helper structure to hide which map to use.

Author: Shawn Hurley

pkg/cache/internal/informers_map.go

@@ -77,6 +77,9 @@ type InformersMap struct {
 
 	// unstructuredInformerByGVK is a cache of informers for unstructured types
 	// keyed by groupVersionKind
+	// This is separate from informerByGVK because you don't want to
+	// request a structured object but get an unstructured informer and
+	// vice versa
 	unstructuredInformerByGVK map[schema.GroupVersionKind]*MapEntry
 
 	// codecs is used to create a new REST client
@@ -100,6 +103,12 @@ type InformersMap struct {
 	started bool
 }
 
+type mutexMap struct {
+	informerByGVK map[schema.GroupVersionKind]*MapEntry
+	// mu guards access to the unstructured map
+	mu *sync.RWMutex
+}
+
 // Start calls Run on each of the informers and sets started to true.  Blocks on the stop channel.
 func (ip *InformersMap) Start(stop <-chan struct{}) error {
 	func() {
@@ -140,28 +149,31 @@ func (ip *InformersMap) WaitForCacheSync(stop <-chan struct{}) bool {
 	return cache.WaitForCacheSync(stop, syncedFuncs...)
 }
 
-func (ip *InformersMap) getMapEntry(gvk schema.GroupVersionKind, isUnstructured bool) (*MapEntry, bool) {
-	if isUnstructured {
-		ip.unstructuredMu.RLock()
-		defer ip.unstructuredMu.RUnlock()
-		i, ok := ip.unstructuredInformerByGVK[gvk]
-		return i, ok
-	}
-	ip.mu.RLock()
-	defer ip.mu.RUnlock()
-	i, ok := ip.informersByGVK[gvk]
-	return i, ok
-
-}
-
 // Get will create a new Informer and add it to the map of InformersMap if none exists.  Returns
 // the Informer from the map.
 func (ip *InformersMap) Get(gvk schema.GroupVersionKind, obj runtime.Object) (*MapEntry, error) {
 	_, isUnstructured := obj.(*unstructured.Unstructured)
 	_, isUnstructuredList := obj.(*unstructured.UnstructuredList)
-	isUnstructured = isUnstructured || isUnstructuredList
+	mm := mutexMap{
+		informerByGVK: ip.informersByGVK,
+		mu:            &ip.mu,
+	}
+	// If unstructured use the unstructured mutext and map.
+	if isUnstructured || isUnstructuredList {
+		mm = mutexMap{
+			informerByGVK: ip.unstructuredInformerByGVK,
+			mu:            &ip.unstructuredMu,
+		}
+	}
+
 	// Return the informer if it is found
-	i, ok := ip.getMapEntry(gvk, isUnstructured)
+	i, ok := func() (*MapEntry, bool) {
+		mm.mu.RLock()
+		defer mm.mu.RUnlock()
+		i, ok := mm.informerByGVK[gvk]
+		return i, ok
+
+	}()
 	if ok {
 		return i, nil
 	}
@@ -170,20 +182,9 @@ func (ip *InformersMap) Get(gvk schema.GroupVersionKind, obj runtime.Object) (*M
 	// need to be locked
 	var sync bool
 	i, err := func() (*MapEntry, error) {
-		var ok bool
-		var i *MapEntry
-		// Check the caches to see if we already have an Informer.  If we do, return the Informer.
-		// This is for the case where 2 routines tried to get the informer when it wasn't in the map
-		// so neither returned early, but the first one created it.
-		if isUnstructured {
-			ip.unstructuredMu.Lock()
-			defer ip.unstructuredMu.Unlock()
-			i, ok = ip.unstructuredInformerByGVK[gvk]
-		} else {
-			ip.mu.Lock()
-			defer ip.mu.Unlock()
-			i, ok = ip.informersByGVK[gvk]
-		}
+		mm.mu.Lock()
+		defer mm.mu.Unlock()
+		i, ok = mm.informerByGVK[gvk]
 		if ok {
 			return i, nil
 		}
@@ -201,7 +202,7 @@ func (ip *InformersMap) Get(gvk schema.GroupVersionKind, obj runtime.Object) (*M
 			Informer: ni,
 			Reader:   CacheReader{indexer: ni.GetIndexer(), groupVersionKind: gvk},
 		}
-		ip.setMap(i, gvk, isUnstructured)
+		mm.informerByGVK[gvk] = i
 
 		// Start the Informer if need by
 		// TODO(seans): write thorough tests and document what happens here - can you add indexers?
@@ -226,16 +227,6 @@ func (ip *InformersMap) Get(gvk schema.GroupVersionKind, obj runtime.Object) (*M
 	return i, err
 }
 
-// setMap - helper function to decide which map to add to.
-func (ip *InformersMap) setMap(i *MapEntry, gvk schema.GroupVersionKind, isUnstructured bool) {
-	if isUnstructured {
-		ip.unstructuredInformerByGVK[gvk] = i
-	} else {
-
-		ip.informersByGVK[gvk] = i
-	}
-}
-
 // newListWatch returns a new ListWatch object that can be used to create a SharedIndexInformer.
 func (ip *InformersMap) newListWatch(gvk schema.GroupVersionKind, isUnstructured bool) (*cache.ListWatch, error) {
 	// Kubernetes APIs work against Resources, not GroupVersionKinds.  Map the