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rand.go
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rand.go
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/*
Copyright (c) Meta Platforms, Inc. and affiliates.
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 db
import (
"math/rand"
"sync"
"time"
)
/**
Minimal implementation of a local pseudo-random source (rand.Source).
This is based on the `globalRand` PRNG code from
https://golang.org/src/math/rand/rand.go
*/
type lockedSource struct {
lk sync.Mutex
src rand.Source64
}
func (r *lockedSource) Seed(seed int64) {
r.lk.Lock()
r.src.Seed(seed)
r.lk.Unlock()
}
func (r *lockedSource) Int63() (n int64) {
r.lk.Lock()
n = r.src.Int63()
r.lk.Unlock()
return
}
// NewRand returns a new PRNG with its own source.
func NewRand() *rand.Rand {
return rand.New(&lockedSource{src: rand.NewSource(time.Now().UnixNano()).(rand.Source64)})
}