Merge pull request #63386 from roycaihw/gc-json-patch

Automatic merge from submit-queue (batch tested with PRs 63386, 64624, 62297, 64847). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Let the garbage collector use json merge patch when SMP is not supported

**What this PR does / why we need it**:
Let garbage collector fallback to use json merge patch when strategic merge patch returns 415. This enables orphan delete on custom resources. 

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #56348

**Special notes for your reviewer**:
This PR is developed based on https://github.com/kubernetes/kubernetes/pull/56595. Ref https://github.com/kubernetes/kubernetes/pull/56606 for more information. 

**Release note**:

```release-note
Orphan delete is now supported for custom resources
```

/sig api-machinery

pkg/controller/garbagecollector/graph_builder.go

@@ -78,7 +78,7 @@ type GraphBuilder struct {
 	// each monitor list/watches a resource, the results are funneled to the
 	// dependencyGraphBuilder
 	monitors    monitors
-	monitorLock sync.Mutex
+	monitorLock sync.RWMutex
 	// informersStarted is closed after after all of the controllers have been initialized and are running.
 	// After that it is safe to start them here, before that it is not.
 	informersStarted <-chan struct{}
@@ -111,6 +111,7 @@ type GraphBuilder struct {
 // monitor runs a Controller with a local stop channel.
 type monitor struct {
 	controller cache.Controller
+	store      cache.Store
 
 	// stopCh stops Controller. If stopCh is nil, the monitor is considered to be
 	// not yet started.
@@ -138,7 +139,7 @@ func listWatcher(client dynamic.Interface, resource schema.GroupVersionResource)
 	}
 }
 
-func (gb *GraphBuilder) controllerFor(resource schema.GroupVersionResource, kind schema.GroupVersionKind) (cache.Controller, error) {
+func (gb *GraphBuilder) controllerFor(resource schema.GroupVersionResource, kind schema.GroupVersionKind) (cache.Controller, cache.Store, error) {
 	handlers := cache.ResourceEventHandlerFuncs{
 		// add the event to the dependencyGraphBuilder's graphChanges.
 		AddFunc: func(obj interface{}) {
@@ -178,21 +179,21 @@ func (gb *GraphBuilder) controllerFor(resource schema.GroupVersionResource, kind
 		glog.V(4).Infof("using a shared informer for resource %q, kind %q", resource.String(), kind.String())
 		// need to clone because it's from a shared cache
 		shared.Informer().AddEventHandlerWithResyncPeriod(handlers, ResourceResyncTime)
-		return shared.Informer().GetController(), nil
+		return shared.Informer().GetController(), shared.Informer().GetStore(), nil
 	} else {
 		glog.V(4).Infof("unable to use a shared informer for resource %q, kind %q: %v", resource.String(), kind.String(), err)
 	}
 
 	// TODO: consider store in one storage.
 	glog.V(5).Infof("create storage for resource %s", resource)
-	_, monitor := cache.NewInformer(
+	store, monitor := cache.NewInformer(
 		listWatcher(gb.dynamicClient, resource),
 		nil,
 		ResourceResyncTime,
 		// don't need to clone because it's not from shared cache
 		handlers,
 	)
-	return monitor, nil
+	return monitor, store, nil
 }
 
 // syncMonitors rebuilds the monitor set according to the supplied resources,
@@ -228,12 +229,12 @@ func (gb *GraphBuilder) syncMonitors(resources map[schema.GroupVersionResource]s
 			errs = append(errs, fmt.Errorf("couldn't look up resource %q: %v", resource, err))
 			continue
 		}
-		c, err := gb.controllerFor(resource, kind)
+		c, s, err := gb.controllerFor(resource, kind)
 		if err != nil {
 			errs = append(errs, fmt.Errorf("couldn't start monitor for resource %q: %v", resource, err))
 			continue
 		}
-		current[resource] = &monitor{controller: c}
+		current[resource] = &monitor{store: s, controller: c}
 		added++
 	}
 	gb.monitors = current