Method processNextWorkItem

controller.go:200–236

processNextWorkItem will read a single work item off the workqueue and attempt to process it, by calling the syncHandler.

(ctx context.Context)

// processNextWorkItem will read a single work item off the workqueue and
// attempt to process it, by calling the syncHandler.
func (c *Controller) processNextWorkItem(ctx context.Context) bool {
	objRef, shutdown := c.workqueue.Get()
	logger := klog.FromContext(ctx)

	if shutdown {
		return false
	}

	// We call Done at the end of this func so the workqueue knows we have
	// finished processing this item. We also must remember to call Forget
	// if we do not want this work item being re-queued. For example, we do
	// not call Forget if a transient error occurs, instead the item is
	// put back on the workqueue and attempted again after a back-off
	// period.
	defer c.workqueue.Done(objRef)

	// Run the syncHandler, passing it the structured reference to the object to be synced.
	err := c.syncHandler(ctx, objRef)
	if err == nil {
		// If no error occurs then we Forget this item so it does not
		// get queued again until another change happens.
		c.workqueue.Forget(objRef)
		logger.Info("Successfully synced", "objectName", objRef)
		return true
	}
	// there was a failure so be sure to report it.  This method allows for
	// pluggable error handling which can be used for things like
	// cluster-monitoring.
	utilruntime.HandleErrorWithContext(ctx, err, "Error syncing; requeuing for later retry", "objectReference", objRef)
	// since we failed, we should requeue the item to work on later.  This
	// method will add a backoff to avoid hotlooping on particular items
	// (they're probably still not going to work right away) and overall
	// controller protection (everything I've done is broken, this controller
	// needs to calm down or it can starve other useful work) cases.
	c.workqueue.AddRateLimited(objRef)
	return true
}

// syncHandler compares the actual state with the desired, and attempts to
// converge the two. It then updates the Status block of the Foo resource