Make event handler type aware

Signed-off-by: Danil Grigorev <danil.grigorev@suse.com>

pkg/internal/source/kind.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"reflect"
 	"time"
 
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -17,9 +18,9 @@ import (
 )
 
 // Kind is used to provide a source of events originating inside the cluster from Watches (e.g. Pod Create).
-type Kind struct {
+type Kind[T client.Object] struct {
 	// Type is the type of object to watch.  e.g. &v1.Pod{}
-	Type client.Object
+	Type T
 
 	// Cache used to watch APIs
 	Cache cache.Cache
@@ -32,9 +33,9 @@ type Kind struct {
 
 // Start is internal and should be called only by the Controller to register an EventHandler with the Informer
 // to enqueue reconcile.Requests.
-func (ks *Kind) Start(ctx context.Context, handler handler.EventHandler, queue workqueue.RateLimitingInterface,
+func (ks *Kind[T]) Start(ctx context.Context, handler handler.EventHandler, queue workqueue.RateLimitingInterface,
 	prct ...predicate.Predicate) error {
-	if ks.Type == nil {
+	if reflect.DeepEqual(ks.Type, *new(T)) {
 		return fmt.Errorf("must create Kind with a non-nil object")
 	}
 	if ks.Cache == nil {
@@ -79,7 +80,7 @@ func (ks *Kind) Start(ctx context.Context, handler handler.EventHandler, queue w
 			return
 		}
 
-		_, err := i.AddEventHandler(NewEventHandler(ctx, queue, handler, prct).HandlerFuncs())
+		_, err := i.AddEventHandler(NewObjectEventHandler[T](ctx, queue, handler, prct).HandlerFuncs())
 		if err != nil {
 			ks.started <- err
 			return
@@ -94,16 +95,16 @@ func (ks *Kind) Start(ctx context.Context, handler handler.EventHandler, queue w
 	return nil
 }
 
-func (ks *Kind) String() string {
-	if ks.Type != nil {
+func (ks *Kind[T]) String() string {
+	if !reflect.DeepEqual(ks.Type, *new(T)) {
 		return fmt.Sprintf("kind source: %T", ks.Type)
 	}
 	return "kind source: unknown type"
 }
 
 // WaitForSync implements SyncingSource to allow controllers to wait with starting
 // workers until the cache is synced.
-func (ks *Kind) WaitForSync(ctx context.Context) error {
+func (ks *Kind[T]) WaitForSync(ctx context.Context) error {
 	select {
 	case err := <-ks.started:
 		return err

pkg/internal/source/object_event_handler.go

@@ -0,0 +1,167 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package internal
+
+import (
+	"context"
+	"fmt"
+
+	"k8s.io/client-go/tools/cache"
+	"k8s.io/client-go/util/workqueue"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/event"
+	"sigs.k8s.io/controller-runtime/pkg/handler"
+
+	"sigs.k8s.io/controller-runtime/pkg/predicate"
+)
+
+// NewObjectEventHandler creates a new TypedEventHandler.
+func NewObjectEventHandler[T client.Object](ctx context.Context, queue workqueue.RateLimitingInterface, handler handler.EventHandler, predicates []predicate.Predicate) *ObjectEventHandler[T] {
+	return &ObjectEventHandler[T]{
+		ctx:        ctx,
+		handler:    handler,
+		queue:      queue,
+		predicates: predicates,
+	}
+}
+
+// ObjectEventHandler adapts a handler.EventHandler interface to a cache.ResourceEventHandler interface.
+type ObjectEventHandler[T client.Object] struct {
+	// ctx stores the context that created the event handler
+	// that is used to propagate cancellation signals to each handler function.
+	ctx context.Context
+
+	handler    handler.EventHandler
+	queue      workqueue.RateLimitingInterface
+	predicates []predicate.Predicate
+}
+
+// HandlerFuncs converts EventHandler to a ResourceEventHandlerFuncs
+// TODO: switch to ResourceEventHandlerDetailedFuncs with client-go 1.27
+func (e *ObjectEventHandler[T]) HandlerFuncs() cache.ResourceEventHandlerFuncs {
+	return cache.ResourceEventHandlerFuncs{
+		AddFunc:    e.OnAdd,
+		UpdateFunc: e.OnUpdate,
+		DeleteFunc: e.OnDelete,
+	}
+}
+
+// OnAdd creates CreateEvent and calls Create on EventHandler.
+func (e *ObjectEventHandler[T]) OnAdd(obj interface{}) {
+	c := event.CreateEvent{}
+
+	// Pull Object out of the object
+	if o, ok := obj.(T); ok {
+		c.Object = o
+	} else {
+		log.Error(nil, "OnAdd missing Object",
+			"object", obj, "type", fmt.Sprintf("%T", obj))
+		return
+	}
+
+	for _, p := range e.predicates {
+		if !p.Create(c) {
+			return
+		}
+	}
+
+	// Invoke create handler
+	ctx, cancel := context.WithCancel(e.ctx)
+	defer cancel()
+	e.handler.Create(ctx, c, e.queue)
+}
+
+// OnUpdate creates UpdateEvent and calls Update on EventHandler.
+func (e *ObjectEventHandler[T]) OnUpdate(oldObj, newObj interface{}) {
+	u := event.UpdateEvent{}
+
+	if o, ok := oldObj.(T); ok {
+		u.ObjectOld = o
+	} else {
+		log.Error(nil, "OnUpdate missing ObjectOld",
+			"object", oldObj, "type", fmt.Sprintf("%T", oldObj))
+		return
+	}
+
+	// Pull Object out of the object
+	if o, ok := newObj.(T); ok {
+		u.ObjectNew = o
+	} else {
+		log.Error(nil, "OnUpdate missing ObjectNew",
+			"object", newObj, "type", fmt.Sprintf("%T", newObj))
+		return
+	}
+
+	for _, p := range e.predicates {
+		if !p.Update(u) {
+			return
+		}
+	}
+
+	// Invoke update handler
+	ctx, cancel := context.WithCancel(e.ctx)
+	defer cancel()
+	e.handler.Update(ctx, u, e.queue)
+}
+
+// OnDelete creates DeleteEvent and calls Delete on EventHandler.
+func (e *ObjectEventHandler[T]) OnDelete(obj interface{}) {
+	d := event.DeleteEvent{}
+
+	// Deal with tombstone events by pulling the object out.  Tombstone events wrap the object in a
+	// DeleteFinalStateUnknown struct, so the object needs to be pulled out.
+	// Copied from sample-controller
+	// This should never happen if we aren't missing events, which we have concluded that we are not
+	// and made decisions off of this belief.  Maybe this shouldn't be here?
+	var ok bool
+	if _, ok = obj.(T); !ok {
+		// If the object doesn't have Metadata, assume it is a tombstone object of type DeletedFinalStateUnknown
+		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
+		if !ok {
+			log.Error(nil, "Error decoding objects.  Expected cache.DeletedFinalStateUnknown",
+				"type", fmt.Sprintf("%T", obj),
+				"object", obj)
+			return
+		}
+
+		// Set DeleteStateUnknown to true
+		d.DeleteStateUnknown = true
+
+		// Set obj to the tombstone obj
+		obj = tombstone.Obj
+	}
+
+	// Pull Object out of the object
+	if o, ok := obj.(T); ok {
+		d.Object = o
+	} else {
+		log.Error(nil, "OnDelete missing Object",
+			"object", obj, "type", fmt.Sprintf("%T", obj))
+		return
+	}
+
+	for _, p := range e.predicates {
+		if !p.Delete(d) {
+			return
+		}
+	}
+
+	// Invoke delete handler
+	ctx, cancel := context.WithCancel(e.ctx)
+	defer cancel()
+	e.handler.Delete(ctx, d, e.queue)
+}