perf: replace fmt.Sprintf with direct concat in hot paths

Replace fmt.Sprintf("%s/%s") with direct string concatenation
in reconciliation hot paths to reduce heap allocations.

- translator_listeners: namespace/ref.Name key construction
- backend_tls: ClientCertificateRef construction
- backend_tls_policy: backendClusterKey with strconv.Itoa
- mesh/frontends: servicePortKey with strconv.Itoa
- status/reconciler_listener_sets: listener set key lookup

Removes fmt import from 4 files. Adds strconv to 1 file.

Author: mahmut-Abi

internal/mesh/frontends.go

@@ -198,7 +198,7 @@ func serviceKey(namespace string, name string) string {
 }
 
 func servicePortKey(namespace string, name string, port int32) string {
-	return fmt.Sprintf("%s/%s/%d", namespace, name, port)
+	return namespace + "/" + name + "/" + strconv.Itoa(int(port))
 }
 
 func namespaceOrDefault(namespace *gatewayv1.Namespace, defaultNamespace string) string {

internal/status/reconciler_listener_sets.go

@@ -2,7 +2,6 @@ package status
 
 import (
 	"context"
-	"fmt"
 
 	apiequality "k8s.io/apimachinery/pkg/api/equality"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
@@ -15,7 +14,7 @@ import (
 func (r *Reconciler) reconcileListenerSetStatuses(ctx context.Context, lses []gatewayv1.ListenerSet, evals map[string]listenerSetEvaluation) error {
 	for i := range lses {
 		key := client.ObjectKeyFromObject(&lses[i])
-		eval, ok := evals[fmt.Sprintf("%s/%s", lses[i].Namespace, lses[i].Name)]
+		eval, ok := evals[lses[i].Namespace+"/"+lses[i].Name]
 		if !ok {
 			continue
 		}

internal/translator/backend_tls.go

@@ -2,7 +2,6 @@ package translator
 
 import (
 	"crypto/tls"
-	"fmt"
 
 	corev1 "k8s.io/api/core/v1"
 	gatewayv1 "sigs.k8s.io/gateway-api/apis/v1"
@@ -69,7 +68,7 @@ func backendTLSForGatewayWithIndexes(
 	}
 
 	return &ir.BackendTLSConfig{
-		ClientCertificateRef: fmt.Sprintf("%s/%s", targetNamespace, ref.Name),
+		ClientCertificateRef: targetNamespace + "/" + string(ref.Name),
 	}
 }
 

internal/translator/backend_tls_policy.go

@@ -2,8 +2,8 @@ package translator
 
 import (
 	"crypto/x509"
-	"fmt"
 	"sort"
+	"strconv"
 
 	corev1 "k8s.io/api/core/v1"
 	gatewayv1 "sigs.k8s.io/gateway-api/apis/v1"
@@ -383,7 +383,7 @@ func serviceImportBackendKeys(
 }
 
 func backendClusterKey(namespace, name string, port int32) string {
-	return fmt.Sprintf("%s/%s:%d", namespace, name, port)
+	return namespace + "/" + name + ":" + strconv.Itoa(int(port))
 }
 
 func compactStrings(items []string) []string {

internal/translator/translator_listeners.go

@@ -2,7 +2,6 @@ package translator
 
 import (
 	"crypto/tls"
-	"fmt"
 	"net"
 	"sort"
 	"strings"
@@ -141,7 +140,7 @@ func listenerCertificateSecretRefsWithIndexes(
 			continue
 		}
 
-		key := fmt.Sprintf("%s/%s", targetNamespace, ref.Name)
+		key := targetNamespace + "/" + string(ref.Name)
 		if _, exists := seen[key]; exists {
 			continue
 		}