@Override
  public int getId(
      @NotNull VirtualFile parent, @NotNull String childName, @NotNull NewVirtualFileSystem fs) {
    int parentId = getFileId(parent);
    int[] children = FSRecords.list(parentId);

    if (children.length > 0) {
      // fast path, check that some child has same nameId as given name, this avoid O(N) on
      // retrieving names for processing non-cached children
      int nameId = FSRecords.getNameId(childName);
      for (final int childId : children) {
        if (nameId == FSRecords.getNameId(childId)) {
          return childId;
        }
      }
      // for case sensitive system the above check is exhaustive in consistent state of vfs
    }

    for (final int childId : children) {
      if (namesEqual(fs, childName, FSRecords.getName(childId))) return childId;
    }

    final VirtualFile fake = new FakeVirtualFile(parent, childName);
    final FileAttributes attributes = fs.getAttributes(fake);
    if (attributes != null) {
      final int child = createAndFillRecord(fs, fake, parentId, attributes);
      FSRecords.updateList(parentId, ArrayUtil.append(children, child));
      return child;
    }

    return 0;
  }
 private static void appendIdToParentList(final int parentId, final int childId) {
   int[] childrenList = FSRecords.list(parentId);
   childrenList = ArrayUtil.append(childrenList, childId);
   FSRecords.updateList(parentId, childrenList);
 }