optimize configmeta generation (#58521)

* optimize config meta building

Signed-off-by: Rama Chavali <[email protected]>

* add benchmark

Signed-off-by: Rama Chavali <[email protected]>

* remove string builder

Signed-off-by: Rama Chavali <[email protected]>

---------

Signed-off-by: Rama Chavali <[email protected]>

Author: ramaraochavali

pilot/pkg/networking/util/util.go

@@ -22,6 +22,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 
 	core "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
 	endpoint "github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3"
@@ -92,6 +93,20 @@ const (
 	AlpnOverrideMetadataKey = "alpn_override"
 )
 
+// kindToKebabCache caches the conversion from CamelCase Kind to kebab-case.
+// This avoids repeated string allocations for the same Kind values.
+var kindToKebabCache sync.Map
+
+// getKebabKind returns the kebab-case version of a Kind, using a cache to avoid repeated allocations.
+func getKebabKind(kind string) string {
+	if cached, ok := kindToKebabCache.Load(kind); ok {
+		return cached.(string)
+	}
+	kebab := strcase.CamelCaseToKebabCase(kind)
+	kindToKebabCache.Store(kind, kebab)
+	return kebab
+}
+
 // ALPNH2Only advertises that Proxy is going to use HTTP/2 when talking to the cluster.
 var ALPNH2Only = pm.ALPNH2Only
 
@@ -356,17 +371,21 @@ func BuildConfigInfoMetadata(config config.Meta) *core.Metadata {
 func AddConfigInfoMetadata(metadata *core.Metadata, config config.Meta) *core.Metadata {
 	if metadata == nil {
 		metadata = &core.Metadata{
-			FilterMetadata: map[string]*structpb.Struct{},
+			FilterMetadata: make(map[string]*structpb.Struct, 1),
 		}
 	}
+
 	s := "/apis/" + config.GroupVersionKind.Group + "/" + config.GroupVersionKind.Version + "/namespaces/" + config.Namespace + "/" +
-		strcase.CamelCaseToKebabCase(config.GroupVersionKind.Kind) + "/" + config.Name
-	if _, ok := metadata.FilterMetadata[IstioMetadataKey]; !ok {
-		metadata.FilterMetadata[IstioMetadataKey] = &structpb.Struct{
-			Fields: map[string]*structpb.Value{},
+		getKebabKind(config.GroupVersionKind.Kind) + "/" + config.Name
+
+	istioMeta, ok := metadata.FilterMetadata[IstioMetadataKey]
+	if !ok {
+		istioMeta = &structpb.Struct{
+			Fields: make(map[string]*structpb.Value, 1),
 		}
+		metadata.FilterMetadata[IstioMetadataKey] = istioMeta
 	}
-	metadata.FilterMetadata[IstioMetadataKey].Fields["config"] = &structpb.Value{
+	istioMeta.Fields["config"] = &structpb.Value{
 		Kind: &structpb.Value_StringValue{
 			StringValue: s,
 		},

pilot/pkg/networking/util/util_test.go

@@ -1864,3 +1864,54 @@ func TestMeshNetworksToEnvoyInternalAddressConfig(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkAddConfigInfoMetadata(b *testing.B) {
+	configs := []config.Meta{
+		{
+			Name:             "my-virtual-service",
+			Namespace:        "default",
+			GroupVersionKind: gvk.VirtualService,
+		},
+		{
+			Name:             "my-destination-rule",
+			Namespace:        "istio-system",
+			GroupVersionKind: gvk.DestinationRule,
+		},
+		{
+			Name:             "my-gateway",
+			Namespace:        "production",
+			GroupVersionKind: gvk.Gateway,
+		},
+	}
+
+	b.Run("NilMetadata", func(b *testing.B) {
+		cfg := configs[0]
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = AddConfigInfoMetadata(nil, cfg)
+		}
+	})
+
+	b.Run("ExistingMetadata", func(b *testing.B) {
+		cfg := configs[0]
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			meta := &core.Metadata{
+				FilterMetadata: map[string]*structpb.Struct{},
+			}
+			_ = AddConfigInfoMetadata(meta, cfg)
+		}
+	})
+
+	b.Run("MultipleConfigs", func(b *testing.B) {
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			for _, cfg := range configs {
+				_ = AddConfigInfoMetadata(nil, cfg)
+			}
+		}
+	})
+}