unistore: split ListIterator and ListHistory in StorageBackend (#105654)

split listIterator from ListHistory

pkg/storage/unified/sql/backend.go

@@ -569,10 +569,6 @@ func (b *backend) ListIterator(ctx context.Context, req *resourcepb.ListRequest,
 		return 0, fmt.Errorf("missing group or resource")
 	}
 
-	if req.Source != resourcepb.ListRequest_STORE {
-		return b.getHistory(ctx, req, cb)
-	}
-
 	// TODO: think about how to handler VersionMatch. We should be able to use latest for the first page (only).
 
 	// TODO: add support for RemainingItemCount
@@ -583,6 +579,13 @@ func (b *backend) ListIterator(ctx context.Context, req *resourcepb.ListRequest,
 	return b.listLatest(ctx, req, cb)
 }
 
+func (b *backend) ListHistory(ctx context.Context, req *resourcepb.ListRequest, cb func(resource.ListIterator) error) (int64, error) {
+	ctx, span := b.tracer.Start(ctx, tracePrefix+"ListHistory")
+	defer span.End()
+
+	return b.getHistory(ctx, req, cb)
+}
+
 // listLatest fetches the resources from the resource table.
 func (b *backend) listLatest(ctx context.Context, req *resourcepb.ListRequest, cb func(resource.ListIterator) error) (int64, error) {
 	ctx, span := b.tracer.Start(ctx, tracePrefix+"listLatest")
@@ -733,7 +736,9 @@ func (b *backend) getHistory(ctx context.Context, req *resourcepb.ListRequest, c
 	// for Unset (default) and Exact matching.
 	listReq.SortAscending = req.GetVersionMatchV2() == resourcepb.ResourceVersionMatchV2_NotOlderThan
 
-	iter := &listIter{}
+	iter := &listIter{
+		useCurrentRV: true, // use the current RV for the continue token instead of the listRV
+	}
 	if req.NextPageToken != "" {
 		continueToken, err := resource.GetContinueToken(req.NextPageToken)
 		if err != nil {

pkg/storage/unified/sql/list_iterator.go

@@ -8,10 +8,11 @@ import (
 var _ resource.ListIterator = (*listIter)(nil)
 
 type listIter struct {
-	rows    db.Rows
-	offset  int64
-	listRV  int64
-	sortAsc bool
+	rows         db.Rows
+	offset       int64
+	listRV       int64
+	sortAsc      bool
+	useCurrentRV bool
 
 	// any error
 	err error
@@ -29,13 +30,12 @@ type listIter struct {
 
 // ContinueToken implements resource.ListIterator.
 func (l *listIter) ContinueToken() string {
+	if l.useCurrentRV {
+		return resource.ContinueToken{ResourceVersion: l.rv, StartOffset: l.offset, SortAscending: l.sortAsc}.String()
+	}
 	return resource.ContinueToken{ResourceVersion: l.listRV, StartOffset: l.offset, SortAscending: l.sortAsc}.String()
 }
 
-func (l *listIter) ContinueTokenWithCurrentRV() string {
-	return resource.ContinueToken{ResourceVersion: l.rv, StartOffset: l.offset, SortAscending: l.sortAsc}.String()
-}
-
 func (l *listIter) Error() error {
 	return l.err
 }

pkg/storage/unified/sql/list_iterator_test.go

@@ -219,7 +219,7 @@ func TestListIter(t *testing.T) {
 		require.Equal(t, expected, actual)
 	})
 
-	t.Run("ContinueTokenWithCurrentRV uses current row's RV", func(t *testing.T) {
+	t.Run("ContinueToken uses the current row's RV", func(t *testing.T) {
 		listReq := sqlResourceListRequest{
 			SQLTemplate: sqltemplate.New(dialect),
 			Request:     new(resourcepb.ListRequest),
@@ -229,14 +229,15 @@ func TestListIter(t *testing.T) {
 		require.NoError(t, err)
 
 		iter := &listIter{
-			rows:    rows,
-			listRV:  300,
-			sortAsc: true,
+			rows:         rows,
+			listRV:       300,
+			sortAsc:      true,
+			useCurrentRV: true, // use the current RV for the continue token instead of the listRV
 		}
 
 		require.True(t, iter.Next())
 
-		token := iter.ContinueTokenWithCurrentRV()
+		token := iter.ContinueToken()
 
 		var actual resource.ContinueToken
 		b, err := base64.StdEncoding.DecodeString(token)