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rand.go
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rand.go
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// Copyright 2016 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package importer
import (
"fmt"
"math/rand"
"strconv"
"time"
)
const (
alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
yearFormat = "2006"
dateFormat = "2006-01-02"
timeFormat = "15:04:05"
dateTimeFormat = "2006-01-02 15:04:05"
// Used by randString
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 init() {
rand.Seed(time.Now().UnixNano())
}
func randInt(min int, max int) int {
return min + rand.Intn(max-min+1)
}
func randInt64(min int64, max int64) int64 {
return min + rand.Int63n(max-min+1)
}
func randFloat64(min int64, max int64, prec int) float64 {
value := float64(randInt64(min, max))
fvalue := strconv.FormatFloat(value, 'f', prec, 64)
value, _ = strconv.ParseFloat(fvalue, 64)
return value
}
func randBool() bool {
value := randInt(0, 1)
return value == 1
}
// reference: http://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-golang
func randString(n int) string {
b := make([]byte, n)
// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
for i, cache, remain := n-1, rand.Int63(), letterIdxMax; i >= 0; {
if remain == 0 {
cache, remain = rand.Int63(), letterIdxMax
}
if idx := int(cache & letterIdxMask); idx < len(alphabet) {
b[i] = alphabet[idx]
i--
}
cache >>= letterIdxBits
remain--
}
return string(b)
}
func randDuration(n time.Duration) time.Duration {
duration := randInt(0, int(n))
return time.Duration(duration)
}
func randDate(min string, max string) string {
if len(min) == 0 {
year := time.Now().Year()
month := randInt(1, 12)
day := randInt(1, 28)
return fmt.Sprintf("%04d-%02d-%02d", year, month, day)
}
minTime, _ := time.Parse(dateFormat, min)
if len(max) == 0 {
t := minTime.Add(time.Duration(randInt(0, 365)) * 24 * time.Hour)
return fmt.Sprintf("%04d-%02d-%02d", t.Year(), t.Month(), t.Day())
}
maxTime, _ := time.Parse(dateFormat, max)
days := int(maxTime.Sub(minTime).Hours() / 24)
t := minTime.Add(time.Duration(randInt(0, days)) * 24 * time.Hour)
return fmt.Sprintf("%04d-%02d-%02d", t.Year(), t.Month(), t.Day())
}
func randTime(min string, max string) string {
if len(min) == 0 || len(max) == 0 {
hour := randInt(0, 23)
min := randInt(0, 59)
sec := randInt(0, 59)
return fmt.Sprintf("%02d:%02d:%02d", hour, min, sec)
}
minTime, _ := time.Parse(timeFormat, min)
maxTime, _ := time.Parse(timeFormat, max)
seconds := int(maxTime.Sub(minTime).Seconds())
t := minTime.Add(time.Duration(randInt(0, seconds)) * time.Second)
return fmt.Sprintf("%02d:%02d:%02d", t.Hour(), t.Minute(), t.Second())
}
func randTimestamp(min string, max string) string {
if len(min) == 0 {
year := time.Now().Year()
month := randInt(1, 12)
day := randInt(1, 28)
hour := randInt(0, 23)
min := randInt(0, 59)
sec := randInt(0, 59)
return fmt.Sprintf("%04d-%02d-%02d %02d:%02d:%02d", year, month, day, hour, min, sec)
}
minTime, _ := time.Parse(dateTimeFormat, min)
if len(max) == 0 {
t := minTime.Add(time.Duration(randInt(0, 365)) * 24 * time.Hour)
return fmt.Sprintf("%04d-%02d-%02d %02d:%02d:%02d", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())
}
maxTime, _ := time.Parse(dateTimeFormat, max)
seconds := int(maxTime.Sub(minTime).Seconds())
t := minTime.Add(time.Duration(randInt(0, seconds)) * time.Second)
return fmt.Sprintf("%04d-%02d-%02d %02d:%02d:%02d", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())
}
func randYear(min string, max string) string {
if len(min) == 0 || len(max) == 0 {
return fmt.Sprintf("%04d", time.Now().Year()-randInt(0, 10))
}
minTime, _ := time.Parse(yearFormat, min)
maxTime, _ := time.Parse(yearFormat, max)
seconds := int(maxTime.Sub(minTime).Seconds())
t := minTime.Add(time.Duration(randInt(0, seconds)) * time.Second)
return fmt.Sprintf("%04d", t.Year())
}