snapshot cache: fix heartbeat panic

pkg/cache/v3/simple.go

@@ -184,7 +184,11 @@ func NewSnapshotCacheWithHeartbeating(ctx context.Context, ads bool, hash NodeHa
 }
 
 func (cache *snapshotCache) sendHeartbeats(ctx context.Context, node string) {
- snapshot := cache.snapshots[node]
+ snapshot, ok := cache.snapshots[node]
+ if !ok {
+ return
+ }
+
  if info, ok := cache.status[node]; ok {
  info.mu.Lock()
  for id, watch := range info.watches {

pkg/cache/v3/simple_test.go

@@ -604,3 +604,34 @@ func TestSnapshotSingleResourceFetch(t *testing.T) {
  protocmp.Transform()),
  )
 }
+
+func TestAvertPanicForWatchOnNonExistentSnapshot(t *testing.T) {
+ ctx := context.Background()
+ c := cache.NewSnapshotCacheWithHeartbeating(ctx, false, cache.IDHash{}, nil, time.Millisecond)
+
+ // Create watch.
+ req := &cache.Request{
+ Node: &core.Node{Id: "test"},
+ ResourceNames: []string{"rtds"},
+ TypeUrl: rsrc.RuntimeType,
+ }
+ ss := stream.NewStreamState(false, map[string]string{"cluster": "abcdef"})
+ responder := make(chan cache.Response)
+ c.CreateWatch(req, ss, responder)
+
+ go func() {
+ // Wait for at least one heartbeat to occur, then set snapshot.
+ time.Sleep(time.Millisecond * 5)
+ srs := &singleResourceSnapshot{
+ version: "version-one",
+ typeurl: rsrc.RuntimeType,
+ name: "one-second",
+ resource: durationpb.New(time.Second),
+ }
+ if err := c.SetSnapshot(ctx, "test", srs); err != nil {
+ t.Errorf("unexpected error setting snapshot %v", err)
+ }
+ }()
+
+ <-responder
+}