优化随机数

xrand/rand.go

@@ -1,60 +1,38 @@
 package xrand
 
 import (
+	randx "crypto/rand"
+	"math"
+	"math/big"
 	"math/rand"
-	"time"
 )
 
 var rd *rand.Rand
 
 func init() {
-	rd = rand.New(rand.NewSource(time.Now().UnixNano()))
+	rd = rand.New(rand.NewSource(randInt64()))
+}
+
+// 用系统熵构建更自然的随机数，比"math/rand"构建的线性同余自然随机数要慢
+func randInt64() int64 {
+	n, _ := randx.Int(randx.Reader, big.NewInt(math.MaxInt64))
+	return n.Int64()
 }
 
 // 随机值
-func Rand[T int | int32 | int64 | uint32 | uint64 | float32 | float64]() T {
-	switch any(T(0)).(type) {
-	case int:
-		return T(rd.Int())
-	case int32:
-		return T(rd.Int31())
-	case int64:
-		return T(rd.Int63())
-	case uint32:
-		return T(rd.Uint32())
-	case uint64:
-		return T(rd.Uint64())
-	case float32:
-		return T(rd.Float32())
-	case float64:
-		return T(rd.Float64())
-	default:
-		panic("不支持的类型")
-	}
+func Rand[T int | int32 | int64 | uint32 | uint64]() T {
+	return T(randInt64())
 }
 
 // 从[0,n)范围里随机值
-func RandN[T int | int32 | int64 | uint32 | uint64](n T) T {
+func RandN[T int | int32 | int64 | uint | uint32 | uint64](n T) T {
 	if int64(n) < 1 {
 		return 0
 	}
-	switch any(n).(type) {
-	case int:
-		return T(rd.Intn(int(n))) // [0,n) 的随机整数
-	case int32:
-		return T(rd.Int31n(int32(n)))
-	case int64:
-		return T(rd.Int63n(int64(n)))
-	case uint32:
-		return T(rd.Uint32() % uint32(n)) // 注意：这里有小偏差
-	case uint64:
-		return T(rand.Uint64() % uint64(n))
-	default:
-		panic("不支持的类型")
-	}
+	return T(randInt64() % int64(n)) // [0,n) 的随机整数
 }
 
-// 从[0,n)范围里随机值
+// 从[min,max)范围里随机值
 func RandRange[T int | int32 | int64 | uint32 | uint64](min, max T) T {
 	if int64(max) < 1 || int64(min) < 1 || max < min {
 		return 0