mtypes: Fix 0 divide crash, making prior test pass

Signed-off-by: Craig Ringer <[email protected]>

Author: ringerc

cmd/mtypes/main.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math"
 	"net/http"
 	"net/url"
 	"os"
@@ -78,7 +79,8 @@ func main() {
 	if *avalancheFlagsForTotal > 0 {
 		fmt.Fprintln(os.Stdout)
 		fmt.Fprintln(os.Stdout, "Avalanche flags for the similar distribution to get to the adjusted series goal of:", *avalancheFlagsForTotal)
-		flags, adjustedSum := computeAvalancheFlags(*avalancheFlagsForTotal, total, statistics)
+		seriesCount := 10
+		flags, adjustedSum := computeAvalancheFlags(*avalancheFlagsForTotal, seriesCount, total, statistics)
 		for _, f := range flags {
 			fmt.Fprintln(os.Stdout, f)
 		}
@@ -96,10 +98,10 @@ func computeTotal(statistics map[dto.MetricType]stats) stats {
 	return total
 }
 
-func computeAvalancheFlags(avalancheFlagsForTotal int, total stats, statistics map[dto.MetricType]stats) ([]string, int) {
+func computeAvalancheFlags(avalancheFlagsForTotal, seriesCount int, total stats, statistics map[dto.MetricType]stats) ([]string, int) {
 	// adjustedGoal is tracking the # of adjusted series we want to generate with avalanche.
 	adjustedGoal := float64(avalancheFlagsForTotal)
-	adjustedGoal /= 10.0 // Assuming --series-count=10
+	adjustedGoal /= float64(seriesCount)
 	// adjustedSum is tracking the total sum of series so far (at the end hopefully adjustedSum ~= adjustedGoal)
 	adjustedSum := 0
 	// Accumulate flags
@@ -113,7 +115,10 @@ func computeAvalancheFlags(avalancheFlagsForTotal int, total stats, statistics m
 
 		// adjustedSeriesForType is tracking (per metric type), how many unique series of that
 		// metric type avalanche needs to create according to the ratio we got from our input.
-		adjustedSeriesForType := int(adjustedGoal * adjustedSeriesRatio)
+		var adjustedSeriesForType int
+		if !math.IsNaN(adjustedSeriesRatio) {
+			adjustedSeriesForType = int(adjustedGoal * adjustedSeriesRatio)
+		}
 
 		switch mtype {
 		case dto.MetricType_GAUGE:
@@ -123,27 +128,37 @@ func computeAvalancheFlags(avalancheFlagsForTotal int, total stats, statistics m
 			flags = append(flags, fmt.Sprintf("--counter-metric-count=%v", adjustedSeriesForType))
 			adjustedSum += adjustedSeriesForType
 		case dto.MetricType_HISTOGRAM:
-			avgBkts := s.buckets / s.series
-			adjustedSeriesForType /= 2 + avgBkts
+			var avgBkts int
+			if s.series > 0 {
+				avgBkts = s.buckets / s.series
+				adjustedSeriesForType /= 2 + avgBkts
+			}
 			flags = append(flags, fmt.Sprintf("--histogram-metric-count=%v", adjustedSeriesForType))
-			flags = append(flags, fmt.Sprintf("--histogram-metric-bucket-count=%v", avgBkts-1)) // -1 is due to caveat of additional +Inf not added by avalanche.
+			if s.series > 0 {
+				flags = append(flags, fmt.Sprintf("--histogram-metric-bucket-count=%v", avgBkts-1)) // -1 is due to caveat of additional +Inf not added by avalanche.
+			}
 			adjustedSum += adjustedSeriesForType * (2 + avgBkts)
 		case metricType_NATIVE_HISTOGRAM:
 			flags = append(flags, fmt.Sprintf("--native-histogram-metric-count=%v", adjustedSeriesForType))
 			adjustedSum += adjustedSeriesForType
 		case dto.MetricType_SUMMARY:
-			avgObjs := s.objectives / s.series
-			adjustedSeriesForType /= 2 + avgObjs
+			var avgObjs int
+			if s.series > 0 {
+				avgObjs = s.objectives / s.series
+				adjustedSeriesForType /= 2 + avgObjs
+			}
 			flags = append(flags, fmt.Sprintf("--summary-metric-count=%v", adjustedSeriesForType))
-			flags = append(flags, fmt.Sprintf("--summary-metric-objective-count=%v", avgObjs))
+			if s.series > 0 {
+				flags = append(flags, fmt.Sprintf("--summary-metric-objective-count=%v", avgObjs))
+			}
 			adjustedSum += adjustedSeriesForType * (2 + avgObjs)
 		default:
 			if s.series > 0 {
 				log.Fatalf("not supported %v metric in avalanche", mtype)
 			}
 		}
 	}
-	flags = append(flags, fmt.Sprintf("--series-count=10"))
+	flags = append(flags, fmt.Sprintf("--series-count=%v", seriesCount))
 	// Changes values every 5m.
 	flags = append(flags, "--value-interval=300")
 	// 1h series churn.

cmd/mtypes/main_test.go

@@ -1100,6 +1100,7 @@ func TestComputeAvalancheFlags(t *testing.T) {
 	for _, tc := range []struct {
 		testName               string
 		avalancheFlagsForTotal int
+		seriesCount            int
 		statistics             map[dto.MetricType]stats
 		total                  stats
 		expectedSum            int
@@ -1108,6 +1109,7 @@ func TestComputeAvalancheFlags(t *testing.T) {
 		{
 			testName:               "samplePromInput",
 			avalancheFlagsForTotal: 1000,
+			seriesCount:            10,
 			statistics: map[dto.MetricType]stats{
 				dto.MetricType_COUNTER:   {families: 104, series: 166, adjustedSeries: 166},
 				dto.MetricType_GAUGE:     {families: 77, series: 94, adjustedSeries: 94},
@@ -1135,14 +1137,25 @@ func TestComputeAvalancheFlags(t *testing.T) {
 		{
 			testName:               "noInput",
 			avalancheFlagsForTotal: 1000,
+			seriesCount:            10,
 			statistics:             map[dto.MetricType]stats{},
 			total:                  stats{},
-			expectedSum:            84,
-			expectedFlags:          []string{},
+			expectedSum:            0,
+			expectedFlags: []string{
+				"--gauge-metric-count=0",
+				"--counter-metric-count=0",
+				"--histogram-metric-count=0",
+				"--native-histogram-metric-count=0",
+				"--summary-metric-count=0",
+				"--series-count=10",
+				"--value-interval=300",
+				"--series-interval=3600",
+				"--metric-interval=0",
+			},
 		},
 	} {
 		t.Run(tc.testName, func(t *testing.T) {
-			avalancheFlags, adjustedSum := computeAvalancheFlags(tc.avalancheFlagsForTotal, tc.total, tc.statistics)
+			avalancheFlags, adjustedSum := computeAvalancheFlags(tc.avalancheFlagsForTotal, tc.seriesCount, tc.total, tc.statistics)
 			assert.Equal(t, tc.expectedSum, adjustedSum)
 			assert.Equal(t, tc.expectedFlags, avalancheFlags)
 		})