/
utils.go
75 lines (68 loc) · 2.07 KB
/
utils.go
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// Copyright 2016 CoreOS, Inc.
//
// 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 web
import (
"fmt"
"math/rand"
"time"
)
const (
letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
letterIdxBits = 6 // 6 bits to represent a letter index
letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
)
func randBytes(bytesN int) []byte {
src := rand.NewSource(time.Now().UnixNano())
b := make([]byte, bytesN)
for i, cache, remain := bytesN-1, src.Int63(), letterIdxMax; i >= 0; {
if remain == 0 {
cache, remain = src.Int63(), letterIdxMax
}
if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
b[i] = letterBytes[idx]
i--
}
cache >>= letterIdxBits
remain--
}
return b
}
func multiRandStrings(bytesN, sliceN int, prefix string) []string {
m := make(map[string]struct{})
rs := make([]string, 0, sliceN)
for len(rs) != sliceN {
b := randBytes(bytesN)
s := fmt.Sprintf("%s%s%d", prefix, b, len(rs)+1)
if _, ok := m[s]; !ok {
rs = append(rs, s)
m[s] = struct{}{}
}
}
return rs
}
func multiRandKeyValues(keyPrefix, valPrefix string, bytesN, sliceN int) []KeyValue {
keys, vals := multiRandStrings(bytesN, sliceN, keyPrefix), multiRandStrings(bytesN, sliceN, valPrefix)
kvs := make([]KeyValue, sliceN)
for i := range kvs {
kvs[i].Key = keys[i]
kvs[i].Value = vals[i]
}
return kvs
}
func roundDownDuration(d, scale time.Duration) time.Duration {
d /= scale // round down in scale
d *= scale
return d
}