replace --min-wait and --max-wait with --interval and --jitter

coder · johnstcn · Oct 2, 2023 · Sep 28, 2023 · Sep 28, 2023 · Sep 28, 2023
commit 0805f2ee03318db474d7a06e8d17290f04a04078
diff --git a/cli/exp_scaletest.go b/cli/exp_scaletest.go
@@ -1047,8 +1047,8 @@ func (r *RootCmd) scaletestWorkspaceTraffic() *clibase.Cmd {
 
 func (r *RootCmd) scaletestDashboard() *clibase.Cmd {
 	var (
-		minWait  time.Duration
-		maxWait  time.Duration
+		interval time.Duration
+		jitter   time.Duration
 		headless bool
 		randSeed int64
 
@@ -1067,11 +1067,11 @@ func (r *RootCmd) scaletestDashboard() *clibase.Cmd {
 			r.InitClient(client),
 		),
 		Handler: func(inv *clibase.Invocation) error {
-			if !(minWait > 0) {
-				return xerrors.Errorf("--min-wait must be greater than zero")
+			if !(interval > 0) {
+				return xerrors.Errorf("--interval must be greater than zero")
 			}
-			if !(maxWait > minWait) {
-				return xerrors.Errorf("--max-wait must be greater than --min-wait")
+			if !(jitter < interval) {
+				return xerrors.Errorf("--jitter must be less than --interval")
 			}
 			ctx := inv.Context()
 			logger := slog.Make(sloghuman.Sink(inv.Stdout)).Leveled(slog.LevelInfo)
@@ -1124,16 +1124,16 @@ func (r *RootCmd) scaletestDashboard() *clibase.Cmd {
 				userClient.SetSessionToken(userTokResp.Key)
 
 				config := dashboard.Config{
-					MinWait:    minWait,
-					MaxWait:    maxWait,
+					Interval:   interval,
+					Jitter:     jitter,
 					Trace:      tracingEnabled,
 					Logger:     logger.Named(name),
 					Headless:   headless,
 					ActionFunc: dashboard.ClickRandomElement,
 					RandIntn:   rndGen.Intn,
 				}
 				//nolint:gocritic
-				logger.Info(ctx, "runner config", slog.F("min_wait", minWait), slog.F("max_wait", maxWait), slog.F("headless", headless), slog.F("trace", tracingEnabled))
+				logger.Info(ctx, "runner config", slog.F("min_wait", interval), slog.F("max_wait", jitter), slog.F("headless", headless), slog.F("trace", tracingEnabled))
 				if err := config.Validate(); err != nil {
 					return err
 				}
@@ -1174,18 +1174,18 @@ func (r *RootCmd) scaletestDashboard() *clibase.Cmd {
 
 	cmd.Options = []clibase.Option{
 		{
-			Flag:        "min-wait",
-			Env:         "CODER_SCALETEST_DASHBOARD_MIN_WAIT",
-			Default:     "1s",
-			Description: "Minimum wait between fetches.",
-			Value:       clibase.DurationOf(&minWait),
+			Flag:        "interval",
+			Env:         "CODER_SCALETEST_DASHBOARD_INTERVAL",
+			Default:     "3s",
+			Description: "Interval between actions.",
+			Value:       clibase.DurationOf(&interval),
 		},
 		{
-			Flag:        "max-wait",
-			Env:         "CODER_SCALETEST_DASHBOARD_MAX_WAIT",
-			Default:     "10s",
-			Description: "Maximum wait between fetches.",
-			Value:       clibase.DurationOf(&maxWait),
+			Flag:        "jitter",
+			Env:         "CODER_SCALETEST_DASHBOARD_JITTER",
+			Default:     "2s",
+			Description: "Jitter between actions.",
+			Value:       clibase.DurationOf(&jitter),
 		},
 		{
 			Flag:        "headless",

diff --git a/cli/exp_scaletest_test.go b/cli/exp_scaletest_test.go
@@ -104,15 +104,15 @@ func TestScaleTestDashboard(t *testing.T) {
 		_ = coderdtest.CreateFirstUser(t, client)
 
 		inv, root := clitest.New(t, "exp", "scaletest", "dashboard",
-			"--min-wait", "0s",
+			"--interval", "0s",
 		)
 		clitest.SetupConfig(t, client, root)
 		pty := ptytest.New(t)
 		inv.Stdout = pty.Output()
 		inv.Stderr = pty.Output()
 
 		err := inv.WithContext(ctx).Run()
-		require.ErrorContains(t, err, "--min-wait must be greater than zero")
+		require.ErrorContains(t, err, "--interval must be greater than zero")
 	})
 
 	t.Run("MaxWait", func(t *testing.T) {
@@ -127,16 +127,16 @@ func TestScaleTestDashboard(t *testing.T) {
 		_ = coderdtest.CreateFirstUser(t, client)
 
 		inv, root := clitest.New(t, "exp", "scaletest", "dashboard",
-			"--min-wait", "1s",
-			"--max-wait", "1s",
+			"--interval", "1s",
+			"--jitter", "1s",
 		)
 		clitest.SetupConfig(t, client, root)
 		pty := ptytest.New(t)
 		inv.Stdout = pty.Output()
 		inv.Stderr = pty.Output()
 
 		err := inv.WithContext(ctx).Run()
-		require.ErrorContains(t, err, "--max-wait must be greater than --min-wait")
+		require.ErrorContains(t, err, "--jitter must be less than --interval")
 	})
 
 	t.Run("OK", func(t *testing.T) {
@@ -151,8 +151,8 @@ func TestScaleTestDashboard(t *testing.T) {
 		_ = coderdtest.CreateFirstUser(t, client)
 
 		inv, root := clitest.New(t, "exp", "scaletest", "dashboard",
-			"--min-wait", "100ms",
-			"--max-wait", "1s",
+			"--interval", "1s",
+			"--jitter", "500ms",
 			"--timeout", "5s",
 			"--scaletest-prometheus-address", "127.0.0.1:0",
 			"--scaletest-prometheus-wait", "0s",

diff --git a/scaletest/dashboard/config.go b/scaletest/dashboard/config.go
@@ -10,10 +10,10 @@ import (
 )
 
 type Config struct {
-	// MinWait is the minimum interval between fetches.
-	MinWait time.Duration `json:"min_wait"`
-	// MaxWait is the maximum interval between fetches.
-	MaxWait time.Duration `json:"max_wait"`
+	// Interval is the minimum interval between fetches.
+	Interval time.Duration `json:"interval"`
+	// Jitter is the maximum interval between fetches.
+	Jitter time.Duration `json:"jitter"`
 	// Trace is whether to trace the requests.
 	Trace bool `json:"trace"`
 	// Logger is the logger to use.
@@ -27,17 +27,21 @@ type Config struct {
 }
 
 func (c Config) Validate() error {
-	if !(c.MinWait > 0) {
-		return xerrors.Errorf("validate min_wait: must be greater than zero")
+	if !(c.Interval > 0) {
+		return xerrors.Errorf("validate interval: must be greater than zero")
 	}
 
-	if !(c.MaxWait > c.MinWait) {
-		return xerrors.Errorf("validate max_wait: must be greater than min_wait")
+	if !(c.Jitter < c.Interval) {
+		return xerrors.Errorf("validate jitter: must be less than interval")
 	}
 
 	if c.ActionFunc == nil {
 		return xerrors.Errorf("validate action func: must not be nil")
 	}
 
+	if c.RandIntn == nil {
+		return xerrors.Errorf("validate rand intn: must not be nil")
+	}
+
 	return nil
 }
diff --git a/scaletest/dashboard/run.go b/scaletest/dashboard/run.go
@@ -3,7 +3,6 @@ package dashboard
 import (
 	"context"
 	"io"
-	"math/rand"
 	"time"
 
 	"golang.org/x/xerrors"
@@ -59,7 +58,12 @@ func (r *Runner) Run(ctx context.Context, _ string, _ io.Writer) error {
 		case <-cdpCtx.Done():
 			return nil
 		case <-t.C:
-			t.Reset(r.randWait())
+			var offset time.Duration
+			if r.cfg.Jitter > 0 {
+				offset = time.Duration(r.cfg.RandIntn(int(2*r.cfg.Jitter)) - int(r.cfg.Jitter))
+			}
+			wait := r.cfg.Interval + offset
+			t.Reset(wait)
 			l, act, err := r.cfg.ActionFunc(cdpCtx, r.cfg.RandIntn)
 			if err != nil {
 				r.cfg.Logger.Error(ctx, "calling ActionFunc", slog.Error(err))
@@ -84,9 +88,3 @@ func (r *Runner) Run(ctx context.Context, _ string, _ io.Writer) error {
 func (*Runner) Cleanup(_ context.Context, _ string) error {
 	return nil
 }
-
-func (r *Runner) randWait() time.Duration {
-	//nolint:gosec // This is not for cryptographic purposes. Chill, gosec. Chill.
-	wait := time.Duration(rand.Intn(int(r.cfg.MaxWait) - int(r.cfg.MinWait)))
-	return r.cfg.MinWait + wait
-}
diff --git a/scaletest/dashboard/run_test.go b/scaletest/dashboard/run_test.go
@@ -47,8 +47,8 @@ func Test_Run(t *testing.T) {
 	})
 	m := &testMetrics{}
 	cfg := dashboard.Config{
-		MinWait:  100 * time.Millisecond,
-		MaxWait:  500 * time.Millisecond,
+		Interval: 500 * time.Millisecond,
+		Jitter:   100 * time.Millisecond,
 		Logger:   log,
 		Headless: true,
 		ActionFunc: func(_ context.Context, rnd func(int) int) (dashboard.Label, dashboard.Action, error) {