Function newInformer

tools/cache/controller.go:334–380

newInformer returns a controller for populating the store while also providing event notifications. Parameters * lw is list and watch functions for the source of the resource you want to be informed of. * objType is an object of the type that you expect to receive. * resyncPeriod: if non-zero, will

(
	lw ListerWatcher,
	objType runtime.Object,
	resyncPeriod time.Duration,
	h ResourceEventHandler,
	clientState Store,
)

//  * clientState is the store you want to populate
//
func newInformer(
	lw ListerWatcher,
	objType runtime.Object,
	resyncPeriod time.Duration,
	h ResourceEventHandler,
	clientState Store,
) Controller {
	// This will hold incoming changes. Note how we pass clientState in as a
	// KeyLister, that way resync operations will result in the correct set
	// of update/delete deltas.
	fifo := NewDeltaFIFO(MetaNamespaceKeyFunc, clientState)

	cfg := &Config{
		Queue:            fifo,
		ListerWatcher:    lw,
		ObjectType:       objType,
		FullResyncPeriod: resyncPeriod,
		RetryOnError:     false,

		Process: func(obj interface{}) error {
			// from oldest to newest
			for _, d := range obj.(Deltas) {
				switch d.Type {
				case Sync, Added, Updated:
					if old, exists, err := clientState.Get(d.Object); err == nil && exists {
						if err := clientState.Update(d.Object); err != nil {
							return err
						}
						h.OnUpdate(old, d.Object)
					} else {
						if err := clientState.Add(d.Object); err != nil {
							return err
						}
						h.OnAdd(d.Object)
					}
				case Deleted:
					if err := clientState.Delete(d.Object); err != nil {
						return err
					}
					h.OnDelete(d.Object)
				}
			}
			return nil
		},
	}
	return New(cfg)
}