// returns list of resolved files if updated successfully, or null if write action or dumb mode
  // started
  private int[] processFile(
      @NotNull final VirtualFile file, int fileId, @NotNull final ProgressIndicator indicator) {
    final TIntHashSet forward;
    try {
      forward = calcForwardRefs(file, indicator);
    } catch (IndexNotReadyException e) {
      return null;
    } catch (ApplicationUtil.CannotRunReadActionException e) {
      return null;
    } catch (ProcessCanceledException e) {
      throw e;
    } catch (Exception e) {
      log(ExceptionUtil.getThrowableText(e));
      flushLog();
      return null;
    }

    int[] forwardIds = forward.toArray();
    fileIsResolved.set(fileId);
    logf(
        "  ---- " + file.getPresentableUrl() + " processed. forwardIds: " + toVfString(forwardIds));
    for (Listener listener : myListeners) {
      listener.fileResolved(file);
    }
    return forwardIds;
  }