storagenode/piecestore: notify if download piece was restored from trash

Updates #6146

Change-Id: Iece285eb5ecb6898b29096416ab10e43338480b0

storagenode/piecestore/endpoint.go

@@ -665,6 +665,7 @@ func (endpoint *Endpoint) Download(stream pb.DRPCPiecestore_DownloadStream) (err
 		close(downloadedBytes)
 	}()
 
+	restoredFromTrash := false
 	pieceReader, err = endpoint.store.Reader(ctx, limit.SatelliteId, limit.PieceId)
 	if err != nil {
 		if !errs.Is(err, fs.ErrNotExist) {
@@ -683,6 +684,7 @@ func (endpoint *Endpoint) Download(stream pb.DRPCPiecestore_DownloadStream) (err
 			endpoint.monitor.VerifyDirReadableLoop.TriggerWait()
 			return rpcstatus.Wrap(rpcstatus.NotFound, tryRestoreErr)
 		}
+		restoredFromTrash = true
 		mon.Meter("download_file_in_trash", monkit.NewSeriesTag("namespace", limit.SatelliteId.String()), monkit.NewSeriesTag("piece_id", limit.PieceId.String())).Mark(1)
 		endpoint.log.Warn("file found in trash", zap.Stringer("Piece ID", limit.PieceId), zap.Stringer("Satellite ID", limit.SatelliteId), zap.Stringer("Action", limit.Action), zap.String("Remote Address", remoteAddr))
 
@@ -713,12 +715,21 @@ func (endpoint *Endpoint) Download(stream pb.DRPCPiecestore_DownloadStream) (err
 		}
 
 		err = rpctimeout.Run(ctx, endpoint.config.StreamOperationTimeout, func(_ context.Context) (err error) {
-			return stream.Send(&pb.PieceDownloadResponse{Hash: &pieceHash, Limit: &orderLimit})
+			return stream.Send(&pb.PieceDownloadResponse{Hash: &pieceHash, Limit: &orderLimit, RestoredFromTrash: restoredFromTrash})
 		})
 		if err != nil {
 			endpoint.log.Error("error sending hash and order limit", zap.Error(err))
 			return rpcstatus.Wrap(rpcstatus.Internal, err)
 		}
+	} else if restoredFromTrash {
+		// notify that the piece was restored from trash
+		err = rpctimeout.Run(ctx, endpoint.config.StreamOperationTimeout, func(_ context.Context) (err error) {
+			return stream.Send(&pb.PieceDownloadResponse{RestoredFromTrash: restoredFromTrash})
+		})
+		if err != nil {
+			endpoint.log.Error("error sending response", zap.Error(err))
+			return rpcstatus.Wrap(rpcstatus.Internal, err)
+		}
 	}
 
 	// TODO: verify chunk.Size behavior logic with regards to reading all