update kube and vendor dependencies

With kubernetes 1.18 release of client-go, signatures on methods in
generated clientsets, dynamic, metadata, and scale clients have been
modified to accept context.Context as a first argument.
Signatures of Create, Update, and Patch methods have been updated
to accept CreateOptions, UpdateOptions and PatchOptions respectively.
Signatures of Delete and DeleteCollection methods now accept
DeleteOptions by value instead of by reference.
These changes are now accommodated with this PR and client-go
and dependencies are updated to v1.18.0

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

vendor/k8s.io/client-go/tools/cache/mutation_detector.go

@@ -36,9 +36,12 @@ func init() {
 	mutationDetectionEnabled, _ = strconv.ParseBool(os.Getenv("KUBE_CACHE_MUTATION_DETECTOR"))
 }
 
-// MutationDetector is able to monitor if the object be modified outside.
+// MutationDetector is able to monitor objects for mutation within a limited window of time
 type MutationDetector interface {
+	// AddObject adds the given object to the set being monitored for a while from now
 	AddObject(obj interface{})
+
+	// Run starts the monitoring and does not return until the monitoring is stopped.
 	Run(stopCh <-chan struct{})
 }
 
@@ -65,7 +68,13 @@ type defaultCacheMutationDetector struct {
 	name   string
 	period time.Duration
 
-	lock       sync.Mutex
+	// compareLock ensures only a single call to CompareObjects runs at a time
+	compareObjectsLock sync.Mutex
+
+	// addLock guards addedObjs between AddObject and CompareObjects
+	addedObjsLock sync.Mutex
+	addedObjs     []cacheObj
+
 	cachedObjs []cacheObj
 
 	retainDuration     time.Duration
@@ -115,15 +124,22 @@ func (d *defaultCacheMutationDetector) AddObject(obj interface{}) {
 	if obj, ok := obj.(runtime.Object); ok {
 		copiedObj := obj.DeepCopyObject()
 
-		d.lock.Lock()
-		defer d.lock.Unlock()
-		d.cachedObjs = append(d.cachedObjs, cacheObj{cached: obj, copied: copiedObj})
+		d.addedObjsLock.Lock()
+		defer d.addedObjsLock.Unlock()
+		d.addedObjs = append(d.addedObjs, cacheObj{cached: obj, copied: copiedObj})
 	}
 }
 
 func (d *defaultCacheMutationDetector) CompareObjects() {
-	d.lock.Lock()
-	defer d.lock.Unlock()
+	d.compareObjectsLock.Lock()
+	defer d.compareObjectsLock.Unlock()
+
+	// move addedObjs into cachedObjs under lock
+	// this keeps the critical section small to avoid blocking AddObject while we compare cachedObjs
+	d.addedObjsLock.Lock()
+	d.cachedObjs = append(d.cachedObjs, d.addedObjs...)
+	d.addedObjs = nil
+	d.addedObjsLock.Unlock()
 
 	altered := false
 	for i, obj := range d.cachedObjs {