lib/promscrape/discovery: add a benchmark for measuring the performance of creating pod meta-labels

lib/promscrape/discovery/kubernetes/node_test.go

@@ -289,6 +289,18 @@ func TestParseNodeListSuccess(t *testing.T) {
 }
 
 func getSortedLabelss(objectsByKey map[string]object) [][]prompbmarshal.Label {
+	gw := newTestGroupWatcher()
+	var result [][]prompbmarshal.Label
+	for _, o := range objectsByKey {
+		labelss := o.getTargetLabels(gw)
+		for _, labels := range labelss {
+			result = append(result, discoveryutils.GetSortedLabels(labels))
+		}
+	}
+	return result
+}
+
+func newTestGroupWatcher() *groupWatcher {
 	var gw groupWatcher
 	gw.m = map[string]*urlWatcher{
 		"node": {
@@ -308,14 +320,7 @@ func getSortedLabelss(objectsByKey map[string]object) [][]prompbmarshal.Label {
 		},
 	}
 	gw.attachNodeMetadata = true
-	var result [][]prompbmarshal.Label
-	for _, o := range objectsByKey {
-		labelss := o.getTargetLabels(&gw)
-		for _, labels := range labelss {
-			result = append(result, discoveryutils.GetSortedLabels(labels))
-		}
-	}
-	return result
+	return &gw
 }
 
 func areEqualLabelss(a, b [][]prompbmarshal.Label) bool {

lib/promscrape/discovery/kubernetes/pod_test.go

@@ -26,8 +26,7 @@ func TestParsePodListFailure(t *testing.T) {
 	f(`{"items":[{"metadata":{"labels":[1]}}]}`)
 }
 
-func TestParsePodListSuccess(t *testing.T) {
-	data := `
+const testPodsList = `
 {
   "kind": "PodList",
   "apiVersion": "v1",
@@ -229,7 +228,9 @@ func TestParsePodListSuccess(t *testing.T) {
   ]
 }
 `
-	r := bytes.NewBufferString(data)
+
+func TestParsePodListSuccess(t *testing.T) {
+	r := bytes.NewBufferString(testPodsList)
 	objectsByKey, meta, err := parsePodList(r)
 	if err != nil {
 		t.Fatalf("unexpected error: %s", err)

lib/promscrape/discovery/kubernetes/pod_timing_test.go

@@ -0,0 +1,34 @@
+package kubernetes
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+)
+
+func BenchmarkPodGetTargetLabels(b *testing.B) {
+	r := bytes.NewBufferString(testPodsList)
+	objectsByKey, _, err := parsePodList(r)
+	if err != nil {
+		panic(fmt.Errorf("BUG: unexpected error: %s", err))
+	}
+	var o object
+	for _, srcObject := range objectsByKey {
+		o = srcObject
+		break
+	}
+	if o == nil {
+		panic(fmt.Errorf("BUG: expecting at least a single pod object"))
+	}
+	gw := newTestGroupWatcher()
+	b.ReportAllocs()
+	b.SetBytes(1)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			labelss := o.getTargetLabels(gw)
+			if len(labelss) != 1 {
+				panic(fmt.Errorf("BUG: unexpected number of labelss returned: %d; want 1", len(labelss)))
+			}
+		}
+	})
+}