如何避免在同步时调用`updateFunc`？

Question

From what I understand (and experience) - kubernetes informers calls updateFunc each "sync" event of its cache - From what I gather it is due to this annoying peace of code.

An example informer definition:

informer:= NewInformer(
&cache.ListWatch{
ListFunc: func(options api.ListOptions) (runtime.Object, error) {
  return kubeClient.Batch().Jobs(api.NamespaceAll).List(options)
},
WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
  return kubeClient.Batch().Jobs(api.NamespaceAll).Watch(options)
},....)

...

informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
    AddFunc: func(obj interface{}){},
    // Make this function be called *only* on update. 
    UpdateFunc: func(old, current interface{}){},
    DeleteFunc: func(current interface{}){},
})

But for my use case - calling updateFunc should really happen only when that resource is updated (e.g. I am doing some intense computation on each update or going to I/O).

I was wandering is there a way to call updateFunc only on update?

Answer 1

I found answer in this github issue:

If resourceVersion differs between old and new, an actual update event was observed.