fx build fix

api/server/internal/mutil/flrstring/flrstring.go

@@ -0,0 +1,35 @@
+package flrstring
+
+import (
+	"math/rand"
+	"time"
+)
+
+// Constants and variables for random string generation
+const (
+	letterBytes   = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	letterIdxBits = 6
+	letterIdxMask = 1<<letterIdxBits - 1
+	letterIdxMax  = 63 / letterIdxBits
+)
+
+var src = rand.NewSource(time.Now().UnixNano())
+
+// createRandString creates a random string with the size of n
+// See: http://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-golang
+func CreateRandString(n int) string {
+	b := make([]byte, n)
+	for i, cache, remain := n-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 string(b)
+}