Merge pull request #24509 from caesarxuchao/primitive-gc

Automatic merge from submit-queue

Adding garbage collector controller

Adding the propagator and garbage processor of the gc.

Design doc is at https://github.com/kubernetes/kubernetes/blob/master/docs/proposals/garbage-collection.md

<!-- Reviewable:start -->
---
This change is [<img src="http://reviewable.k8s.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](http://reviewable.k8s.io/reviews/kubernetes/kubernetes/24509)
<!-- Reviewable:end -->

cmd/kube-controller-manager/app/controllermanager.go

@@ -298,7 +298,7 @@ func StartControllers(s *options.CMServer, kubeClient *client.Client, kubeconfig
 	// Find the list of namespaced resources via discovery that the namespace controller must manage
 	namespaceKubeClient := clientset.NewForConfigOrDie(restclient.AddUserAgent(kubeconfig, "namespace-controller"))
 	namespaceClientPool := dynamic.NewClientPool(restclient.AddUserAgent(kubeconfig, "namespace-controller"), dynamic.LegacyAPIPathResolverFunc)
-	groupVersionResources, err := namespacecontroller.ServerPreferredNamespacedGroupVersionResources(namespaceKubeClient.Discovery())
+	groupVersionResources, err := namespaceKubeClient.Discovery().ServerPreferredNamespacedResources()
 	if err != nil {
 		glog.Fatalf("Failed to get supported resources from server: %v", err)
 	}

contrib/mesos/pkg/controllermanager/controllermanager.go

@@ -220,7 +220,7 @@ func (s *CMServer) Run(_ []string) error {
 	// Find the list of namespaced resources via discovery that the namespace controller must manage
 	namespaceKubeClient := clientset.NewForConfigOrDie(restclient.AddUserAgent(kubeconfig, "namespace-controller"))
 	namespaceClientPool := dynamic.NewClientPool(restclient.AddUserAgent(kubeconfig, "namespace-controller"), dynamic.LegacyAPIPathResolverFunc)
-	groupVersionResources, err := namespacecontroller.ServerPreferredNamespacedGroupVersionResources(namespaceKubeClient.Discovery())
+	groupVersionResources, err := namespaceKubeClient.Discovery().ServerPreferredNamespacedResources()
 	if err != nil {
 		glog.Fatalf("Failed to get supported resources from server: %v", err)
 	}

hack/test-integration.sh

@@ -32,7 +32,9 @@ source "${KUBE_ROOT}/hack/lib/init.sh"
 KUBE_TEST_API_VERSIONS=${KUBE_TEST_API_VERSIONS:-"v1,extensions/v1beta1;v1,autoscaling/v1,batch/v1,apps/v1alpha1,policy/v1alpha1,extensions/v1beta1"}
 
 # Give integration tests longer to run
-KUBE_TIMEOUT=${KUBE_TIMEOUT:--timeout 240s}
+# TODO: allow a larger value to be passed in
+#KUBE_TIMEOUT=${KUBE_TIMEOUT:--timeout 240s}
+KUBE_TIMEOUT="-timeout 600s"
 KUBE_INTEGRATION_TEST_MAX_CONCURRENCY=${KUBE_INTEGRATION_TEST_MAX_CONCURRENCY:-"-1"}
 LOG_LEVEL=${LOG_LEVEL:-2}
 

pkg/api/meta.go

@@ -17,6 +17,7 @@ limitations under the License.
 package api
 
 import (
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/conversion"
 	"k8s.io/kubernetes/pkg/runtime"
@@ -89,3 +90,25 @@ func (meta *ObjectMeta) GetLabels() map[string]string                 { return m
 func (meta *ObjectMeta) SetLabels(labels map[string]string)           { meta.Labels = labels }
 func (meta *ObjectMeta) GetAnnotations() map[string]string            { return meta.Annotations }
 func (meta *ObjectMeta) SetAnnotations(annotations map[string]string) { meta.Annotations = annotations }
+
+func (meta *ObjectMeta) GetOwnerReferences() []metatypes.OwnerReference {
+	ret := make([]metatypes.OwnerReference, len(meta.OwnerReferences))
+	for i := 0; i < len(meta.OwnerReferences); i++ {
+		ret[i].Kind = meta.OwnerReferences[i].Kind
+		ret[i].Name = meta.OwnerReferences[i].Name
+		ret[i].UID = meta.OwnerReferences[i].UID
+		ret[i].APIVersion = meta.OwnerReferences[i].APIVersion
+	}
+	return ret
+}
+
+func (meta *ObjectMeta) SetOwnerReferences(references []metatypes.OwnerReference) {
+	newReferences := make([]OwnerReference, len(references))
+	for i := 0; i < len(references); i++ {
+		newReferences[i].Kind = references[i].Kind
+		newReferences[i].Name = references[i].Name
+		newReferences[i].UID = references[i].UID
+		newReferences[i].APIVersion = references[i].APIVersion
+	}
+	meta.OwnerReferences = newReferences
+}

pkg/api/meta/interfaces.go

@@ -17,6 +17,7 @@ limitations under the License.
 package meta
 
 import (
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/types"
@@ -57,6 +58,14 @@ type Object interface {
 	SetLabels(labels map[string]string)
 	GetAnnotations() map[string]string
 	SetAnnotations(annotations map[string]string)
+	GetOwnerReferences() []metatypes.OwnerReference
+	SetOwnerReferences([]metatypes.OwnerReference)
+}
+
+var _ Object = &runtime.Unstructured{}
+
+type ListMetaAccessor interface {
+	GetListMeta() List
 }
 
 // List lets you work with list metadata from any of the versioned or
@@ -177,5 +186,3 @@ type RESTMapper interface {
 	AliasesForResource(resource string) ([]string, bool)
 	ResourceSingularizer(resource string) (singular string, err error)
 }
-
-var _ Object = &runtime.Unstructured{}

pkg/api/meta/meta.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"reflect"
 
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/conversion"
 	"k8s.io/kubernetes/pkg/runtime"
@@ -28,19 +29,53 @@ import (
 	"github.com/golang/glog"
 )
 
+func ListAccessor(obj interface{}) (List, error) {
+	if listMetaAccessor, ok := obj.(ListMetaAccessor); ok {
+		if om := listMetaAccessor.GetListMeta(); om != nil {
+			return om, nil
+		}
+	}
+	// we may get passed an object that is directly portable to List
+	if list, ok := obj.(List); ok {
+		return list, nil
+	}
+	glog.V(4).Infof("Calling ListAccessor on non-internal object: %v", reflect.TypeOf(obj))
+	// legacy path for objects that do not implement List and ListMetaAccessor via
+	// reflection - very slow code path.
+	v, err := conversion.EnforcePtr(obj)
+	if err != nil {
+		return nil, err
+	}
+	t := v.Type()
+	if v.Kind() != reflect.Struct {
+		return nil, fmt.Errorf("expected struct, but got %v: %v (%#v)", v.Kind(), t, v.Interface())
+	}
+	a := &genericAccessor{}
+	listMeta := v.FieldByName("ListMeta")
+	if listMeta.IsValid() {
+		// look for the ListMeta fields
+		if err := extractFromListMeta(listMeta, a); err != nil {
+			return nil, fmt.Errorf("unable to find list fields on %#v: %v", listMeta, err)
+		}
+	} else {
+		return nil, fmt.Errorf("unable to find listMeta on %#v", v)
+	}
+	return a, nil
+}
+
 // Accessor takes an arbitrary object pointer and returns meta.Interface.
 // obj must be a pointer to an API type. An error is returned if the minimum
 // required fields are missing. Fields that are not required return the default
 // value and are a no-op if set.
 func Accessor(obj interface{}) (Object, error) {
-	if oi, ok := obj.(ObjectMetaAccessor); ok {
-		if om := oi.GetObjectMeta(); om != nil {
+	if objectMetaAccessor, ok := obj.(ObjectMetaAccessor); ok {
+		if om := objectMetaAccessor.GetObjectMeta(); om != nil {
 			return om, nil
 		}
 	}
 	// we may get passed an object that is directly portable to Object
-	if oi, ok := obj.(Object); ok {
-		return oi, nil
+	if object, ok := obj.(Object); ok {
+		return object, nil
 	}
 
 	glog.V(4).Infof("Calling Accessor on non-internal object: %v", reflect.TypeOf(obj))
@@ -310,6 +345,40 @@ func (resourceAccessor) SetResourceVersion(obj runtime.Object, version string) e
 	return nil
 }
 
+// extractFromOwnerReference extracts v to o. v is the OwnerReferences field of an object.
+func extractFromOwnerReference(v reflect.Value, o *metatypes.OwnerReference) error {
+	if err := runtime.Field(v, "APIVersion", &o.APIVersion); err != nil {
+		return err
+	}
+	if err := runtime.Field(v, "Kind", &o.Kind); err != nil {
+		return err
+	}
+	if err := runtime.Field(v, "Name", &o.Name); err != nil {
+		return err
+	}
+	if err := runtime.Field(v, "UID", &o.UID); err != nil {
+		return err
+	}
+	return nil
+}
+
+// setOwnerReference sets v to o. v is the OwnerReferences field of an object.
+func setOwnerReference(v reflect.Value, o *metatypes.OwnerReference) error {
+	if err := runtime.SetField(o.APIVersion, v, "APIVersion"); err != nil {
+		return err
+	}
+	if err := runtime.SetField(o.Kind, v, "Kind"); err != nil {
+		return err
+	}
+	if err := runtime.SetField(o.Name, v, "Name"); err != nil {
+		return err
+	}
+	if err := runtime.SetField(o.UID, v, "UID"); err != nil {
+		return err
+	}
+	return nil
+}
+
 // genericAccessor contains pointers to strings that can modify an arbitrary
 // struct and implements the Accessor interface.
 type genericAccessor struct {
@@ -325,6 +394,7 @@ type genericAccessor struct {
 	deletionTimestamp **unversioned.Time
 	labels            *map[string]string
 	annotations       *map[string]string
+	ownerReferences   reflect.Value
 }
 
 func (a genericAccessor) GetNamespace() string {
@@ -457,6 +527,41 @@ func (a genericAccessor) SetAnnotations(annotations map[string]string) {
 	*a.annotations = annotations
 }
 
+func (a genericAccessor) GetOwnerReferences() []metatypes.OwnerReference {
+	var ret []metatypes.OwnerReference
+	s := a.ownerReferences
+	if s.Kind() != reflect.Ptr || s.Elem().Kind() != reflect.Slice {
+		glog.Errorf("expect %v to be a pointer to slice", s)
+		return ret
+	}
+	s = s.Elem()
+	// Set the capacity to one element greater to avoid copy if the caller later append an element.
+	ret = make([]metatypes.OwnerReference, s.Len(), s.Len()+1)
+	for i := 0; i < s.Len(); i++ {
+		if err := extractFromOwnerReference(s.Index(i), &ret[i]); err != nil {
+			glog.Errorf("extractFromOwnerReference failed: %v", err)
+			return ret
+		}
+	}
+	return ret
+}
+
+func (a genericAccessor) SetOwnerReferences(references []metatypes.OwnerReference) {
+	s := a.ownerReferences
+	if s.Kind() != reflect.Ptr || s.Elem().Kind() != reflect.Slice {
+		glog.Errorf("expect %v to be a pointer to slice", s)
+	}
+	s = s.Elem()
+	newReferences := reflect.MakeSlice(s.Type(), len(references), len(references))
+	for i := 0; i < len(references); i++ {
+		if err := setOwnerReference(newReferences.Index(i), &references[i]); err != nil {
+			glog.Errorf("setOwnerReference failed: %v", err)
+			return
+		}
+	}
+	s.Set(newReferences)
+}
+
 // extractFromTypeMeta extracts pointers to version and kind fields from an object
 func extractFromTypeMeta(v reflect.Value, a *genericAccessor) error {
 	if err := runtime.FieldPtr(v, "APIVersion", &a.apiVersion); err != nil {
@@ -494,6 +599,14 @@ func extractFromObjectMeta(v reflect.Value, a *genericAccessor) error {
 	if err := runtime.FieldPtr(v, "Annotations", &a.annotations); err != nil {
 		return err
 	}
+	ownerReferences := v.FieldByName("OwnerReferences")
+	if !ownerReferences.IsValid() {
+		return fmt.Errorf("struct %#v lacks OwnerReferences type", v)
+	}
+	if ownerReferences.Kind() != reflect.Slice {
+		return fmt.Errorf("expect %v to be a slice", ownerReferences.Kind())
+	}
+	a.ownerReferences = ownerReferences.Addr()
 	return nil
 }
 

pkg/api/meta/meta_test.go

@@ -20,9 +20,13 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/google/gofuzz"
+
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/api/meta"
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/api/v1"
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/types"
 )
@@ -138,6 +142,7 @@ func TestGenericTypeMeta(t *testing.T) {
 		APIVersion        string               `json:"apiVersion,omitempty"`
 		Labels            map[string]string    `json:"labels,omitempty"`
 		Annotations       map[string]string    `json:"annotations,omitempty"`
+		OwnerReferences   []api.OwnerReference `json:"ownerReferences,omitempty"`
 	}
 	type Object struct {
 		TypeMeta `json:",inline"`
@@ -247,7 +252,9 @@ type InternalTypeMeta struct {
 	APIVersion        string               `json:"apiVersion,omitempty"`
 	Labels            map[string]string    `json:"labels,omitempty"`
 	Annotations       map[string]string    `json:"annotations,omitempty"`
+	OwnerReferences   []api.OwnerReference `json:"ownerReferences,omitempty"`
 }
+
 type InternalObject struct {
 	TypeMeta InternalTypeMeta `json:",inline"`
 }
@@ -273,6 +280,7 @@ func TestGenericTypeMetaAccessor(t *testing.T) {
 			SelfLink:        "some/place/only/we/know",
 			Labels:          map[string]string{"foo": "bar"},
 			Annotations:     map[string]string{"x": "y"},
+			// OwnerReferences are tested separately
 		},
 	}
 	accessor := meta.NewAccessor()
@@ -427,6 +435,7 @@ func TestGenericObjectMeta(t *testing.T) {
 		ResourceVersion   string               `json:"resourceVersion,omitempty"`
 		Labels            map[string]string    `json:"labels,omitempty"`
 		Annotations       map[string]string    `json:"annotations,omitempty"`
+		OwnerReferences   []api.OwnerReference `json:"ownerReferences,omitempty"`
 	}
 	type Object struct {
 		TypeMeta   `json:",inline"`
@@ -722,6 +731,66 @@ func TestTypeMetaSelfLinker(t *testing.T) {
 	}
 }
 
+type MyAPIObject2 struct {
+	unversioned.TypeMeta
+	v1.ObjectMeta
+}
+
+func getObjectMetaAndOwnerRefereneces() (myAPIObject2 MyAPIObject2, metaOwnerReferences []metatypes.OwnerReference) {
+	fuzz.New().NilChance(.5).NumElements(1, 5).Fuzz(&myAPIObject2)
+	references := myAPIObject2.ObjectMeta.OwnerReferences
+	// This is necessary for the test to pass because the getter will return a
+	// non-nil slice.
+	metaOwnerReferences = make([]metatypes.OwnerReference, 0)
+	for i := 0; i < len(references); i++ {
+		metaOwnerReferences = append(metaOwnerReferences, metatypes.OwnerReference{
+			Kind:       references[i].Kind,
+			Name:       references[i].Name,
+			UID:        references[i].UID,
+			APIVersion: references[i].APIVersion,
+		})
+	}
+	if len(references) == 0 {
+		// This is necessary for the test to pass because the setter will make a
+		// non-nil slice.
+		myAPIObject2.ObjectMeta.OwnerReferences = make([]v1.OwnerReference, 0)
+	}
+	return myAPIObject2, metaOwnerReferences
+}
+
+func testGetOwnerReferences(t *testing.T) {
+	obj, expected := getObjectMetaAndOwnerRefereneces()
+	accessor, err := meta.Accessor(&obj)
+	if err != nil {
+		t.Error(err)
+	}
+	references := accessor.GetOwnerReferences()
+	if !reflect.DeepEqual(references, expected) {
+		t.Errorf("expect %#v\n got %#v", expected, references)
+	}
+}
+
+func testSetOwnerReferences(t *testing.T) {
+	expected, references := getObjectMetaAndOwnerRefereneces()
+	obj := MyAPIObject2{}
+	accessor, err := meta.Accessor(&obj)
+	if err != nil {
+		t.Error(err)
+	}
+	accessor.SetOwnerReferences(references)
+	if e, a := expected.ObjectMeta.OwnerReferences, obj.ObjectMeta.OwnerReferences; !reflect.DeepEqual(e, a) {
+		t.Errorf("expect %#v\n got %#v", e, a)
+	}
+}
+
+func TestAccessOwnerReferences(t *testing.T) {
+	fuzzIter := 5
+	for i := 0; i < fuzzIter; i++ {
+		testGetOwnerReferences(t)
+		testSetOwnerReferences(t)
+	}
+}
+
 // BenchmarkAccessorSetFastPath shows the interface fast path
 func BenchmarkAccessorSetFastPath(b *testing.B) {
 	obj := &api.Pod{

pkg/api/meta/metatypes/deep_copy_generated.go

@@ -0,0 +1,33 @@
+// +build !ignore_autogenerated
+
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+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.
+*/
+
+// This file was autogenerated by deepcopy-gen. Do not edit it manually!
+
+package metatypes
+
+import (
+	conversion "k8s.io/kubernetes/pkg/conversion"
+)
+
+func DeepCopy_metatypes_OwnerReference(in OwnerReference, out *OwnerReference, c *conversion.Cloner) error {
+	out.APIVersion = in.APIVersion
+	out.Kind = in.Kind
+	out.UID = in.UID
+	out.Name = in.Name
+	return nil
+}

pkg/api/meta/metatypes/types.go

@@ -0,0 +1,29 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+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.
+*/
+
+// The types defined in this package are used by the meta package to represent
+// the in-memory version of objects. We cannot reuse the __internal version of
+// API objects because it causes import cycle.
+package metatypes
+
+import "k8s.io/kubernetes/pkg/types"
+
+type OwnerReference struct {
+	APIVersion string
+	Kind       string
+	UID        types.UID
+	Name       string
+}

pkg/api/meta_test.go

@@ -17,10 +17,14 @@ limitations under the License.
 package api_test
 
 import (
+	"reflect"
 	"testing"
 
+	"github.com/google/gofuzz"
+
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/api/meta"
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 )
 
 var _ meta.Object = &api.ObjectMeta{}
@@ -49,3 +53,46 @@ func TestHasObjectMetaSystemFieldValues(t *testing.T) {
 		t.Errorf("the resource does have all fields populated, but incorrectly reports it does not")
 	}
 }
+
+func getObjectMetaAndOwnerReferences() (objectMeta api.ObjectMeta, metaOwnerReferences []metatypes.OwnerReference) {
+	fuzz.New().NilChance(.5).NumElements(1, 5).Fuzz(&objectMeta)
+	references := objectMeta.OwnerReferences
+	metaOwnerReferences = make([]metatypes.OwnerReference, 0)
+	for i := 0; i < len(references); i++ {
+		metaOwnerReferences = append(metaOwnerReferences, metatypes.OwnerReference{
+			Kind:       references[i].Kind,
+			Name:       references[i].Name,
+			UID:        references[i].UID,
+			APIVersion: references[i].APIVersion,
+		})
+	}
+	if len(references) == 0 {
+		objectMeta.OwnerReferences = make([]api.OwnerReference, 0)
+	}
+	return objectMeta, metaOwnerReferences
+}
+
+func testGetOwnerReferences(t *testing.T) {
+	meta, expected := getObjectMetaAndOwnerReferences()
+	refs := meta.GetOwnerReferences()
+	if !reflect.DeepEqual(refs, expected) {
+		t.Errorf("expect %v\n got %v", expected, refs)
+	}
+}
+
+func testSetOwnerReferences(t *testing.T) {
+	expected, newRefs := getObjectMetaAndOwnerReferences()
+	objectMeta := &api.ObjectMeta{}
+	objectMeta.SetOwnerReferences(newRefs)
+	if !reflect.DeepEqual(expected.OwnerReferences, objectMeta.OwnerReferences) {
+		t.Errorf("expect: %#v\n got: %#v", expected.OwnerReferences, objectMeta.OwnerReferences)
+	}
+}
+
+func TestAccessOwnerReferences(t *testing.T) {
+	fuzzIter := 5
+	for i := 0; i < fuzzIter; i++ {
+		testGetOwnerReferences(t)
+		testSetOwnerReferences(t)
+	}
+}

pkg/client/cache/reflector.go

@@ -292,11 +292,11 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
 	if err != nil {
 		return fmt.Errorf("%s: Failed to list %v: %v", r.name, r.expectedType, err)
 	}
-	metaInterface, err := meta.Accessor(list)
+	listMetaInterface, err := meta.ListAccessor(list)
 	if err != nil {
-		return fmt.Errorf("%s: Unable to understand list result %#v", r.name, list)
+		return fmt.Errorf("%s: Unable to understand list result %#v: %v", r.name, list, err)
 	}
-	resourceVersion = metaInterface.GetResourceVersion()
+	resourceVersion = listMetaInterface.GetResourceVersion()
 	items, err := meta.ExtractList(list)
 	if err != nil {
 		return fmt.Errorf("%s: Unable to understand list result %#v (%v)", r.name, list, err)

pkg/client/typed/discovery/discovery_client.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/url"
+	"strings"
 
 	"github.com/emicklei/go-restful/swagger"
 
@@ -30,6 +31,7 @@ import (
 	"k8s.io/kubernetes/pkg/client/restclient"
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/runtime/serializer"
+	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/version"
 )
 
@@ -55,6 +57,12 @@ type ServerResourcesInterface interface {
 	ServerResourcesForGroupVersion(groupVersion string) (*unversioned.APIResourceList, error)
 	// ServerResources returns the supported resources for all groups and versions.
 	ServerResources() (map[string]*unversioned.APIResourceList, error)
+	// ServerPreferredResources returns the supported resources with the version preferred by the
+	// server.
+	ServerPreferredResources() ([]unversioned.GroupVersionResource, error)
+	// ServerPreferredNamespacedResources returns the supported namespaced resources with the
+	// version preferred by the server.
+	ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error)
 }
 
 // ServerVersionInterface has a method for retrieving the server's version.
@@ -163,6 +171,50 @@ func (d *DiscoveryClient) ServerResources() (map[string]*unversioned.APIResource
 	return result, nil
 }
 
+// serverPreferredResources returns the supported resources with the version preferred by the
+// server. If namespaced is true, only namespaced resources will be returned.
+func (d *DiscoveryClient) serverPreferredResources(namespaced bool) ([]unversioned.GroupVersionResource, error) {
+	results := []unversioned.GroupVersionResource{}
+	serverGroupList, err := d.ServerGroups()
+	if err != nil {
+		return results, err
+	}
+
+	allErrs := []error{}
+	for _, apiGroup := range serverGroupList.Groups {
+		preferredVersion := apiGroup.PreferredVersion
+		apiResourceList, err := d.ServerResourcesForGroupVersion(preferredVersion.GroupVersion)
+		if err != nil {
+			allErrs = append(allErrs, err)
+			continue
+		}
+		groupVersion := unversioned.GroupVersion{Group: apiGroup.Name, Version: preferredVersion.Version}
+		for _, apiResource := range apiResourceList.APIResources {
+			// ignore the root scoped resources if "namespaced" is true.
+			if namespaced && !apiResource.Namespaced {
+				continue
+			}
+			if strings.Contains(apiResource.Name, "/") {
+				continue
+			}
+			results = append(results, groupVersion.WithResource(apiResource.Name))
+		}
+	}
+	return results, utilerrors.NewAggregate(allErrs)
+}
+
+// ServerPreferredResources returns the supported resources with the version preferred by the
+// server.
+func (d *DiscoveryClient) ServerPreferredResources() ([]unversioned.GroupVersionResource, error) {
+	return d.serverPreferredResources(false)
+}
+
+// ServerPreferredNamespacedResources returns the supported namespaced resources with the
+// version preferred by the server.
+func (d *DiscoveryClient) ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error) {
+	return d.serverPreferredResources(true)
+}
+
 // ServerVersion retrieves and parses the server's version (git version).
 func (d *DiscoveryClient) ServerVersion() (*version.Info, error) {
 	body, err := d.Get().AbsPath("/version").Do().Raw()

pkg/client/typed/discovery/fake/discovery.go

@@ -46,6 +46,14 @@ func (c *FakeDiscovery) ServerResources() (map[string]*unversioned.APIResourceLi
 	return c.Resources, nil
 }
 
+func (c *FakeDiscovery) ServerPreferredResources() ([]unversioned.GroupVersionResource, error) {
+	return nil, nil
+}
+
+func (c *FakeDiscovery) ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error) {
+	return nil, nil
+}
+
 func (c *FakeDiscovery) ServerGroups() (*unversioned.APIGroupList, error) {
 	return nil, nil
 }

pkg/client/unversioned/testclient/testclient.go

@@ -382,6 +382,14 @@ type FakeDiscovery struct {
 	*Fake
 }
 
+func (c *FakeDiscovery) ServerPreferredResources() ([]unversioned.GroupVersionResource, error) {
+	return nil, nil
+}
+
+func (c *FakeDiscovery) ServerPreferredNamespacedResources() ([]unversioned.GroupVersionResource, error) {
+	return nil, nil
+}
+
 func (c *FakeDiscovery) ServerResourcesForGroupVersion(groupVersion string) (*unversioned.APIResourceList, error) {
 	action := ActionImpl{
 		Verb:     "get",

pkg/controller/garbagecollector/garbagecollector.go

@@ -0,0 +1,506 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+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 garbagecollector
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/golang/glog"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/errors"
+	"k8s.io/kubernetes/pkg/api/meta"
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
+	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/api/v1"
+	"k8s.io/kubernetes/pkg/apimachinery/registered"
+	"k8s.io/kubernetes/pkg/client/cache"
+	"k8s.io/kubernetes/pkg/client/typed/dynamic"
+	"k8s.io/kubernetes/pkg/controller/framework"
+	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/types"
+	utilruntime "k8s.io/kubernetes/pkg/util/runtime"
+	"k8s.io/kubernetes/pkg/util/sets"
+	"k8s.io/kubernetes/pkg/util/wait"
+	"k8s.io/kubernetes/pkg/util/workqueue"
+	"k8s.io/kubernetes/pkg/watch"
+)
+
+const ResourceResyncTime = 60 * time.Second
+
+type monitor struct {
+	store      cache.Store
+	controller *framework.Controller
+}
+
+type objectReference struct {
+	metatypes.OwnerReference
+	// This is needed by the dynamic client
+	Namespace string
+}
+
+func (s objectReference) String() string {
+	return fmt.Sprintf("[%s/%s, namespace: %s, name: %s, uid: %s]", s.APIVersion, s.Kind, s.Namespace, s.Name, s.UID)
+}
+
+// node does not require a lock to protect. The single-threaded
+// Propagator.processEvent() is the sole writer of the nodes. The multi-threaded
+// GarbageCollector.processItem() reads the nodes, but it only reads the fields
+// that never get changed by Propagator.processEvent().
+type node struct {
+	identity   objectReference
+	dependents map[*node]struct{}
+	// When processing an Update event, we need to compare the updated
+	// ownerReferences with the owners recorded in the graph.
+	owners []metatypes.OwnerReference
+}
+
+type eventType int
+
+const (
+	addEvent eventType = iota
+	updateEvent
+	deleteEvent
+)
+
+type event struct {
+	eventType eventType
+	obj       interface{}
+	// the update event comes with an old object, but it's not used by the garbage collector.
+	oldObj interface{}
+}
+
+type Propagator struct {
+	eventQueue *workqueue.Type
+	// uidToNode doesn't require a lock to protect, because only the
+	// single-threaded Propagator.processEvent() reads/writes it.
+	uidToNode map[types.UID]*node
+	gc        *GarbageCollector
+}
+
+// addDependentToOwners adds n to owners' dependents list. If the owner does not
+// exist in the p.uidToNode yet, a "virtual" node will be created to represent
+// the owner. The "virtual" node will be enqueued to the dirtyQueue, so that
+// processItem() will verify if the owner exists according to the API server.
+func (p *Propagator) addDependentToOwners(n *node, owners []metatypes.OwnerReference) {
+	for _, owner := range owners {
+		ownerNode, ok := p.uidToNode[owner.UID]
+		if !ok {
+			// Create a "virtual" node in the graph for the owner if it doesn't
+			// exist in the graph yet. Then enqueue the virtual node into the
+			// dirtyQueue. The garbage processor will enqueue a virtual delete
+			// event to delete it from the graph if API server confirms this
+			// owner doesn't exist.
+			ownerNode = &node{
+				identity: objectReference{
+					OwnerReference: owner,
+					Namespace:      n.identity.Namespace,
+				},
+				dependents: make(map[*node]struct{}),
+			}
+			p.uidToNode[ownerNode.identity.UID] = ownerNode
+			p.gc.dirtyQueue.Add(ownerNode)
+		}
+		ownerNode.dependents[n] = struct{}{}
+	}
+}
+
+// insertNode insert the node to p.uidToNode; then it finds all owners as listed
+// in n.owners, and adds the node to their dependents list.
+func (p *Propagator) insertNode(n *node) {
+	p.uidToNode[n.identity.UID] = n
+	p.addDependentToOwners(n, n.owners)
+}
+
+// removeDependentFromOwners remove n from owners' dependents list.
+func (p *Propagator) removeDependentFromOwners(n *node, owners []metatypes.OwnerReference) {
+	for _, owner := range owners {
+		ownerNode, ok := p.uidToNode[owner.UID]
+		if !ok {
+			continue
+		}
+		delete(ownerNode.dependents, n)
+	}
+}
+
+// removeNode removes the node from p.uidToNode, then finds all
+// owners as listed in n.owners, and removes n from their dependents list.
+func (p *Propagator) removeNode(n *node) {
+	delete(p.uidToNode, n.identity.UID)
+	p.removeDependentFromOwners(n, n.owners)
+}
+
+// TODO: profile this function to see if a naive N^2 algorithm performs better
+// when the number of references is small.
+func referencesDiffs(old []metatypes.OwnerReference, new []metatypes.OwnerReference) (added []metatypes.OwnerReference, removed []metatypes.OwnerReference) {
+	oldUIDToRef := make(map[string]metatypes.OwnerReference)
+	for i := 0; i < len(old); i++ {
+		oldUIDToRef[string(old[i].UID)] = old[i]
+	}
+	oldUIDSet := sets.StringKeySet(oldUIDToRef)
+	newUIDToRef := make(map[string]metatypes.OwnerReference)
+	for i := 0; i < len(new); i++ {
+		newUIDToRef[string(new[i].UID)] = new[i]
+	}
+	newUIDSet := sets.StringKeySet(newUIDToRef)
+
+	addedUID := newUIDSet.Difference(oldUIDSet)
+	removedUID := oldUIDSet.Difference(newUIDSet)
+
+	for uid := range addedUID {
+		added = append(added, newUIDToRef[uid])
+	}
+	for uid := range removedUID {
+		removed = append(removed, oldUIDToRef[uid])
+	}
+	return added, removed
+}
+
+// Dequeueing an event from eventQueue, updating graph, populating dirty_queue.
+func (p *Propagator) processEvent() {
+	key, quit := p.eventQueue.Get()
+	if quit {
+		return
+	}
+	defer p.eventQueue.Done(key)
+	event, ok := key.(event)
+	if !ok {
+		utilruntime.HandleError(fmt.Errorf("expect an event, got %v", key))
+		return
+	}
+	obj := event.obj
+	accessor, err := meta.Accessor(obj)
+	if err != nil {
+		utilruntime.HandleError(fmt.Errorf("cannot access obj: %v", err))
+		return
+	}
+	typeAccessor, err := meta.TypeAccessor(obj)
+	if err != nil {
+		utilruntime.HandleError(fmt.Errorf("cannot access obj: %v", err))
+		return
+	}
+	glog.V(6).Infof("Propagator process object: %s/%s, namespace %s, name %s, event type %s", typeAccessor.GetAPIVersion(), typeAccessor.GetKind(), accessor.GetNamespace(), accessor.GetName(), event.eventType)
+	// Check if the node already exsits
+	existingNode, found := p.uidToNode[accessor.GetUID()]
+	switch {
+	case (event.eventType == addEvent || event.eventType == updateEvent) && !found:
+		newNode := &node{
+			identity: objectReference{
+				OwnerReference: metatypes.OwnerReference{
+					APIVersion: typeAccessor.GetAPIVersion(),
+					Kind:       typeAccessor.GetKind(),
+					UID:        accessor.GetUID(),
+					Name:       accessor.GetName(),
+				},
+				Namespace: accessor.GetNamespace(),
+			},
+			dependents: make(map[*node]struct{}),
+			owners:     accessor.GetOwnerReferences(),
+		}
+		p.insertNode(newNode)
+	case (event.eventType == addEvent || event.eventType == updateEvent) && found:
+		// TODO: finalizer: Check if ObjectMeta.DeletionTimestamp is updated from nil to non-nil
+		// We only need to add/remove owner refs for now
+		added, removed := referencesDiffs(existingNode.owners, accessor.GetOwnerReferences())
+		if len(added) == 0 && len(removed) == 0 {
+			glog.V(6).Infof("The updateEvent %#v doesn't change node references, ignore", event)
+			return
+		}
+		// update the node itself
+		existingNode.owners = accessor.GetOwnerReferences()
+		// Add the node to its new owners' dependent lists.
+		p.addDependentToOwners(existingNode, added)
+		// remove the node from the dependent list of node that are no long in
+		// the node's owners list.
+		p.removeDependentFromOwners(existingNode, removed)
+	case event.eventType == deleteEvent:
+		if !found {
+			glog.V(6).Infof("%v doesn't exist in the graph, this shouldn't happen", accessor.GetUID())
+			return
+		}
+		p.removeNode(existingNode)
+		for dep := range existingNode.dependents {
+			p.gc.dirtyQueue.Add(dep)
+		}
+	}
+}
+
+// GarbageCollector is responsible for carrying out cascading deletion, and
+// removing ownerReferences from the dependents if the owner is deleted with
+// DeleteOptions.OrphanDependents=true.
+type GarbageCollector struct {
+	restMapper meta.RESTMapper
+	clientPool dynamic.ClientPool
+	dirtyQueue *workqueue.Type
+	monitors   []monitor
+	propagator *Propagator
+}
+
+func monitorFor(p *Propagator, clientPool dynamic.ClientPool, resource unversioned.GroupVersionResource) (monitor, error) {
+	// TODO: consider store in one storage.
+	glog.V(6).Infof("create storage for resource %s", resource)
+	var monitor monitor
+	client, err := clientPool.ClientForGroupVersion(resource.GroupVersion())
+	if err != nil {
+		return monitor, err
+	}
+	monitor.store, monitor.controller = framework.NewInformer(
+		// TODO: make special List and Watch function that removes fields other
+		// than ObjectMeta.
+		&cache.ListWatch{
+			ListFunc: func(options api.ListOptions) (runtime.Object, error) {
+				// APIResource.Kind is not used by the dynamic client, so
+				// leave it empty. We want to list this resource in all
+				// namespaces if it's namespace scoped, so leave
+				// APIResource.Namespaced as false is all right.
+				apiResource := unversioned.APIResource{Name: resource.Resource}
+				return client.Resource(&apiResource, api.NamespaceAll).List(&options)
+			},
+			WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
+				// APIResource.Kind is not used by the dynamic client, so
+				// leave it empty. We want to list this resource in all
+				// namespaces if it's namespace scoped, so leave
+				// APIResource.Namespaced as false is all right.
+				apiResource := unversioned.APIResource{Name: resource.Resource}
+				return client.Resource(&apiResource, api.NamespaceAll).Watch(&options)
+			},
+		},
+		nil,
+		ResourceResyncTime,
+		framework.ResourceEventHandlerFuncs{
+			// add the event to the propagator's eventQueue.
+			AddFunc: func(obj interface{}) {
+				event := event{
+					eventType: addEvent,
+					obj:       obj,
+				}
+				p.eventQueue.Add(event)
+			},
+			UpdateFunc: func(oldObj, newObj interface{}) {
+				event := event{updateEvent, newObj, oldObj}
+				p.eventQueue.Add(event)
+			},
+			DeleteFunc: func(obj interface{}) {
+				// delta fifo may wrap the object in a cache.DeletedFinalStateUnknown, unwrap it
+				if deletedFinalStateUnknown, ok := obj.(cache.DeletedFinalStateUnknown); ok {
+					obj = deletedFinalStateUnknown.Obj
+				}
+				event := event{
+					eventType: deleteEvent,
+					obj:       obj,
+				}
+				p.eventQueue.Add(event)
+			},
+		},
+	)
+	return monitor, nil
+}
+
+var ignoredResources = map[unversioned.GroupVersionResource]struct{}{
+	unversioned.GroupVersionResource{Group: "extensions", Version: "v1beta1", Resource: "replicationcontrollers"}: {},
+	unversioned.GroupVersionResource{Group: "", Version: "v1", Resource: "bindings"}:                              {},
+	unversioned.GroupVersionResource{Group: "", Version: "v1", Resource: "componentstatuses"}:                     {},
+	unversioned.GroupVersionResource{Group: "", Version: "v1", Resource: "events"}:                                {},
+}
+
+func NewGarbageCollector(clientPool dynamic.ClientPool, resources []unversioned.GroupVersionResource) (*GarbageCollector, error) {
+	gc := &GarbageCollector{
+		clientPool: clientPool,
+		dirtyQueue: workqueue.New(),
+		// TODO: should use a dynamic RESTMapper built from the discovery results.
+		restMapper: registered.RESTMapper(),
+	}
+	gc.propagator = &Propagator{
+		eventQueue: workqueue.New(),
+		uidToNode:  make(map[types.UID]*node),
+		gc:         gc,
+	}
+	for _, resource := range resources {
+		if _, ok := ignoredResources[resource]; ok {
+			glog.V(6).Infof("ignore resource %#v", resource)
+			continue
+		}
+		monitor, err := monitorFor(gc.propagator, gc.clientPool, resource)
+		if err != nil {
+			return nil, err
+		}
+		gc.monitors = append(gc.monitors, monitor)
+	}
+	return gc, nil
+}
+
+func (gc *GarbageCollector) worker() {
+	key, quit := gc.dirtyQueue.Get()
+	if quit {
+		return
+	}
+	defer gc.dirtyQueue.Done(key)
+	err := gc.processItem(key.(*node))
+	if err != nil {
+		utilruntime.HandleError(fmt.Errorf("Error syncing item %v: %v", key, err))
+	}
+}
+
+// apiResource consults the REST mapper to translate an <apiVersion, kind,
+// namespace> tuple to a unversioned.APIResource struct.
+func (gc *GarbageCollector) apiResource(apiVersion, kind string, namespaced bool) (*unversioned.APIResource, error) {
+	fqKind := unversioned.FromAPIVersionAndKind(apiVersion, kind)
+	mapping, err := gc.restMapper.RESTMapping(fqKind.GroupKind(), apiVersion)
+	if err != nil {
+		return nil, fmt.Errorf("unable to get REST mapping for kind: %s, version: %s", kind, apiVersion)
+	}
+	glog.V(6).Infof("map kind %s, version %s to resource %s", kind, apiVersion, mapping.Resource)
+	resource := unversioned.APIResource{
+		Name:       mapping.Resource,
+		Namespaced: namespaced,
+		Kind:       kind,
+	}
+	return &resource, nil
+}
+
+func (gc *GarbageCollector) deleteObject(item objectReference) error {
+	fqKind := unversioned.FromAPIVersionAndKind(item.APIVersion, item.Kind)
+	client, err := gc.clientPool.ClientForGroupVersion(fqKind.GroupVersion())
+	resource, err := gc.apiResource(item.APIVersion, item.Kind, len(item.Namespace) != 0)
+	if err != nil {
+		return err
+	}
+	uid := item.UID
+	preconditions := v1.Preconditions{UID: &uid}
+	deleteOptions := v1.DeleteOptions{Preconditions: &preconditions}
+	return client.Resource(resource, item.Namespace).Delete(item.Name, &deleteOptions)
+}
+
+func (gc *GarbageCollector) getObject(item objectReference) (*runtime.Unstructured, error) {
+	fqKind := unversioned.FromAPIVersionAndKind(item.APIVersion, item.Kind)
+	client, err := gc.clientPool.ClientForGroupVersion(fqKind.GroupVersion())
+	resource, err := gc.apiResource(item.APIVersion, item.Kind, len(item.Namespace) != 0)
+	if err != nil {
+		return nil, err
+	}
+	return client.Resource(resource, item.Namespace).Get(item.Name)
+}
+
+func objectReferenceToUnstructured(ref objectReference) *runtime.Unstructured {
+	ret := &runtime.Unstructured{}
+	ret.SetKind(ref.Kind)
+	ret.SetAPIVersion(ref.APIVersion)
+	ret.SetUID(ref.UID)
+	ret.SetNamespace(ref.Namespace)
+	ret.SetName(ref.Name)
+	return ret
+}
+
+func (gc *GarbageCollector) processItem(item *node) error {
+	// Get the latest item from the API server
+	latest, err := gc.getObject(item.identity)
+	if err != nil {
+		if errors.IsNotFound(err) {
+			// the Propagator can add "virtual" node for an owner that doesn't
+			// exist yet, so we need to enqueue a virtual Delete event to remove
+			// the virtual node from Propagator.uidToNode.
+			glog.V(6).Infof("item %v not found, generating a virtual delete event", item.identity)
+			event := event{
+				eventType: deleteEvent,
+				obj:       objectReferenceToUnstructured(item.identity),
+			}
+			gc.propagator.eventQueue.Add(event)
+			return nil
+		}
+		return err
+	}
+	if latest.GetUID() != item.identity.UID {
+		glog.V(6).Infof("UID doesn't match, item %v not found, ignore it", item.identity)
+		return nil
+	}
+	ownerReferences := latest.GetOwnerReferences()
+	if len(ownerReferences) == 0 {
+		glog.V(6).Infof("object %s's doesn't have an owner, continue on next item", item.identity)
+		return nil
+	}
+	// TODO: we need to remove dangling references if the object is not to be
+	// deleted.
+	for _, reference := range ownerReferences {
+		// TODO: we need to verify the reference resource is supported by the
+		// system. If it's not a valid resource, the garbage collector should i)
+		// ignore the reference when decide if the object should be deleted, and
+		// ii) should update the object to remove such references. This is to
+		// prevent objects having references to an old resource from being
+		// deleted during a cluster upgrade.
+		fqKind := unversioned.FromAPIVersionAndKind(reference.APIVersion, reference.Kind)
+		client, err := gc.clientPool.ClientForGroupVersion(fqKind.GroupVersion())
+		if err != nil {
+			return err
+		}
+		resource, err := gc.apiResource(reference.APIVersion, reference.Kind, len(item.identity.Namespace) != 0)
+		if err != nil {
+			return err
+		}
+		owner, err := client.Resource(resource, item.identity.Namespace).Get(reference.Name)
+		if err == nil {
+			if owner.GetUID() != reference.UID {
+				glog.V(6).Infof("object %s's owner %s/%s, %s is not found, UID mismatch", item.identity.UID, reference.APIVersion, reference.Kind, reference.Name)
+				continue
+			}
+			glog.V(6).Infof("object %s has at least an existing owner, will not garbage collect", item.identity.UID)
+			return nil
+		} else if errors.IsNotFound(err) {
+			glog.V(6).Infof("object %s's owner %s/%s, %s is not found", item.identity.UID, reference.APIVersion, reference.Kind, reference.Name)
+		} else {
+			return err
+		}
+	}
+	glog.V(2).Infof("none of object %s's owners exist any more, will garbage collect it", item.identity)
+	return gc.deleteObject(item.identity)
+}
+
+func (gc *GarbageCollector) Run(workers int, stopCh <-chan struct{}) {
+	for _, monitor := range gc.monitors {
+		go monitor.controller.Run(stopCh)
+	}
+
+	// worker
+	go wait.Until(gc.propagator.processEvent, 0, stopCh)
+
+	for i := 0; i < workers; i++ {
+		go wait.Until(gc.worker, 0, stopCh)
+	}
+	<-stopCh
+	glog.Infof("Shutting down garbage collector")
+	gc.dirtyQueue.ShutDown()
+	gc.propagator.eventQueue.ShutDown()
+}
+
+// QueueDrained returns if the dirtyQueue and eventQueue are drained. It's
+// useful for debugging.
+func (gc *GarbageCollector) QueuesDrained() bool {
+	return gc.dirtyQueue.Len() == 0 && gc.propagator.eventQueue.Len() == 0
+}
+
+// *FOR TEST USE ONLY* It's not safe to call this function when the GC is still
+// busy.
+// GraphHasUID returns if the Propagator has a particular UID store in its
+// uidToNode graph. It's useful for debugging.
+func (gc *GarbageCollector) GraphHasUID(UIDs []types.UID) bool {
+	for _, u := range UIDs {
+		if _, ok := gc.propagator.uidToNode[u]; ok {
+			return true
+		}
+	}
+	return false
+}

pkg/controller/garbagecollector/garbagecollector_test.go

@@ -0,0 +1,287 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+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 garbagecollector
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"testing"
+
+	_ "k8s.io/kubernetes/pkg/api/install"
+
+	"github.com/stretchr/testify/assert"
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
+	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/api/v1"
+	"k8s.io/kubernetes/pkg/client/restclient"
+	"k8s.io/kubernetes/pkg/client/typed/dynamic"
+	"k8s.io/kubernetes/pkg/types"
+	"k8s.io/kubernetes/pkg/util/json"
+	"k8s.io/kubernetes/pkg/util/sets"
+	"k8s.io/kubernetes/pkg/util/workqueue"
+)
+
+func TestNewGarbageCollector(t *testing.T) {
+	clientPool := dynamic.NewClientPool(&restclient.Config{}, dynamic.LegacyAPIPathResolverFunc)
+	podResource := []unversioned.GroupVersionResource{{Version: "v1", Resource: "pods"}}
+	gc, err := NewGarbageCollector(clientPool, podResource)
+	if err != nil {
+		t.Fatal(err)
+	}
+	assert.Equal(t, 1, len(gc.monitors))
+}
+
+// fakeAction records information about requests to aid in testing.
+type fakeAction struct {
+	method string
+	path   string
+}
+
+// String returns method=path to aid in testing
+func (f *fakeAction) String() string {
+	return strings.Join([]string{f.method, f.path}, "=")
+}
+
+type FakeResponse struct {
+	statusCode int
+	content    []byte
+}
+
+// fakeActionHandler holds a list of fakeActions received
+type fakeActionHandler struct {
+	// statusCode and content returned by this handler for different method + path.
+	response map[string]FakeResponse
+
+	lock    sync.Mutex
+	actions []fakeAction
+}
+
+// ServeHTTP logs the action that occurred and always returns the associated status code
+func (f *fakeActionHandler) ServeHTTP(response http.ResponseWriter, request *http.Request) {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	f.actions = append(f.actions, fakeAction{method: request.Method, path: request.URL.Path})
+	fakeResponse, ok := f.response[request.Method+request.URL.Path]
+	if !ok {
+		fakeResponse.statusCode = 200
+		fakeResponse.content = []byte("{\"kind\": \"List\"}")
+	}
+	response.WriteHeader(fakeResponse.statusCode)
+	response.Write(fakeResponse.content)
+}
+
+// testServerAndClientConfig returns a server that listens and a config that can reference it
+func testServerAndClientConfig(handler func(http.ResponseWriter, *http.Request)) (*httptest.Server, *restclient.Config) {
+	srv := httptest.NewServer(http.HandlerFunc(handler))
+	config := &restclient.Config{
+		Host: srv.URL,
+	}
+	return srv, config
+}
+
+func newDanglingPod() *v1.Pod {
+	return &v1.Pod{
+		TypeMeta: unversioned.TypeMeta{
+			Kind:       "Pod",
+			APIVersion: "v1",
+		},
+		ObjectMeta: v1.ObjectMeta{
+			Name:      "ToBeDeletedPod",
+			Namespace: "ns1",
+			OwnerReferences: []v1.OwnerReference{
+				{
+					Kind:       "ReplicationController",
+					Name:       "owner1",
+					UID:        "123",
+					APIVersion: "v1",
+				},
+			},
+		},
+	}
+}
+
+// test the processItem function making the expected actions.
+func TestProcessItem(t *testing.T) {
+	pod := newDanglingPod()
+	podBytes, err := json.Marshal(pod)
+	if err != nil {
+		t.Fatal(err)
+	}
+	testHandler := &fakeActionHandler{
+		response: map[string]FakeResponse{
+			"GET" + "/api/v1/namespaces/ns1/replicationcontrollers/owner1": {
+				404,
+				[]byte{},
+			},
+			"GET" + "/api/v1/namespaces/ns1/pods/ToBeDeletedPod": {
+				200,
+				podBytes,
+			},
+		},
+	}
+	podResource := []unversioned.GroupVersionResource{{Version: "v1", Resource: "pods"}}
+	srv, clientConfig := testServerAndClientConfig(testHandler.ServeHTTP)
+	defer srv.Close()
+	clientPool := dynamic.NewClientPool(clientConfig, dynamic.LegacyAPIPathResolverFunc)
+	gc, err := NewGarbageCollector(clientPool, podResource)
+	if err != nil {
+		t.Fatal(err)
+	}
+	item := &node{
+		identity: objectReference{
+			OwnerReference: metatypes.OwnerReference{
+				Kind:       pod.Kind,
+				APIVersion: pod.APIVersion,
+				Name:       pod.Name,
+				UID:        pod.UID,
+			},
+			Namespace: pod.Namespace,
+		},
+		// owners are intentionally left empty. The processItem routine should get the latest item from the server.
+		owners: nil,
+	}
+	err = gc.processItem(item)
+	if err != nil {
+		t.Errorf("Unexpected Error: %v", err)
+	}
+	expectedActionSet := sets.NewString()
+	expectedActionSet.Insert("GET=/api/v1/namespaces/ns1/replicationcontrollers/owner1")
+	expectedActionSet.Insert("DELETE=/api/v1/namespaces/ns1/pods/ToBeDeletedPod")
+	expectedActionSet.Insert("GET=/api/v1/namespaces/ns1/pods/ToBeDeletedPod")
+
+	actualActionSet := sets.NewString()
+	for _, action := range testHandler.actions {
+		actualActionSet.Insert(action.String())
+	}
+	if !expectedActionSet.Equal(actualActionSet) {
+		t.Errorf("expected actions:\n%v\n but got:\n%v\nDifference:\n%v", expectedActionSet,
+			actualActionSet, expectedActionSet.Difference(actualActionSet))
+	}
+}
+
+// verifyGraphInvariants verifies that all of a node's owners list the node as a
+// dependent and vice versa. uidToNode has all the nodes in the graph.
+func verifyGraphInvariants(scenario string, uidToNode map[types.UID]*node, t *testing.T) {
+	for myUID, node := range uidToNode {
+		for dependentNode := range node.dependents {
+			found := false
+			for _, owner := range dependentNode.owners {
+				if owner.UID == myUID {
+					found = true
+					break
+				}
+			}
+			if !found {
+				t.Errorf("scenario: %s: node %s has node %s as a dependent, but it's not present in the latter node's owners list", scenario, node.identity, dependentNode.identity)
+			}
+		}
+
+		for _, owner := range node.owners {
+			ownerNode, ok := uidToNode[owner.UID]
+			if !ok {
+				// It's possible that the owner node doesn't exist
+				continue
+			}
+			if _, ok := ownerNode.dependents[node]; !ok {
+				t.Errorf("node %s has node %s as an owner, but it's not present in the latter node's dependents list", node.identity, ownerNode.identity)
+			}
+		}
+	}
+}
+
+func createEvent(eventType eventType, selfUID string, owners []string) event {
+	var ownerReferences []api.OwnerReference
+	for i := 0; i < len(owners); i++ {
+		ownerReferences = append(ownerReferences, api.OwnerReference{UID: types.UID(owners[i])})
+	}
+	return event{
+		eventType: eventType,
+		obj: &api.Pod{
+			ObjectMeta: api.ObjectMeta{
+				UID:             types.UID(selfUID),
+				OwnerReferences: ownerReferences,
+			},
+		},
+	}
+}
+
+func TestProcessEvent(t *testing.T) {
+	var testScenarios = []struct {
+		name string
+		// a series of events that will be supplied to the
+		// Propagator.eventQueue.
+		events []event
+	}{
+		{
+			name: "test1",
+			events: []event{
+				createEvent(addEvent, "1", []string{}),
+				createEvent(addEvent, "2", []string{"1"}),
+				createEvent(addEvent, "3", []string{"1", "2"}),
+			},
+		},
+		{
+			name: "test2",
+			events: []event{
+				createEvent(addEvent, "1", []string{}),
+				createEvent(addEvent, "2", []string{"1"}),
+				createEvent(addEvent, "3", []string{"1", "2"}),
+				createEvent(addEvent, "4", []string{"2"}),
+				createEvent(deleteEvent, "2", []string{"doesn't matter"}),
+			},
+		},
+		{
+			name: "test3",
+			events: []event{
+				createEvent(addEvent, "1", []string{}),
+				createEvent(addEvent, "2", []string{"1"}),
+				createEvent(addEvent, "3", []string{"1", "2"}),
+				createEvent(addEvent, "4", []string{"3"}),
+				createEvent(updateEvent, "2", []string{"4"}),
+			},
+		},
+		{
+			name: "reverse test2",
+			events: []event{
+				createEvent(addEvent, "4", []string{"2"}),
+				createEvent(addEvent, "3", []string{"1", "2"}),
+				createEvent(addEvent, "2", []string{"1"}),
+				createEvent(addEvent, "1", []string{}),
+				createEvent(deleteEvent, "2", []string{"doesn't matter"}),
+			},
+		},
+	}
+
+	for _, scenario := range testScenarios {
+		propagator := &Propagator{
+			eventQueue: workqueue.New(),
+			uidToNode:  make(map[types.UID]*node),
+			gc: &GarbageCollector{
+				dirtyQueue: workqueue.New(),
+			},
+		}
+		for i := 0; i < len(scenario.events); i++ {
+			propagator.eventQueue.Add(scenario.events[i])
+			propagator.processEvent()
+			verifyGraphInvariants(scenario.name, propagator.uidToNode, t)
+		}
+	}
+}

pkg/controller/namespace/namespace_controller_utils.go

@@ -18,7 +18,6 @@ package namespace
 
 import (
 	"fmt"
-	"strings"
 	"time"
 
 	"k8s.io/kubernetes/pkg/api"
@@ -26,10 +25,8 @@ import (
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/api/v1"
 	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
-	"k8s.io/kubernetes/pkg/client/typed/discovery"
 	"k8s.io/kubernetes/pkg/client/typed/dynamic"
 	"k8s.io/kubernetes/pkg/runtime"
-	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/util/sets"
 
 	"github.com/golang/glog"
@@ -452,33 +449,3 @@ func estimateGracefulTerminationForPods(kubeClient clientset.Interface, ns strin
 	}
 	return estimate, nil
 }
-
-// ServerPreferredNamespacedGroupVersionResources uses the specified client to discover the set of preferred groupVersionResources that are namespaced
-func ServerPreferredNamespacedGroupVersionResources(discoveryClient discovery.DiscoveryInterface) ([]unversioned.GroupVersionResource, error) {
-	results := []unversioned.GroupVersionResource{}
-	serverGroupList, err := discoveryClient.ServerGroups()
-	if err != nil {
-		return results, err
-	}
-
-	allErrs := []error{}
-	for _, apiGroup := range serverGroupList.Groups {
-		preferredVersion := apiGroup.PreferredVersion
-		apiResourceList, err := discoveryClient.ServerResourcesForGroupVersion(preferredVersion.GroupVersion)
-		if err != nil {
-			allErrs = append(allErrs, err)
-			continue
-		}
-		groupVersion := unversioned.GroupVersion{Group: apiGroup.Name, Version: preferredVersion.Version}
-		for _, apiResource := range apiResourceList.APIResources {
-			if !apiResource.Namespaced {
-				continue
-			}
-			if strings.Contains(apiResource.Name, "/") {
-				continue
-			}
-			results = append(results, groupVersion.WithResource(apiResource.Name))
-		}
-	}
-	return results, utilerrors.NewAggregate(allErrs)
-}

pkg/runtime/helper.go

@@ -68,6 +68,47 @@ func UnsafeObjectConvertor(scheme *Scheme) ObjectConvertor {
 	return unsafeObjectConvertor{scheme}
 }
 
+// SetField puts the value of src, into fieldName, which must be a member of v.
+// The value of src must be assignable to the field.
+func SetField(src interface{}, v reflect.Value, fieldName string) error {
+	field := v.FieldByName(fieldName)
+	if !field.IsValid() {
+		return fmt.Errorf("couldn't find %v field in %#v", fieldName, v.Interface())
+	}
+	srcValue := reflect.ValueOf(src)
+	if srcValue.Type().AssignableTo(field.Type()) {
+		field.Set(srcValue)
+		return nil
+	}
+	if srcValue.Type().ConvertibleTo(field.Type()) {
+		field.Set(srcValue.Convert(field.Type()))
+		return nil
+	}
+	return fmt.Errorf("couldn't assign/convert %v to %v", srcValue.Type(), field.Type())
+}
+
+// Field puts the value of fieldName, which must be a member of v, into dest,
+// which must be a variable to which this field's value can be assigned.
+func Field(v reflect.Value, fieldName string, dest interface{}) error {
+	field := v.FieldByName(fieldName)
+	if !field.IsValid() {
+		return fmt.Errorf("couldn't find %v field in %#v", fieldName, v.Interface())
+	}
+	destValue, err := conversion.EnforcePtr(dest)
+	if err != nil {
+		return err
+	}
+	if field.Type().AssignableTo(destValue.Type()) {
+		destValue.Set(field)
+		return nil
+	}
+	if field.Type().ConvertibleTo(destValue.Type()) {
+		destValue.Set(field.Convert(destValue.Type()))
+		return nil
+	}
+	return fmt.Errorf("couldn't assign/convert %v to %v", field.Type(), destValue.Type())
+}
+
 // fieldPtr puts the address of fieldName, which must be a member of v,
 // into dest, which must be an address of a variable to which this field's
 // address can be assigned.

pkg/runtime/types.go

@@ -17,6 +17,11 @@ limitations under the License.
 package runtime
 
 import (
+	"fmt"
+
+	"github.com/golang/glog"
+
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/types"
 )
@@ -196,6 +201,71 @@ func (u *Unstructured) setNestedMap(value map[string]string, fields ...string) {
 	setNestedMap(u.Object, value, fields...)
 }
 
+func extractOwnerReference(src interface{}) metatypes.OwnerReference {
+	v := src.(map[string]interface{})
+	return metatypes.OwnerReference{
+		Kind:       getNestedString(v, "kind"),
+		Name:       getNestedString(v, "name"),
+		APIVersion: getNestedString(v, "apiVersion"),
+		UID:        (types.UID)(getNestedString(v, "uid")),
+	}
+}
+
+func setOwnerReference(src metatypes.OwnerReference) map[string]interface{} {
+	ret := make(map[string]interface{})
+	setNestedField(ret, src.Kind, "kind")
+	setNestedField(ret, src.Name, "name")
+	setNestedField(ret, src.APIVersion, "apiVersion")
+	setNestedField(ret, string(src.UID), "uid")
+	return ret
+}
+
+func getOwnerReferences(object map[string]interface{}) ([]map[string]interface{}, error) {
+	field := getNestedField(object, "metadata", "ownerReferences")
+	if field == nil {
+		return nil, fmt.Errorf("cannot find field metadata.ownerReferences in %v", object)
+	}
+	ownerReferences, ok := field.([]map[string]interface{})
+	if ok {
+		return ownerReferences, nil
+	}
+	// TODO: This is hacky...
+	interfaces, ok := field.([]interface{})
+	if !ok {
+		return nil, fmt.Errorf("expect metadata.ownerReferences to be a slice in %#v", object)
+	}
+	ownerReferences = make([]map[string]interface{}, 0, len(interfaces))
+	for i := 0; i < len(interfaces); i++ {
+		r, ok := interfaces[i].(map[string]interface{})
+		if !ok {
+			return nil, fmt.Errorf("expect element metadata.ownerReferences to be a map[string]interface{} in %#v", object)
+		}
+		ownerReferences = append(ownerReferences, r)
+	}
+	return ownerReferences, nil
+}
+
+func (u *Unstructured) GetOwnerReferences() []metatypes.OwnerReference {
+	original, err := getOwnerReferences(u.Object)
+	if err != nil {
+		glog.V(6).Info(err)
+		return nil
+	}
+	ret := make([]metatypes.OwnerReference, 0, len(original))
+	for i := 0; i < len(original); i++ {
+		ret = append(ret, extractOwnerReference(original[i]))
+	}
+	return ret
+}
+
+func (u *Unstructured) SetOwnerReferences(references []metatypes.OwnerReference) {
+	var newReferences = make([]map[string]interface{}, 0, len(references))
+	for i := 0; i < len(references); i++ {
+		newReferences = append(newReferences, setOwnerReference(references[i]))
+	}
+	u.setNestedField(newReferences, "metadata", "ownerReferences")
+}
+
 func (u *Unstructured) GetAPIVersion() string {
 	return getNestedString(u.Object, "apiVersion")
 }

pkg/runtime/unstructured.go

@@ -19,6 +19,7 @@ package runtime
 import (
 	gojson "encoding/json"
 	"io"
+	"strings"
 
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/util/json"
@@ -128,6 +129,12 @@ func (s unstructuredJSONScheme) decodeToList(data []byte, list *UnstructuredList
 		return err
 	}
 
+	// For typed lists, e.g., a PodList, API server doesn't set each item's
+	// APIVersion and Kind. We need to set it.
+	listAPIVersion := list.GetAPIVersion()
+	listKind := list.GetKind()
+	itemKind := strings.TrimSuffix(listKind, "List")
+
 	delete(list.Object, "items")
 	list.Items = nil
 	for _, i := range dList.Items {
@@ -135,6 +142,12 @@ func (s unstructuredJSONScheme) decodeToList(data []byte, list *UnstructuredList
 		if err := s.decodeToUnstructured([]byte(i), unstruct); err != nil {
 			return err
 		}
+		// This is hacky. Set the item's Kind and APIVersion to those inferred
+		// from the List.
+		if len(unstruct.GetKind()) == 0 && len(unstruct.GetAPIVersion()) == 0 {
+			unstruct.SetKind(itemKind)
+			unstruct.SetAPIVersion(listAPIVersion)
+		}
 		list.Items = append(list.Items, unstruct)
 	}
 	return nil

pkg/runtime/unstructured_test.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/meta/metatypes"
 	"k8s.io/kubernetes/pkg/api/testapi"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/api/validation"
@@ -141,6 +142,20 @@ func TestUnstructuredGetters(t *testing.T) {
 				"annotations": map[string]interface{}{
 					"test_annotation": "test_value",
 				},
+				"ownerReferences": []map[string]interface{}{
+					{
+						"kind":       "Pod",
+						"name":       "poda",
+						"apiVersion": "v1",
+						"uid":        "1",
+					},
+					{
+						"kind":       "Pod",
+						"name":       "podb",
+						"apiVersion": "v1",
+						"uid":        "2",
+					},
+				},
 			},
 		},
 	}
@@ -192,6 +207,24 @@ func TestUnstructuredGetters(t *testing.T) {
 	if got, want := unstruct.GetAnnotations(), map[string]string{"test_annotation": "test_value"}; !reflect.DeepEqual(got, want) {
 		t.Errorf("GetAnnotations() = %s, want %s", got, want)
 	}
+	refs := unstruct.GetOwnerReferences()
+	expectedOwnerReferences := []metatypes.OwnerReference{
+		{
+			Kind:       "Pod",
+			Name:       "poda",
+			APIVersion: "v1",
+			UID:        "1",
+		},
+		{
+			Kind:       "Pod",
+			Name:       "podb",
+			APIVersion: "v1",
+			UID:        "2",
+		},
+	}
+	if got, want := refs, expectedOwnerReferences; !reflect.DeepEqual(got, want) {
+		t.Errorf("GetOwnerReference()=%v, want %v", got, want)
+	}
 }
 
 func TestUnstructuredSetters(t *testing.T) {
@@ -216,6 +249,20 @@ func TestUnstructuredSetters(t *testing.T) {
 				"annotations": map[string]interface{}{
 					"test_annotation": "test_value",
 				},
+				"ownerReferences": []map[string]interface{}{
+					{
+						"kind":       "Pod",
+						"name":       "poda",
+						"apiVersion": "v1",
+						"uid":        "1",
+					},
+					{
+						"kind":       "Pod",
+						"name":       "podb",
+						"apiVersion": "v1",
+						"uid":        "2",
+					},
+				},
 			},
 		},
 	}
@@ -233,9 +280,24 @@ func TestUnstructuredSetters(t *testing.T) {
 	unstruct.SetDeletionTimestamp(&date)
 	unstruct.SetLabels(map[string]string{"test_label": "test_value"})
 	unstruct.SetAnnotations(map[string]string{"test_annotation": "test_value"})
+	newOwnerReferences := []metatypes.OwnerReference{
+		{
+			Kind:       "Pod",
+			Name:       "poda",
+			APIVersion: "v1",
+			UID:        "1",
+		},
+		{
+			Kind:       "Pod",
+			Name:       "podb",
+			APIVersion: "v1",
+			UID:        "2",
+		},
+	}
+	unstruct.SetOwnerReferences(newOwnerReferences)
 
 	if !reflect.DeepEqual(unstruct, want) {
-		t.Errorf("Wanted: \n%s\n Got:\n%s", unstruct, want)
+		t.Errorf("Wanted: \n%s\n Got:\n%s", want, unstruct)
 	}
 }
 

test/integration/garbage_collector_test.go

@@ -0,0 +1,357 @@
+// +build integration,!no-etcd
+
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/errors"
+	"k8s.io/kubernetes/pkg/api/unversioned"
+	"k8s.io/kubernetes/pkg/api/v1"
+	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/release_1_3"
+	"k8s.io/kubernetes/pkg/client/restclient"
+	"k8s.io/kubernetes/pkg/client/typed/dynamic"
+	"k8s.io/kubernetes/pkg/controller/garbagecollector"
+	"k8s.io/kubernetes/pkg/master"
+	"k8s.io/kubernetes/pkg/types"
+	"k8s.io/kubernetes/pkg/util/wait"
+	"k8s.io/kubernetes/test/integration/framework"
+)
+
+const garbageCollectedPodName = "test.pod.1"
+const independentPodName = "test.pod.2"
+const oneValidOwnerPodName = "test.pod.3"
+const toBeDeletedRCName = "test.rc.1"
+const remainingRCName = "test.rc.2"
+
+func newPod(podName string, ownerReferences []v1.OwnerReference) *v1.Pod {
+	for i := 0; i < len(ownerReferences); i++ {
+		ownerReferences[i].Kind = "ReplicationController"
+		ownerReferences[i].APIVersion = "v1"
+	}
+	return &v1.Pod{
+		TypeMeta: unversioned.TypeMeta{
+			Kind:       "Pod",
+			APIVersion: "v1",
+		},
+		ObjectMeta: v1.ObjectMeta{
+			Name:            podName,
+			Namespace:       framework.TestNS,
+			OwnerReferences: ownerReferences,
+		},
+		Spec: v1.PodSpec{
+			Containers: []v1.Container{
+				{
+					Name:  "fake-name",
+					Image: "fakeimage",
+				},
+			},
+		},
+	}
+}
+
+func newOwnerRC(name string) *v1.ReplicationController {
+	return &v1.ReplicationController{
+		TypeMeta: unversioned.TypeMeta{
+			Kind:       "ReplicationController",
+			APIVersion: "v1",
+		},
+		ObjectMeta: v1.ObjectMeta{
+			Namespace: framework.TestNS,
+			Name:      name,
+		},
+		Spec: v1.ReplicationControllerSpec{
+			Selector: map[string]string{"name": "test"},
+			Template: &v1.PodTemplateSpec{
+				ObjectMeta: v1.ObjectMeta{
+					Labels: map[string]string{"name": "test"},
+				},
+				Spec: v1.PodSpec{
+					Containers: []v1.Container{
+						{
+							Name:  "fake-name",
+							Image: "fakeimage",
+						},
+					},
+				},
+			},
+		},
+	}
+}
+
+func setup(t *testing.T) (*garbagecollector.GarbageCollector, clientset.Interface) {
+	var m *master.Master
+	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		m.Handler.ServeHTTP(w, req)
+	}))
+	// TODO: close the http server
+
+	masterConfig := framework.NewIntegrationTestMasterConfig()
+	masterConfig.EnableCoreControllers = false
+	m, err := master.New(masterConfig)
+	if err != nil {
+		t.Fatalf("Error in bringing up the master: %v", err)
+	}
+
+	framework.DeleteAllEtcdKeys()
+	clientSet, err := clientset.NewForConfig(&restclient.Config{Host: s.URL})
+	if err != nil {
+		t.Fatalf("Error in create clientset: %v", err)
+	}
+	groupVersionResources, err := clientSet.Discovery().ServerPreferredResources()
+	if err != nil {
+		t.Fatalf("Failed to get supported resources from server: %v", err)
+	}
+	clientPool := dynamic.NewClientPool(&restclient.Config{Host: s.URL}, dynamic.LegacyAPIPathResolverFunc)
+	gc, err := garbagecollector.NewGarbageCollector(clientPool, groupVersionResources)
+	if err != nil {
+		t.Fatalf("Failed to create garbage collector")
+	}
+	return gc, clientSet
+}
+
+// This test simulates the cascading deletion.
+func TestCascadingDeletion(t *testing.T) {
+	gc, clientSet := setup(t)
+	rcClient := clientSet.Core().ReplicationControllers(framework.TestNS)
+	podClient := clientSet.Core().Pods(framework.TestNS)
+
+	toBeDeletedRC, err := rcClient.Create(newOwnerRC(toBeDeletedRCName))
+	if err != nil {
+		t.Fatalf("Failed to create replication controller: %v", err)
+	}
+	remainingRC, err := rcClient.Create(newOwnerRC(remainingRCName))
+	if err != nil {
+		t.Fatalf("Failed to create replication controller: %v", err)
+	}
+
+	rcs, err := rcClient.List(api.ListOptions{})
+	if err != nil {
+		t.Fatalf("Failed to list replication controllers: %v", err)
+	}
+	if len(rcs.Items) != 2 {
+		t.Fatalf("Expect only 2 replication controller")
+	}
+
+	// this pod should be cascadingly deleted.
+	pod := newPod(garbageCollectedPodName, []v1.OwnerReference{{UID: toBeDeletedRC.ObjectMeta.UID, Name: toBeDeletedRCName}})
+	_, err = podClient.Create(pod)
+	if err != nil {
+		t.Fatalf("Failed to create Pod: %v", err)
+	}
+
+	// this pod shouldn't be cascadingly deleted, because it has a valid referenece.
+	pod = newPod(oneValidOwnerPodName, []v1.OwnerReference{
+		{UID: toBeDeletedRC.ObjectMeta.UID, Name: toBeDeletedRCName},
+		{UID: remainingRC.ObjectMeta.UID, Name: remainingRCName},
+	})
+	_, err = podClient.Create(pod)
+	if err != nil {
+		t.Fatalf("Failed to create Pod: %v", err)
+	}
+
+	// this pod shouldn't be cascadingly deleted, because it doesn't have an owner.
+	pod = newPod(independentPodName, []v1.OwnerReference{})
+	_, err = podClient.Create(pod)
+	if err != nil {
+		t.Fatalf("Failed to create Pod: %v", err)
+	}
+
+	// set up watch
+	pods, err := podClient.List(api.ListOptions{})
+	if err != nil {
+		t.Fatalf("Failed to list pods: %v", err)
+	}
+	if len(pods.Items) != 3 {
+		t.Fatalf("Expect only 3 pods")
+	}
+	stopCh := make(chan struct{})
+	go gc.Run(5, stopCh)
+	defer close(stopCh)
+	// delete one of the replication controller
+	if err := rcClient.Delete(toBeDeletedRCName, nil); err != nil {
+		t.Fatalf("failed to delete replication controller: %v", err)
+	}
+
+	// wait for the garbage collector to drain its queue
+	if err := wait.Poll(10*time.Second, 120*time.Second, func() (bool, error) {
+		return gc.QueuesDrained(), nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	// sometimes the deletion of the RC takes long time to be observed by
+	// the gc, so wait for the garbage collector to observe the deletion of
+	// the toBeDeletedRC
+	if err := wait.Poll(10*time.Second, 120*time.Second, func() (bool, error) {
+		return !gc.GraphHasUID([]types.UID{toBeDeletedRC.ObjectMeta.UID}), nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	// wait for the garbage collector to drain its queue again because it's
+	// possible it just processed the delete of the toBeDeletedRC.
+	if err := wait.Poll(10*time.Second, 120*time.Second, func() (bool, error) {
+		return gc.QueuesDrained(), nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("garbage collector queues drained")
+	// checks the garbage collect doesn't delete pods it shouldn't do.
+	if _, err := podClient.Get(independentPodName); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := podClient.Get(oneValidOwnerPodName); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := podClient.Get(garbageCollectedPodName); err == nil || !errors.IsNotFound(err) {
+		t.Fatalf("expect pod %s to be garbage collected, got err= %v", garbageCollectedPodName, err)
+	}
+}
+
+// This test simulates the case where an object is created with an owner that
+// doesn't exist. It verifies the GC will delete such an object.
+func TestCreateWithNonExisitentOwner(t *testing.T) {
+	gc, clientSet := setup(t)
+	podClient := clientSet.Core().Pods(framework.TestNS)
+
+	pod := newPod(garbageCollectedPodName, []v1.OwnerReference{{UID: "doesn't matter", Name: toBeDeletedRCName}})
+	_, err := podClient.Create(pod)
+	if err != nil {
+		t.Fatalf("Failed to create Pod: %v", err)
+	}
+
+	// set up watch
+	pods, err := podClient.List(api.ListOptions{})
+	if err != nil {
+		t.Fatalf("Failed to list pods: %v", err)
+	}
+	if len(pods.Items) != 1 {
+		t.Fatalf("Expect only 1 pod")
+	}
+	stopCh := make(chan struct{})
+	go gc.Run(5, stopCh)
+	defer close(stopCh)
+	// wait for the garbage collector to drain its queue
+	if err := wait.Poll(10*time.Second, 120*time.Second, func() (bool, error) {
+		return gc.QueuesDrained(), nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("garbage collector queues drained")
+	if _, err := podClient.Get(garbageCollectedPodName); err == nil || !errors.IsNotFound(err) {
+		t.Fatalf("expect pod %s to be garbage collected", garbageCollectedPodName)
+	}
+}
+
+func createRemoveRCsPods(t *testing.T, clientSet clientset.Interface, id int, wg *sync.WaitGroup, rcUIDs chan types.UID) {
+	defer wg.Done()
+	rcClient := clientSet.Core().ReplicationControllers(framework.TestNS)
+	podClient := clientSet.Core().Pods(framework.TestNS)
+	// create rc.
+	rcName := toBeDeletedRCName + strconv.Itoa(id)
+	toBeDeletedRC, err := rcClient.Create(newOwnerRC(rcName))
+	if err != nil {
+		t.Fatalf("Failed to create replication controller: %v", err)
+	}
+	rcUIDs <- toBeDeletedRC.ObjectMeta.UID
+	// create pods. These pods should be cascadingly deleted.
+	for j := 0; j < 3; j++ {
+		podName := garbageCollectedPodName + strconv.Itoa(id) + "-" + strconv.Itoa(j)
+		pod := newPod(podName, []v1.OwnerReference{{UID: toBeDeletedRC.ObjectMeta.UID, Name: rcName}})
+		_, err = podClient.Create(pod)
+		if err != nil {
+			t.Fatalf("Failed to create Pod: %v", err)
+		}
+	}
+	// delete the rc
+	if err := rcClient.Delete(rcName, nil); err != nil {
+		t.Fatalf("failed to delete replication controller: %v", err)
+	}
+}
+
+func allObjectsRemoved(clientSet clientset.Interface) (bool, error) {
+	rcClient := clientSet.Core().ReplicationControllers(framework.TestNS)
+	podClient := clientSet.Core().Pods(framework.TestNS)
+	pods, err := podClient.List(api.ListOptions{})
+	if err != nil {
+		return false, fmt.Errorf("Failed to list pods: %v", err)
+	}
+	if len(pods.Items) != 0 {
+		return false, nil
+	}
+	rcs, err := rcClient.List(api.ListOptions{})
+	if err != nil {
+		return false, fmt.Errorf("Failed to list replication controllers: %v", err)
+	}
+	if len(rcs.Items) != 0 {
+		return false, nil
+	}
+	return true, nil
+}
+
+// This stress test the garbage collector
+func TestStressingCascadingDeletion(t *testing.T) {
+	t.Logf("starts garbage collector stress test")
+	gc, clientSet := setup(t)
+	stopCh := make(chan struct{})
+	go gc.Run(5, stopCh)
+	defer close(stopCh)
+
+	const collections = 50
+	var wg sync.WaitGroup
+	wg.Add(collections)
+	rcUIDs := make(chan types.UID, collections)
+	for i := 0; i < collections; i++ {
+		go createRemoveRCsPods(t, clientSet, i, &wg, rcUIDs)
+	}
+	wg.Wait()
+	t.Logf("all pods are created, all replications controllers are created then deleted")
+	// wait for the garbage collector to drain its queue
+	if err := wait.Poll(10*time.Second, 300*time.Second, func() (bool, error) {
+		return gc.QueuesDrained(), nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("garbage collector queues drained")
+	// wait for all replication controllers and pods to be deleted. This
+	// shouldn't take long, because the queues are already drained.
+	if err := wait.Poll(5*time.Second, 30*time.Second, func() (bool, error) {
+		return allObjectsRemoved(clientSet)
+	}); err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("all replication controllers and pods are deleted")
+
+	// verify there is no node representing replication controllers in the gc's graph
+	uids := make([]types.UID, 0, collections)
+	for i := 0; i < collections; i++ {
+		uid := <-rcUIDs
+		uids = append(uids, uid)
+	}
+	if gc.GraphHasUID(uids) {
+		t.Errorf("Expect all nodes representing replication controllers are removed from the Propagator's graph")
+	}
+}