v1.0.0

common/dice/dice.go

@@ -0,0 +1,52 @@
+// Package dice contains common functions to generate random number.
+// It also initialize math/rand with the time in seconds at launch time.
+package dice // import "github.com/xtls/xray-core/v1/common/dice"
+
+import (
+	"math/rand"
+	"time"
+)
+
+// Roll returns a non-negative number between 0 (inclusive) and n (exclusive).
+func Roll(n int) int {
+	if n == 1 {
+		return 0
+	}
+	return rand.Intn(n)
+}
+
+// Roll returns a non-negative number between 0 (inclusive) and n (exclusive).
+func RollDeterministic(n int, seed int64) int {
+	if n == 1 {
+		return 0
+	}
+	return rand.New(rand.NewSource(seed)).Intn(n)
+}
+
+// RollUint16 returns a random uint16 value.
+func RollUint16() uint16 {
+	return uint16(rand.Int63() >> 47)
+}
+
+func RollUint64() uint64 {
+	return rand.Uint64()
+}
+
+func NewDeterministicDice(seed int64) *DeterministicDice {
+	return &DeterministicDice{rand.New(rand.NewSource(seed))}
+}
+
+type DeterministicDice struct {
+	*rand.Rand
+}
+
+func (dd *DeterministicDice) Roll(n int) int {
+	if n == 1 {
+		return 0
+	}
+	return dd.Intn(n)
+}
+
+func init() {
+	rand.Seed(time.Now().Unix())
+}

common/dice/dice_test.go

@@ -0,0 +1,50 @@
+package dice_test
+
+import (
+	"math/rand"
+	"testing"
+
+	. "github.com/xtls/xray-core/v1/common/dice"
+)
+
+func BenchmarkRoll1(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Roll(1)
+	}
+}
+
+func BenchmarkRoll20(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Roll(20)
+	}
+}
+
+func BenchmarkIntn1(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		rand.Intn(1)
+	}
+}
+
+func BenchmarkIntn20(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		rand.Intn(20)
+	}
+}
+
+func BenchmarkInt63(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = uint16(rand.Int63() >> 47)
+	}
+}
+
+func BenchmarkInt31(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = uint16(rand.Int31() >> 15)
+	}
+}
+
+func BenchmarkIntn(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = uint16(rand.Intn(65536))
+	}
+}