Add a rand instance for the generator

Signed-off-by: Hongyu <[email protected]>

Author: HongyuHe

cmd/load.go

@@ -35,6 +35,8 @@ var (
 	rpsSlot     = flag.Int("slot", 1, "Time slot in minutes for each RPS in the `stress` mode")
 	rpsStep     = flag.Int("step", 1, "Step size for increasing RPS in the `stress` mode")
 
+	seed = flag.Int64("seed", 42, "Random seed for the generator")
+
 	// withWarmup = flag.Int("withWarmup", -1000, "Duration of the withWarmup")
 	withWarmup = flag.Bool("warmup", false, "Enable warmup")
 )
@@ -64,6 +66,8 @@ func init() {
 }
 
 func main() {
+	gen.InitSeed(*seed)
+
 	switch *mode {
 	case "trace":
 		runTraceMode()

pkg/generate/generate.go

@@ -26,8 +26,13 @@ const (
 // 	rand.Seed(time.Now().UnixNano())
 // }
 
-func GenerateInterarrivalTimesInMicro(seed int, invocationsPerMinute int, uniform bool) []float64 {
-	rand.Seed(int64(seed)) //! Fix randomness.
+var iatRand *rand.Rand
+
+func InitSeed(s int64) {
+	iatRand = rand.New(rand.NewSource(s))
+}
+
+func GenerateInterarrivalTimesInMicro(invocationsPerMinute int, uniform bool) []float64 {
 	oneSecondInMicro := 1000_000.0
 	oneMinuteInMicro := 60*oneSecondInMicro - 1000
 
@@ -40,7 +45,7 @@ func GenerateInterarrivalTimesInMicro(seed int, invocationsPerMinute int, unifor
 		if uniform {
 			iat = oneSecondInMicro / rps
 		} else {
-			iat = rand.ExpFloat64() / rps * oneSecondInMicro
+			iat = iatRand.ExpFloat64() / rps * oneSecondInMicro
 		}
 		//* Only guarantee microsecond-level ganularity.
 		if iat < 1 {
@@ -104,7 +109,6 @@ func GenerateStressLoads(rpsStart int, rpsStep int, stressSlotInMinutes int, fun
 stress_generation:
 	for {
 		iats := GenerateInterarrivalTimesInMicro(
-			999, //! Fix randomness.
 			rps*60,
 			true,
 		)
@@ -230,7 +234,6 @@ trace_generation:
 		var invocationCount int32
 
 		iats = GenerateInterarrivalTimesInMicro(
-			minute, //! Fix randomness.
 			numInvocatonsThisMinute,
 			isFixedRate,
 		)

pkg/test/generate_test.go

@@ -25,8 +25,10 @@ func TestGenCheckOverload(t *testing.T) {
 }
 
 func TestGenerateIat(t *testing.T) {
+	gen.InitSeed(42)
+
 	invocationsPerMinute := 20_000
-	iats := gen.GenerateInterarrivalTimesInMicro(0, invocationsPerMinute, true)
+	iats := gen.GenerateInterarrivalTimesInMicro(invocationsPerMinute, true)
 	duration, _ := stats.Sum(stats.LoadRawData(iats))
 
 	assert.Equal(t, iats[rand.Intn(len(iats))], iats[rand.Intn(len(iats))])
@@ -37,7 +39,7 @@ func TestGenerateIat(t *testing.T) {
 		assert.GreaterOrEqual(t, iat, 1.0)
 	}
 
-	iats = gen.GenerateInterarrivalTimesInMicro(0, invocationsPerMinute, false)
+	iats = gen.GenerateInterarrivalTimesInMicro(invocationsPerMinute, false)
 	duration, _ = stats.Sum(stats.LoadRawData(iats))
 
 	assert.Equal(t, invocationsPerMinute, len(iats))