forked from cockroachdb/cockroach
/
rand.go
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/
rand.go
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// Copyright 2014 The Cockroach Authors.
//
// 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. See the AUTHORS file
// for names of contributors.
//
// Author: Ben Darnell
package util
import (
crypto_rand "crypto/rand"
"encoding/binary"
"math/rand"
)
// NewPseudoRand returns an instance of math/rand.Rand seeded from crypto/rand
// so we can easily and cheaply generate unique streams of numbers.
func NewPseudoRand() *rand.Rand {
var seed int64
err := binary.Read(crypto_rand.Reader, binary.LittleEndian, &seed)
if err != nil {
panic(Errorf("could not read from crypto/rand: %s", err))
}
return rand.New(rand.NewSource(seed))
}
// RandIntInRange returns a value in [min, max)
func RandIntInRange(r *rand.Rand, min, max int) int {
return min + r.Intn(max-min)
}
// CachedRand is a global singleton rand.Rand object cached for
// one-off purposes to generate random numbers.
var CachedRand = NewPseudoRand()