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84 lines
2.1 KiB
Go
84 lines
2.1 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package rand provides utilities related to randomization.
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package rand
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import (
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"math/rand"
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"sync"
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"time"
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)
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var letters = []rune("abcdefghijklmnopqrstuvwxyz0123456789")
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var numLetters = len(letters)
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var rng = struct {
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sync.Mutex
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rand *rand.Rand
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}{
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rand: rand.New(rand.NewSource(time.Now().UTC().UnixNano())),
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}
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// Intn generates an integer in range [0,max).
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// By design this should panic if input is invalid, <= 0.
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func Intn(max int) int {
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rng.Lock()
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defer rng.Unlock()
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return rng.rand.Intn(max)
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}
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// IntnRange generates an integer in range [min,max).
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// By design this should panic if input is invalid, <= 0.
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func IntnRange(min, max int) int {
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rng.Lock()
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defer rng.Unlock()
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return rng.rand.Intn(max-min) + min
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}
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// IntnRange generates an int64 integer in range [min,max).
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// By design this should panic if input is invalid, <= 0.
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func Int63nRange(min, max int64) int64 {
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rng.Lock()
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defer rng.Unlock()
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return rng.rand.Int63n(max-min) + min
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}
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// Seed seeds the rng with the provided seed.
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func Seed(seed int64) {
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rng.Lock()
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defer rng.Unlock()
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rng.rand = rand.New(rand.NewSource(seed))
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}
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// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n)
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// from the default Source.
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func Perm(n int) []int {
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rng.Lock()
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defer rng.Unlock()
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return rng.rand.Perm(n)
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}
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// String generates a random alphanumeric string n characters long. This will
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// panic if n is less than zero.
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func String(length int) string {
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b := make([]rune, length)
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for i := range b {
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b[i] = letters[Intn(numLetters)]
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}
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return string(b)
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}
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