* It does not deal as well with large jumps back in time.
 * <p>
 * When the system wall clock jumps back in time, this clock will effectively slow down until it is back in sync.
 * All syncing timestamps will be the same as the previously issued timestamp.
 * The rate by which this clock slows, and therefore the time it takes to resync,
 * is determined by how frequently the clock is read.

	key, quit := c.queue.Get()
	if quit {
		return false
	}
	defer c.queue.Done(key)

	if err := c.syncConfigMap(); err != nil {
		utilruntime.HandleError(fmt.Errorf("while syncing ConfigMap %q, err: %w", key, err))
		c.queue.AddRateLimited(key)
		return true
	}
	c.queue.Forget(key)
	return true
}

func (c *Controller) syncConfigMap() error {

* Simple object filtering. Beyond just static filters on objects, `kclient` supports _dynamic filters_ that can change at runtime.
  When a filter changes and includes/removes new objects, those are automatically handled.
* Proper syncing and shutdown logic. Checking for when an informer has fully started can be quite tricky; `kclient` automatically handles it.

Under the `kclient` package, `clienttest` also provides similar interfaces meant for writing unit tests.

func (m *workloadManager) Start() error {
	// Run the pod controller.
	go m.podController.Run(m.stopCh)

	// Wait for the cache to sync.
	if !m.podController.WaitForSync(m.stopCh) {
		return fmt.Errorf(
			"failed syncing cache for echo %s/%s: controller stopping",
			m.cfg.Namespace.Name(),
			m.cfg.Service)
	}

	// Wait until all pods are ready.
	_, err := m.WaitForReadyWorkloads()
	return err
}

	if !proxier.isInitialized() {
		klog.V(2).InfoS("Not syncing hns until Services and Endpoints have been received from master")
		return
	}

	// Keep track of how long syncs take.
	start := time.Now()
	defer func() {
		metrics.SyncProxyRulesLatency.Observe(metrics.SinceInSeconds(start))
		klog.V(4).InfoS("Syncing proxy rules complete", "elapsed", time.Since(start))
	}()

			//    after the next discovery sync.
			// For now, record the error and retry.
			logger.V(5).Error(err, "error syncing item", "item", n.identity)
		} else {
			utilruntime.HandleError(fmt.Errorf("error syncing item %s: %v", n, err))
		}
		// retry if garbage collection of an object failed.
		return requeueItem
	} else if !n.isObserved() {

	return true
}

func (tc *TokenCleaner) syncFunc(ctx context.Context, key string) error {
	logger := klog.FromContext(ctx)
	startTime := time.Now()
	defer func() {
		logger.V(4).Info("Finished syncing secret", "secret", key, "elapsedTime", time.Since(startTime))
	}()

	namespace, name, err := cache.SplitMetaNamespaceKey(key)
	if err != nil {
		return err
	}

	if err := c.syncPods(); err != nil {
		log.Errorf("one or more errors force-syncing pods: %v", err)
	}
	if err := c.endpoints.initializeNamespace(metav1.NamespaceAll, true); err != nil {
		log.Errorf("one or more errors force-syncing endpoints: %v", err)
	}
	c.reloadNetworkGateways()

		// Foo resource to be synced.
		if err := r.syncNode(ctx, key); err != nil {
			// Put the item back on the queue to handle any transient errors.
			r.queue.AddRateLimited(key)
			return fmt.Errorf("error syncing '%s': %s, requeuing", key, err.Error())
		}
		// Finally, if no error occurs we Forget this item so it does not
		// get queue again until another change happens.
		r.queue.Forget(obj)

	return true
}
func (c *ServiceAccountsController) syncNamespace(ctx context.Context, key string) error {
	startTime := time.Now()
	defer func() {
		klog.FromContext(ctx).V(4).Info("Finished syncing namespace", "namespace", key, "duration", time.Since(startTime))
	}()

	ns, err := c.nsLister.Get(key)
	if apierrors.IsNotFound(err) {
		return nil
	}
	if err != nil {
		return err
	}