fix(object-cache): improve reliability of object cache management (#508)

* make sure objects expire after DefaultTTLSeconds
* make cached objects have GKV information
* fix cache retrieval and removal logic

Closes #502

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>
Signed-off-by: Armando Ruocco <armando.ruocco@enterprisedb.com>
Co-authored-by: Armando Ruocco <armando.ruocco@enterprisedb.com>

internal/cnpgi/instance/internal/client/client.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/cloudnative-pg/machinery/pkg/log"
 	corev1 "k8s.io/api/core/v1"
-	"k8s.io/apimachinery/pkg/runtime"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	pluginBarman "github.com/cloudnative-pg/plugin-barman-cloud/api/v1"
@@ -21,11 +20,11 @@ const DefaultTTLSeconds = 10
 type cachedEntry struct {
 	entry         client.Object
 	fetchUnixTime int64
-	ttl           time.Duration
+	ttlSeconds    int64
 }
 
 func (e *cachedEntry) isExpired() bool {
-	return time.Now().Unix()-e.fetchUnixTime > int64(e.ttl)
+	return time.Now().Unix()-e.fetchUnixTime > e.ttlSeconds
 }
 
 // ExtendedClient is an extended client that is capable of caching multiple secrets without relying on informers
@@ -91,7 +90,7 @@ func (e *ExtendedClient) getCachedObject(
 		if cacheEntry.entry.GetNamespace() != key.Namespace || cacheEntry.entry.GetName() != key.Name {
 			continue
 		}
-		if cacheEntry.entry.GetObjectKind().GroupVersionKind() != obj.GetObjectKind().GroupVersionKind() {
+		if reflect.TypeOf(cacheEntry.entry) != reflect.TypeOf(obj) {
 			continue
 		}
 		if cacheEntry.isExpired() {
@@ -121,8 +120,9 @@ func (e *ExtendedClient) getCachedObject(
 	}
 
 	cs := cachedEntry{
-		entry:         obj.(runtime.Object).DeepCopyObject().(client.Object),
+		entry:         obj.DeepCopyObject().(client.Object),
 		fetchUnixTime: time.Now().Unix(),
+		ttlSeconds:    DefaultTTLSeconds,
 	}
 
 	contextLogger.Debug("setting object in the cache")
@@ -143,7 +143,7 @@ func (e *ExtendedClient) removeObject(object client.Object) {
 	for i, cache := range e.cachedObjects {
 		if cache.entry.GetNamespace() == object.GetNamespace() &&
 			cache.entry.GetName() == object.GetName() &&
-			cache.entry.GetObjectKind().GroupVersionKind() != object.GetObjectKind().GroupVersionKind() {
+			reflect.TypeOf(cache.entry) == reflect.TypeOf(object) {
 			e.cachedObjects = append(e.cachedObjects[:i], e.cachedObjects[i+1:]...)
 			return
 		}

internal/cnpgi/instance/internal/client/client_test.go

@@ -9,7 +9,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/fake"
 
-	v1 "github.com/cloudnative-pg/plugin-barman-cloud/api/v1"
+	barmancloudv1 "github.com/cloudnative-pg/plugin-barman-cloud/api/v1"
 
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
@@ -20,16 +20,26 @@ var scheme = buildScheme()
 func buildScheme() *runtime.Scheme {
 	scheme := runtime.NewScheme()
 	_ = corev1.AddToScheme(scheme)
-	_ = v1.AddToScheme(scheme)
+	_ = barmancloudv1.AddToScheme(scheme)
 
 	return scheme
 }
 
+func addToCache(c *ExtendedClient, obj client.Object, fetchUnixTime int64) {
+	ce := cachedEntry{
+		entry:         obj.DeepCopyObject().(client.Object),
+		fetchUnixTime: fetchUnixTime,
+		ttlSeconds:    DefaultTTLSeconds,
+	}
+	ce.entry.SetResourceVersion("from cache")
+	c.cachedObjects = append(c.cachedObjects, ce)
+}
+
 var _ = Describe("ExtendedClient Get", func() {
 	var (
 		extendedClient *ExtendedClient
 		secretInClient *corev1.Secret
-		objectStore    *v1.ObjectStore
+		objectStore    *barmancloudv1.ObjectStore
 	)
 
 	BeforeEach(func() {
@@ -39,12 +49,12 @@ var _ = Describe("ExtendedClient Get", func() {
 				Name:      "test-secret",
 			},
 		}
-		objectStore = &v1.ObjectStore{
+		objectStore = &barmancloudv1.ObjectStore{
 			ObjectMeta: metav1.ObjectMeta{
 				Namespace: "default",
 				Name:      "test-object-store",
 			},
-			Spec: v1.ObjectStoreSpec{},
+			Spec: barmancloudv1.ObjectStoreSpec{},
 		}
 
 		baseClient := fake.NewClientBuilder().
@@ -61,35 +71,34 @@ var _ = Describe("ExtendedClient Get", func() {
 			},
 		}
 
-		// manually add the secret to the cache, this is not present in the fake client so we are sure it is from the
+		// manually add the secret to the cache, this is not present in the fake client,
-		// cache
+		// so we are sure it is from the cache
-		extendedClient.cachedObjects = []cachedEntry{
+		addToCache(extendedClient, secretNotInClient, time.Now().Unix())
-			{
-				entry:         secretNotInClient,
-				fetchUnixTime: time.Now().Unix(),
-			},
-		}
 
 		err := extendedClient.Get(ctx, client.ObjectKeyFromObject(secretNotInClient), secretInClient)
 		Expect(err).NotTo(HaveOccurred())
-		Expect(secretNotInClient).To(Equal(extendedClient.cachedObjects[0].entry))
+		Expect(secretInClient).To(Equal(extendedClient.cachedObjects[0].entry))
+		Expect(secretInClient.GetResourceVersion()).To(Equal("from cache"))
 	})
 
 	It("fetches secret from base client if cache is expired", func(ctx SpecContext) {
-		extendedClient.cachedObjects = []cachedEntry{
+		addToCache(extendedClient, secretInClient, time.Now().Add(-2*time.Minute).Unix())
-			{
-				entry:         secretInClient.DeepCopy(),
-				fetchUnixTime: time.Now().Add(-2 * time.Minute).Unix(),
-			},
-		}
 
 		err := extendedClient.Get(ctx, client.ObjectKeyFromObject(secretInClient), secretInClient)
 		Expect(err).NotTo(HaveOccurred())
+		Expect(secretInClient.GetResourceVersion()).NotTo(Equal("from cache"))
+
+		// the cache is updated with the new value
+		Expect(extendedClient.cachedObjects).To(HaveLen(1))
+		Expect(extendedClient.cachedObjects[0].entry.GetResourceVersion()).NotTo(Equal("from cache"))
 	})
 
 	It("fetches secret from base client if not in cache", func(ctx SpecContext) {
 		err := extendedClient.Get(ctx, client.ObjectKeyFromObject(secretInClient), secretInClient)
 		Expect(err).NotTo(HaveOccurred())
+
+		// the cache is updated with the new value
+		Expect(extendedClient.cachedObjects).To(HaveLen(1))
 	})
 
 	It("does not cache non-secret objects", func(ctx SpecContext) {
@@ -106,4 +115,33 @@ var _ = Describe("ExtendedClient Get", func() {
 		Expect(err).NotTo(HaveOccurred())
 		Expect(extendedClient.cachedObjects).To(BeEmpty())
 	})
+
+	It("returns the correct object from cache when multiple objects with the same object key are cached",
+		func(ctx SpecContext) {
+			secretNotInClient := &corev1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: "default",
+					Name:      "common-name",
+				},
+			}
+			objectStoreNotInClient := &barmancloudv1.ObjectStore{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: "default",
+					Name:      "common-name",
+				},
+			}
+
+			// manually add the objects to the cache, these are not present in the fake client,
+			// so we are sure they are from the cache
+			addToCache(extendedClient, secretNotInClient, time.Now().Unix())
+			addToCache(extendedClient, objectStoreNotInClient, time.Now().Unix())
+
+			err := extendedClient.Get(ctx, client.ObjectKeyFromObject(secretNotInClient), secretInClient)
+			Expect(err).NotTo(HaveOccurred())
+			err = extendedClient.Get(ctx, client.ObjectKeyFromObject(objectStoreNotInClient), objectStore)
+			Expect(err).NotTo(HaveOccurred())
+
+			Expect(secretInClient.GetResourceVersion()).To(Equal("from cache"))
+			Expect(objectStore.GetResourceVersion()).To(Equal("from cache"))
+		})
 })