[chore][prometheusreceiver] Simplify metric family and metric group data structures.

receiver/prometheusreceiver/internal/metricfamily.go

@@ -37,9 +37,7 @@ const (
 )
 
 type metricFamily struct {
-	mtype pmetric.MetricType
-	// isMonotonic only applies to sums
-	isMonotonic bool
+	mtype       pmetric.MetricType
 	groups      map[uint64]*metricGroup
 	name        string
 	metadata    *scrape.MetricMetadata
@@ -50,7 +48,6 @@ type metricFamily struct {
 // a couple data complexValue (buckets and count/sum), a group of a metric family always share a same set of tags. for
 // simple types like counter and gauge, each data point is a group of itself
 type metricGroup struct {
-	mtype        pmetric.MetricType
 	ts           int64
 	ls           labels.Labels
 	count        float64
@@ -64,17 +61,16 @@ type metricGroup struct {
 
 func newMetricFamily(metricName string, mc scrape.MetricMetadataStore, logger *zap.Logger) *metricFamily {
 	metadata, familyName := metadataForMetric(metricName, mc)
-	mtype, isMonotonic := convToMetricType(metadata.Type)
+	mtype := convToMetricType(metadata.Type)
 	if mtype == pmetric.MetricTypeEmpty {
 		logger.Debug(fmt.Sprintf("Unknown-typed metric : %s %+v", metricName, metadata))
 	}
 
 	return &metricFamily{
-		mtype:       mtype,
-		isMonotonic: isMonotonic,
-		groups:      make(map[uint64]*metricGroup),
-		name:        familyName,
-		metadata:    metadata,
+		mtype:    mtype,
+		groups:   make(map[uint64]*metricGroup),
+		name:     familyName,
+		metadata: metadata,
 	}
 }
 
@@ -200,11 +196,11 @@ func (mg *metricGroup) toSummaryPoint(dest pmetric.SummaryDataPointSlice) {
 	populateAttributes(pmetric.MetricTypeSummary, mg.ls, point.Attributes())
 }
 
-func (mg *metricGroup) toNumberDataPoint(dest pmetric.NumberDataPointSlice) {
+func (mg *metricGroup) toNumberDataPoint(dest pmetric.NumberDataPointSlice, mType pmetric.MetricType) {
 	tsNanos := timestampFromMs(mg.ts)
 	point := dest.AppendEmpty()
 	// gauge/undefined types have no start time.
-	if mg.mtype == pmetric.MetricTypeSum {
+	if mType == pmetric.MetricTypeSum {
 		point.SetStartTimestamp(tsNanos) // metrics_adjuster adjusts the startTimestamp to the initial scrape timestamp
 	}
 	point.SetTimestamp(tsNanos)
@@ -240,7 +236,6 @@ func (mf *metricFamily) loadMetricGroupOrCreate(groupKey uint64, ls labels.Label
 	mg, ok := mf.groups[groupKey]
 	if !ok {
 		mg = &metricGroup{
-			mtype:     mf.mtype,
 			ts:        ts,
 			ls:        ls,
 			exemplars: pmetric.NewExemplarSlice(),
@@ -312,18 +307,19 @@ func (mf *metricFamily) appendMetric(metrics pmetric.MetricSlice, normalizer *pr
 	case pmetric.MetricTypeSum:
 		sum := metric.SetEmptySum()
 		sum.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
-		sum.SetIsMonotonic(mf.isMonotonic)
+		// is_monotonic MUST be equal to true
+		sum.SetIsMonotonic(true)
 		sdpL := sum.DataPoints()
 		for _, mg := range mf.groupOrders {
-			mg.toNumberDataPoint(sdpL)
+			mg.toNumberDataPoint(sdpL, pmetric.MetricTypeSum)
 		}
 		pointCount = sdpL.Len()
 
 	default: // Everything else should be set to a Gauge.
 		gauge := metric.SetEmptyGauge()
 		gdpL := gauge.DataPoints()
 		for _, mg := range mf.groupOrders {
-			mg.toNumberDataPoint(gdpL)
+			mg.toNumberDataPoint(gdpL, pmetric.MetricTypeGauge)
 		}
 		pointCount = gdpL.Len()
 	}

receiver/prometheusreceiver/internal/util.go

@@ -102,27 +102,27 @@ func getBoundary(metricType pmetric.MetricType, labels labels.Labels) (float64,
 }
 
 // convToMetricType returns the data type and if it is monotonic
-func convToMetricType(metricType textparse.MetricType) (pmetric.MetricType, bool) {
+func convToMetricType(metricType textparse.MetricType) pmetric.MetricType {
 	switch metricType {
 	case textparse.MetricTypeCounter:
 		// always use float64, as it's the internal data type used in prometheus
-		return pmetric.MetricTypeSum, true
+		return pmetric.MetricTypeSum
 	// textparse.MetricTypeUnknown is converted to gauge by default to prevent Prometheus untyped metrics from being dropped
 	case textparse.MetricTypeGauge, textparse.MetricTypeUnknown:
-		return pmetric.MetricTypeGauge, false
+		return pmetric.MetricTypeGauge
 	case textparse.MetricTypeHistogram:
-		return pmetric.MetricTypeHistogram, true
+		return pmetric.MetricTypeHistogram
 	// dropping support for gaugehistogram for now until we have an official spec of its implementation
 	// a draft can be found in: https://docs.google.com/document/d/1KwV0mAXwwbvvifBvDKH_LU1YjyXE_wxCkHNoCGq1GX0/edit#heading=h.1cvzqd4ksd23
 	// case textparse.MetricTypeGaugeHistogram:
 	//	return <pdata gauge histogram type>
 	case textparse.MetricTypeSummary:
-		return pmetric.MetricTypeSummary, true
+		return pmetric.MetricTypeSummary
 	case textparse.MetricTypeInfo, textparse.MetricTypeStateset:
-		return pmetric.MetricTypeSum, false
+		return pmetric.MetricTypeSum
 	default:
 		// including: textparse.MetricTypeGaugeHistogram
-		return pmetric.MetricTypeEmpty, false
+		return pmetric.MetricTypeEmpty
 	}
 }
 

receiver/prometheusreceiver/internal/util_test.go

@@ -63,67 +63,57 @@ func TestTimestampFromFloat64(t *testing.T) {
 
 func TestConvToMetricType(t *testing.T) {
 	tests := []struct {
-		name          string
-		mtype         textparse.MetricType
-		want          pmetric.MetricType
-		wantMonotonic bool
+		name  string
+		mtype textparse.MetricType
+		want  pmetric.MetricType
 	}{
 		{
-			name:          "textparse.counter",
-			mtype:         textparse.MetricTypeCounter,
-			want:          pmetric.MetricTypeSum,
-			wantMonotonic: true,
+			name:  "textparse.counter",
+			mtype: textparse.MetricTypeCounter,
+			want:  pmetric.MetricTypeSum,
 		},
 		{
-			name:          "textparse.gauge",
-			mtype:         textparse.MetricTypeGauge,
-			want:          pmetric.MetricTypeGauge,
-			wantMonotonic: false,
+			name:  "textparse.gauge",
+			mtype: textparse.MetricTypeGauge,
+			want:  pmetric.MetricTypeGauge,
 		},
 		{
-			name:          "textparse.unknown",
-			mtype:         textparse.MetricTypeUnknown,
-			want:          pmetric.MetricTypeGauge,
-			wantMonotonic: false,
+			name:  "textparse.unknown",
+			mtype: textparse.MetricTypeUnknown,
+			want:  pmetric.MetricTypeGauge,
 		},
 		{
-			name:          "textparse.histogram",
-			mtype:         textparse.MetricTypeHistogram,
-			want:          pmetric.MetricTypeHistogram,
-			wantMonotonic: true,
+			name:  "textparse.histogram",
+			mtype: textparse.MetricTypeHistogram,
+			want:  pmetric.MetricTypeHistogram,
 		},
 		{
-			name:          "textparse.summary",
-			mtype:         textparse.MetricTypeSummary,
-			want:          pmetric.MetricTypeSummary,
-			wantMonotonic: true,
+			name:  "textparse.summary",
+			mtype: textparse.MetricTypeSummary,
+			want:  pmetric.MetricTypeSummary,
 		},
 		{
-			name:          "textparse.metric_type_info",
-			mtype:         textparse.MetricTypeInfo,
-			want:          pmetric.MetricTypeSum,
-			wantMonotonic: false,
+			name:  "textparse.metric_type_info",
+			mtype: textparse.MetricTypeInfo,
+			want:  pmetric.MetricTypeSum,
 		},
 		{
-			name:          "textparse.metric_state_set",
-			mtype:         textparse.MetricTypeStateset,
-			want:          pmetric.MetricTypeSum,
-			wantMonotonic: false,
+			name:  "textparse.metric_state_set",
+			mtype: textparse.MetricTypeStateset,
+			want:  pmetric.MetricTypeSum,
 		},
 		{
-			name:          "textparse.metric_gauge_hostogram",
-			mtype:         textparse.MetricTypeGaugeHistogram,
-			want:          pmetric.MetricTypeEmpty,
-			wantMonotonic: false,
+			name:  "textparse.metric_gauge_hostogram",
+			mtype: textparse.MetricTypeGaugeHistogram,
+			want:  pmetric.MetricTypeEmpty,
 		},
 	}
 
 	for _, tt := range tests {
 		tt := tt
 		t.Run(tt.name, func(t *testing.T) {
-			got, monotonic := convToMetricType(tt.mtype)
+			got := convToMetricType(tt.mtype)
 			require.Equal(t, got.String(), tt.want.String())
-			require.Equal(t, monotonic, tt.wantMonotonic)
 		})
 	}
 }