random.go

// Copyright 2015 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 ddltest

import (
	"math/rand"
)

func randomInt() int {
	return rand.Int()
}

func randomIntn(n int) int {
	return rand.Intn(n)
}

func randomFloat() float64 {
	return rand.Float64()
}

func randomString(n int) string {
	const alphanum = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
	var bytes = make([]byte, n)
	for i := range bytes {
		bytes[i] = alphanum[randomIntn(len(alphanum))]
	}
	return string(bytes)
}

// Args
// 0 -> min
// 1 -> max
// randomNum(1,10) -> [1,10)
// randomNum(-1) -> random
// randomNum() -> random
func randomNum(args ...int) int {
	if len(args) > 1 {
		return args[0] + randomIntn(args[1]-args[0])
	} else if len(args) == 1 {
		return randomIntn(args[0])
	} else {
		return randomInt()
	}
}