fix: fix race conditions

Author: nithinputhenveettil

delayed_spans.go

@@ -33,12 +33,20 @@ func (ds *delayedSpans) flush() {
 		case s := <-ds.spans:
 			t, ok := s.Tracer().(Tracer)
 			if !ok {
-				sensor.logger.Debug("span tracer has unexpected type")
+				muSensor.Lock()
+				if sensor != nil {
+					sensor.logger.Debug("span tracer has unexpected type")
+				}
+				muSensor.Unlock()
 				continue
 			}
 
 			if err := ds.processSpan(s, t.Options()); err != nil {
-				sensor.logger.Debug("error while processing spans:", err.Error())
+				muSensor.Lock()
+				if sensor != nil {
+					sensor.logger.Debug("error while processing spans:", err.Error())
+				}
+				muSensor.Unlock()
 				continue
 			}
 

event.go

@@ -80,6 +80,10 @@ func sendEvent(event *EventData) {
 
 	// we do fire & forget here, because the whole pid dance isn't necessary to send events
 	go func() {
-		_ = sensor.Agent().SendEvent(event)
+		muSensor.Lock()
+		if sensor != nil {
+			_ = sensor.Agent().SendEvent(event)
+		}
+		muSensor.Unlock()
 	}()
 }

meter.go

@@ -43,9 +43,19 @@ func (m *meterS) Run(collectInterval time.Duration) {
 		case <-m.done:
 			return
 		case <-ticker.C:
-			if sensor.Agent().Ready() {
+			// Get agent ready status under proper synchronization
+			muSensor.Lock()
+			agentReady := sensor != nil && sensor.Agent().Ready()
+			muSensor.Unlock()
+
+			if agentReady {
 				go func() {
-					_ = sensor.Agent().SendMetrics(m.collectMetrics())
+					metrics := m.collectMetrics()
+					muSensor.Lock()
+					if sensor != nil {
+						_ = sensor.Agent().SendMetrics(metrics)
+					}
+					muSensor.Unlock()
 				}()
 			}
 		}

recorder.go

@@ -81,7 +81,7 @@ func (r *Recorder) RecordSpan(span *spanS) {
 		return
 	}
 
-	agentReady := sensor.Agent().Ready()
+	agentReady := sensor != nil && sensor.Agent().Ready()
 	maxBufferedSpans := sensor.options.MaxBufferedSpans
 	forceTransmissionAt := sensor.options.ForceTransmissionStartingAt
 	logger := sensor.logger

sensor.go

@@ -224,13 +224,23 @@ func InitSensor(options *Options) {
 	})
 
 	autoprofile.SetSendProfilesFunc(func(profiles []autoprofile.Profile) error {
-		if !sensor.Agent().Ready() {
+		// Get agent ready status under proper synchronization
+		muSensor.Lock()
+		agentReady := sensor != nil && sensor.Agent().Ready()
+		muSensor.Unlock()
+
+		if !agentReady {
 			return errors.New("sender not ready")
 		}
 
 		sensor.logger.Debug("sending profiles to agent")
 
-		return sensor.Agent().SendProfiles(profiles)
+		// Use the same lock for sending profiles
+		muSensor.Lock()
+		err := sensor.Agent().SendProfiles(profiles)
+		muSensor.Unlock()
+
+		return err
 	})
 
 	if _, ok := os.LookupEnv("INSTANA_AUTO_PROFILE"); ok || options.EnableAutoProfile {

span.go

@@ -86,7 +86,12 @@ func (r *spanS) FinishWithOptions(opts ot.FinishOptions) {
 
 	r.Duration = duration
 	if r.sendSpanToAgent() {
-		if sensor.Agent().Ready() {
+		// Get agent ready status under proper synchronization
+		muSensor.Lock()
+		agentReady := sensor != nil && sensor.Agent().Ready()
+		muSensor.Unlock()
+
+		if agentReady {
 			r.tracer.recorder.RecordSpan(r)
 		} else {
 			delayed.append(r)

tracer.go

@@ -135,5 +135,12 @@ func (r *tracerS) Flush(ctx context.Context) error {
 		return err
 	}
 
+	muSensor.Lock()
+	defer muSensor.Unlock()
+
+	if sensor == nil {
+		return nil
+	}
+
 	return sensor.Agent().Flush(ctx)
 }