metric type is not set for gauges. (#1082)

metric/gauge_test.go

@@ -41,6 +41,7 @@ func TestGauge(t *testing.T) {
 			Descriptor: metricdata.Descriptor{
 				Name:      "TestGauge",
 				LabelKeys: []string{"k1", "k2"},
+				Type:      metricdata.TypeGaugeFloat64,
 			},
 			TimeSeries: []*metricdata.TimeSeries{
 				{
@@ -79,6 +80,26 @@ func TestGauge(t *testing.T) {
 	}
 }
 
+func TestGaugeMetricDescriptor(t *testing.T) {
+	unit := metricdata.UnitDimensionless
+	r := NewRegistry()
+
+	gf, _ := r.AddFloat64Gauge("float64_gauge", "", unit)
+	compareType(gf.g.desc.Type, metricdata.TypeGaugeFloat64, t)
+	gi, _ := r.AddInt64Gauge("int64_gauge", "", unit)
+	compareType(gi.g.desc.Type, metricdata.TypeGaugeInt64, t)
+	dgf, _ := r.AddFloat64DerivedGauge("derived_float64_gauge", "", unit)
+	compareType(dgf.g.desc.Type, metricdata.TypeGaugeFloat64, t)
+	dgi, _ := r.AddInt64DerivedGauge("derived_int64_gauge", "", unit)
+	compareType(dgi.g.desc.Type, metricdata.TypeGaugeInt64, t)
+}
+
+func compareType(got, want metricdata.Type, t *testing.T) {
+	if got != want {
+		t.Errorf("metricdata type: got %v, want %v\n", got, want)
+	}
+}
+
 func TestFloat64Entry_Add(t *testing.T) {
 	r := NewRegistry()
 	g, _ := r.AddFloat64Gauge("g", "", metricdata.UnitDimensionless)

metric/registry.go

@@ -102,6 +102,21 @@ func (r *Registry) AddFloat64DerivedGauge(name, description string, unit metricd
 	return f, nil
 }
 
+func gTypeToMetricType(g *gauge) metricdata.Type {
+	switch g.gType {
+	case derivedGaugeFloat64:
+		return metricdata.TypeGaugeFloat64
+	case derivedGaugeInt64:
+		return metricdata.TypeGaugeInt64
+	case gaugeFloat64:
+		return metricdata.TypeGaugeFloat64
+	case gaugeInt64:
+		return metricdata.TypeGaugeInt64
+	default:
+		panic("unsupported gauge type")
+	}
+}
+
 func (r *Registry) initGauge(g *gauge, labelKeys []string, name string, description string, unit metricdata.Unit) (*gauge, error) {
 	val, ok := r.gauges.Load(name)
 	if ok {
@@ -117,6 +132,7 @@ func (r *Registry) initGauge(g *gauge, labelKeys []string, name string, descript
 		Description: description,
 		Unit:        unit,
 		LabelKeys:   labelKeys,
+		Type:        gTypeToMetricType(g),
 	}
 	r.gauges.Store(name, g)
 	return g, nil