Support floats in statsd percentiles (#5572)

plugins/inputs/statsd/README.md

@@ -34,8 +34,8 @@
   ## Reset timings & histograms every interval (default=true)
   delete_timings = true
 
-  ## Percentiles to calculate for timing & histogram stats
-  percentiles = [90]
+  ## Percentiles to calculate for timing & histogram stats.
+  percentiles = [50.0, 90.0, 99.0, 99.9, 99.95, 100.0]
 
   ## separator to use between elements of a statsd metric
   metric_separator = "_"

plugins/inputs/statsd/running_stats.go

@@ -99,7 +99,7 @@ func (rs *RunningStats) Count() int64 {
 	return rs.n
 }
 
-func (rs *RunningStats) Percentile(n int) float64 {
+func (rs *RunningStats) Percentile(n float64) float64 {
 	if n > 100 {
 		n = 100
 	}
@@ -109,16 +109,16 @@ func (rs *RunningStats) Percentile(n int) float64 {
 		rs.sorted = true
 	}
 
-	i := int(float64(len(rs.perc)) * float64(n) / float64(100))
+	i := float64(len(rs.perc)) * n / float64(100)
 	return rs.perc[clamp(i, 0, len(rs.perc)-1)]
 }
 
-func clamp(i int, min int, max int) int {
-	if i < min {
+func clamp(i float64, min int, max int) int {
+	if i < float64(min) {
 		return min
 	}
-	if i > max {
+	if i > float64(max) {
 		return max
 	}
-	return i
+	return int(i)
 }

plugins/inputs/statsd/running_stats_test.go

@@ -26,6 +26,9 @@ func TestRunningStats_Single(t *testing.T) {
 	if rs.Percentile(100) != 10.1 {
 		t.Errorf("Expected %v, got %v", 10.1, rs.Percentile(100))
 	}
+	if rs.Percentile(99.95) != 10.1 {
+		t.Errorf("Expected %v, got %v", 10.1, rs.Percentile(99.95))
+	}
 	if rs.Percentile(90) != 10.1 {
 		t.Errorf("Expected %v, got %v", 10.1, rs.Percentile(90))
 	}
@@ -67,6 +70,9 @@ func TestRunningStats_Duplicate(t *testing.T) {
 	if rs.Percentile(100) != 10.1 {
 		t.Errorf("Expected %v, got %v", 10.1, rs.Percentile(100))
 	}
+	if rs.Percentile(99.95) != 10.1 {
+		t.Errorf("Expected %v, got %v", 10.1, rs.Percentile(99.95))
+	}
 	if rs.Percentile(90) != 10.1 {
 		t.Errorf("Expected %v, got %v", 10.1, rs.Percentile(90))
 	}
@@ -108,12 +114,21 @@ func TestRunningStats(t *testing.T) {
 	if rs.Percentile(100) != 45 {
 		t.Errorf("Expected %v, got %v", 45, rs.Percentile(100))
 	}
+	if rs.Percentile(99.98) != 45 {
+		t.Errorf("Expected %v, got %v", 45, rs.Percentile(99.98))
+	}
 	if rs.Percentile(90) != 32 {
 		t.Errorf("Expected %v, got %v", 32, rs.Percentile(90))
 	}
+	if rs.Percentile(50.1) != 11 {
+		t.Errorf("Expected %v, got %v", 11, rs.Percentile(50.1))
+	}
 	if rs.Percentile(50) != 11 {
 		t.Errorf("Expected %v, got %v", 11, rs.Percentile(50))
 	}
+	if rs.Percentile(49.9) != 10 {
+		t.Errorf("Expected %v, got %v", 10, rs.Percentile(49.9))
+	}
 	if rs.Percentile(0) != 5 {
 		t.Errorf("Expected %v, got %v", 5, rs.Percentile(0))
 	}

plugins/inputs/statsd/statsd.go

@@ -55,7 +55,7 @@ type Statsd struct {
 
 	// Percentiles specifies the percentiles that will be calculated for timing
 	// and histogram stats.
-	Percentiles     []int
+	Percentiles     []internal.Number
 	PercentileLimit int
 
 	DeleteGauges   bool
@@ -217,7 +217,7 @@ const sampleConfig = `
   delete_timings = true
 
   ## Percentiles to calculate for timing & histogram stats
-  percentiles = [90]
+  percentiles = [50.0, 90.0, 99.0, 99.9, 99.95, 100.0]
 
   ## separator to use between elements of a statsd metric
   metric_separator = "_"
@@ -271,8 +271,8 @@ func (s *Statsd) Gather(acc telegraf.Accumulator) error {
 			fields[prefix+"lower"] = stats.Lower()
 			fields[prefix+"count"] = stats.Count()
 			for _, percentile := range s.Percentiles {
-				name := fmt.Sprintf("%s%v_percentile", prefix, percentile)
-				fields[name] = stats.Percentile(percentile)
+				name := fmt.Sprintf("%s%v_percentile", prefix, percentile.Value)
+				fields[name] = stats.Percentile(percentile.Value)
 			}
 		}
 

plugins/inputs/statsd/statsd_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -397,7 +398,7 @@ func TestParse_Counters(t *testing.T) {
 // Tests low-level functionality of timings
 func TestParse_Timings(t *testing.T) {
 	s := NewTestStatsd()
-	s.Percentiles = []int{90}
+	s.Percentiles = []internal.Number{{Value: 90.0}}
 	acc := &testutil.Accumulator{}
 
 	// Test that counters work
@@ -1181,7 +1182,7 @@ func TestParse_MeasurementsWithMultipleValues(t *testing.T) {
 func TestParse_TimingsMultipleFieldsWithTemplate(t *testing.T) {
 	s := NewTestStatsd()
 	s.Templates = []string{"measurement.field"}
-	s.Percentiles = []int{90}
+	s.Percentiles = []internal.Number{{Value: 90.0}}
 	acc := &testutil.Accumulator{}
 
 	validLines := []string{
@@ -1232,7 +1233,7 @@ func TestParse_TimingsMultipleFieldsWithTemplate(t *testing.T) {
 func TestParse_TimingsMultipleFieldsWithoutTemplate(t *testing.T) {
 	s := NewTestStatsd()
 	s.Templates = []string{}
-	s.Percentiles = []int{90}
+	s.Percentiles = []internal.Number{{Value: 90.0}}
 	acc := &testutil.Accumulator{}
 
 	validLines := []string{