Fixing Potential Race Condition in EndpointSlice Controller.

This adds a new EndpointSlice tracker to keep track of the expected resource versions of EndpointSlices associated with each Service managed by the EndpointSlice controller. This should prevent a potential race where a syncService call could happen with an incomplete view of EndpointSlices if additions or deletions hadn't fully propagated to the cache yet. Additionally, this ensures that external changes to EndpointSlices will be handled by the EndpointSlice controller.

pkg/controller/endpointslice/utils_test.go

@@ -310,6 +310,49 @@ func TestPodChangedWithPodEndpointChanged(t *testing.T) {
 	newPod.ObjectMeta.DeletionTimestamp = oldPod.ObjectMeta.DeletionTimestamp.DeepCopy()
 }
 
+func TestServiceControllerKey(t *testing.T) {
+	testCases := map[string]struct {
+		endpointSlice *discovery.EndpointSlice
+		expectedKey   string
+		expectedErr   error
+	}{
+		"nil EndpointSlice": {
+			endpointSlice: nil,
+			expectedKey:   "",
+			expectedErr:   fmt.Errorf("nil EndpointSlice passed to serviceControllerKey()"),
+		},
+		"empty EndpointSlice": {
+			endpointSlice: &discovery.EndpointSlice{},
+			expectedKey:   "",
+			expectedErr:   fmt.Errorf("EndpointSlice missing kubernetes.io/service-name label"),
+		},
+		"valid EndpointSlice": {
+			endpointSlice: &discovery.EndpointSlice{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: "ns",
+					Labels: map[string]string{
+						discovery.LabelServiceName: "svc",
+					},
+				},
+			},
+			expectedKey: "ns/svc",
+			expectedErr: nil,
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			actualKey, actualErr := serviceControllerKey(tc.endpointSlice)
+			if !reflect.DeepEqual(actualErr, tc.expectedErr) {
+				t.Errorf("Expected %s, got %s", tc.expectedErr, actualErr)
+			}
+			if actualKey != tc.expectedKey {
+				t.Errorf("Expected %s, got %s", tc.expectedKey, actualKey)
+			}
+		})
+	}
+}
+
 // Test helpers
 
 func newPod(n int, namespace string, ready bool, nPorts int) *v1.Pod {