/
rand.go
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/
rand.go
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//
// Copyright (C) 2019-2024 vdaas.org vald team <vald@vdaas.org>
//
// 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
//
// https://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 rand provides random number algorithms
package rand
import (
"sync/atomic"
"github.com/kpango/fastime"
"github.com/vdaas/vald/internal/sync"
)
type rand struct {
x *uint32
}
var pool = sync.Pool{
New: func() interface{} {
return (&rand{
x: new(uint32),
}).init()
},
}
func Uint32() (x uint32) {
r := pool.Get().(*rand)
x = r.Uint32()
pool.Put(r)
return
}
func LimitedUint32(max uint64) uint32 {
return uint32(uint64(Uint32()) * max >> 32)
}
func Float32() float32 {
return float32(Uint32()) / (1 << 32)
}
func (r *rand) Uint32() (x uint32) {
if atomic.LoadUint32(r.x) == 0 {
r.init()
}
x = atomic.LoadUint32(r.x)
x ^= x << 13
x ^= x >> 17
x ^= x << 5
atomic.StoreUint32(r.x, x)
return
}
func (r *rand) init() *rand {
if r.x == nil {
r.x = new(uint32)
}
x := fastime.UnixNanoNow()
atomic.StoreUint32(r.x, uint32((x>>32)^x))
return r
}