CA: remove Clear from ClusterSnapshot

It's now redundant - SetClusterState with empty arguments does the same
thing.

cluster-autoscaler/simulator/clustersnapshot/basic.go

@@ -196,7 +196,7 @@ func (data *internalBasicSnapshotData) removePod(namespace, podName, nodeName st
 // NewBasicClusterSnapshot creates instances of BasicClusterSnapshot.
 func NewBasicClusterSnapshot() *BasicClusterSnapshot {
 	snapshot := &BasicClusterSnapshot{}
-	snapshot.Clear()
+	snapshot.clear()
 	return snapshot
 }
 
@@ -234,7 +234,7 @@ func (snapshot *BasicClusterSnapshot) AddNodeInfo(nodeInfo *framework.NodeInfo)
 
 // SetClusterState sets the cluster state.
 func (snapshot *BasicClusterSnapshot) SetClusterState(nodes []*apiv1.Node, scheduledPods []*apiv1.Pod) error {
-	snapshot.Clear()
+	snapshot.clear()
 
 	knownNodes := make(map[string]bool)
 	for _, node := range nodes {
@@ -297,8 +297,8 @@ func (snapshot *BasicClusterSnapshot) Commit() error {
 	return nil
 }
 
-// Clear reset cluster snapshot to empty, unforked state
-func (snapshot *BasicClusterSnapshot) Clear() {
+// clear reset cluster snapshot to empty, unforked state
+func (snapshot *BasicClusterSnapshot) clear() {
 	baseData := newInternalBasicSnapshotData()
 	snapshot.data = []*internalBasicSnapshotData{baseData}
 }

cluster-autoscaler/simulator/clustersnapshot/clustersnapshot.go

@@ -59,8 +59,6 @@ type ClusterSnapshot interface {
 	Revert()
 	// Commit commits changes done after forking.
 	Commit() error
-	// Clear reset cluster snapshot to empty, unforked state.
-	Clear()
 }
 
 // ErrNodeNotFound means that a node wasn't found in the snapshot.

cluster-autoscaler/simulator/clustersnapshot/clustersnapshot_benchmark_test.go

@@ -80,7 +80,7 @@ func BenchmarkAddNodeInfo(b *testing.B) {
 			b.Run(fmt.Sprintf("%s: AddNodeInfo() %d", snapshotName, tc), func(b *testing.B) {
 				for i := 0; i < b.N; i++ {
 					b.StopTimer()
-					clusterSnapshot.Clear()
+					assert.NoError(b, clusterSnapshot.SetClusterState(nil, nil))
 					b.StartTimer()
 					for _, node := range nodes {
 						err := clusterSnapshot.AddNodeInfo(framework.NewTestNodeInfo(node))

cluster-autoscaler/simulator/clustersnapshot/clustersnapshot_test.go

@@ -275,7 +275,7 @@ func TestForking(t *testing.T) {
 	}
 }
 
-func TestClear(t *testing.T) {
+func TestSetClusterState(t *testing.T) {
 	// Run with -count=1 to avoid caching.
 	localRand := rand.New(rand.NewSource(time.Now().Unix()))
 
@@ -309,10 +309,21 @@ func TestClear(t *testing.T) {
 				snapshot := startSnapshot(t, snapshotFactory, state)
 				compareStates(t, state, getSnapshotState(t, snapshot))
 
-				snapshot.Clear()
+				assert.NoError(t, snapshot.SetClusterState(nil, nil))
 
 				compareStates(t, snapshotState{}, getSnapshotState(t, snapshot))
 			})
+		t.Run(fmt.Sprintf("%s: clear base %d nodes %d pods and set a new state", name, nodeCount, podCount),
+			func(t *testing.T) {
+				snapshot := startSnapshot(t, snapshotFactory, state)
+				compareStates(t, state, getSnapshotState(t, snapshot))
+
+				newNodes, newPods := createTestNodes(13), createTestPods(37)
+				assignPodsToNodes(newPods, newNodes)
+				assert.NoError(t, snapshot.SetClusterState(newNodes, newPods))
+
+				compareStates(t, snapshotState{nodes: newNodes, pods: newPods}, getSnapshotState(t, snapshot))
+			})
 		t.Run(fmt.Sprintf("%s: clear fork %d nodes %d pods %d extra nodes %d extra pods", name, nodeCount, podCount, extraNodeCount, extraPodCount),
 			func(t *testing.T) {
 				snapshot := startSnapshot(t, snapshotFactory, state)
@@ -332,11 +343,11 @@ func TestClear(t *testing.T) {
 
 				compareStates(t, snapshotState{allNodes, allPods}, getSnapshotState(t, snapshot))
 
-				snapshot.Clear()
+				assert.NoError(t, snapshot.SetClusterState(nil, nil))
 
 				compareStates(t, snapshotState{}, getSnapshotState(t, snapshot))
 
-				// Clear() should break out of forked state.
+				// SetClusterState() should break out of forked state.
 				snapshot.Fork()
 			})
 	}
@@ -718,7 +729,7 @@ func TestPVCClearAndFork(t *testing.T) {
 			volumeExists := snapshot.StorageInfos().IsPVCUsedByPods(schedulerframework.GetNamespacedName("default", "claim1"))
 			assert.Equal(t, true, volumeExists)
 
-			snapshot.Clear()
+			assert.NoError(t, snapshot.SetClusterState(nil, nil))
 			volumeExists = snapshot.StorageInfos().IsPVCUsedByPods(schedulerframework.GetNamespacedName("default", "claim1"))
 			assert.Equal(t, false, volumeExists)
 

cluster-autoscaler/simulator/clustersnapshot/delta.go

@@ -389,7 +389,7 @@ func (snapshot *DeltaClusterSnapshot) StorageInfos() schedulerframework.StorageI
 // NewDeltaClusterSnapshot creates instances of DeltaClusterSnapshot.
 func NewDeltaClusterSnapshot() *DeltaClusterSnapshot {
 	snapshot := &DeltaClusterSnapshot{}
-	snapshot.Clear()
+	snapshot.clear()
 	return snapshot
 }
 
@@ -423,7 +423,7 @@ func (snapshot *DeltaClusterSnapshot) AddNodeInfo(nodeInfo *framework.NodeInfo)
 
 // SetClusterState sets the cluster state.
 func (snapshot *DeltaClusterSnapshot) SetClusterState(nodes []*apiv1.Node, scheduledPods []*apiv1.Pod) error {
-	snapshot.Clear()
+	snapshot.clear()
 
 	knownNodes := make(map[string]bool)
 	for _, node := range nodes {
@@ -489,6 +489,6 @@ func (snapshot *DeltaClusterSnapshot) Commit() error {
 
 // Clear reset cluster snapshot to empty, unforked state
 // Time: O(1)
-func (snapshot *DeltaClusterSnapshot) Clear() {
+func (snapshot *DeltaClusterSnapshot) clear() {
 	snapshot.data = newInternalDeltaSnapshotData()
 }

cluster-autoscaler/simulator/clustersnapshot/test_utils.go

@@ -34,7 +34,7 @@ func InitializeClusterSnapshotOrDie(
 	pods []*apiv1.Pod) {
 	var err error
 
-	snapshot.Clear()
+	assert.NoError(t, snapshot.SetClusterState(nil, nil))
 
 	for _, node := range nodes {
 		err = snapshot.AddNodeInfo(framework.NewTestNodeInfo(node))