POC for wrapping handler.EventHandler

Author: erikgb

pkg/builder/controller.go

@@ -97,10 +97,11 @@ func (blder *Builder) For(object client.Object, opts ...ForOption) *Builder {
 
 // OwnsInput represents the information set by Owns method.
 type OwnsInput struct {
-	matchEveryOwner  bool
-	object           client.Object
-	predicates       []predicate.Predicate
-	objectProjection objectProjection
+	matchEveryOwner     bool
+	object              client.Object
+	predicates          []predicate.Predicate
+	objectProjection    objectProjection
+	eventHandlerWrapper handler.EventHandlerWrapper
 }
 
 // Owns defines types of Objects being *generated* by the ControllerManagedBy, and configures the ControllerManagedBy to respond to
@@ -300,6 +301,9 @@ func (blder *Builder) doWatch() error {
 			blder.forInput.object,
 			opts...,
 		)
+		if own.eventHandlerWrapper != nil {
+			hdler = own.eventHandlerWrapper.Wrap(hdler)
+		}
 		allPredicates := append([]predicate.Predicate(nil), blder.globalPredicates...)
 		allPredicates = append(allPredicates, own.predicates...)
 		if err := blder.ctrl.Watch(src, hdler, allPredicates...); err != nil {

pkg/builder/options.go

@@ -17,6 +17,7 @@ limitations under the License.
 package builder
 
 import (
+	"sigs.k8s.io/controller-runtime/pkg/handler"
 	"sigs.k8s.io/controller-runtime/pkg/predicate"
 )
 
@@ -154,3 +155,20 @@ type matchEveryOwner struct{}
 func (o matchEveryOwner) ApplyToOwns(opts *OwnsInput) {
 	opts.matchEveryOwner = true
 }
+
+// WithEventHandlerWrapper sets the given wrapper event handler.
+func WithEventHandlerWrapper(wrapper handler.EventHandlerWrapper) EventHandlerWrapper {
+	return EventHandlerWrapper{
+		wrapper: wrapper,
+	}
+}
+
+// EventHandlerWrapper can act as a decorator for another EventHandler
+type EventHandlerWrapper struct {
+	wrapper handler.EventHandlerWrapper
+}
+
+// ApplyToOwns applies this configuration to the given OwnsInput options.
+func (e EventHandlerWrapper) ApplyToOwns(opts *OwnsInput) {
+	opts.eventHandlerWrapper = e.wrapper
+}

pkg/handler/eventhandler.go

@@ -56,6 +56,12 @@ type EventHandler interface {
 	Generic(context.Context, event.GenericEvent, workqueue.RateLimitingInterface)
 }
 
+// EventHandlerWrapper can act as a decorator for another EventHandler
+type EventHandlerWrapper interface {
+	EventHandler
+	Wrap(wrappee EventHandler) EventHandler
+}
+
 var _ EventHandler = Funcs{}
 
 // Funcs implements EventHandler.