[client-go #1415] Use transformer from provided store within internal stores in reflector to limit memory usage bursts

Signed-off-by: Valerian Roche <valerian.roche@datadoghq.com>

Kubernetes-commit: 585ed0a5cb378e794e4775bc846d5309ca65f2c6

tools/cache/reflector.go

@@ -76,6 +76,13 @@ type ReflectorStore interface {
 	Resync() error
 }
 
+// TransformingStore is an optional interface that can be implemented by the provided store.
+// If implemented on the provided store reflector will use the same transformer in its internal stores.
+type TransformingStore interface {
+	Store
+	Transformer() TransformFunc
+}
+
 // Reflector watches a specified resource and causes all changes to be reflected in the given store.
 type Reflector struct {
 	// name identifies this reflector. By default, it will be a file:line if possible.
@@ -718,6 +725,11 @@ func (r *Reflector) watchList(ctx context.Context) (watch.Interface, error) {
 		return false
 	}
 
+	storeOpts := []StoreOption{}
+	if tr, ok := r.store.(TransformingStore); ok && tr.Transformer() != nil {
+		storeOpts = append(storeOpts, WithTransformer(tr.Transformer()))
+	}
+
 	initTrace := trace.New("Reflector WatchList", trace.Field{Key: "name", Value: r.name})
 	defer initTrace.LogIfLong(10 * time.Second)
 	for {
@@ -729,7 +741,7 @@ func (r *Reflector) watchList(ctx context.Context) (watch.Interface, error) {
 
 		resourceVersion = ""
 		lastKnownRV := r.rewatchResourceVersion()
-		temporaryStore = NewStore(DeletionHandlingMetaNamespaceKeyFunc)
+		temporaryStore = NewStore(DeletionHandlingMetaNamespaceKeyFunc, storeOpts...)
 		// TODO(#115478): large "list", slow clients, slow network, p&f
 		//  might slow down streaming and eventually fail.
 		//  maybe in such a case we should retry with an increased timeout?