argo-cd/gitops-engine/pkg/cache/cluster_test.go

package cache

import (
	"context"
	"errors"
	"fmt"
	"sort"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/sync/semaphore"
	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"

	"github.com/google/uuid"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	extensionsv1beta1 "k8s.io/api/extensions/v1beta1"
	rbacv1 "k8s.io/api/rbac/v1"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/watch"
	"k8s.io/client-go/dynamic/fake"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/rest"
	testcore "k8s.io/client-go/testing"
	"sigs.k8s.io/yaml"

	"github.com/argoproj/argo-cd/gitops-engine/pkg/utils/kube"
	"github.com/argoproj/argo-cd/gitops-engine/pkg/utils/kube/kubetest"
)

func mustToUnstructured(obj any) *unstructured.Unstructured {
	un, err := kube.ToUnstructured(obj)
	if err != nil {
		panic(err)
	}
	return un
}

func strToUnstructured(jsonStr string) *unstructured.Unstructured {
	obj := make(map[string]any)
	err := yaml.Unmarshal([]byte(jsonStr), &obj)
	if err != nil {
		panic(err)
	}
	return &unstructured.Unstructured{Object: obj}
}

var (
	testCreationTime, _ = time.Parse(time.RFC3339, "2018-09-20T06:47:27Z")

	testService = strToUnstructured(fmt.Sprintf(`
  apiVersion: v1
  kind: Service
  metadata:
    name: helm-guestbook
    namespace: default
    resourceVersion: "123"
    uid: "4"
    creationTimestamp: "%s"
  spec:
    selector:
      app: guestbook
    type: LoadBalancer
  status:
    loadBalancer:
      ingress:
      - hostname: localhost`, testCreationTime.UTC().Format(time.RFC3339)))
)

func newCluster(tb testing.TB, objs ...runtime.Object) *clusterCache {
	tb.Helper()
	cache := newClusterWithOptions(tb, []UpdateSettingsFunc{}, objs...)

	tb.Cleanup(func() {
		cache.Invalidate()
	})

	return cache
}

func newClusterWithOptions(_ testing.TB, opts []UpdateSettingsFunc, objs ...runtime.Object) *clusterCache {
	client := fake.NewSimpleDynamicClient(scheme.Scheme, objs...)
	reactor := client.ReactionChain[0]
	client.PrependReactor("list", "*", func(action testcore.Action) (handled bool, ret runtime.Object, err error) {
		handled, ret, err = reactor.React(action)
		if err != nil || !handled {
			return handled, ret, fmt.Errorf("reactor failed: %w", err)
		}
		// make sure list response have resource version
		ret.(metav1.ListInterface).SetResourceVersion("123")
		return handled, ret, nil
	})

	apiResources := []kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Pod"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}, {
		GroupKind:            schema.GroupKind{Group: "apps", Kind: "ReplicaSet"},
		GroupVersionResource: schema.GroupVersionResource{Group: "apps", Version: "v1", Resource: "replicasets"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}, {
		GroupKind:            schema.GroupKind{Group: "apps", Kind: "Deployment"},
		GroupVersionResource: schema.GroupVersionResource{Group: "apps", Version: "v1", Resource: "deployments"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}, {
		GroupKind:            schema.GroupKind{Group: "apps", Kind: "StatefulSet"},
		GroupVersionResource: schema.GroupVersionResource{Group: "apps", Version: "v1", Resource: "statefulsets"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}, {
		GroupKind:            schema.GroupKind{Group: "extensions", Kind: "ReplicaSet"},
		GroupVersionResource: schema.GroupVersionResource{Group: "extensions", Version: "v1beta1", Resource: "replicasets"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}}

	opts = append([]UpdateSettingsFunc{
		SetKubectl(&kubetest.MockKubectlCmd{APIResources: apiResources, DynamicClient: client}),
	}, opts...)

	cache := NewClusterCache(
		&rest.Config{Host: "https://test"},
		opts...,
	)
	return cache
}

func (c *clusterCache) WithAPIResources(newApiResources []kube.APIResourceInfo) *clusterCache {
	apiResources := c.kubectl.(*kubetest.MockKubectlCmd).APIResources
	apiResources = append(apiResources, newApiResources...)
	c.kubectl.(*kubetest.MockKubectlCmd).APIResources = apiResources
	return c
}

func getChildren(cluster *clusterCache, un *unstructured.Unstructured) []*Resource {
	hierarchy := make([]*Resource, 0)
	cluster.IterateHierarchyV2([]kube.ResourceKey{kube.GetResourceKey(un)}, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
		hierarchy = append(hierarchy, child)
		return true
	})
	return hierarchy[1:]
}

// Benchmark_sync is meant to simulate cluster initialization when populateResourceInfoHandler does nontrivial work.
func Benchmark_sync(t *testing.B) {
	resources := []runtime.Object{}
	for i := 0; i < 100; i++ {
		resources = append(resources, &corev1.Pod{
			ObjectMeta: metav1.ObjectMeta{
				Name:      fmt.Sprintf("pod-%d", i),
				Namespace: "default",
			},
		}, &appsv1.ReplicaSet{
			ObjectMeta: metav1.ObjectMeta{
				Name:      fmt.Sprintf("rs-%d", i),
				Namespace: "default",
			},
		}, &appsv1.Deployment{
			ObjectMeta: metav1.ObjectMeta{
				Name:      fmt.Sprintf("deploy-%d", i),
				Namespace: "default",
			},
		}, &appsv1.StatefulSet{
			ObjectMeta: metav1.ObjectMeta{
				Name:      fmt.Sprintf("sts-%d", i),
				Namespace: "default",
			},
		})
	}

	c := newCluster(t, resources...)

	c.populateResourceInfoHandler = func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		time.Sleep(10 * time.Microsecond)
		return nil, false
	}

	t.ResetTimer()

	for n := 0; n < t.N; n++ {
		err := c.sync()
		require.NoError(t, err)
	}
}

// Benchmark_sync_CrossNamespace tests sync performance with cross-namespace relationships.
// This measures the one-time cost of building cross-namespace indexes during cache synchronization.
func Benchmark_sync_CrossNamespace(b *testing.B) {
	testCases := []struct {
		name                         string
		totalNamespaces              int
		resourcesPerNamespace        int
		namespacesWithCrossNS        int // Number of namespaces with cross-NS children
		crossNSResourcesPerNamespace int // Cross-NS children in each affected namespace
	}{
		// Baseline
		{"50NS_0pct_100perNS", 50, 100, 0, 0},

		// Primary dimension: Percentage of namespaces with cross-NS children
		{"50NS_2pct_100perNS", 50, 100, 1, 10},
		{"50NS_10pct_100perNS", 50, 100, 5, 10},
		{"50NS_20pct_100perNS", 50, 100, 10, 10},
	}

	for _, tc := range testCases {
		b.Run(tc.name, func(b *testing.B) {

			resources := []runtime.Object{}

			// Create cluster-scoped parents (ClusterRoles)
			numClusterParents := 100
			clusterUIDs := make(map[string]types.UID)
			for i := 0; i < numClusterParents; i++ {
				uid := types.UID(fmt.Sprintf("cluster-uid-%d", i))
				clusterUIDs[fmt.Sprintf("cluster-role-%d", i)] = uid
				resources = append(resources, &rbacv1.ClusterRole{
					ObjectMeta: metav1.ObjectMeta{
						Name: fmt.Sprintf("cluster-role-%d", i),
						UID:  uid,
					},
				})
			}

			// Create namespaced resources
			for ns := 0; ns < tc.totalNamespaces; ns++ {
				namespace := fmt.Sprintf("namespace-%d", ns)
				hasCrossNS := ns < tc.namespacesWithCrossNS
				regularPods := tc.resourcesPerNamespace
				crossNSPods := 0

				if hasCrossNS {
					regularPods = tc.resourcesPerNamespace - tc.crossNSResourcesPerNamespace
					crossNSPods = tc.crossNSResourcesPerNamespace
				}

				// Regular pods without cross-namespace parents
				for i := 0; i < regularPods; i++ {
					resources = append(resources, &corev1.Pod{
						ObjectMeta: metav1.ObjectMeta{
							Name:      fmt.Sprintf("pod-%d", i),
							Namespace: namespace,
							UID:       types.UID(fmt.Sprintf("pod-uid-%d-%d", ns, i)),
						},
					})
				}

				// Pods with cross-namespace parents
				for i := 0; i < crossNSPods; i++ {
					clusterRoleName := fmt.Sprintf("cluster-role-%d", i%numClusterParents)
					resources = append(resources, &corev1.Pod{
						ObjectMeta: metav1.ObjectMeta{
							Name:      fmt.Sprintf("cross-ns-pod-%d", i),
							Namespace: namespace,
							UID:       types.UID(fmt.Sprintf("cross-ns-pod-uid-%d-%d", ns, i)),
							OwnerReferences: []metav1.OwnerReference{{
								APIVersion: "rbac.authorization.k8s.io/v1",
								Kind:       "ClusterRole",
								Name:       clusterRoleName,
								UID:        clusterUIDs[clusterRoleName],
							}},
						},
					})
				}
			}

			// Need to add API resources for ClusterRole
			c := newCluster(b, resources...).WithAPIResources([]kube.APIResourceInfo{{
				GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
				GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
				Meta:                 metav1.APIResource{Namespaced: false},
			}})

			b.ResetTimer()
			b.ReportAllocs()

			for n := 0; n < b.N; n++ {
				err := c.sync()
				require.NoError(b, err)
			}
		})
	}
}

func TestEnsureSynced(t *testing.T) {
	obj1 := &appsv1.Deployment{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apps/v1",
			Kind:       "Deployment",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "helm-guestbook1",
			Namespace: "default1",
		},
	}
	obj2 := &appsv1.Deployment{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apps/v1",
			Kind:       "Deployment",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "helm-guestbook2",
			Namespace: "default2",
		},
	}

	cluster := newCluster(t, obj1, obj2)
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	cluster.lock.Lock()
	defer cluster.lock.Unlock()

	assert.Len(t, cluster.resources, 2)
	var names []string
	for k := range cluster.resources {
		names = append(names, k.Name)
	}
	assert.ElementsMatch(t, []string{"helm-guestbook1", "helm-guestbook2"}, names)
}

func TestStatefulSetOwnershipInferred(t *testing.T) {
	var opts []UpdateSettingsFunc
	opts = append(opts, func(c *clusterCache) {
		c.batchEventsProcessing = true
		c.eventProcessingInterval = 1 * time.Millisecond
	})

	sts := &appsv1.StatefulSet{
		TypeMeta:   metav1.TypeMeta{APIVersion: "apps/v1", Kind: kube.StatefulSetKind},
		ObjectMeta: metav1.ObjectMeta{UID: "123", Name: "web", Namespace: "default"},
		Spec: appsv1.StatefulSetSpec{
			VolumeClaimTemplates: []corev1.PersistentVolumeClaim{{
				ObjectMeta: metav1.ObjectMeta{
					Name: "www",
				},
			}},
		},
	}

	tests := []struct {
		name          string
		cluster       *clusterCache
		pvc           *corev1.PersistentVolumeClaim
		expectedRefs  []metav1.OwnerReference
		expectNoOwner bool
	}{
		{
			name:    "STSTemplateNameNotMatching",
			cluster: newCluster(t, sts),
			pvc: &corev1.PersistentVolumeClaim{
				TypeMeta:   metav1.TypeMeta{Kind: kube.PersistentVolumeClaimKind},
				ObjectMeta: metav1.ObjectMeta{Name: "www1-web-0", Namespace: "default"},
			},
			expectNoOwner: true,
		},
		{
			name:    "MatchingSTSExists",
			cluster: newCluster(t, sts),
			pvc: &corev1.PersistentVolumeClaim{
				TypeMeta:   metav1.TypeMeta{Kind: kube.PersistentVolumeClaimKind},
				ObjectMeta: metav1.ObjectMeta{Name: "www-web-0", Namespace: "default"},
			},
			expectedRefs: []metav1.OwnerReference{{APIVersion: "apps/v1", Kind: kube.StatefulSetKind, Name: "web", UID: "123"}},
		},
		{
			name:    "STSTemplateNameNotMatchingWithBatchProcessing",
			cluster: newClusterWithOptions(t, opts, sts),
			pvc: &corev1.PersistentVolumeClaim{
				TypeMeta:   metav1.TypeMeta{Kind: kube.PersistentVolumeClaimKind},
				ObjectMeta: metav1.ObjectMeta{Name: "www1-web-0", Namespace: "default"},
			},
			expectNoOwner: true,
		},
		{
			name:    "MatchingSTSExistsWithBatchProcessing",
			cluster: newClusterWithOptions(t, opts, sts),
			pvc: &corev1.PersistentVolumeClaim{
				TypeMeta:   metav1.TypeMeta{Kind: kube.PersistentVolumeClaimKind},
				ObjectMeta: metav1.ObjectMeta{Name: "www-web-0", Namespace: "default"},
			},
			expectedRefs: []metav1.OwnerReference{{APIVersion: "apps/v1", Kind: kube.StatefulSetKind, Name: "web", UID: "123"}},
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			err := tc.cluster.EnsureSynced()
			require.NoError(t, err)

			pvc := mustToUnstructured(tc.pvc)
			tc.cluster.recordEvent(watch.Added, pvc)

			require.Eventually(t, func() bool {
				tc.cluster.lock.Lock()
				defer tc.cluster.lock.Unlock()

				resource := tc.cluster.resources[kube.GetResourceKey(pvc)]
				if resource == nil {
					return false // Resource not ready yet, keep retrying
				}
				refs := resource.OwnerRefs
				if tc.expectNoOwner {
					return len(refs) == 0
				}
				return assert.ElementsMatch(t, refs, tc.expectedRefs)
			}, 5*time.Second, 20*time.Millisecond, "Expected PVC to have correct owner reference")
		})
	}
}

// TestStatefulSetPVC_ParentToChildrenIndex verifies that inferred StatefulSet → PVC
// relationships are correctly captured in the parentUIDToChildren index during initial sync.
//
// The index is updated inline when inferred owner refs are added in setNode()
// (see the inferred parent handling section in clusterCache.setNode).
func TestStatefulSetPVC_ParentToChildrenIndex(t *testing.T) {
	stsUID := types.UID("sts-uid-123")

	// StatefulSet with volumeClaimTemplate named "data"
	sts := &appsv1.StatefulSet{
		TypeMeta:   metav1.TypeMeta{APIVersion: "apps/v1", Kind: kube.StatefulSetKind},
		ObjectMeta: metav1.ObjectMeta{UID: stsUID, Name: "web", Namespace: "default"},
		Spec: appsv1.StatefulSetSpec{
			VolumeClaimTemplates: []corev1.PersistentVolumeClaim{{
				ObjectMeta: metav1.ObjectMeta{Name: "data"},
			}},
		},
	}

	// PVCs that match the StatefulSet's volumeClaimTemplate pattern: <template>-<sts>-<ordinal>
	// These have NO explicit owner references - the relationship is INFERRED
	pvc0 := &corev1.PersistentVolumeClaim{
		TypeMeta:   metav1.TypeMeta{APIVersion: "v1", Kind: kube.PersistentVolumeClaimKind},
		ObjectMeta: metav1.ObjectMeta{UID: "pvc-0-uid", Name: "data-web-0", Namespace: "default"},
	}
	pvc1 := &corev1.PersistentVolumeClaim{
		TypeMeta:   metav1.TypeMeta{APIVersion: "v1", Kind: kube.PersistentVolumeClaimKind},
		ObjectMeta: metav1.ObjectMeta{UID: "pvc-1-uid", Name: "data-web-1", Namespace: "default"},
	}

	// Create cluster with all resources
	// Must add PersistentVolumeClaim to API resources since it's not in the default set
	cluster := newCluster(t, sts, pvc0, pvc1).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: kube.PersistentVolumeClaimKind},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "persistentvolumeclaims"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	// Verify the parentUIDToChildren index contains the inferred relationships
	cluster.lock.RLock()
	defer cluster.lock.RUnlock()

	pvc0Key := kube.ResourceKey{Group: "", Kind: kube.PersistentVolumeClaimKind, Namespace: "default", Name: "data-web-0"}
	pvc1Key := kube.ResourceKey{Group: "", Kind: kube.PersistentVolumeClaimKind, Namespace: "default", Name: "data-web-1"}

	children, ok := cluster.parentUIDToChildren[stsUID]
	require.True(t, ok, "StatefulSet should have entry in parentUIDToChildren index")
	require.Contains(t, children, pvc0Key, "PVC data-web-0 should be in StatefulSet's children (inferred relationship)")
	require.Contains(t, children, pvc1Key, "PVC data-web-1 should be in StatefulSet's children (inferred relationship)")

	// Also verify the OwnerRefs were set correctly on the PVCs
	pvc0Resource := cluster.resources[pvc0Key]
	require.NotNil(t, pvc0Resource)
	require.Len(t, pvc0Resource.OwnerRefs, 1, "PVC0 should have inferred owner ref")
	require.Equal(t, stsUID, pvc0Resource.OwnerRefs[0].UID, "PVC0 owner should be the StatefulSet")

	pvc1Resource := cluster.resources[pvc1Key]
	require.NotNil(t, pvc1Resource)
	require.Len(t, pvc1Resource.OwnerRefs, 1, "PVC1 should have inferred owner ref")
	require.Equal(t, stsUID, pvc1Resource.OwnerRefs[0].UID, "PVC1 owner should be the StatefulSet")
}

// TestStatefulSetPVC_WatchEvent_IndexUpdated verifies that when a PVC is added
// via watch event (after initial sync), both the inferred owner reference AND
// the parentUIDToChildren index are updated correctly.
//
// This tests the inline index update logic in setNode() which updates the index
// immediately when inferred owner refs are added.
func TestStatefulSetPVC_WatchEvent_IndexUpdated(t *testing.T) {
	stsUID := types.UID("sts-uid-456")

	// StatefulSet with volumeClaimTemplate
	sts := &appsv1.StatefulSet{
		TypeMeta:   metav1.TypeMeta{APIVersion: "apps/v1", Kind: kube.StatefulSetKind},
		ObjectMeta: metav1.ObjectMeta{UID: stsUID, Name: "db", Namespace: "default"},
		Spec: appsv1.StatefulSetSpec{
			VolumeClaimTemplates: []corev1.PersistentVolumeClaim{{
				ObjectMeta: metav1.ObjectMeta{Name: "storage"},
			}},
		},
	}

	// Create cluster with ONLY the StatefulSet - PVC will be added via watch event
	cluster := newCluster(t, sts).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: kube.PersistentVolumeClaimKind},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "persistentvolumeclaims"},
		Meta:                 metav1.APIResource{Namespaced: true},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	// PVC that matches the StatefulSet's volumeClaimTemplate pattern
	// Added via watch event AFTER initial sync
	pvc := &corev1.PersistentVolumeClaim{
		TypeMeta:   metav1.TypeMeta{APIVersion: "v1", Kind: kube.PersistentVolumeClaimKind},
		ObjectMeta: metav1.ObjectMeta{UID: "pvc-watch-uid", Name: "storage-db-0", Namespace: "default"},
	}

	// Simulate watch event adding the PVC
	cluster.lock.Lock()
	cluster.setNode(cluster.newResource(mustToUnstructured(pvc)))
	cluster.lock.Unlock()

	cluster.lock.RLock()
	defer cluster.lock.RUnlock()

	pvcKey := kube.ResourceKey{Group: "", Kind: kube.PersistentVolumeClaimKind, Namespace: "default", Name: "storage-db-0"}

	// Verify the OwnerRef IS correctly set
	pvcResource := cluster.resources[pvcKey]
	require.NotNil(t, pvcResource, "PVC should exist in cache")
	require.Len(t, pvcResource.OwnerRefs, 1, "PVC should have inferred owner ref from StatefulSet")
	require.Equal(t, stsUID, pvcResource.OwnerRefs[0].UID, "Owner should be the StatefulSet")

	// Verify the index IS updated for inferred refs via watch events
	children, indexUpdated := cluster.parentUIDToChildren[stsUID]
	require.True(t, indexUpdated, "Index should be updated when inferred refs are added via watch events")
	require.Contains(t, children, pvcKey, "PVC should be in StatefulSet's children (inferred relationship)")
}

func TestEnsureSyncedSingleNamespace(t *testing.T) {
	obj1 := &appsv1.Deployment{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apps/v1",
			Kind:       "Deployment",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "helm-guestbook1",
			Namespace: "default1",
		},
	}
	obj2 := &appsv1.Deployment{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apps/v1",
			Kind:       "Deployment",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:      "helm-guestbook2",
			Namespace: "default2",
		},
	}

	cluster := newCluster(t, obj1, obj2)
	cluster.namespaces = []string{"default1"}
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	cluster.lock.Lock()
	defer cluster.lock.Unlock()

	assert.Len(t, cluster.resources, 1)
	var names []string
	for k := range cluster.resources {
		names = append(names, k.Name)
	}
	assert.ElementsMatch(t, []string{"helm-guestbook1"}, names)
}

func TestGetChildren(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	rsChildren := getChildren(cluster, mustToUnstructured(testRS()))
	assert.Equal(t, []*Resource{{
		Ref: corev1.ObjectReference{
			Kind:       "Pod",
			Namespace:  "default",
			Name:       "helm-guestbook-pod-1",
			APIVersion: "v1",
			UID:        "1",
		},
		OwnerRefs: []metav1.OwnerReference{{
			APIVersion: "apps/v1",
			Kind:       "ReplicaSet",
			Name:       "helm-guestbook-rs",
			UID:        "2",
		}},
		ResourceVersion: "123",
		CreationTimestamp: &metav1.Time{
			Time: testCreationTime.Local(),
		},
	}}, rsChildren)
	deployChildren := getChildren(cluster, mustToUnstructured(testDeploy()))

	assert.Equal(t, append([]*Resource{{
		Ref: corev1.ObjectReference{
			Kind:       "ReplicaSet",
			Namespace:  "default",
			Name:       "helm-guestbook-rs",
			APIVersion: "apps/v1",
			UID:        "2",
		},
		ResourceVersion: "123",
		OwnerRefs:       []metav1.OwnerReference{{APIVersion: "apps/v1beta1", Kind: "Deployment", Name: "helm-guestbook", UID: "3"}},
		CreationTimestamp: &metav1.Time{
			Time: testCreationTime.Local(),
		},
	}}, rsChildren...), deployChildren)
}

func TestGetManagedLiveObjs(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		return nil, true
	}))

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	targetDeploy := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  labels:
    app: helm-guestbook`)

	managedObjs, err := cluster.GetManagedLiveObjs([]*unstructured.Unstructured{targetDeploy}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	require.NoError(t, err)
	assert.Equal(t, map[kube.ResourceKey]*unstructured.Unstructured{
		kube.NewResourceKey("apps", "Deployment", "default", "helm-guestbook"): mustToUnstructured(testDeploy()),
	}, managedObjs)
}

func TestGetManagedLiveObjsNamespacedModeClusterLevelResource(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		return nil, true
	}))
	cluster.namespaces = []string{"default", "production"}

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	targetDeploy := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  labels:
    app: helm-guestbook`)

	managedObjs, err := cluster.GetManagedLiveObjs([]*unstructured.Unstructured{targetDeploy}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	assert.Nil(t, managedObjs)
	assert.EqualError(t, err, "cluster level Deployment \"helm-guestbook\" can not be managed when in namespaced mode")
}

func TestGetManagedLiveObjsNamespacedModeClusterLevelResource_ClusterResourceEnabled(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		return nil, true
	}))
	cluster.namespaces = []string{"default", "production"}
	cluster.clusterResources = true

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	clusterLevelRes := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  labels:
    app: helm-guestbook`)

	cluster.clusterResources = true
	_, err = cluster.GetManagedLiveObjs([]*unstructured.Unstructured{clusterLevelRes}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	require.NoError(t, err)

	otherNamespaceRes := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  namespace: some-other-namespace
  labels:
    app: helm-guestbook`)

	cluster.clusterResources = true
	_, err = cluster.GetManagedLiveObjs([]*unstructured.Unstructured{otherNamespaceRes}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	assert.EqualError(t, err, "namespace \"some-other-namespace\" for Deployment \"helm-guestbook\" is not managed")
}

func TestGetManagedLiveObjsAllNamespaces(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		return nil, true
	}))
	cluster.namespaces = nil

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	targetDeploy := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  namespace: production
  labels:
    app: helm-guestbook`)

	managedObjs, err := cluster.GetManagedLiveObjs([]*unstructured.Unstructured{targetDeploy}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	require.NoError(t, err)
	assert.Equal(t, map[kube.ResourceKey]*unstructured.Unstructured{
		kube.NewResourceKey("apps", "Deployment", "default", "helm-guestbook"): mustToUnstructured(testDeploy()),
	}, managedObjs)
}

func TestGetManagedLiveObjsValidNamespace(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		return nil, true
	}))
	cluster.namespaces = []string{"default", "production"}

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	targetDeploy := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  namespace: production
  labels:
    app: helm-guestbook`)

	managedObjs, err := cluster.GetManagedLiveObjs([]*unstructured.Unstructured{targetDeploy}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	require.NoError(t, err)
	assert.Equal(t, map[kube.ResourceKey]*unstructured.Unstructured{
		kube.NewResourceKey("apps", "Deployment", "default", "helm-guestbook"): mustToUnstructured(testDeploy()),
	}, managedObjs)
}

func TestGetManagedLiveObjsInvalidNamespace(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
		return nil, true
	}))
	cluster.namespaces = []string{"default", "develop"}

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	targetDeploy := strToUnstructured(`
apiVersion: apps/v1
kind: Deployment
metadata:
  name: helm-guestbook
  namespace: production
  labels:
    app: helm-guestbook`)

	managedObjs, err := cluster.GetManagedLiveObjs([]*unstructured.Unstructured{targetDeploy}, func(r *Resource) bool {
		return len(r.OwnerRefs) == 0
	})
	assert.Nil(t, managedObjs)
	assert.EqualError(t, err, "namespace \"production\" for Deployment \"helm-guestbook\" is not managed")
}

func TestGetManagedLiveObjsFailedConversion(t *testing.T) {
	cronTabGroup := "stable.example.com"

	testCases := []struct {
		name                         string
		localConvertFails            bool
		expectConvertToVersionCalled bool
		expectGetResourceCalled      bool
	}{
		{
			name:                         "local convert fails, so GetResource is called",
			localConvertFails:            true,
			expectConvertToVersionCalled: true,
			expectGetResourceCalled:      true,
		},
		{
			name:                         "local convert succeeds, so GetResource is not called",
			localConvertFails:            false,
			expectConvertToVersionCalled: true,
			expectGetResourceCalled:      false,
		},
	}

	for _, testCase := range testCases {
		testCaseCopy := testCase
		t.Run(testCaseCopy.name, func(t *testing.T) {
			err := apiextensions.AddToScheme(scheme.Scheme)
			require.NoError(t, err)
			cluster := newCluster(t, testCRD(), testCronTab()).
				WithAPIResources([]kube.APIResourceInfo{
					{
						GroupKind:            schema.GroupKind{Group: cronTabGroup, Kind: "CronTab"},
						GroupVersionResource: schema.GroupVersionResource{Group: cronTabGroup, Version: "v1", Resource: "crontabs"},
						Meta:                 metav1.APIResource{Namespaced: true},
					},
				})
			cluster.Invalidate(SetPopulateResourceInfoHandler(func(_ *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
				return nil, true
			}))
			cluster.namespaces = []string{"default"}

			err = cluster.EnsureSynced()
			require.NoError(t, err)

			targetDeploy := strToUnstructured(`
apiVersion: stable.example.com/v1
kind: CronTab
metadata:
  name: test-crontab
  namespace: default`)

			convertToVersionWasCalled := false
			getResourceWasCalled := false
			cluster.kubectl.(*kubetest.MockKubectlCmd).
				WithConvertToVersionFunc(func(obj *unstructured.Unstructured, _ string, _ string) (*unstructured.Unstructured, error) {
					convertToVersionWasCalled = true

					if testCaseCopy.localConvertFails {
						return nil, errors.New("failed to convert resource client-side")
					}

					return obj, nil
				}).
				WithGetResourceFunc(func(_ context.Context, _ *rest.Config, _ schema.GroupVersionKind, _ string, _ string) (*unstructured.Unstructured, error) {
					getResourceWasCalled = true
					return testCronTab(), nil
				})

			managedObjs, err := cluster.GetManagedLiveObjs([]*unstructured.Unstructured{targetDeploy}, func(_ *Resource) bool {
				return true
			})
			require.NoError(t, err)
			assert.Equal(t, testCaseCopy.expectConvertToVersionCalled, convertToVersionWasCalled)
			assert.Equal(t, testCaseCopy.expectGetResourceCalled, getResourceWasCalled)
			assert.Equal(t, map[kube.ResourceKey]*unstructured.Unstructured{
				kube.NewResourceKey(cronTabGroup, "CronTab", "default", "test-crontab"): mustToUnstructured(testCronTab()),
			}, managedObjs)
		})
	}
}

func TestChildDeletedEvent(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	cluster.recordEvent(watch.Deleted, mustToUnstructured(testPod1()))

	rsChildren := getChildren(cluster, mustToUnstructured(testRS()))
	assert.Equal(t, []*Resource{}, rsChildren)
}

func TestProcessNewChildEvent(t *testing.T) {
	cluster := newCluster(t, testPod1(), testRS(), testDeploy())
	err := cluster.EnsureSynced()
	require.NoError(t, err)
	newPod := strToUnstructured(`
  apiVersion: v1
  kind: Pod
  metadata:
    uid: "5"
    name: helm-guestbook-pod-1-new
    namespace: default
    ownerReferences:
    - apiVersion: apps/v1
      kind: ReplicaSet
      name: helm-guestbook-rs
      uid: "2"
    resourceVersion: "123"`)

	cluster.recordEvent(watch.Added, newPod)

	rsChildren := getChildren(cluster, mustToUnstructured(testRS()))
	sort.Slice(rsChildren, func(i, j int) bool {
		return strings.Compare(rsChildren[i].Ref.Name, rsChildren[j].Ref.Name) < 0
	})
	assert.Equal(t, []*Resource{{
		Ref: corev1.ObjectReference{
			Kind:       "Pod",
			Namespace:  "default",
			Name:       "helm-guestbook-pod-1",
			APIVersion: "v1",
			UID:        "1",
		},
		OwnerRefs: []metav1.OwnerReference{{
			APIVersion: "apps/v1",
			Kind:       "ReplicaSet",
			Name:       "helm-guestbook-rs",
			UID:        "2",
		}},
		ResourceVersion: "123",
		CreationTimestamp: &metav1.Time{
			Time: testCreationTime.Local(),
		},
	}, {
		Ref: corev1.ObjectReference{
			Kind:       "Pod",
			Namespace:  "default",
			Name:       "helm-guestbook-pod-1-new",
			APIVersion: "v1",
			UID:        "5",
		},
		OwnerRefs: []metav1.OwnerReference{{
			APIVersion: "apps/v1",
			Kind:       "ReplicaSet",
			Name:       "helm-guestbook-rs",
			UID:        "2",
		}},
		ResourceVersion: "123",
	}}, rsChildren)
}

func TestWatchCacheUpdated(t *testing.T) {
	removed := testPod1()
	removed.SetName(removed.GetName() + "-removed-pod")

	updated := testPod1()
	updated.SetName(updated.GetName() + "-updated-pod")
	updated.SetResourceVersion("updated-pod-version")

	cluster := newCluster(t, removed, updated)
	err := cluster.EnsureSynced()

	require.NoError(t, err)

	added := testPod1()
	added.SetName(added.GetName() + "-new-pod")

	podGroupKind := testPod1().GroupVersionKind().GroupKind()

	cluster.lock.Lock()
	defer cluster.lock.Unlock()
	cluster.replaceResourceCache(podGroupKind, []*Resource{cluster.newResource(mustToUnstructured(updated)), cluster.newResource(mustToUnstructured(added))}, "")

	_, ok := cluster.resources[getResourceKey(t, removed)]
	assert.False(t, ok)
}

func TestNamespaceModeReplace(t *testing.T) {
	ns1Pod := testPod1()
	ns1Pod.SetNamespace("ns1")
	ns1Pod.SetName("pod1")

	ns2Pod := testPod1()
	ns2Pod.SetNamespace("ns2")
	podGroupKind := testPod1().GroupVersionKind().GroupKind()

	cluster := newCluster(t, ns1Pod, ns2Pod)
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	cluster.lock.Lock()
	defer cluster.lock.Unlock()

	cluster.replaceResourceCache(podGroupKind, nil, "ns1")

	_, ok := cluster.resources[getResourceKey(t, ns1Pod)]
	assert.False(t, ok)

	_, ok = cluster.resources[getResourceKey(t, ns2Pod)]
	assert.True(t, ok)
}

func TestGetDuplicatedChildren(t *testing.T) {
	extensionsRS := testExtensionsRS()
	cluster := newCluster(t, testDeploy(), testRS(), extensionsRS)
	err := cluster.EnsureSynced()

	require.NoError(t, err)

	// Get children multiple times to make sure the right child is picked up every time.
	for i := 0; i < 5; i++ {
		children := getChildren(cluster, mustToUnstructured(testDeploy()))
		assert.Len(t, children, 1)
		assert.Equal(t, "apps/v1", children[0].Ref.APIVersion)
		assert.Equal(t, kube.ReplicaSetKind, children[0].Ref.Kind)
		assert.Equal(t, testRS().GetName(), children[0].Ref.Name)
	}
}

func TestGetClusterInfo(t *testing.T) {
	cluster := newCluster(t)
	cluster.apiResources = []kube.APIResourceInfo{{GroupKind: schema.GroupKind{Group: "test", Kind: "test kind"}}}
	cluster.serverVersion = "v1.16"
	info := cluster.GetClusterInfo()
	assert.Equal(t, ClusterInfo{
		Server:       cluster.config.Host,
		APIResources: cluster.apiResources,
		K8SVersion:   cluster.serverVersion,
	}, info)
}

func TestDeleteAPIResource(t *testing.T) {
	cluster := newCluster(t)
	cluster.apiResources = []kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "test", Kind: "test kind"},
		GroupVersionResource: schema.GroupVersionResource{Version: "v1"},
	}}

	cluster.deleteAPIResource(kube.APIResourceInfo{GroupKind: schema.GroupKind{Group: "wrong group", Kind: "wrong kind"}})
	assert.Len(t, cluster.apiResources, 1)
	cluster.deleteAPIResource(kube.APIResourceInfo{
		GroupKind:            schema.GroupKind{Group: "test", Kind: "test kind"},
		GroupVersionResource: schema.GroupVersionResource{Version: "wrong version"},
	})
	assert.Len(t, cluster.apiResources, 1)

	cluster.deleteAPIResource(kube.APIResourceInfo{
		GroupKind:            schema.GroupKind{Group: "test", Kind: "test kind"},
		GroupVersionResource: schema.GroupVersionResource{Version: "v1"},
	})
	assert.Empty(t, cluster.apiResources)
}

func TestAppendAPIResource(t *testing.T) {
	cluster := newCluster(t)

	resourceInfo := kube.APIResourceInfo{
		GroupKind:            schema.GroupKind{Group: "test", Kind: "test kind"},
		GroupVersionResource: schema.GroupVersionResource{Version: "v1"},
	}

	cluster.appendAPIResource(resourceInfo)
	assert.ElementsMatch(t, []kube.APIResourceInfo{resourceInfo}, cluster.apiResources)

	// make sure same group, kind version is not added twice
	cluster.appendAPIResource(resourceInfo)
	assert.ElementsMatch(t, []kube.APIResourceInfo{resourceInfo}, cluster.apiResources)
}

func ExampleNewClusterCache_resourceUpdatedEvents() {
	// kubernetes cluster config here
	config := &rest.Config{}

	clusterCache := NewClusterCache(config)
	// Ensure cluster is synced before using it
	if err := clusterCache.EnsureSynced(); err != nil {
		panic(err)
	}
	unsubscribe := clusterCache.OnResourceUpdated(func(newRes *Resource, oldRes *Resource, _ map[kube.ResourceKey]*Resource) {
		switch {
		case newRes == nil:
			fmt.Printf("%s deleted\n", oldRes.Ref.String())
		case oldRes == nil:
			fmt.Printf("%s created\n", newRes.Ref.String())
		default:
			fmt.Printf("%s updated\n", newRes.Ref.String())
		}
	})
	defer unsubscribe()
	// observe resource modifications for 1 minute
	time.Sleep(time.Minute)
}

func getResourceKey(t *testing.T, obj runtime.Object) kube.ResourceKey {
	t.Helper()
	gvk := obj.GetObjectKind().GroupVersionKind()
	m, err := meta.Accessor(obj)
	require.NoError(t, err)
	return kube.NewResourceKey(gvk.Group, gvk.Kind, m.GetNamespace(), m.GetName())
}

func testPod1() *corev1.Pod {
	return &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:              "helm-guestbook-pod-1",
			Namespace:         "default",
			UID:               "1",
			ResourceVersion:   "123",
			CreationTimestamp: metav1.NewTime(testCreationTime),
			OwnerReferences: []metav1.OwnerReference{
				{
					APIVersion: "apps/v1",
					Kind:       "ReplicaSet",
					Name:       "helm-guestbook-rs",
					UID:        "2",
				},
			},
		},
	}
}

// Similar to pod1, but owner reference lacks uid
func testPod2() *corev1.Pod {
	return &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:              "helm-guestbook-pod-2",
			Namespace:         "default",
			UID:               "4",
			ResourceVersion:   "123",
			CreationTimestamp: metav1.NewTime(testCreationTime),
			OwnerReferences: []metav1.OwnerReference{
				{
					APIVersion: "apps/v1",
					Kind:       "ReplicaSet",
					Name:       "helm-guestbook-rs",
				},
			},
		},
	}
}

func testCRD() *apiextensions.CustomResourceDefinition {
	return &apiextensions.CustomResourceDefinition{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apiextensions.k8s.io/v1",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name: "crontabs.stable.example.com",
		},
		Spec: apiextensions.CustomResourceDefinitionSpec{
			Group: "stable.example.com",
			Versions: []apiextensions.CustomResourceDefinitionVersion{
				{
					Name:    "v1",
					Served:  true,
					Storage: true,
					Schema: &apiextensions.CustomResourceValidation{
						OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
							Type: "object",
							Properties: map[string]apiextensions.JSONSchemaProps{
								"cronSpec": {Type: "string"},
								"image":    {Type: "string"},
								"replicas": {Type: "integer"},
							},
						},
					},
				},
			},
			Scope: "Namespaced",
			Names: apiextensions.CustomResourceDefinitionNames{
				Plural:     "crontabs",
				Singular:   "crontab",
				ShortNames: []string{"ct"},
				Kind:       "CronTab",
			},
		},
	}
}

func testCronTab() *unstructured.Unstructured {
	return &unstructured.Unstructured{Object: map[string]any{
		"apiVersion": "stable.example.com/v1",
		"kind":       "CronTab",
		"metadata": map[string]any{
			"name":      "test-crontab",
			"namespace": "default",
		},
		"spec": map[string]any{
			"cronSpec": "* * * * */5",
			"image":    "my-awesome-cron-image",
		},
	}}
}

func testExtensionsRS() *extensionsv1beta1.ReplicaSet {
	return &extensionsv1beta1.ReplicaSet{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "extensions/v1beta1",
			Kind:       "ReplicaSet",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:              "helm-guestbook-rs",
			Namespace:         "default",
			UID:               "2",
			ResourceVersion:   "123",
			CreationTimestamp: metav1.NewTime(testCreationTime),
			Annotations: map[string]string{
				"deployment.kubernetes.io/revision": "2",
			},
			OwnerReferences: []metav1.OwnerReference{
				{
					APIVersion: "apps/v1beta1",
					Kind:       "Deployment",
					Name:       "helm-guestbook",
					UID:        "3",
				},
			},
		},
	}
}

func testRS() *appsv1.ReplicaSet {
	return &appsv1.ReplicaSet{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apps/v1",
			Kind:       "ReplicaSet",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:              "helm-guestbook-rs",
			Namespace:         "default",
			UID:               "2",
			ResourceVersion:   "123",
			CreationTimestamp: metav1.NewTime(testCreationTime),
			Annotations: map[string]string{
				"deployment.kubernetes.io/revision": "2",
			},
			OwnerReferences: []metav1.OwnerReference{
				{
					APIVersion: "apps/v1beta1",
					Kind:       "Deployment",
					Name:       "helm-guestbook",
					UID:        "3",
				},
			},
		},
		Spec:   appsv1.ReplicaSetSpec{},
		Status: appsv1.ReplicaSetStatus{},
	}
}

func testDeploy() *appsv1.Deployment {
	return &appsv1.Deployment{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "apps/v1",
			Kind:       "Deployment",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:              "helm-guestbook",
			Namespace:         "default",
			UID:               "3",
			ResourceVersion:   "123",
			CreationTimestamp: metav1.NewTime(testCreationTime),
			Labels: map[string]string{
				"app.kubernetes.io/instance": "helm-guestbook",
			},
		},
	}
}

func TestIterateHierarchyV2(t *testing.T) {
	cluster := newCluster(t, testPod1(), testPod2(), testRS(), testExtensionsRS(), testDeploy())
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	t.Run("IterateAll", func(t *testing.T) {
		startKeys := []kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(testDeploy()))}
		keys := []kube.ResourceKey{}
		cluster.IterateHierarchyV2(startKeys, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, child.ResourceKey())
			return true
		})

		assert.ElementsMatch(t,
			[]kube.ResourceKey{
				kube.GetResourceKey(mustToUnstructured(testPod1())),
				kube.GetResourceKey(mustToUnstructured(testPod2())),
				kube.GetResourceKey(mustToUnstructured(testRS())),
				kube.GetResourceKey(mustToUnstructured(testDeploy())),
			},
			keys)
	})

	t.Run("ExitAtRoot", func(t *testing.T) {
		startKeys := []kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(testDeploy()))}
		keys := []kube.ResourceKey{}
		cluster.IterateHierarchyV2(startKeys, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, child.ResourceKey())
			return false
		})

		assert.ElementsMatch(t,
			[]kube.ResourceKey{
				kube.GetResourceKey(mustToUnstructured(testDeploy())),
			},
			keys)
	})

	t.Run("ExitAtSecondLevelChild", func(t *testing.T) {
		startKeys := []kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(testDeploy()))}
		keys := []kube.ResourceKey{}
		cluster.IterateHierarchyV2(startKeys, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, child.ResourceKey())
			return child.ResourceKey().Kind != kube.ReplicaSetKind
		})

		assert.ElementsMatch(t,
			[]kube.ResourceKey{
				kube.GetResourceKey(mustToUnstructured(testDeploy())),
				kube.GetResourceKey(mustToUnstructured(testRS())),
			},
			keys)
	})

	t.Run("ExitAtThirdLevelChild", func(t *testing.T) {
		startKeys := []kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(testDeploy()))}
		keys := []kube.ResourceKey{}
		cluster.IterateHierarchyV2(startKeys, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, child.ResourceKey())
			return child.ResourceKey().Kind != kube.PodKind
		})

		assert.ElementsMatch(t,
			[]kube.ResourceKey{
				kube.GetResourceKey(mustToUnstructured(testDeploy())),
				kube.GetResourceKey(mustToUnstructured(testRS())),
				kube.GetResourceKey(mustToUnstructured(testPod1())),
				kube.GetResourceKey(mustToUnstructured(testPod2())),
			},
			keys)
	})

	t.Run("IterateAllStartFromMultiple", func(t *testing.T) {
		startKeys := []kube.ResourceKey{
			kube.GetResourceKey(mustToUnstructured(testRS())),
			kube.GetResourceKey(mustToUnstructured(testDeploy())),
		}
		keys := []kube.ResourceKey{}
		cluster.IterateHierarchyV2(startKeys, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, child.ResourceKey())
			return true
		})

		assert.ElementsMatch(t,
			[]kube.ResourceKey{
				kube.GetResourceKey(mustToUnstructured(testPod1())),
				kube.GetResourceKey(mustToUnstructured(testPod2())),
				kube.GetResourceKey(mustToUnstructured(testRS())),
				kube.GetResourceKey(mustToUnstructured(testDeploy())),
			},
			keys)
	})

	// After uid is backfilled for owner of pod2, it should appear in results here as well.
	t.Run("IterateStartFromExtensionsRS", func(t *testing.T) {
		startKeys := []kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(testExtensionsRS()))}
		keys := []kube.ResourceKey{}
		cluster.IterateHierarchyV2(startKeys, func(child *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, child.ResourceKey())
			return true
		})

		assert.ElementsMatch(t,
			[]kube.ResourceKey{
				kube.GetResourceKey(mustToUnstructured(testPod1())),
				kube.GetResourceKey(mustToUnstructured(testPod2())),
				kube.GetResourceKey(mustToUnstructured(testExtensionsRS())),
			},
			keys)
	})
}

func testClusterParent() *corev1.Namespace {
	return &corev1.Namespace{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Namespace",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "test-cluster-parent",
			UID:             "cluster-parent-123",
			ResourceVersion: "123",
		},
	}
}

func testNamespacedChild() *corev1.Pod {
	return &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "namespaced-child",
			Namespace:       "test-namespace",
			UID:             "namespaced-child-456",
			ResourceVersion: "123",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "test-cluster-parent",
				UID:        "cluster-parent-123",
			}},
		},
	}
}

func testClusterChild() *rbacv1.ClusterRole {
	return &rbacv1.ClusterRole{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "rbac.authorization.k8s.io/v1",
			Kind:       "ClusterRole",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "cluster-child",
			UID:             "cluster-child-789",
			ResourceVersion: "123",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "test-cluster-parent",
				UID:        "cluster-parent-123",
			}},
		},
	}
}


func TestIterateHierarchyV2_ClusterScopedParent_FindsAllChildren(t *testing.T) {
	// Test that cluster-scoped parents automatically find all their children (both cluster-scoped and namespaced)
	// This is the core behavior of the new implementation - cross-namespace relationships are always tracked
	cluster := newCluster(t, testClusterParent(), testNamespacedChild(), testClusterChild()).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}, {
		GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
		GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	keys := []kube.ResourceKey{}
	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(testClusterParent()))},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, resource.ResourceKey())
			return true
		},
	)

	// Should find the parent and all its children (both cluster-scoped and namespaced)
	expected := []kube.ResourceKey{
		kube.GetResourceKey(mustToUnstructured(testClusterParent())),
		kube.GetResourceKey(mustToUnstructured(testClusterChild())),
		kube.GetResourceKey(mustToUnstructured(testNamespacedChild())),
	}
	assert.ElementsMatch(t, expected, keys)
}

func TestIterateHierarchyV2_MultiLevelClusterScoped_FindsNamespacedGrandchildren(t *testing.T) {
	// Test 3-level hierarchy: ClusterScoped -> ClusterScoped -> Namespaced
	// This test the scenario where:
	//   Provider (managed) -> ProviderRevision (dynamic) -> Deployment (namespaced)
	// The namespaced grandchildren should be found even when only the root is passed as a key.

	// Level 1: Cluster-scoped parent (like Provider - this is the "managed" resource)
	clusterParent := &corev1.Namespace{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Namespace",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "root-cluster-parent",
			UID:             "root-parent-uid",
			ResourceVersion: "1",
		},
	}

	// Level 2: Cluster-scoped intermediate (like ProviderRevision - dynamically created, NOT managed)
	clusterIntermediate := &rbacv1.ClusterRole{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "rbac.authorization.k8s.io/v1",
			Kind:       "ClusterRole",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "intermediate-cluster-child",
			UID:             "intermediate-uid",
			ResourceVersion: "1",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "root-cluster-parent",
				UID:        "root-parent-uid",
			}},
		},
	}

	// Level 3: Namespaced grandchild (like Deployment owned by ProviderRevision)
	namespacedGrandchild := &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "namespaced-grandchild",
			Namespace:       "some-namespace",
			UID:             "grandchild-uid",
			ResourceVersion: "1",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "rbac.authorization.k8s.io/v1",
				Kind:       "ClusterRole",
				Name:       "intermediate-cluster-child",
				UID:        "intermediate-uid",
			}},
		},
	}

	cluster := newCluster(t, clusterParent, clusterIntermediate, namespacedGrandchild).WithAPIResources([]kube.APIResourceInfo{
		{
			GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
			GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
			Meta:                 metav1.APIResource{Namespaced: false},
		},
		{
			GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
			GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
			Meta:                 metav1.APIResource{Namespaced: false},
		},
	})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	// Only pass the root cluster-scoped parent as a key (simulating managed resources)
	// The intermediate and grandchild should be discovered through traversal
	keys := []kube.ResourceKey{}
	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(clusterParent))},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, resource.ResourceKey())
			return true
		},
	)

	// Should find all 3 levels: parent, intermediate, AND the namespaced grandchild
	expected := []kube.ResourceKey{
		kube.GetResourceKey(mustToUnstructured(clusterParent)),
		kube.GetResourceKey(mustToUnstructured(clusterIntermediate)),
		kube.GetResourceKey(mustToUnstructured(namespacedGrandchild)), // This is the bug - currently NOT found
	}
	assert.ElementsMatch(t, expected, keys)
}

func TestIterateHierarchyV2_ClusterScopedParentOnly_InferredUID(t *testing.T) {
	// Test that passing only a cluster-scoped parent finds children even with inferred UIDs.
	// This should never happen but we coded defensively for this case, and at worst it would link a child
	// to the wrong parent if there were multiple parents with the same name (i.e. deleted and recreated).
	namespacedChildNoUID := &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "namespaced-child-no-uid",
			Namespace:       "test-namespace",
			UID:             "namespaced-child-789",
			ResourceVersion: "123",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "test-cluster-parent",
				// Note: No UID here - will need to be inferred
			}},
		},
	}

	cluster := newCluster(t, testClusterParent(), namespacedChildNoUID, testClusterChild()).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}, {
		GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
		GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	keys := []kube.ResourceKey{}
	// Test with all namespaces - need to pass both cluster parent and namespaced children
	// as explicit keys to find them all
	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{
			kube.GetResourceKey(mustToUnstructured(testClusterParent())),
			kube.GetResourceKey(mustToUnstructured(namespacedChildNoUID)),
		},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			keys = append(keys, resource.ResourceKey())
			return true
		},
	)

	// Should find the parent and all its children, even with inferred UID
	assert.ElementsMatch(t, []kube.ResourceKey{
		kube.GetResourceKey(mustToUnstructured(testClusterParent())),
		kube.GetResourceKey(mustToUnstructured(namespacedChildNoUID)),
		kube.GetResourceKey(mustToUnstructured(testClusterChild())),
	}, keys)
}

func TestOrphanedChildrenCleanup(t *testing.T) {
	// Test that parent-to-children index is properly cleaned up when resources are deleted
	clusterParent := testClusterParent()
	namespacedChild := testNamespacedChild()

	cluster := newCluster(t, clusterParent, namespacedChild).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	// Verify child is tracked in parentUIDToChildren index
	cluster.lock.RLock()
	childKey := kube.GetResourceKey(mustToUnstructured(namespacedChild))
	parentUID := clusterParent.GetUID()

	// Check that the child is in parentUIDToChildren
	children, ok := cluster.parentUIDToChildren[parentUID]
	require.True(t, ok, "parent should have entry in parentUIDToChildren")
	require.Contains(t, children, childKey, "child should be in parent's children list")
	cluster.lock.RUnlock()

	// Delete the child
	cluster.lock.Lock()
	cluster.onNodeRemoved(childKey)
	cluster.lock.Unlock()

	// Verify cleanup: child removed from parentUIDToChildren
	cluster.lock.RLock()
	children, ok = cluster.parentUIDToChildren[parentUID]
	if ok {
		assert.NotContains(t, children, childKey, "child should be removed from parent's children list")
	}
	cluster.lock.RUnlock()

	// Re-add the child and verify it re-populates correctly
	cluster.lock.Lock()
	cluster.setNode(cluster.newResource(mustToUnstructured(namespacedChild)))
	cluster.lock.Unlock()

	cluster.lock.RLock()
	children, ok = cluster.parentUIDToChildren[parentUID]
	require.True(t, ok, "parent should be back in parentUIDToChildren")
	require.Contains(t, children, childKey, "child should be back in parent's children list")
	cluster.lock.RUnlock()
}

func TestOrphanedChildrenIndex_OwnerRefLifecycle(t *testing.T) {
	// Test realistic scenarios of owner references being added and removed
	clusterParent := testClusterParent()

	// Start with a child that has NO owner reference
	childNoOwner := &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "child-no-owner",
			Namespace:       "test-namespace",
			UID:             "child-uid-123",
			ResourceVersion: "1",
			// No OwnerReferences
		},
	}

	cluster := newCluster(t, clusterParent, childNoOwner).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	childKey := kube.GetResourceKey(mustToUnstructured(childNoOwner))
	parentUID := clusterParent.GetUID()

	// Verify child is NOT tracked initially (no owner ref)
	cluster.lock.RLock()
	children, ok := cluster.parentUIDToChildren[parentUID]
	if ok {
		assert.NotContains(t, children, childKey, "child without owner ref should not be in parentUIDToChildren")
	}
	cluster.lock.RUnlock()

	// Simulate controller adding owner reference (e.g., adoption)
	childWithOwner := &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "child-no-owner",
			Namespace:       "test-namespace",
			UID:             "child-uid-123",
			ResourceVersion: "2",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "test-cluster-parent",
				UID:        "cluster-parent-123",
			}},
		},
	}

	cluster.lock.Lock()
	cluster.setNode(cluster.newResource(mustToUnstructured(childWithOwner)))
	cluster.lock.Unlock()

	// Verify child is NOW tracked (owner ref added)
	cluster.lock.RLock()
	children, ok = cluster.parentUIDToChildren[parentUID]
	require.True(t, ok, "parent should have entry in parentUIDToChildren after adding owner ref")
	require.Contains(t, children, childKey, "child should be in parent's children list after adding owner ref")
	cluster.lock.RUnlock()

	// Simulate removing owner reference (e.g., parent deletion with orphanDependents: true)
	childWithoutOwnerAgain := &corev1.Pod{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Pod",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "child-no-owner",
			Namespace:       "test-namespace",
			UID:             "child-uid-123",
			ResourceVersion: "3",
			// OwnerReferences removed
		},
	}

	cluster.lock.Lock()
	cluster.setNode(cluster.newResource(mustToUnstructured(childWithoutOwnerAgain)))
	cluster.lock.Unlock()

	// Verify child is NO LONGER tracked (owner ref removed)
	cluster.lock.RLock()
	children, ok = cluster.parentUIDToChildren[parentUID]
	if ok {
		assert.NotContains(t, children, childKey, "child should be removed from parentUIDToChildren after removing owner ref")
	}
	cluster.lock.RUnlock()

	// Verify empty entry cleanup: parent entry should be cleaned up if it has no children
	cluster.lock.RLock()
	children, ok = cluster.parentUIDToChildren[parentUID]
	if ok {
		assert.Empty(t, children, "parent's children list should be empty or cleaned up")
	}
	cluster.lock.RUnlock()
}

// Test_watchEvents_Deadlock validates that starting watches will not create a deadlock
// caused by using improper locking in various callback methods when there is a high load on the
// system.
func Test_watchEvents_Deadlock(t *testing.T) {
	// deadlock lock is used to simulate a user function calling the cluster cache while holding a lock
	// and using this lock in callbacks such as OnPopulateResourceInfoHandler.
	deadlock := sync.RWMutex{}

	hasDeadlock := false
	res1 := testPod1()
	res2 := testRS()

	cluster := newClusterWithOptions(t, []UpdateSettingsFunc{
		// Set low blocking semaphore
		SetListSemaphore(semaphore.NewWeighted(1)),
		// Resync watches often to use the semaphore and trigger the rate limiting behavior
		SetResyncTimeout(500 * time.Millisecond),
		// Use new resource handler to run code in the list callbacks
		SetPopulateResourceInfoHandler(func(un *unstructured.Unstructured, _ bool) (info any, cacheManifest bool) {
			if un.GroupVersionKind().GroupKind() == res1.GroupVersionKind().GroupKind() ||
				un.GroupVersionKind().GroupKind() == res2.GroupVersionKind().GroupKind() {
				// Create a bottleneck for resources holding the semaphore
				time.Sleep(2 * time.Second)
			}

			//// Uncommenting the following code will simulate a different deadlock on purpose caused by
			//// client code holding a lock and trying to acquire the same lock in the event callback.
			//// It provides an easy way to validate if the test detect deadlocks as expected.
			//// If the test fails with this code commented, a deadlock do exist in the codebase.
			// deadlock.RLock()
			// defer deadlock.RUnlock()

			return
		}),
	}, res1, res2, testDeploy())
	defer func() {
		// Invalidate() is a blocking method and cannot be called safely in case of deadlock
		if !hasDeadlock {
			cluster.Invalidate()
		}
	}()

	err := cluster.EnsureSynced()
	require.NoError(t, err)

	for i := 0; i < 2; i++ {
		done := make(chan bool, 1)
		go func() {
			// Stop the watches, so startMissingWatches will restart them
			cluster.stopWatching(res1.GroupVersionKind().GroupKind(), res1.Namespace)
			cluster.stopWatching(res2.GroupVersionKind().GroupKind(), res2.Namespace)

			// calling startMissingWatches to simulate that a CRD event was received
			// TODO: how to simulate real watch events and test the full watchEvents function?
			err = runSynced(&cluster.lock, func() error {
				deadlock.Lock()
				defer deadlock.Unlock()
				return cluster.startMissingWatches()
			})
			require.NoError(t, err)
			done <- true
		}()
		select {
		case v := <-done:
			require.True(t, v)
		case <-time.After(10 * time.Second):
			hasDeadlock = true
			t.Errorf("timeout reached on attempt %d. It is possible that a deadlock occurred", i)
			// Tip: to debug the deadlock, increase the timer to a value higher than X in "go test -timeout X"
			// This will make the test panic with the goroutines information
			t.FailNow()
		}
	}
}

func buildTestResourceMap() map[kube.ResourceKey]*Resource {
	ns := make(map[kube.ResourceKey]*Resource)
	for i := 0; i < 100000; i++ {
		name := fmt.Sprintf("test-%d", i)
		ownerName := fmt.Sprintf("test-%d", i/10)
		uid := uuid.New().String()
		key := kube.ResourceKey{
			Namespace: "default",
			Name:      name,
			Kind:      "Pod",
		}
		resourceYaml := fmt.Sprintf(`
apiVersion: v1
kind: Pod
metadata:
  namespace: default
  name: %s
  uid: %s`, name, uid)
		if i/10 != 0 {
			owner := ns[kube.ResourceKey{
				Namespace: "default",
				Name:      ownerName,
				Kind:      "Pod",
			}]
			ownerUid := owner.Ref.UID
			resourceYaml += fmt.Sprintf(`
  ownerReferences:
  - apiVersion: v1
    kind: Pod
    name: %s
    uid: %s`, ownerName, ownerUid)
		}
		ns[key] = cacheTest.newResource(strToUnstructured(resourceYaml))
	}
	return ns
}

func BenchmarkBuildGraph(b *testing.B) {
	testResources := buildTestResourceMap()
	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		buildGraph(testResources)
	}
}

func BenchmarkIterateHierarchyV2(b *testing.B) {
	cluster := newCluster(b)
	testResources := buildTestResourceMap()
	for _, resource := range testResources {
		cluster.setNode(resource)
	}
	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		cluster.IterateHierarchyV2([]kube.ResourceKey{
			{Namespace: "default", Name: "test-1", Kind: "Pod"},
		}, func(_ *Resource, _ map[kube.ResourceKey]*Resource) bool {
			return true
		})
	}
}

// buildClusterParentTestResourceMap creates test resources with configurable namespace distribution.
// Parameters:
//   - clusterParents: number of cluster-scoped parent resources (ClusterRoles)
//   - totalNamespaces: total number of namespaces to create
//   - namespacesWithCrossNS: how many of those namespaces contain cross-namespace children
//   - resourcesPerNamespace: resources in each namespace
//   - crossNSResourcesPerNamespace: how many cross-namespace children in each affected namespace
func buildClusterParentTestResourceMap(
	clusterParents, totalNamespaces, namespacesWithCrossNS, resourcesPerNamespace, crossNSResourcesPerNamespace int,
) map[kube.ResourceKey]*Resource {
	resources := make(map[kube.ResourceKey]*Resource)

	// Create cluster-scoped parents (ClusterRoles)
	clusterParentUIDs := make(map[string]string)
	for i := 0; i < clusterParents; i++ {
		clusterRoleName := fmt.Sprintf("cluster-role-%d", i)
		uid := uuid.New().String()
		clusterParentUIDs[clusterRoleName] = uid

		key := kube.ResourceKey{
			Group:     "rbac.authorization.k8s.io",
			Kind:      "ClusterRole",
			Namespace: "",
			Name:      clusterRoleName,
		}

		resourceYaml := fmt.Sprintf(`
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: %s
  uid: %s
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get", "list"]`, clusterRoleName, uid)

		resources[key] = cacheTest.newResource(strToUnstructured(resourceYaml))
	}

	// Generate namespace names
	namespaces := make([]string, totalNamespaces)
	for i := 0; i < totalNamespaces; i++ {
		namespaces[i] = fmt.Sprintf("ns-%d", i)
	}

	// For each namespace
	for nsIdx, namespace := range namespaces {
		hasCrossNS := nsIdx < namespacesWithCrossNS
		regularPodsInNS := resourcesPerNamespace
		crossNSPodsInNS := 0

		if hasCrossNS {
			regularPodsInNS = resourcesPerNamespace - crossNSResourcesPerNamespace
			crossNSPodsInNS = crossNSResourcesPerNamespace
		}

		// Create regular namespaced resources (Pods)
		for i := 0; i < regularPodsInNS; i++ {
			name := fmt.Sprintf("pod-%s-%d", namespace, i)
			uid := uuid.New().String()

			key := kube.ResourceKey{
				Namespace: namespace,
				Name:      name,
				Kind:      "Pod",
			}

			resourceYaml := fmt.Sprintf(`
apiVersion: v1
kind: Pod
metadata:
  namespace: %s
  name: %s
  uid: %s`, namespace, name, uid)

			resources[key] = cacheTest.newResource(strToUnstructured(resourceYaml))
		}

		// Create cross-namespace children if this namespace has them
		for i := 0; i < crossNSPodsInNS; i++ {
			podName := fmt.Sprintf("cross-ns-pod-%s-%d", namespace, i)
			clusterRoleIndex := i % clusterParents
			clusterRoleName := fmt.Sprintf("cluster-role-%d", clusterRoleIndex)
			parentUID := clusterParentUIDs[clusterRoleName]
			uid := uuid.New().String()

			key := kube.ResourceKey{
				Namespace: namespace,
				Name:      podName,
				Kind:      "Pod",
			}

			resourceYaml := fmt.Sprintf(`
apiVersion: v1
kind: Pod
metadata:
  name: %s
  namespace: %s
  uid: %s
  ownerReferences:
  - apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRole
    name: %s
    uid: %s`, podName, namespace, uid, clusterRoleName, parentUID)

			resources[key] = cacheTest.newResource(strToUnstructured(resourceYaml))
		}
	}

	return resources
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

// BenchmarkIterateHierarchyV2_ClusterParentTraversal benchmarks full hierarchy traversal
// starting from cluster-scoped parents with varying percentages of namespaces containing
// cross-namespace children. This tests the actual performance impact of the cross-namespace
// relationship tracking feature.
func BenchmarkIterateHierarchyV2_ClusterParentTraversal(b *testing.B) {
	testCases := []struct {
		name                         string
		totalNamespaces              int
		resourcesPerNamespace        int
		namespacesWithCrossNS        int // Number of namespaces with cross-NS children
		crossNSResourcesPerNamespace int // Cross-NS children in each affected namespace
	}{
		// Baseline: 0% of namespaces have cross-NS children
		{"50NS_0pct_100perNS", 50, 100, 0, 0},

		// Primary dimension: Percentage of namespaces with cross-NS children
		// 5,000 total resources (50 NS × 100 resources/NS), 10 cross-NS children per affected namespace
		{"50NS_2pct_100perNS_10cross", 50, 100, 1, 10},   // 2% of namespaces (1/50)
		{"50NS_4pct_100perNS_10cross", 50, 100, 2, 10},   // 4% of namespaces (2/50)
		{"50NS_10pct_100perNS_10cross", 50, 100, 5, 10},  // 10% of namespaces (5/50)
		{"50NS_20pct_100perNS_10cross", 50, 100, 10, 10}, // 20% of namespaces (10/50)

		// Secondary dimension: Within a namespace, % of resources that are cross-NS
		// 5,000 total resources, 2% of namespaces (1/50) have cross-NS children
		{"50NS_2pct_100perNS_10cross", 50, 100, 1, 10},  // 10% of namespace resources (10/100)
		{"50NS_2pct_100perNS_25cross", 50, 100, 1, 25},  // 25% of namespace resources (25/100)
		{"50NS_2pct_100perNS_50cross", 50, 100, 1, 50},  // 50% of namespace resources (50/100)

		// Edge cases
		{"100NS_1pct_100perNS_10cross", 100, 100, 1, 10},   // 1% of namespaces (1/100) - extreme clustering
		{"50NS_100pct_100perNS_10cross", 50, 100, 50, 10},  // 100% of namespaces - worst case
	}

	for _, tc := range testCases {
		b.Run(tc.name, func(b *testing.B) {

			cluster := newCluster(b).WithAPIResources([]kube.APIResourceInfo{{
				GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
				GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
				Meta:                 metav1.APIResource{Namespaced: false},
			}, {
				GroupKind:            schema.GroupKind{Group: "", Kind: "Pod"},
				GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"},
				Meta:                 metav1.APIResource{Namespaced: true},
			}})

			// CRITICAL: Initialize namespacedResources so setNode will populate orphanedChildren index
			cluster.namespacedResources = map[schema.GroupKind]bool{
				{Group: "", Kind: "Pod"}:                                   true,
				{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"}: false,
			}

			clusterParents := 100 // Fixed number of cluster-scoped resources

			testResources := buildClusterParentTestResourceMap(
				clusterParents,
				tc.totalNamespaces,
				tc.namespacesWithCrossNS,
				tc.resourcesPerNamespace,
				tc.crossNSResourcesPerNamespace,
			)

			// Add resources to cache - this will populate orphanedChildren index
			for _, resource := range testResources {
				cluster.setNode(resource)
			}

			// Verify indexes are populated (sanity check)
			if tc.namespacesWithCrossNS > 0 {
				if len(cluster.parentUIDToChildren) == 0 {
					b.Fatal("parentUIDToChildren index not populated - benchmark setup is broken")
				}
			}

			// Always start from a cluster-scoped parent to test cross-namespace traversal
			startKey := kube.ResourceKey{
				Group:     "rbac.authorization.k8s.io",
				Kind:      "ClusterRole",
				Namespace: "",
				Name:      "cluster-role-0",
			}

			b.ResetTimer()
			b.ReportAllocs()

			for n := 0; n < b.N; n++ {
				cluster.IterateHierarchyV2([]kube.ResourceKey{startKey}, func(_ *Resource, _ map[kube.ResourceKey]*Resource) bool {
					return true
				})
			}
		})
	}
}

// BenchmarkIterateHierarchyV2_MultiLevelClusterScoped tests the performance of
// multi-level cluster-scoped hierarchies: ClusterScoped -> ClusterScoped -> Namespaced
func BenchmarkIterateHierarchyV2_MultiLevelClusterScoped(b *testing.B) {
	testCases := []struct {
		name                  string
		intermediateChildren  int // Number of intermediate cluster-scoped children per root
		namespacedGrandchildren int // Number of namespaced grandchildren per intermediate
		totalNamespaces       int
	}{
		// Baseline: no multi-level hierarchy
		{"NoMultiLevel", 0, 0, 10},
		// Typical Crossplane scenario: 1 ProviderRevision per Provider, few Deployments
		{"1Intermediate_5Grandchildren", 1, 5, 10},
		// Multiple ProviderRevisions per Provider
		{"5Intermediate_5Grandchildren", 5, 5, 10},
		// Larger hierarchy
		{"10Intermediate_10Grandchildren", 10, 10, 20},
		// Stress test
		{"20Intermediate_20Grandchildren", 20, 20, 50},
	}

	for _, tc := range testCases {
		b.Run(tc.name, func(b *testing.B) {
			cluster := newCluster(b).WithAPIResources([]kube.APIResourceInfo{{
				GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
				GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
				Meta:                 metav1.APIResource{Namespaced: false},
			}, {
				GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
				GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
				Meta:                 metav1.APIResource{Namespaced: false},
			}, {
				GroupKind:            schema.GroupKind{Group: "", Kind: "Pod"},
				GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"},
				Meta:                 metav1.APIResource{Namespaced: true},
			}})

			cluster.namespacedResources = map[schema.GroupKind]bool{
				{Group: "", Kind: "Pod"}:                                   true,
				{Group: "", Kind: "Namespace"}:                             false,
				{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"}: false,
			}

			// Create root cluster-scoped parent (Namespace, simulating Provider)
			rootUID := uuid.New().String()
			rootYaml := fmt.Sprintf(`
apiVersion: v1
kind: Namespace
metadata:
  name: root-parent
  uid: %s`, rootUID)
			rootKey := kube.ResourceKey{Kind: "Namespace", Name: "root-parent"}
			cluster.setNode(cacheTest.newResource(strToUnstructured(rootYaml)))

			// Create intermediate cluster-scoped children (ClusterRoles, simulating ProviderRevisions)
			intermediateUIDs := make([]string, tc.intermediateChildren)
			for i := 0; i < tc.intermediateChildren; i++ {
				uid := uuid.New().String()
				intermediateUIDs[i] = uid
				name := fmt.Sprintf("intermediate-%d", i)
				intermediateYaml := fmt.Sprintf(`
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: %s
  uid: %s
  ownerReferences:
  - apiVersion: v1
    kind: Namespace
    name: root-parent
    uid: %s
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get"]`, name, uid, rootUID)
				cluster.setNode(cacheTest.newResource(strToUnstructured(intermediateYaml)))
			}

			// Create namespaced grandchildren (Pods, simulating Deployments)
			for i := 0; i < tc.intermediateChildren; i++ {
				for j := 0; j < tc.namespacedGrandchildren; j++ {
					nsIdx := (i*tc.namespacedGrandchildren + j) % tc.totalNamespaces
					namespace := fmt.Sprintf("ns-%d", nsIdx)
					podName := fmt.Sprintf("grandchild-%d-%d", i, j)
					podUID := uuid.New().String()
					podYaml := fmt.Sprintf(`
apiVersion: v1
kind: Pod
metadata:
  name: %s
  namespace: %s
  uid: %s
  ownerReferences:
  - apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRole
    name: intermediate-%d
    uid: %s`, podName, namespace, podUID, i, intermediateUIDs[i])
					cluster.setNode(cacheTest.newResource(strToUnstructured(podYaml)))
				}
			}

			b.ResetTimer()
			b.ReportAllocs()

			for n := 0; n < b.N; n++ {
				cluster.IterateHierarchyV2([]kube.ResourceKey{rootKey}, func(_ *Resource, _ map[kube.ResourceKey]*Resource) bool {
					return true
				})
			}
		})
	}
}

func TestIterateHierarchyV2_NoDuplicatesInSameNamespace(t *testing.T) {
	// Create a parent-child relationship in the same namespace
	parent := &appsv1.Deployment{
		TypeMeta: metav1.TypeMeta{APIVersion: "apps/v1", Kind: "Deployment"},
		ObjectMeta: metav1.ObjectMeta{
			Name: "parent", Namespace: "default", UID: "parent-uid",
		},
	}
	child := &appsv1.ReplicaSet{
		TypeMeta: metav1.TypeMeta{APIVersion: "apps/v1", Kind: "ReplicaSet"},
		ObjectMeta: metav1.ObjectMeta{
			Name: "child", Namespace: "default", UID: "child-uid",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "apps/v1", Kind: "Deployment", Name: "parent", UID: "parent-uid",
			}},
		},
	}

	cluster := newCluster(t, parent, child)
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	visitCount := make(map[string]int)
	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{
			kube.GetResourceKey(mustToUnstructured(parent)),
			kube.GetResourceKey(mustToUnstructured(child)),
		},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			visitCount[resource.Ref.Name]++
			return true
		},
	)

	// Each resource should be visited exactly once
	assert.Equal(t, 1, visitCount["parent"], "parent should be visited once")
	assert.Equal(t, 1, visitCount["child"], "child should be visited once")
}

func TestIterateHierarchyV2_NoDuplicatesCrossNamespace(t *testing.T) {
	// Test that cross-namespace parent-child relationships don't cause duplicates
	visitCount := make(map[string]int)

	cluster := newCluster(t, testClusterParent(), testNamespacedChild(), testClusterChild()).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}, {
		GroupKind:            schema.GroupKind{Group: "rbac.authorization.k8s.io", Kind: "ClusterRole"},
		GroupVersionResource: schema.GroupVersionResource{Group: "rbac.authorization.k8s.io", Version: "v1", Resource: "clusterroles"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{
			kube.GetResourceKey(mustToUnstructured(testClusterParent())),
			kube.GetResourceKey(mustToUnstructured(testNamespacedChild())),
			kube.GetResourceKey(mustToUnstructured(testClusterChild())),
		},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			visitCount[resource.Ref.Name]++
			return true
		},
	)

	// Each resource should be visited exactly once, even with cross-namespace relationships
	assert.Equal(t, 1, visitCount["test-cluster-parent"], "cluster parent should be visited once")
	assert.Equal(t, 1, visitCount["namespaced-child"], "namespaced child should be visited once")
	assert.Equal(t, 1, visitCount["cluster-child"], "cluster child should be visited once")
}

func TestIterateHierarchyV2_CircularOwnerReference_NoStackOverflow(t *testing.T) {
	// Test that self-referencing resources (circular ownerReferences) don't cause stack overflow.
	// This reproduces the bug reported in https://github.com/argoproj/argo-cd/issues/26783
	// where a resource with an ownerReference pointing to itself caused infinite recursion.

	// Create a cluster-scoped resource that owns itself (self-referencing)
	selfReferencingResource := &corev1.Namespace{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Namespace",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "self-referencing",
			UID:             "self-ref-uid",
			ResourceVersion: "1",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "self-referencing",
				UID:        "self-ref-uid", // Points to itself
			}},
		},
	}

	cluster := newCluster(t, selfReferencingResource).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	visitCount := 0
	// This should complete without stack overflow
	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(selfReferencingResource))},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			visitCount++
			return true
		},
	)

	// The self-referencing resource should be visited exactly once
	assert.Equal(t, 1, visitCount, "self-referencing resource should be visited exactly once")
}

func TestIterateHierarchyV2_CircularOwnerChain_NoStackOverflow(t *testing.T) {
	// Test that circular ownership chains (A -> B -> A) don't cause stack overflow.
	// This is a more complex case where two resources own each other.

	resourceA := &corev1.Namespace{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Namespace",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "resource-a",
			UID:             "uid-a",
			ResourceVersion: "1",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "resource-b",
				UID:        "uid-b", // A is owned by B
			}},
		},
	}

	resourceB := &corev1.Namespace{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "v1",
			Kind:       "Namespace",
		},
		ObjectMeta: metav1.ObjectMeta{
			Name:            "resource-b",
			UID:             "uid-b",
			ResourceVersion: "1",
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: "v1",
				Kind:       "Namespace",
				Name:       "resource-a",
				UID:        "uid-a", // B is owned by A
			}},
		},
	}

	cluster := newCluster(t, resourceA, resourceB).WithAPIResources([]kube.APIResourceInfo{{
		GroupKind:            schema.GroupKind{Group: "", Kind: "Namespace"},
		GroupVersionResource: schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"},
		Meta:                 metav1.APIResource{Namespaced: false},
	}})
	err := cluster.EnsureSynced()
	require.NoError(t, err)

	visitCount := make(map[string]int)
	// This should complete without stack overflow
	cluster.IterateHierarchyV2(
		[]kube.ResourceKey{kube.GetResourceKey(mustToUnstructured(resourceA))},
		func(resource *Resource, _ map[kube.ResourceKey]*Resource) bool {
			visitCount[resource.Ref.Name]++
			return true
		},
	)

	// Each resource in the circular chain should be visited exactly once
	assert.Equal(t, 1, visitCount["resource-a"], "resource-a should be visited exactly once")
	assert.Equal(t, 1, visitCount["resource-b"], "resource-b should be visited exactly once")
}

// BenchmarkSync_ParentToChildrenIndex measures the overhead of parent-to-children index
// operations during sync. This benchmark was created to investigate performance regression
// reported in https://github.com/argoproj/argo-cd/issues/26863
//
// The index is now maintained with O(1) operations (set-based) and updated inline
// in setNode() for both explicit and inferred owner refs. No rebuild is needed.
//
// This benchmark measures sync performance with resources that have owner references
// to quantify the index-building overhead at different scales.
func BenchmarkSync_ParentToChildrenIndex(b *testing.B) {
	testCases := []struct {
		name             string
		totalResources   int
		pctWithOwnerRefs int // Percentage of resources with owner references
	}{
		// Baseline: no owner refs (index operations are no-ops)
		{"1000res_0pctOwnerRefs", 1000, 0},
		{"5000res_0pctOwnerRefs", 5000, 0},
		{"10000res_0pctOwnerRefs", 10000, 0},

		// Typical case: ~80% of resources have owner refs (pods owned by RS, RS owned by Deployment)
		{"1000res_80pctOwnerRefs", 1000, 80},
		{"5000res_80pctOwnerRefs", 5000, 80},
		{"10000res_80pctOwnerRefs", 10000, 80},

		// Heavy case: all resources have owner refs
		{"1000res_100pctOwnerRefs", 1000, 100},
		{"5000res_100pctOwnerRefs", 5000, 100},
		{"10000res_100pctOwnerRefs", 10000, 100},

		// Stress test: larger scale
		{"20000res_80pctOwnerRefs", 20000, 80},
	}

	for _, tc := range testCases {
		b.Run(tc.name, func(b *testing.B) {
			resources := make([]runtime.Object, 0, tc.totalResources)

			// Create parent resources (deployments) - these won't have owner refs
			numParents := tc.totalResources / 10 // 10% are parents
			if numParents < 1 {
				numParents = 1
			}
			parentUIDs := make([]types.UID, numParents)
			for i := 0; i < numParents; i++ {
				uid := types.UID(fmt.Sprintf("deploy-uid-%d", i))
				parentUIDs[i] = uid
				resources = append(resources, &appsv1.Deployment{
					TypeMeta: metav1.TypeMeta{APIVersion: "apps/v1", Kind: "Deployment"},
					ObjectMeta: metav1.ObjectMeta{
						Name:      fmt.Sprintf("deploy-%d", i),
						Namespace: "default",
						UID:       uid,
					},
				})
			}

			// Create child resources (pods) - some with owner refs
			numChildren := tc.totalResources - numParents
			numWithOwnerRefs := (numChildren * tc.pctWithOwnerRefs) / 100

			for i := 0; i < numChildren; i++ {
				pod := &corev1.Pod{
					TypeMeta: metav1.TypeMeta{APIVersion: "v1", Kind: "Pod"},
					ObjectMeta: metav1.ObjectMeta{
						Name:      fmt.Sprintf("pod-%d", i),
						Namespace: "default",
						UID:       types.UID(fmt.Sprintf("pod-uid-%d", i)),
					},
				}

				// Add owner refs to the first numWithOwnerRefs pods
				if i < numWithOwnerRefs {
					parentIdx := i % numParents
					pod.OwnerReferences = []metav1.OwnerReference{{
						APIVersion: "apps/v1",
						Kind:       "Deployment",
						Name:       fmt.Sprintf("deploy-%d", parentIdx),
						UID:        parentUIDs[parentIdx],
					}}
				}

				resources = append(resources, pod)
			}

			cluster := newCluster(b, resources...)

			b.ResetTimer()
			b.ReportAllocs()

			for n := 0; n < b.N; n++ {
				// sync() reinitializes resources, parentUIDToChildren, etc. at the start,
				// so no manual reset is needed here.
				err := cluster.sync()
				if err != nil {
					b.Fatal(err)
				}
			}
		})
	}
}

// BenchmarkUpdateParentUIDToChildren measures the cost of incremental index updates
// during setNode. This is called for EVERY resource during sync. The index uses
// set-based storage so add/remove operations are O(1) regardless of children count.
func BenchmarkUpdateParentUIDToChildren(b *testing.B) {
	testCases := []struct {
		name            string
		childrenPerParent int
	}{
		{"10children", 10},
		{"50children", 50},
		{"100children", 100},
		{"500children", 500},
		{"1000children", 1000},
	}

	for _, tc := range testCases {
		b.Run(tc.name, func(b *testing.B) {
			cluster := newCluster(b)
			err := cluster.EnsureSynced()
			if err != nil {
				b.Fatal(err)
			}

			parentUID := types.UID("parent-uid")

			// Pre-populate with existing children
			childrenSet := make(map[kube.ResourceKey]struct{})
			for i := 0; i < tc.childrenPerParent; i++ {
				childKey := kube.ResourceKey{
					Group:     "",
					Kind:      "Pod",
					Namespace: "default",
					Name:      fmt.Sprintf("existing-child-%d", i),
				}
				childrenSet[childKey] = struct{}{}
			}
			cluster.parentUIDToChildren[parentUID] = childrenSet

			// Create a new child key to add
			newChildKey := kube.ResourceKey{
				Group:     "",
				Kind:      "Pod",
				Namespace: "default",
				Name:      "new-child",
			}

			b.ResetTimer()
			b.ReportAllocs()

			for n := 0; n < b.N; n++ {
				// Simulate adding a new child - O(1) set insertion
				cluster.addToParentUIDToChildren(parentUID, newChildKey)
				// Remove it so we can add it again in the next iteration
				cluster.removeFromParentUIDToChildren(parentUID, newChildKey)
			}
		})
	}
}

// BenchmarkIncrementalIndexBuild measures the cost of incremental index updates
// via addToParentUIDToChildren during sync. The index uses O(1) set-based operations.
//
// This benchmark was created to investigate issue #26863 and verify the fix.
func BenchmarkIncrementalIndexBuild(b *testing.B) {
	testCases := []struct {
		name              string
		numParents        int
		childrenPerParent int
	}{
		{"100parents_10children", 100, 10},
		{"100parents_50children", 100, 50},
		{"100parents_100children", 100, 100},
		{"1000parents_10children", 1000, 10},
		{"1000parents_100children", 1000, 100},
	}

	for _, tc := range testCases {
		// Benchmark incremental approach (what happens during setNode)
		b.Run(tc.name+"_incremental", func(b *testing.B) {
			cluster := newCluster(b)
			err := cluster.EnsureSynced()
			if err != nil {
				b.Fatal(err)
			}

			// Prepare parent UIDs and child keys
			type childInfo struct {
				parentUID types.UID
				childKey  kube.ResourceKey
			}
			children := make([]childInfo, 0, tc.numParents*tc.childrenPerParent)
			for p := 0; p < tc.numParents; p++ {
				parentUID := types.UID(fmt.Sprintf("parent-%d", p))
				for c := 0; c < tc.childrenPerParent; c++ {
					children = append(children, childInfo{
						parentUID: parentUID,
						childKey: kube.ResourceKey{
							Kind:      "Pod",
							Namespace: "default",
							Name:      fmt.Sprintf("child-%d-%d", p, c),
						},
					})
				}
			}

			b.ResetTimer()
			b.ReportAllocs()

			for n := 0; n < b.N; n++ {
				// Clear the index
				cluster.parentUIDToChildren = make(map[types.UID]map[kube.ResourceKey]struct{})

				// Simulate incremental adds (O(1) set insertions)
				for _, child := range children {
					cluster.addToParentUIDToChildren(child.parentUID, child.childKey)
				}
			}
		})
	}
}