/**
  * Recursively compute the difference between snapshots under a given directory/file.
  *
  * @param node The directory/file under which the diff is computed.
  * @param parentPath Relative path (corresponding to the snapshot root) of the node's parent.
  * @param diffReport data structure used to store the diff.
  */
 private void computeDiffRecursively(
     INode node, List<byte[]> parentPath, SnapshotDiffInfo diffReport) {
   ChildrenDiff diff = new ChildrenDiff();
   byte[][] relativePath = parentPath.toArray(new byte[parentPath.size()][]);
   if (node.isDirectory()) {
     INodeDirectory dir = node.asDirectory();
     if (dir instanceof INodeDirectoryWithSnapshot) {
       INodeDirectoryWithSnapshot sdir = (INodeDirectoryWithSnapshot) dir;
       boolean change = sdir.computeDiffBetweenSnapshots(diffReport.from, diffReport.to, diff);
       if (change) {
         diffReport.addDirDiff(sdir, relativePath, diff);
       }
     }
     ReadOnlyList<INode> children =
         dir.getChildrenList(diffReport.isFromEarlier() ? diffReport.to : diffReport.from);
     for (INode child : children) {
       final byte[] name = child.getLocalNameBytes();
       if (diff.searchIndex(ListType.CREATED, name) < 0
           && diff.searchIndex(ListType.DELETED, name) < 0) {
         parentPath.add(name);
         computeDiffRecursively(child, parentPath, diffReport);
         parentPath.remove(parentPath.size() - 1);
       }
     }
   } else if (node.isFile() && node.asFile() instanceof FileWithSnapshot) {
     FileWithSnapshot file = (FileWithSnapshot) node.asFile();
     Snapshot earlierSnapshot = diffReport.isFromEarlier() ? diffReport.from : diffReport.to;
     Snapshot laterSnapshot = diffReport.isFromEarlier() ? diffReport.to : diffReport.from;
     boolean change = file.getDiffs().changedBetweenSnapshots(earlierSnapshot, laterSnapshot);
     if (change) {
       diffReport.addFileDiff(file.asINodeFile(), relativePath);
     }
   }
 }
 @Override
 public int compare(INode left, INode right) {
   if (left == null) {
     return right == null ? 0 : -1;
   } else {
     if (right == null) {
       return 1;
     } else {
       int cmp = compare(left.getParent(), right.getParent());
       return cmp == 0
           ? SignedBytes.lexicographicalComparator()
               .compare(left.getLocalNameBytes(), right.getLocalNameBytes())
           : cmp;
     }
   }
 }
 private void saveCreatedList(List<INode> created, OutputStream out) throws IOException {
   // local names of the created list member
   for (INode c : created) {
     SnapshotDiffSection.CreatedListEntry.newBuilder()
         .setName(ByteString.copyFrom(c.getLocalNameBytes()))
         .build()
         .writeDelimitedTo(out);
   }
 }