diff --git a/staging/src/k8s.io/client-go/tools/cache/controller.go b/staging/src/k8s.io/client-go/tools/cache/controller.go index e8fe670651c..2c97b86580c 100644 --- a/staging/src/k8s.io/client-go/tools/cache/controller.go +++ b/staging/src/k8s.io/client-go/tools/cache/controller.go @@ -207,6 +207,47 @@ func (r ResourceEventHandlerFuncs) OnDelete(obj interface{}) { } } +// FilteringResourceEventHandler applies the provided filter to all events coming +// in, ensuring the appropriate nested handler method is invoked. An object +// that starts passing the filter after an update is considered an add, and an +// object that stops passing the filter after an update is considered a delete. +type FilteringResourceEventHandler struct { + FilterFunc func(obj interface{}) bool + Handler ResourceEventHandler +} + +// OnAdd calls the nested handler only if the filter succeeds +func (r FilteringResourceEventHandler) OnAdd(obj interface{}) { + if !r.FilterFunc(obj) { + return + } + r.Handler.OnAdd(obj) +} + +// OnUpdate ensures the proper handler is called depending on whether the filter matches +func (r FilteringResourceEventHandler) OnUpdate(oldObj, newObj interface{}) { + newer := r.FilterFunc(newObj) + older := r.FilterFunc(oldObj) + switch { + case newer && older: + r.Handler.OnUpdate(oldObj, newObj) + case newer && !older: + r.Handler.OnAdd(newObj) + case !newer && older: + r.Handler.OnDelete(oldObj) + default: + // do nothing + } +} + +// OnDelete calls the nested handler only if the filter succeeds +func (r FilteringResourceEventHandler) OnDelete(obj interface{}) { + if !r.FilterFunc(obj) { + return + } + r.Handler.OnDelete(obj) +} + // DeletionHandlingMetaNamespaceKeyFunc checks for // DeletedFinalStateUnknown objects before calling // MetaNamespaceKeyFunc.