Merge pull request #1518 from grafana/fix-removeabovebelowpercentile-panic

Fix removeabovebelowpercentile panic

Author: Dieterbe

expr/data_test.go

@@ -61,6 +61,15 @@ var d = []schema.Point{
 	{Val: 250, Ts: 60},
 }
 
+var allNulls = []schema.Point{
+	{Val: math.NaN(), Ts: 10},
+	{Val: math.NaN(), Ts: 20},
+	{Val: math.NaN(), Ts: 30},
+	{Val: math.NaN(), Ts: 40},
+	{Val: math.NaN(), Ts: 50},
+	{Val: math.NaN(), Ts: 60},
+}
+
 var sumab = []schema.Point{
 	{Val: 0, Ts: 10},
 	{Val: math.MaxFloat64, Ts: 20},

expr/func_removeabovebelowpercentile.go

@@ -58,6 +58,9 @@ func (s *FuncRemoveAboveBelowPercentile) Exec(cache map[Req][]models.Series) ([]
 		serie.Tags = serie.CopyTagsWith("nPercentile", fmt.Sprintf("%g", s.n))
 
 		percentile := getPercentileValue(serie.Datapoints, s.n, sortedDatapointVals)
+		if math.IsNaN(percentile) {
+			continue
+		}
 
 		out := pointSlicePool.Get().([]schema.Point)
 		for _, p := range serie.Datapoints {
@@ -91,6 +94,10 @@ func getPercentileValue(datapoints []schema.Point, n float64, sortedDatapointVal
 		}
 	}
 
+	if len(sortedDatapointVals) == 0 {
+		return math.NaN()
+	}
+
 	sort.Float64s(sortedDatapointVals)
 
 	index := math.Min(math.Ceil(n/100.0*float64(len(sortedDatapointVals)+1)), float64(len(sortedDatapointVals))) - 1

expr/func_removeabovebelowpercentile_test.go

@@ -181,6 +181,59 @@ func TestRemoveBelowPercentileSingleAllNonNull(t *testing.T) {
 	)
 }
 
+// TestRemoveBelowPercentileWithNulls verifies that, just like Graphite, series with all nulls, are removed from the output
+func TestRemoveBelowPercentileWithNulls(t *testing.T) {
+	testRemoveAboveBelowPercentile(
+		"removeBelowPercentile",
+		false,
+		50,
+		[]models.Series{
+			{
+				Interval:   10,
+				QueryPatt:  "abcd",
+				Target:     "a",
+				Datapoints: getCopy(a),
+			},
+			{
+				Interval:   10,
+				QueryPatt:  "abcd",
+				Target:     "b",
+				Datapoints: getCopy(allNulls),
+			},
+		},
+		[]models.Series{
+			{
+				Interval:  10,
+				QueryPatt: "removeBelowPercentile(a, 50)",
+				Datapoints: []schema.Point{
+					{Val: math.NaN(), Ts: 10},
+					{Val: math.NaN(), Ts: 20},
+					{Val: 5.5, Ts: 30},
+					{Val: math.NaN(), Ts: 40},
+					{Val: math.NaN(), Ts: 50},
+					{Val: 1234567890, Ts: 60},
+				},
+			},
+		},
+		t,
+	)
+	testRemoveAboveBelowPercentile(
+		"removeBelowPercentile",
+		false,
+		50,
+		[]models.Series{
+			{
+				Interval:   10,
+				QueryPatt:  "abcd",
+				Target:     "b",
+				Datapoints: getCopy(allNulls),
+			},
+		},
+		[]models.Series{},
+		t,
+	)
+}
+
 func testRemoveAboveBelowPercentile(name string, above bool, n float64, in []models.Series, out []models.Series, t *testing.T) {
 	f := NewRemoveAboveBelowPercentileConstructor(above)()
 	f.(*FuncRemoveAboveBelowPercentile).in = NewMock(in)