vendor files

vendor/k8s.io/apimachinery/pkg/util/rand/rand.go

@@ -0,0 +1,120 @@
+/*
+Copyright 2015 The Kubernetes 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.
+*/
+
+// Package rand provides utilities related to randomization.
+package rand
+
+import (
+	"math/rand"
+	"sync"
+	"time"
+)
+
+var rng = struct {
+	sync.Mutex
+	rand *rand.Rand
+}{
+	rand: rand.New(rand.NewSource(time.Now().UTC().UnixNano())),
+}
+
+// Intn generates an integer in range [0,max).
+// By design this should panic if input is invalid, <= 0.
+func Intn(max int) int {
+	rng.Lock()
+	defer rng.Unlock()
+	return rng.rand.Intn(max)
+}
+
+// IntnRange generates an integer in range [min,max).
+// By design this should panic if input is invalid, <= 0.
+func IntnRange(min, max int) int {
+	rng.Lock()
+	defer rng.Unlock()
+	return rng.rand.Intn(max-min) + min
+}
+
+// IntnRange generates an int64 integer in range [min,max).
+// By design this should panic if input is invalid, <= 0.
+func Int63nRange(min, max int64) int64 {
+	rng.Lock()
+	defer rng.Unlock()
+	return rng.rand.Int63n(max-min) + min
+}
+
+// Seed seeds the rng with the provided seed.
+func Seed(seed int64) {
+	rng.Lock()
+	defer rng.Unlock()
+
+	rng.rand = rand.New(rand.NewSource(seed))
+}
+
+// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n)
+// from the default Source.
+func Perm(n int) []int {
+	rng.Lock()
+	defer rng.Unlock()
+	return rng.rand.Perm(n)
+}
+
+const (
+	// We omit vowels from the set of available characters to reduce the chances
+	// of "bad words" being formed.
+	alphanums = "bcdfghjklmnpqrstvwxz2456789"
+	// No. of bits required to index into alphanums string.
+	alphanumsIdxBits = 5
+	// Mask used to extract last alphanumsIdxBits of an int.
+	alphanumsIdxMask = 1<<alphanumsIdxBits - 1
+	// No. of random letters we can extract from a single int63.
+	maxAlphanumsPerInt = 63 / alphanumsIdxBits
+)
+
+// String generates a random alphanumeric string, without vowels, which is n
+// characters long.  This will panic if n is less than zero.
+// How the random string is created:
+// - we generate random int63's
+// - from each int63, we are extracting multiple random letters by bit-shifting and masking
+// - if some index is out of range of alphanums we neglect it (unlikely to happen multiple times in a row)
+func String(n int) string {
+	b := make([]byte, n)
+	rng.Lock()
+	defer rng.Unlock()
+
+	randomInt63 := rng.rand.Int63()
+	remaining := maxAlphanumsPerInt
+	for i := 0; i < n; {
+		if remaining == 0 {
+			randomInt63, remaining = rng.rand.Int63(), maxAlphanumsPerInt
+		}
+		if idx := int(randomInt63 & alphanumsIdxMask); idx < len(alphanums) {
+			b[i] = alphanums[idx]
+			i++
+		}
+		randomInt63 >>= alphanumsIdxBits
+		remaining--
+	}
+	return string(b)
+}
+
+// SafeEncodeString encodes s using the same characters as rand.String. This reduces the chances of bad words and
+// ensures that strings generated from hash functions appear consistent throughout the API.
+func SafeEncodeString(s string) string {
+	r := make([]byte, len(s))
+	for i, b := range []rune(s) {
+		r[i] = alphanums[(int(b) % len(alphanums))]
+	}
+	return string(r)
+}