Add an option to set metric name prefix (#84)

* Add an option for setting metric name prefix

* renaming

* renaming

ocagent.go

@@ -75,6 +75,7 @@ type Exporter struct {
 	compressor         string
 	headers            map[string]string
 	lastConnectErrPtr  unsafe.Pointer
+	metricNamePerfix   string
 
 	startOnce      sync.Once
 	stopCh         chan bool
@@ -513,14 +514,14 @@ func (ae *Exporter) uploadTraces(sdl []*trace.SpanData) {
 	}
 }
 
-func ocViewDataToPbMetrics(vdl []*view.Data) []*metricspb.Metric {
+func ocViewDataToPbMetrics(vdl []*view.Data, metricNamePrefix string) []*metricspb.Metric {
 	if len(vdl) == 0 {
 		return nil
 	}
 	metrics := make([]*metricspb.Metric, 0, len(vdl))
 	for _, vd := range vdl {
 		if vd != nil {
-			vmetric, err := viewDataToMetric(vd)
+			vmetric, err := viewDataToMetric(vd, metricNamePrefix)
 			// TODO: (@odeke-em) somehow report this error, if it is non-nil.
 			if err == nil && vmetric != nil {
 				metrics = append(metrics, vmetric)
@@ -531,7 +532,7 @@ func ocViewDataToPbMetrics(vdl []*view.Data) []*metricspb.Metric {
 }
 
 func (ae *Exporter) uploadViewData(vdl []*view.Data) {
-	protoMetrics := ocViewDataToPbMetrics(vdl)
+	protoMetrics := ocViewDataToPbMetrics(vdl, ae.metricNamePerfix)
 	if len(protoMetrics) == 0 {
 		return
 	}

options.go

@@ -159,3 +159,16 @@ func WithGRPCDialOption(opts ...grpc.DialOption) ExporterOption {
 func (opts grpcDialOptions) withExporter(e *Exporter) {
 	e.grpcDialOptions = opts
 }
+
+type metricNamePrefixSetter string
+
+var _ ExporterOption = (*metricNamePrefixSetter)(nil)
+
+func (p metricNamePrefixSetter) withExporter(e *Exporter) {
+	e.metricNamePerfix = string(p)
+}
+
+// WithMetricNamePrefix provides an option for the caller to add a prefix to metric names.
+func WithMetricNamePrefix(prefix string) ExporterOption {
+	return metricNamePrefixSetter(prefix)
+}

transform_stats_to_metrics.go

@@ -33,12 +33,12 @@ var (
 	errNilViewData = errors.New("expecting a non-nil view.Data")
 )
 
-func viewDataToMetric(vd *view.Data) (*metricspb.Metric, error) {
+func viewDataToMetric(vd *view.Data, metricNamePrefix string) (*metricspb.Metric, error) {
 	if vd == nil {
 		return nil, errNilViewData
 	}
 
-	descriptor, err := viewToMetricDescriptor(vd.View)
+	descriptor, err := viewToMetricDescriptor(vd.View, metricNamePrefix)
 	if err != nil {
 		return nil, err
 	}
@@ -55,16 +55,20 @@ func viewDataToMetric(vd *view.Data) (*metricspb.Metric, error) {
 	return metric, nil
 }
 
-func viewToMetricDescriptor(v *view.View) (*metricspb.MetricDescriptor, error) {
+func viewToMetricDescriptor(v *view.View, metricNamePrefix string) (*metricspb.MetricDescriptor, error) {
 	if v == nil {
 		return nil, errNilView
 	}
 	if v.Measure == nil {
 		return nil, errNilMeasure
 	}
 
+	name := stringOrCall(v.Name, v.Measure.Name)
+	if len(metricNamePrefix) > 0 {
+		name = metricNamePrefix + "/" + name
+	}
 	desc := &metricspb.MetricDescriptor{
-		Name:        stringOrCall(v.Name, v.Measure.Name),
+		Name:        name,
 		Description: stringOrCall(v.Description, v.Measure.Description),
 		Unit:        v.Measure.Unit(),
 		Type:        aggregationToMetricDescriptorType(v),

transform_stats_to_metrics_test.go

@@ -39,9 +39,10 @@ var (
 )
 
 type test struct {
-	in      *view.Data
-	want    *metricspb.Metric
-	wantErr string
+	in               *view.Data
+	metricNamePrefix string
+	want             *metricspb.Metric
+	wantErr          string
 }
 
 func TestViewDataToMetrics_Distribution(t *testing.T) {
@@ -1150,9 +1151,63 @@ func TestViewDataToMetrics_MissingVsEmptyLabelValues(t *testing.T) {
 	testViewDataToMetrics(t, tests)
 }
 
+func TestViewDataToMetrics_WithMetricNamePrefix(t *testing.T) {
+	startTime := time.Date(2018, 11, 25, 15, 38, 18, 997, time.UTC)
+	endTime := startTime.Add(100 * time.Millisecond)
+
+	tests := []*test{
+		// Testing with a stats.Float64 measure.
+		{
+			in: &view.Data{
+				Start: startTime,
+				End:   endTime,
+				View: &view.View{
+					Name:        "latency",
+					Description: "speed of the various runners",
+					Aggregation: view.Sum(),
+					Measure:     mSprinterLatencyMs,
+				},
+				Rows: []*view.Row{
+					{
+						Data: &view.SumData{Value: 27},
+					},
+				},
+			},
+			metricNamePrefix: "foo.bar",
+			want: &metricspb.Metric{
+				MetricDescriptor: &metricspb.MetricDescriptor{
+					Name:        "foo.bar/latency",
+					Description: "speed of the various runners",
+					Unit:        "ms",
+					Type:        metricspb.MetricDescriptor_CUMULATIVE_DOUBLE,
+				},
+				Timeseries: []*metricspb.TimeSeries{
+					{
+						StartTimestamp: &timestamp.Timestamp{
+							Seconds: 1543160298,
+							Nanos:   997,
+						},
+						Points: []*metricspb.Point{
+							{
+								Timestamp: &timestamp.Timestamp{
+									Seconds: 1543160298,
+									Nanos:   100000997,
+								},
+								Value: &metricspb.Point_DoubleValue{DoubleValue: 27},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	testViewDataToMetrics(t, tests)
+}
+
 func testViewDataToMetrics(t *testing.T, tests []*test) {
 	for i, tt := range tests {
-		got, err := viewDataToMetric(tt.in)
+		got, err := viewDataToMetric(tt.in, tt.metricNamePrefix)
 		if tt.wantErr != "" {
 			continue
 		}