Address comments

Signed-off-by: Yuri Shkuro <ys@uber.com>

Author: Yuri Shkuro

cmd/tracegen/main.go

@@ -54,7 +54,7 @@ func main() {
 	opentracing.InitGlobalTracer(tracer)
 	logger.Info("Initialized global tracer")
 
-	cfg.Run(logger)
+	tracegen.Run(cfg, logger)
 
 	logger.Info("Waiting 1.5sec for metrics to flush")
 	time.Sleep(3 * time.Second / 2)

internal/tracegen/.nocover

@@ -0,0 +1 @@
+FIXME

internal/tracegen/config.go

@@ -28,7 +28,7 @@ import (
 type Config struct {
 	Workers  int
 	Traces   int
-	Marshall bool
+	Marshal  bool
 	Debug    bool
 	Pause    time.Duration
 	Duration time.Duration
@@ -38,33 +38,33 @@ type Config struct {
 func (c *Config) Flags(fs *flag.FlagSet) {
 	fs.IntVar(&c.Workers, "workers", 1, "Number of workers (goroutines) to run")
 	fs.IntVar(&c.Traces, "traces", 1, "Number of traces to generate in each worker (ignored if duration is provided")
-	fs.BoolVar(&c.Marshall, "marshall", false, "Whether to marshall trace context via HTTP headers")
+	fs.BoolVar(&c.Marshal, "marshal", false, "Whether to marshal trace context via HTTP headers")
 	fs.BoolVar(&c.Debug, "debug", false, "Whether to set DEBUG flag on the spans to prevent downsampling")
 	fs.DurationVar(&c.Pause, "pause", time.Microsecond, "How long to pause before finishing trace")
 	fs.DurationVar(&c.Duration, "duration", 0, "For how long to run the test")
 }
 
 // Run executes the test scenario.
-func (c *Config) Run(logger *zap.Logger) error {
+func Run(c *Config, logger *zap.Logger) error {
 	if c.Duration > 0 {
 		c.Traces = 0
 	} else if c.Traces <= 0 {
 		return fmt.Errorf("Either `traces` or `duration` must be greater than 0")
 	}
 
-	wg := &sync.WaitGroup{}
+	wg := sync.WaitGroup{}
 	var running uint32 = 1
 	for i := 0; i < c.Workers; i++ {
 		wg.Add(1)
 		w := worker{
 			id:       i,
 			traces:   c.Traces,
-			marshall: c.Marshall,
+			marshal:  c.Marshal,
 			debug:    c.Debug,
 			pause:    c.Pause,
 			duration: c.Duration,
 			running:  &running,
-			wg:       wg,
+			wg:       &wg,
 			logger:   logger.With(zap.Int("worker", i)),
 		}
 

internal/tracegen/worker.go

@@ -26,18 +26,22 @@ import (
 )
 
 type worker struct {
+	running  *uint32         // pointer to shared flag that indicates it's time to stop the test
 	id       int             // worker id
 	traces   int             // how many traces the worker has to generate (only when duration==0)
-	marshall bool            // whether the worker needs to marshall trace context via HTTP headers
+	marshal  bool            // whether the worker needs to marshal trace context via HTTP headers
 	debug    bool            // whether to set DEBUG flag on the spans
 	duration time.Duration   // how long to run the test for (overrides `traces`)
 	pause    time.Duration   // how long to pause before finishing the trace
-	running  *uint32         // pointer to shared flag that indicates it's time to stop the test
 	wg       *sync.WaitGroup // notify when done
 	logger   *zap.Logger
 }
 
-var fakeIP uint32 = 1<<24 | 2<<16 | 3<<8 | 4
+const (
+	fakeIP uint32 = 1<<24 | 2<<16 | 3<<8 | 4
+
+	fakeSpanDuration = 123 * time.Microsecond
+)
 
 func (w worker) simulateTraces() {
 	tracer := opentracing.GlobalTracer()
@@ -52,7 +56,7 @@ func (w worker) simulateTraces() {
 		}
 
 		childCtx := sp.Context()
-		if w.marshall {
+		if w.marshal {
 			m := make(map[string]string)
 			c := opentracing.TextMapCarrier(m)
 			if err := tracer.Inject(sp.Context(), opentracing.TextMap, c); err == nil {
@@ -78,7 +82,7 @@ func (w worker) simulateTraces() {
 			child.Finish()
 			sp.Finish()
 		} else {
-			opt := opentracing.FinishOptions{FinishTime: time.Now().Add(123 * time.Microsecond)}
+			opt := opentracing.FinishOptions{FinishTime: time.Now().Add(fakeSpanDuration)}
 			child.FinishWithOptions(opt)
 			sp.FinishWithOptions(opt)
 		}