gotosocial/vendor/github.com/dolthub/maphash/hasher.go
kim c06e6fb656
[performance] update go-structr and go-mutexes with memory usage improvements (#2909)
* update go-structr and go-mutexes with memory usage improvements

* bump to go-structr v0.8.4
2024-05-13 08:05:46 +00:00

49 lines
1.3 KiB
Go

// Copyright 2022 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package maphash
import "unsafe"
// Hasher hashes values of type K.
// Uses runtime AES-based hashing.
type Hasher[K comparable] struct {
hash hashfn
seed uintptr
}
// NewHasher creates a new Hasher[K] with a random seed.
func NewHasher[K comparable]() Hasher[K] {
return Hasher[K]{
hash: getRuntimeHasher[K](),
seed: newHashSeed(),
}
}
// NewSeed returns a copy of |h| with a new hash seed.
func NewSeed[K comparable](h Hasher[K]) Hasher[K] {
return Hasher[K]{
hash: h.hash,
seed: newHashSeed(),
}
}
// Hash hashes |key|.
func (h Hasher[K]) Hash(key K) uint64 {
// promise to the compiler that pointer
// |p| does not escape the stack.
p := noescape(unsafe.Pointer(&key))
return uint64(h.hash(p, h.seed))
}