Avoid returning Already[Started/Stopped] if omitted after (#3035)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

receiver/opencensusreceiver/opencensus.go

@@ -30,7 +30,6 @@ import (
 	"google.golang.org/grpc"
 
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/component/componenterror"
 	"go.opentelemetry.io/collector/consumer"
 	"go.opentelemetry.io/collector/obsreport"
 	"go.opentelemetry.io/collector/receiver/opencensusreceiver/ocmetrics"
@@ -100,12 +99,36 @@ func newOpenCensusReceiver(
 // Start runs the trace receiver on the gRPC server. Currently
 // it also enables the metrics receiver too.
 func (ocr *ocReceiver) Start(_ context.Context, host component.Host) error {
-	return ocr.start(host)
+	hasConsumer := false
+	if ocr.traceConsumer != nil {
+		hasConsumer = true
+		if err := ocr.registerTraceConsumer(); err != nil {
+			return err
+		}
+	}
+
+	if ocr.metricsConsumer != nil {
+		hasConsumer = true
+		if err := ocr.registerMetricsConsumer(); err != nil {
+			return err
+		}
+	}
+
+	if !hasConsumer {
+		return errors.New("cannot start receiver: no consumers were specified")
+	}
+
+	if err := ocr.startServer(host); err != nil {
+		return err
+	}
+
+	// At this point we've successfully started all the services/receivers.
+	// Add other start routines here.
+	return nil
 }
 
 func (ocr *ocReceiver) registerTraceConsumer() error {
-	var err = componenterror.ErrAlreadyStarted
-
+	var err error
 	ocr.startTracesReceiverOnce.Do(func() {
 		ocr.traceReceiver, err = octrace.New(
 			ocr.instanceName, ocr.traceConsumer, ocr.traceReceiverOpts...)
@@ -119,8 +142,7 @@ func (ocr *ocReceiver) registerTraceConsumer() error {
 }
 
 func (ocr *ocReceiver) registerMetricsConsumer() error {
-	var err = componenterror.ErrAlreadyStarted
-
+	var err error
 	ocr.startMetricsReceiverOnce.Do(func() {
 		ocr.metricsReceiver, err = ocmetrics.New(
 			ocr.instanceName, ocr.metricsConsumer)
@@ -145,51 +167,11 @@ func (ocr *ocReceiver) grpcServer() *grpc.Server {
 
 // Shutdown is a method to turn off receiving.
 func (ocr *ocReceiver) Shutdown(context.Context) error {
-	if err := ocr.stop(); err != componenterror.ErrAlreadyStopped {
-		return err
-	}
-	return nil
-}
-
-// start runs all the receivers/services namely, Trace and Metrics services.
-func (ocr *ocReceiver) start(host component.Host) error {
-	hasConsumer := false
-	if ocr.traceConsumer != nil {
-		hasConsumer = true
-		if err := ocr.registerTraceConsumer(); err != nil && err != componenterror.ErrAlreadyStarted {
-			return err
-		}
-	}
-
-	if ocr.metricsConsumer != nil {
-		hasConsumer = true
-		if err := ocr.registerMetricsConsumer(); err != nil && err != componenterror.ErrAlreadyStarted {
-			return err
-		}
-	}
-
-	if !hasConsumer {
-		return errors.New("cannot start receiver: no consumers were specified")
-	}
-
-	if err := ocr.startServer(host); err != nil && err != componenterror.ErrAlreadyStarted {
-		return err
-	}
-
-	// At this point we've successfully started all the services/receivers.
-	// Add other start routines here.
-	return nil
-}
-
-// stop stops the underlying gRPC server and all the services running on it.
-func (ocr *ocReceiver) stop() error {
 	ocr.mu.Lock()
 	defer ocr.mu.Unlock()
 
-	err := componenterror.ErrAlreadyStopped
+	var err error
 	ocr.stopOnce.Do(func() {
-		err = nil
-
 		if ocr.serverHTTP != nil {
 			_ = ocr.serverHTTP.Close()
 		}
@@ -225,9 +207,8 @@ func (ocr *ocReceiver) httpServer() *http.Server {
 }
 
 func (ocr *ocReceiver) startServer(host component.Host) error {
-	err := componenterror.ErrAlreadyStarted
+	var err error
 	ocr.startServerOnce.Do(func() {
-		err = nil
 		// Register the grpc-gateway on the HTTP server mux
 		c := context.Background()
 		opts := []grpc.DialOption{grpc.WithInsecure()}

receiver/opencensusreceiver/opencensus_test.go

@@ -241,7 +241,7 @@ func TestStopWithoutStartNeverCrashes(t *testing.T) {
 	ocr, err := newOpenCensusReceiver(ocReceiverName, "tcp", addr, nil, nil)
 	require.NoError(t, err, "Failed to create an OpenCensus receiver: %v", err)
 	// Stop it before ever invoking Start*.
-	require.NoError(t, ocr.stop())
+	require.NoError(t, ocr.Shutdown(context.Background()))
 }
 
 func TestNewPortAlreadyUsed(t *testing.T) {