kubectl diff: refactor tracker into a separate type

This means that we can reuse the logic even if we swap out the pruner.

staging/src/k8s.io/kubectl/pkg/cmd/diff/diff.go

@@ -114,7 +114,9 @@ type DiffOptions struct {
 	EnforceNamespace bool
 	Builder          *resource.Builder
 	Diff             *DiffProgram
-	pruner           *pruner
+
+	pruner  *pruner
+	tracker *tracker
 }
 
 func NewDiffOptions(ioStreams genericclioptions.IOStreams) *DiffOptions {
@@ -659,6 +661,7 @@ func (o *DiffOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []str
 		if err != nil {
 			return err
 		}
+		o.tracker = newTracker()
 		o.pruner = newPruner(o.DynamicClient, mapper, resources, o.Selector)
 	}
 
@@ -723,8 +726,8 @@ func (o *DiffOptions) Run() error {
 				IOStreams:       o.Diff.IOStreams,
 			}
 
-			if o.pruner != nil {
+			if o.tracker != nil {
-				o.pruner.MarkVisited(info)
+				o.tracker.MarkVisited(info)
 			}
 
 			err = differ.Diff(obj, printer, o.ShowManagedFields)
@@ -739,7 +742,7 @@ func (o *DiffOptions) Run() error {
 	})
 
 	if o.pruner != nil {
-		prunedObjs, err := o.pruner.pruneAll(o.CmdNamespace != "")
+		prunedObjs, err := o.pruner.pruneAll(o.tracker, o.CmdNamespace != "")
 		if err != nil {
 			klog.Warningf("pruning failed and could not be evaluated err: %v", err)
 		}

staging/src/k8s.io/kubectl/pkg/cmd/diff/prune.go

@@ -31,37 +31,45 @@ import (
 	"k8s.io/kubectl/pkg/util/prune"
 )
 
+type tracker struct {
+	visitedUids       sets.Set[types.UID]
+	visitedNamespaces sets.Set[string]
+}
+
+func newTracker() *tracker {
+	return &tracker{
+		visitedUids:       sets.New[types.UID](),
+		visitedNamespaces: sets.New[string](),
+	}
+}
+
 type pruner struct {
 	mapper        meta.RESTMapper
 	dynamicClient dynamic.Interface
 
-	visitedUids       sets.Set[types.UID]
+	labelSelector string
-	visitedNamespaces sets.Set[string]
+	resources     []prune.Resource
-	labelSelector     string
-	resources         []prune.Resource
 }
 
 func newPruner(dc dynamic.Interface, m meta.RESTMapper, r []prune.Resource, selector string) *pruner {
 	return &pruner{
-		visitedUids:       sets.New[types.UID](),
+		dynamicClient: dc,
-		visitedNamespaces: sets.New[string](),
+		mapper:        m,
-		dynamicClient:     dc,
+		resources:     r,
-		mapper:            m,
+		labelSelector: selector,
-		resources:         r,
-		labelSelector:     selector,
 	}
 }
 
-func (p *pruner) pruneAll(namespaceSpecified bool) ([]runtime.Object, error) {
+func (p *pruner) pruneAll(tracker *tracker, namespaceSpecified bool) ([]runtime.Object, error) {
 	var allPruned []runtime.Object
 	namespacedRESTMappings, nonNamespacedRESTMappings, err := prune.GetRESTMappings(p.mapper, p.resources, namespaceSpecified)
 	if err != nil {
 		return allPruned, fmt.Errorf("error retrieving RESTMappings to prune: %v", err)
 	}
 
-	for n := range p.visitedNamespaces {
+	for n := range tracker.visitedNamespaces {
 		for _, m := range namespacedRESTMappings {
-			if pobjs, err := p.prune(n, m); err != nil {
+			if pobjs, err := p.prune(tracker, n, m); err != nil {
 				return pobjs, fmt.Errorf("error pruning namespaced object %v: %v", m.GroupVersionKind, err)
 			} else {
 				allPruned = append(allPruned, pobjs...)
@@ -69,7 +77,7 @@ func (p *pruner) pruneAll(namespaceSpecified bool) ([]runtime.Object, error) {
 		}
 	}
 	for _, m := range nonNamespacedRESTMappings {
-		if pobjs, err := p.prune(metav1.NamespaceNone, m); err != nil {
+		if pobjs, err := p.prune(tracker, metav1.NamespaceNone, m); err != nil {
 			return allPruned, fmt.Errorf("error pruning nonNamespaced object %v: %v", m.GroupVersionKind, err)
 		} else {
 			allPruned = append(allPruned, pobjs...)
@@ -79,7 +87,7 @@ func (p *pruner) pruneAll(namespaceSpecified bool) ([]runtime.Object, error) {
 	return allPruned, nil
 }
 
-func (p *pruner) prune(namespace string, mapping *meta.RESTMapping) ([]runtime.Object, error) {
+func (p *pruner) prune(tracker *tracker, namespace string, mapping *meta.RESTMapping) ([]runtime.Object, error) {
 	objList, err := p.dynamicClient.Resource(mapping.Resource).
 		Namespace(namespace).
 		List(context.TODO(), metav1.ListOptions{
@@ -105,7 +113,7 @@ func (p *pruner) prune(namespace string, mapping *meta.RESTMapping) ([]runtime.O
 			continue
 		}
 		uid := metadata.GetUID()
-		if p.visitedUids.Has(uid) {
+		if tracker.visitedUids.Has(uid) {
 			continue
 		}
 
@@ -115,14 +123,14 @@ func (p *pruner) prune(namespace string, mapping *meta.RESTMapping) ([]runtime.O
 }
 
 // MarkVisited marks visited namespaces and uids
-func (p *pruner) MarkVisited(info *resource.Info) {
+func (t *tracker) MarkVisited(info *resource.Info) {
 	if info.Namespaced() {
-		p.visitedNamespaces.Insert(info.Namespace)
+		t.visitedNamespaces.Insert(info.Namespace)
 	}
 
 	metadata, err := meta.Accessor(info.Object)
 	if err != nil {
 		return
 	}
-	p.visitedUids.Insert(metadata.GetUID())
+	t.visitedUids.Insert(metadata.GetUID())
 }