[query] Implemented the Graphite cumulative function

src/query/graphite/native/builtin_functions.go

@@ -2079,6 +2079,11 @@ func consolidateBy(_ *common.Context, seriesList singlePathSpec, consolidationAp
 	return r, nil
 }
 
+// cumulative is an alias for consolidateBy(series, 'sum')
+func cumulative(ctx *common.Context, seriesList singlePathSpec) (ts.SeriesList, error) {
+	return consolidateBy(ctx, seriesList, "sum")
+}
+
 // offsetToZero offsets a metric or wildcard seriesList by subtracting the minimum
 // value in the series from each data point.
 func offsetToZero(ctx *common.Context, seriesList singlePathSpec) (ts.SeriesList, error) {
@@ -2181,6 +2186,7 @@ func init() {
 	MustRegisterFunction(consolidateBy)
 	MustRegisterFunction(constantLine)
 	MustRegisterFunction(countSeries)
+	MustRegisterFunction(cumulative)
 	MustRegisterFunction(currentAbove)
 	MustRegisterFunction(currentBelow)
 	MustRegisterFunction(dashed).WithDefaultParams(map[uint8]interface{}{

src/query/graphite/native/builtin_functions_test.go

@@ -3015,6 +3015,39 @@ func TestConsolidateBy(t *testing.T) {
 	require.NotNil(t, err)
 }
 
+func TestCumulative(t *testing.T) {
+	ctx := common.NewTestContext()
+	defer ctx.Close()
+
+	stepSize := 10000
+	input := struct {
+		name        string
+		startTime   time.Time
+		stepInMilli int
+		values      []float64
+	}{
+		"foo",
+		ctx.StartTime,
+		stepSize,
+		[]float64{1.0, 2.0, 3.0, 4.0, math.NaN()},
+	}
+
+	series := ts.NewSeries(
+		ctx,
+		input.name,
+		input.startTime,
+		common.NewTestSeriesValues(ctx, input.stepInMilli, input.values),
+	)
+
+	results, err := cumulative(ctx, singlePathSpec{
+		Values: []*ts.Series{series},
+	})
+	expected := common.TestSeries{Name: `consolidateBy(foo,"sum")`, Data: input.values}
+	require.Nil(t, err)
+	common.CompareOutputsAndExpected(t, input.stepInMilli, input.startTime,
+		[]common.TestSeries{expected}, results.Values)
+}
+
 func TestOffsetToZero(t *testing.T) {
 	ctx := common.NewTestContext()
 	defer ctx.Close()
@@ -3263,6 +3296,7 @@ func TestFunctionsRegistered(t *testing.T) {
 		"consolidateBy",
 		"constantLine",
 		"countSeries",
+		"cumulative",
 		"currentAbove",
 		"currentBelow",
 		"dashed",