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Fix: first time generate same key

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This commit is contained in:
CareyWong 2020-03-29 20:11:00 +08:00
parent 1f239cc0c2
commit 8c6c1fa8c3
1 changed files with 3 additions and 17 deletions
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20
main.go
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@ -30,11 +30,6 @@ type redisPoolConf struct {
} }
const letterBytes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" const letterBytes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
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
)
const defaultPort int = 8002 const defaultPort int = 8002
const defaultExpire = 90 const defaultExpire = 90
@ -173,19 +168,10 @@ func longToShort(longUrl string, ttl int) string {
func generate(bits int) string { func generate(bits int) string {
b := make([]byte, bits) b := make([]byte, bits)
// A rand.Int63() generates 63 random bits, enough for letterIdxMax letters! currentTime := time.Now().Unix()
for i, cache, remain := bits-1, rand.Int63(), letterIdxMax; i >= 0; { for i := range b {
if remain == 0 { b[i] = letterBytes[(currentTime + rand.Int63()) % int64(len(letterBytes))]
cache, remain = rand.Int63(), letterIdxMax
} }
if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
b[i] = letterBytes[idx]
i--
}
cache >>= letterIdxBits
remain--
}
return string(b) return string(b)
} }