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random.go
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random.go
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package random
import (
"math/rand"
"sync"
"time"
)
const (
bufferSize = 32
byte2print = `0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-`
)
var pool = sync.Pool{
New: func() interface{} {
return make([]byte, bufferSize)
},
}
var randomLock sync.Mutex
var auto rand.Source = rand.NewSource(time.Now().UnixNano())
func read(p []byte) {
var val uint64
var on uintptr
div := len(p) / 8
randomLock.Lock()
defer randomLock.Unlock()
for i := 0; i < div; i++ {
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
p[on+2] = byte(val >> 16)
p[on+3] = byte(val >> 24)
p[on+4] = byte(val >> 32)
p[on+5] = byte(val >> 40)
p[on+6] = byte(val >> 48)
p[on+7] = byte(val >> 56)
on += 8
}
switch uintptr(len(p)) - on {
case 0:
return
case 1:
p[on] = byte(auto.Int63())
case 2:
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
case 3:
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
p[on+2] = byte(val >> 16)
case 4:
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
p[on+2] = byte(val >> 16)
p[on+3] = byte(val >> 24)
case 5:
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
p[on+2] = byte(val >> 16)
p[on+3] = byte(val >> 24)
p[on+4] = byte(val >> 32)
case 6:
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
p[on+2] = byte(val >> 16)
p[on+3] = byte(val >> 24)
p[on+4] = byte(val >> 32)
p[on+5] = byte(val >> 40)
case 7:
val = uint64(auto.Int63())
p[on] = byte(val)
p[on+1] = byte(val >> 8)
p[on+2] = byte(val >> 16)
p[on+3] = byte(val >> 24)
p[on+4] = byte(val >> 32)
p[on+5] = byte(val >> 40)
p[on+6] = byte(val >> 48)
}
return
}
func printable(p []byte) {
var val uint64
var on uintptr
div := len(p) / 8
randomLock.Lock()
defer randomLock.Unlock()
for i := 0; i < div; i++ {
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
p[on+2] = byte2print[byte(val>>16)]
p[on+3] = byte2print[byte(val>>24)]
p[on+4] = byte2print[byte(val>>32)]
p[on+5] = byte2print[byte(val>>40)]
p[on+6] = byte2print[byte(val>>48)]
p[on+7] = byte2print[byte(val>>56)]
on += 8
}
switch uintptr(len(p)) - on {
case 0:
return
case 1:
p[on] = byte2print[byte(auto.Int63())]
case 2:
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
case 3:
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
p[on+2] = byte2print[byte(val>>16)]
case 4:
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
p[on+2] = byte2print[byte(val>>16)]
p[on+3] = byte2print[byte(val>>24)]
case 5:
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
p[on+2] = byte2print[byte(val>>16)]
p[on+3] = byte2print[byte(val>>24)]
p[on+4] = byte2print[byte(val>>32)]
case 6:
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
p[on+2] = byte2print[byte(val>>16)]
p[on+3] = byte2print[byte(val>>24)]
p[on+4] = byte2print[byte(val>>32)]
p[on+5] = byte2print[byte(val>>40)]
case 7:
val = uint64(auto.Int63())
p[on] = byte2print[byte(val)]
p[on+1] = byte2print[byte(val>>8)]
p[on+2] = byte2print[byte(val>>16)]
p[on+3] = byte2print[byte(val>>24)]
p[on+4] = byte2print[byte(val>>32)]
p[on+5] = byte2print[byte(val>>40)]
p[on+6] = byte2print[byte(val>>48)]
}
return
}
// String returns a random alphanumeric string given the length parameter.
func String(length int) string {
if length > bufferSize {
p := make([]byte, length)
printable(p)
return string(p)
}
if length <= 0 {
return ``
}
p := pool.Get().([]byte)
defer pool.Put(p)
printable(p[0:length])
return string(p[0:length])
}