libary's hash.Hash interface's Sum() method,
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// the buffer is re-used and overwritten
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// to avoid allocation. The caller determines the byte length of
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// the outputCryptohash by the size of the supplied buffer
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// slice, and this will be exactly equal to the supplies bytes.
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// In this way, shorter or longer hashes can be provided as
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// needed.
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func (w *Blake3Hasher) CryptoHash(input []byte, buffer []byte) (outputCryptohash []byte) {
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w.hasherMu.Lock()
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w.hasher.Reset()
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// "Write implements part of the hash.Hash interface. It never returns an error."
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// -- https://godoc.org/github.com/zeebo/blake3#Hasher.Write
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_, _ = w.hasher.Write(input)
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// Digest.Read reads data from the hasher into buffer.
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// "It always fills the entire buffer and never errors."
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// -- https://godoc.org/github.com/zeebo/blake3#Digest
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_, _ = w.hasher.Digest().Read(buffer)
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// no chance of panic, so avoid any defer cost.
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w.hasherMu.Unlock()
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return buffer
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}
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// Blake3sum16 might be slower because we allocate a new hasher every time, but
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// it is more conenient for writing debug code. It returns
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// a 16 byte hash as a hexidecimal string.
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func Blake3sum16(input []byte) string {
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hasher := blake3.New()
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_, _ = hasher.Write(input)
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var buf [16]byte
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_, _ = hasher.Digest().Read(buf[0:])
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return fmt.Sprintf("%x", buf)
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}
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// CryptoRandInt64 uses crypto/rand to get an random int64
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func CryptoRandInt64() int64 {
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c := 8
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b := make([]byte, c)
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_, err := cryptorand.Read(b)
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if err != nil {
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panic(err)
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}
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r := int64(binary.LittleEndian.Uint64(b))
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return r
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}
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// HashOfDir returns the hash of the local file system directory dir
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func HashOfDir(path string) string {
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prefix := ""
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h, err := dirhash.HashDir(path, prefix, dirhash.Hash1)
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if err != nil {
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panic(err)
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}
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return h
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}
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