// to be more schedulable.
	AssignedPodAdd = framework.ClusterEvent{Resource: framework.Pod, ActionType: framework.Add, Label: "AssignedPodAdd"}
	// NodeAdd is the event when a new node is added to the cluster.
	NodeAdd = framework.ClusterEvent{Resource: framework.Node, ActionType: framework.Add, Label: "NodeAdd"}
	// AssignedPodUpdate is the event when a pod is updated that causes pods with matching affinity
	// terms to be more schedulable.

		t.Fatalf("unexpected error from AddUnschedulableIfNotPresent: %v", err)
	}
	expectInFlightPods(t, q)
	// This NodeAdd event moves unschedulablePodInfo and highPriorityPodInfo to the backoffQ,
	// because of the queueing hint function registered for NodeAdd/fooPlugin.
	q.MoveAllToActiveOrBackoffQueue(logger, NodeAdd, nil, nil, nil)
	q.Add(logger, medPriorityPodInfo.Pod)
	if q.activeQ.Len() != 1 {

		// A new node or updating a node's volume zone labels may make a pod schedulable.
		//
		// A note about UpdateNodeTaint event:
		// NodeAdd QueueingHint isn't always called because of the internal feature called preCheck.
		// As a common problematic scenario,
		// when a node is added but not ready, NodeAdd event is filtered out by preCheck and doesn't arrive.
		// In such cases, this plugin may miss some events that actually make pods schedulable.

		// and make these pod in scheduling schedulable or unschedulable.
		//
		// A note about UpdateNodeTaint event:
		// NodeAdd QueueingHint isn't always called because of the internal feature called preCheck.
		// As a common problematic scenario,
		// when a node is added but not ready, NodeAdd event is filtered out by preCheck and doesn't arrive.
		// In such cases, this plugin may miss some events that actually make pods schedulable.

		// adding an assigned Pod may make it schedulable.
		//
		// A note about UpdateNodeTaint event:
		// NodeAdd QueueingHint isn't always called because of the internal feature called preCheck.
		// As a common problematic scenario,
		// when a node is added but not ready, NodeAdd event is filtered out by preCheck and doesn't arrive.
		// In such cases, this plugin may miss some events that actually make pods schedulable.

		// A new or updated node may make pods schedulable.
		//
		// A note about UpdateNodeTaint event:
		// NodeAdd QueueingHint isn't always called because of the internal feature called preCheck.
		// As a common problematic scenario,
		// when a node is added but not ready, NodeAdd event is filtered out by preCheck and doesn't arrive.
		// In such cases, this plugin may miss some events that actually make pods schedulable.

	// this plugin would implement QueueingHint for Pod/Update event
	// that returns Queue when such label changes are made in unscheduled Pods.
	Pod GVK = "Pod"
	// A note about NodeAdd event and UpdateNodeTaint event:
	// NodeAdd QueueingHint isn't always called because of the internal feature called preCheck.
	// It's definitely not something expected for plugin developers,

		return nil, fmt.Errorf("could not initialize attach detach controller: %w", err)
	}

	nodeInformer.Informer().AddEventHandler(kcache.ResourceEventHandlerFuncs{
		AddFunc: func(obj interface{}) {
			adc.nodeAdd(logger, obj)
		},
		UpdateFunc: func(oldObj, newObj interface{}) {
			adc.nodeUpdate(logger, oldObj, newObj)
		},
		DeleteFunc: func(obj interface{}) {
			adc.nodeDelete(logger, obj)
		},
	})

		return
	}

	logger.V(3).Info("Add event for node", "node", klog.KObj(node))
	nodeInfo := sched.Cache.AddNode(logger, node)
	sched.SchedulingQueue.MoveAllToActiveOrBackoffQueue(logger, queue.NodeAdd, nil, node, preCheckForNode(nodeInfo))
}

func (sched *Scheduler) updateNodeInCache(oldObj, newObj interface{}) {
	logger := sched.logger
	oldNode, ok := oldObj.(*v1.Node)
	if !ok {

		// A new or updated node may make pods schedulable.
		//
		// A note about UpdateNodeTaint event:
		// NodeAdd QueueingHint isn't always called because of the internal feature called preCheck.
		// As a common problematic scenario,
		// when a node is added but not ready, NodeAdd event is filtered out by preCheck and doesn't arrive.
		// In such cases, this plugin may miss some events that actually make pods schedulable.