Fix UpdateSnapshot when Node is partially removed

Change-Id: I5b459e9ea67020183c87d1ce0a2380efb8cc3e05

pkg/scheduler/internal/cache/interface.go

@@ -17,7 +17,7 @@ limitations under the License.
 package cache
 
 import (
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	framework "k8s.io/kubernetes/pkg/scheduler/framework/v1alpha1"
 )
 
@@ -99,6 +99,8 @@ type Cache interface {
 	// UpdateSnapshot updates the passed infoSnapshot to the current contents of Cache.
 	// The node info contains aggregated information of pods scheduled (including assumed to be)
 	// on this node.
+	// The snapshot only includes Nodes that are not deleted at the time this function is called.
+	// nodeinfo.Node() is guaranteed to be not nil for all the nodes in the snapshot.
 	UpdateSnapshot(nodeSnapshot *Snapshot) error
 
 	// Dump produces a dump of the current cache.