add union registry for quota

pkg/controller/resourcequota/replenishment_controller.go

@@ -214,7 +214,7 @@ func (r *replenishmentControllerFactory) NewController(options *ReplenishmentCon
 			},
 		)
 	default:
-		return nil, fmt.Errorf("no replenishment controller available for %s", options.GroupKind)
+		return nil, NewUnhandledGroupKindError(options.GroupKind)
 	}
 	return result, nil
 }
@@ -229,3 +229,38 @@ func ServiceReplenishmentUpdateFunc(options *ReplenishmentControllerOptions) fun
 		}
 	}
 }
+
+type unhandledKindErr struct {
+	kind unversioned.GroupKind
+}
+
+func (e unhandledKindErr) Error() string {
+	return fmt.Sprintf("no replenishment controller available for %s", e.kind)
+}
+
+func NewUnhandledGroupKindError(kind unversioned.GroupKind) error {
+	return unhandledKindErr{kind: kind}
+}
+
+func IsUnhandledGroupKindError(err error) bool {
+	if err == nil {
+		return false
+	}
+	_, ok := err.(unhandledKindErr)
+	return ok
+}
+
+// UnionReplenishmentControllerFactory iterates through its constituent factories ignoring, UnhandledGroupKindErrors
+// returning the first success or failure it hits.  If there are no hits either way, it return an UnhandledGroupKind error
+type UnionReplenishmentControllerFactory []ReplenishmentControllerFactory
+
+func (f UnionReplenishmentControllerFactory) NewController(options *ReplenishmentControllerOptions) (framework.ControllerInterface, error) {
+	for _, factory := range f {
+		controller, err := factory.NewController(options)
+		if !IsUnhandledGroupKindError(err) {
+			return controller, err
+		}
+	}
+
+	return nil, NewUnhandledGroupKindError(options.GroupKind)
+}

pkg/quota/interfaces.go

@@ -64,3 +64,19 @@ type Registry interface {
 	// Evaluators returns the set Evaluator objects registered to a groupKind
 	Evaluators() map[unversioned.GroupKind]Evaluator
 }
+
+// UnionRegistry combines multiple registries.  Order matters because first registry to claim a GroupKind
+// is the "winner"
+type UnionRegistry []Registry
+
+func (r UnionRegistry) Evaluators() map[unversioned.GroupKind]Evaluator {
+	ret := map[unversioned.GroupKind]Evaluator{}
+
+	for i := len(r) - 1; i >= 0; i-- {
+		for k, v := range r[i].Evaluators() {
+			ret[k] = v
+		}
+	}
+
+	return ret
+}