[query] implemented Graphite's powSeries function (#3038)

src/query/graphite/native/aggregation_functions.go

@@ -88,6 +88,13 @@ func minSeries(ctx *common.Context, series multiplePathSpecs) (ts.SeriesList, er
 	return combineSeries(ctx, series, wrapPathExpr(minSeriesFnName, ts.SeriesList(series)), ts.Min)
 }
 
+// powSeries takes a list of series and returns a new series containing the
+// pow value across the series at each datapoint
+// nolint: gocritic
+func powSeries(ctx *common.Context, series multiplePathSpecs) (ts.SeriesList, error) {
+	return combineSeries(ctx, series, wrapPathExpr(powSeriesFnName, ts.SeriesList(series)), ts.Pow)
+}
+
 // maxSeries takes a list of series and returns a new series containing the
 // maximum value across the series at each datapoint
 func maxSeries(ctx *common.Context, series multiplePathSpecs) (ts.SeriesList, error) {

src/query/graphite/native/aggregation_functions_test.go

@@ -166,6 +166,40 @@ func TestStdDevSeries(t *testing.T) {
 	common.CompareOutputsAndExpected(t, 60000, start, expectedResults, result.Values)
 }
 
+func TestPowSeries(t *testing.T) {
+	var (
+		ctrl      = xgomock.NewController(t)
+		store     = storage.NewMockStorage(ctrl)
+		now       = time.Now().Truncate(time.Hour)
+		engine    = NewEngine(store, CompileOptions{})
+		startTime = now.Add(-3 * time.Minute)
+		endTime   = now.Add(-time.Minute)
+		ctx       = common.NewContext(common.ContextOptions{
+			Start:  startTime,
+			End:    endTime,
+			Engine: engine,
+		})
+	)
+
+	fakeSeries1 := ts.NewSeries(ctx, "foo.bar.g.zed.g", startTime,
+		common.NewTestSeriesValues(ctx, 60000, []float64{0, 1, 2, 3, 4}))
+	fakeSeries2 := ts.NewSeries(ctx, "foo.bar.g.zed.g", startTime,
+		common.NewTestSeriesValues(ctx, 60000, []float64{2, 4, 1, 3, 3}))
+	fakeSeries3 := ts.NewSeries(ctx, "foo.bar.g.zed.g", startTime,
+		common.NewTestSeriesValues(ctx, 60000, []float64{5, 4, 3, 2, 1}))
+
+	listOfFakeSeries := []*ts.Series{fakeSeries1, fakeSeries2, fakeSeries3}
+
+	expectedValues := []float64{0, 1, 8, 729, 64}
+	result, err := powSeries(ctx, multiplePathSpecs(singlePathSpec{Values: listOfFakeSeries}))
+	if err != nil {
+		fmt.Println(err)
+	}
+	for i := 0; i < result.Values[0].Len(); i++ {
+		require.Equal(t, result.Values[0].ValueAt(i), expectedValues[i])
+	}
+}
+
 func TestAggregate(t *testing.T) {
 	testAggregatedSeries(t, func(ctx *common.Context, series multiplePathSpecs) (ts.SeriesList, error) {
 		return aggregate(ctx, singlePathSpec(series), "sum")

src/query/graphite/native/builtin_functions.go

@@ -2471,6 +2471,7 @@ func init() {
 	MustRegisterFunction(perSecond).WithDefaultParams(map[uint8]interface{}{
 		2: math.NaN(), // maxValue
 	})
+	MustRegisterFunction(powSeries)
 	MustRegisterFunction(rangeOfSeries)
 	MustRegisterFunction(randomWalkFunction).WithDefaultParams(map[uint8]interface{}{
 		2: 60, // step

src/query/graphite/native/builtin_functions_test.go

@@ -3528,6 +3528,7 @@ func TestFunctionsRegistered(t *testing.T) {
 		"offset",
 		"offsetToZero",
 		"perSecond",
+		"powSeries",
 		"randomWalk",
 		"randomWalkFunction",
 		"rangeOfSeries",

src/query/graphite/native/functions.go

@@ -61,6 +61,7 @@ const (
 	minSeriesFnName      = "minSeries"
 	multiplyFnName       = "multiply"
 	multiplySeriesFnName = "multiplySeries"
+	powSeriesFnName      = "powSeries"
 	rangeFnName          = "range"
 	rangeOfFnName        = "rangeOf"
 	rangeOfSeriesFnName  = "rangeOfSeries"

src/query/graphite/ts/series.go

@@ -599,6 +599,9 @@ func Max(a, b float64, count int) float64 { return math.Max(a, b) }
 // Last finds the latter of two values.
 func Last(a, b float64, count int) float64 { return b }
 
+// Pow returns the first value to the power of the second value
+func Pow(a, b float64, count int) float64 { return math.Pow(a, b) }
+
 // Median finds the median of a slice of values.
 func Median(vals []float64, count int) float64 {
 	if count < 1 {