nrt: test: ensure generation is updated correctly

Add a unit test mainly for GetCachedNRTCopy() to verify the returned
generation. To help with the verification, make FlushNodes not only
report about the new generation (which only updated there) but also
return it so we'd be able to compare the values.

Signed-off-by: Shereen Haj <[email protected]>

Author: shajmakh

pkg/noderesourcetopology/cache/overreserve.go

@@ -340,7 +340,7 @@ func (ov *OverReserve) Resync() {
 }
 
 // FlushNodes drops all the cached information about a given node, resetting its state clean.
-func (ov *OverReserve) FlushNodes(lh logr.Logger, nrts ...*topologyv1alpha2.NodeResourceTopology) {
+func (ov *OverReserve) FlushNodes(lh logr.Logger, nrts ...*topologyv1alpha2.NodeResourceTopology) uint64 {
 	ov.lock.Lock()
 	defer ov.lock.Unlock()
 
@@ -354,12 +354,14 @@ func (ov *OverReserve) FlushNodes(lh logr.Logger, nrts ...*topologyv1alpha2.Node
 	}
 
 	if len(nrts) == 0 {
-		return
+		return ov.generation
 	}
 
 	// increase only if we mutated the internal state
 	ov.generation += 1
 	lh.V(2).Info("generation", "new", ov.generation)
+	return ov.generation
+
 }
 
 // to be used only in tests

pkg/noderesourcetopology/cache/overreserve_test.go

@@ -30,6 +30,7 @@ import (
 	"k8s.io/apimachinery/pkg/api/equality"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	podlisterv1 "k8s.io/client-go/listers/core/v1"
 	"k8s.io/klog/v2"
 
@@ -434,17 +435,35 @@ func TestFlush(t *testing.T) {
 
 	lh := klog.Background()
 
-	nrtCache.FlushNodes(lh, expectedNodeTopology.DeepCopy())
+	expectedGen := nrtCache.generation + 1
+	gen1 := nrtCache.FlushNodes(lh, expectedNodeTopology.DeepCopy())
+	if gen1 != expectedGen {
+		t.Fatalf("generation is expected to increase once after flushing a dirty node\ngot %d expected %d", gen1, expectedGen)
+	}
 
 	dirtyNodes := nrtCache.GetDesyncedNodes(lh)
 	if dirtyNodes.Len() != 0 {
 		t.Errorf("dirty nodes after flush: %v", dirtyNodes)
 	}
 
-	nrtObj, _ := nrtCache.GetCachedNRTCopy(context.Background(), "node1", testPod)
+	nrtObj, nrtInfo := nrtCache.GetCachedNRTCopy(context.Background(), "node1", testPod)
 	if !reflect.DeepEqual(nrtObj, expectedNodeTopology) {
 		t.Fatalf("unexpected object from cache\ngot: %s\nexpected: %s\n", dumpNRT(nrtObj), dumpNRT(nodeTopologies[0]))
 	}
+
+	expectedNrtInfo := CachedNRTInfo{
+		Fresh:      true,
+		Generation: expectedGen,
+	}
+	if !reflect.DeepEqual(nrtInfo, expectedNrtInfo) {
+		t.Fatalf("unexpected NRT info from cache\ngot: %+v\nexpected: %+v\n", nrtInfo, expectedNrtInfo)
+	}
+
+	// flush again without dirty nodes
+	gen2 := nrtCache.FlushNodes(lh)
+	if gen2 != expectedGen {
+		t.Fatalf("generation shouldn't change with no dirty nodes\ngot %d expected %d", gen2, expectedGen)
+	}
 }
 
 func TestResyncNoPodFingerprint(t *testing.T) {
@@ -971,3 +990,49 @@ func TestMakeNodeToPodDataMap(t *testing.T) {
 		})
 	}
 }
+
+func TestOverresevedGetCachedNRTCopyWithForeignPods(t *testing.T) {
+	testNodeName := "worker-node-G"
+	nrt := makeTestNRT(testNodeName)
+	pod := &corev1.Pod{} // API placeholder
+	fakePodLister := &fakePodLister{}
+
+	objs := []runtime.Object{nrt}
+	fakeClient, err := tu.NewFakeClient(objs...)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ctx := context.Background()
+	lh := klog.Background()
+	nrtCache, err := NewOverReserve(ctx, lh, nil, fakeClient, fakePodLister, podprovider.IsPodRelevantAlways)
+	if err != nil {
+		t.Fatalf("unexpected error creating cache: %v", err)
+	}
+
+	expectedNrtInfo := CachedNRTInfo{
+		Generation: 0,
+		Fresh:      true,
+	}
+	_, gotInfo := nrtCache.GetCachedNRTCopy(ctx, testNodeName, pod)
+	if !reflect.DeepEqual(gotInfo, expectedNrtInfo) {
+		t.Errorf("mismatched nrt info from cache, got %+v expected %+v", gotInfo, expectedNrtInfo)
+	}
+
+	// pointless, but will force a generation increase
+	gen := nrtCache.FlushNodes(lh, nrt)
+	if gen == 0 {
+		t.Fatalf("FlushNodes didn't increase the generation")
+	}
+
+	// expected to mark cached data as stale (!fresh)
+	nrtCache.NodeHasForeignPods(testNodeName, pod)
+
+	_, gotInfo = nrtCache.GetCachedNRTCopy(ctx, testNodeName, pod)
+	if gotInfo.Generation != gen {
+		t.Errorf("mismatched generation, got %v expected %v", gotInfo.Generation, gen)
+	}
+	if gotInfo.Fresh {
+		t.Errorf("cached data reported fresh when node has foreign pods")
+	}
+}