add optional mutation checks for shared informer cache

hack/local-up-cluster.sh

@@ -43,6 +43,11 @@ CLOUD_PROVIDER=${CLOUD_PROVIDER:-""}
 CLOUD_CONFIG=${CLOUD_CONFIG:-""}
 FEATURE_GATES=${FEATURE_GATES:-"AllAlpha=true"}
 
+# start the cache mutation detector by default so that cache mutators will be found
+KUBE_CACHE_MUTATION_DETECTOR="${KUBE_CACHE_MUTATION_DETECTOR:-true}"
+export KUBE_CACHE_MUTATION_DETECTOR
+
+
 
 # START_MODE can be 'all', 'kubeletonly', or 'nokubelet'
 START_MODE=${START_MODE:-"all"}

hack/make-rules/test.sh

@@ -23,6 +23,10 @@ source "${KUBE_ROOT}/hack/lib/init.sh"
 
 kube::golang::setup_env
 
+# start the cache mutation detector by default so that cache mutators will be found
+KUBE_CACHE_MUTATION_DETECTOR="${KUBE_CACHE_MUTATION_DETECTOR:-true}"
+export KUBE_CACHE_MUTATION_DETECTOR
+
 kube::test::find_dirs() {
   (
     cd ${KUBE_ROOT}

pkg/client/cache/mutation_detector.go

@@ -0,0 +1,135 @@
+/*
+Copyright 2016 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 cache
+
+import (
+	"fmt"
+	"os"
+	"reflect"
+	"strconv"
+	"sync"
+	"time"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/util/diff"
+)
+
+var mutationDetectionEnabled = false
+
+func init() {
+	mutationDetectionEnabled, _ = strconv.ParseBool(os.Getenv("KUBE_CACHE_MUTATION_DETECTOR"))
+}
+
+type CacheMutationDetector interface {
+	AddObject(obj interface{})
+	Run(stopCh <-chan struct{})
+}
+
+func NewCacheMutationDetector(name string) CacheMutationDetector {
+	if !mutationDetectionEnabled {
+		return dummyMutationDetector{}
+	}
+	return &defaultCacheMutationDetector{name: name, period: 1 * time.Second}
+}
+
+type dummyMutationDetector struct{}
+
+func (dummyMutationDetector) Run(stopCh <-chan struct{}) {
+}
+func (dummyMutationDetector) AddObject(obj interface{}) {
+}
+
+// defaultCacheMutationDetector gives a way to detect if a cached object has been mutated
+// It has a list of cached objects and their copies.  I haven't thought of a way
+// to see WHO is mutating it, just that it's getting mutated.
+type defaultCacheMutationDetector struct {
+	name   string
+	period time.Duration
+
+	lock       sync.Mutex
+	cachedObjs []cacheObj
+
+	// failureFunc is injectable for unit testing.  If you don't have it, the process will panic.
+	// This panic is intentional, since turning on this detection indicates you want a strong
+	// failure signal.  This failure is effectively a p0 bug and you can't trust process results
+	// after a mutation anyway.
+	failureFunc func(message string)
+}
+
+// cacheObj holds the actual object and a copy
+type cacheObj struct {
+	cached interface{}
+	copied interface{}
+}
+
+func (d *defaultCacheMutationDetector) Run(stopCh <-chan struct{}) {
+	// we DON'T want protection from panics.  If we're running this code, we want to die
+	go func() {
+		for {
+			d.CompareObjects()
+
+			select {
+			case <-stopCh:
+				return
+			case <-time.After(d.period):
+			}
+		}
+	}()
+}
+
+// AddObject makes a deep copy of the object for later comparison.  It only works on runtime.Object
+// but that covers the vast majority of our cached objects
+func (d *defaultCacheMutationDetector) AddObject(obj interface{}) {
+	if _, ok := obj.(DeletedFinalStateUnknown); ok {
+		return
+	}
+	if _, ok := obj.(runtime.Object); !ok {
+		return
+	}
+
+	copiedObj, err := api.Scheme.Copy(obj.(runtime.Object))
+	if err != nil {
+		return
+	}
+
+	d.lock.Lock()
+	defer d.lock.Unlock()
+	d.cachedObjs = append(d.cachedObjs, cacheObj{cached: obj, copied: copiedObj})
+}
+
+func (d *defaultCacheMutationDetector) CompareObjects() {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	altered := false
+	for i, obj := range d.cachedObjs {
+		if !reflect.DeepEqual(obj.cached, obj.copied) {
+			fmt.Printf("CACHE %s[%d] ALTERED!\n%v\n", d.name, i, diff.ObjectDiff(obj.cached, obj.copied))
+			altered = true
+		}
+	}
+
+	if altered {
+		msg := fmt.Sprintf("cache %s modified", d.name)
+		if d.failureFunc != nil {
+			d.failureFunc(msg)
+			return
+		}
+		panic(msg)
+	}
+}

pkg/client/cache/mutation_detector_test.go

@@ -0,0 +1,80 @@
+// +build !race
+
+/*
+Copyright 2016 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 cache
+
+import (
+	"testing"
+	"time"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/watch"
+)
+
+func TestMutationDetector(t *testing.T) {
+	fakeWatch := watch.NewFake()
+	lw := &testLW{
+		WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
+			return fakeWatch, nil
+		},
+		ListFunc: func(options api.ListOptions) (runtime.Object, error) {
+			return &api.PodList{}, nil
+		},
+	}
+	pod := &api.Pod{
+		ObjectMeta: api.ObjectMeta{
+			Name:   "anything",
+			Labels: map[string]string{"check": "foo"},
+		},
+	}
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+	addReceived := make(chan bool)
+	mutationFound := make(chan bool)
+
+	informer := NewSharedInformer(lw, &api.Pod{}, 1*time.Second).(*sharedIndexInformer)
+	informer.cacheMutationDetector = &defaultCacheMutationDetector{
+		name:   "name",
+		period: 1 * time.Second,
+		failureFunc: func(message string) {
+			mutationFound <- true
+		},
+	}
+	informer.AddEventHandler(
+		ResourceEventHandlerFuncs{
+			AddFunc: func(obj interface{}) {
+				addReceived <- true
+			},
+		},
+	)
+	go informer.Run(stopCh)
+
+	fakeWatch.Add(pod)
+
+	select {
+	case <-addReceived:
+	}
+
+	pod.Labels["change"] = "true"
+
+	select {
+	case <-mutationFound:
+	}
+
+}

pkg/client/cache/shared_informer.go

@@ -68,11 +68,12 @@ func NewSharedInformer(lw ListerWatcher, objType runtime.Object, resyncPeriod ti
 // be shared amongst all consumers.
 func NewSharedIndexInformer(lw ListerWatcher, objType runtime.Object, resyncPeriod time.Duration, indexers Indexers) SharedIndexInformer {
 	sharedIndexInformer := &sharedIndexInformer{
-		processor:        &sharedProcessor{},
-		indexer:          NewIndexer(DeletionHandlingMetaNamespaceKeyFunc, indexers),
-		listerWatcher:    lw,
-		objectType:       objType,
-		fullResyncPeriod: resyncPeriod,
+		processor:             &sharedProcessor{},
+		indexer:               NewIndexer(DeletionHandlingMetaNamespaceKeyFunc, indexers),
+		listerWatcher:         lw,
+		objectType:            objType,
+		fullResyncPeriod:      resyncPeriod,
+		cacheMutationDetector: NewCacheMutationDetector(fmt.Sprintf("%T", objType)),
 	}
 	return sharedIndexInformer
 }
@@ -109,7 +110,8 @@ type sharedIndexInformer struct {
 	indexer    Indexer
 	controller *Controller
 
-	processor *sharedProcessor
+	processor             *sharedProcessor
+	cacheMutationDetector CacheMutationDetector
 
 	// This block is tracked to handle late initialization of the controller
 	listerWatcher    ListerWatcher
@@ -180,6 +182,7 @@ func (s *sharedIndexInformer) Run(stopCh <-chan struct{}) {
 	}()
 
 	s.stopCh = stopCh
+	s.cacheMutationDetector.Run(stopCh)
 	s.processor.run(stopCh)
 	s.controller.Run(stopCh)
 }
@@ -273,6 +276,7 @@ func (s *sharedIndexInformer) HandleDeltas(obj interface{}) error {
 	for _, d := range obj.(Deltas) {
 		switch d.Type {
 		case Sync, Added, Updated:
+			s.cacheMutationDetector.AddObject(d.Object)
 			if old, exists, err := s.indexer.Get(d.Object); err == nil && exists {
 				if err := s.indexer.Update(d.Object); err != nil {
 					return err