Refactor the util directory to use subpackages.

util/registry/changes.py

@@ -0,0 +1,75 @@
+import marisa_trie
+import os
+import tarfile
+from util.registry.aufs import is_aufs_metadata, get_deleted_prefix
+
+ALLOWED_TYPES = {tarfile.REGTYPE, tarfile.AREGTYPE}
+
+def files_and_dirs_from_tar(source_stream, removed_prefix_collector):
+  try:
+    tar_stream = tarfile.open(mode='r|*', fileobj=source_stream)
+  except tarfile.ReadError:
+    # Empty tar file
+    return
+
+  for tar_info in tar_stream:
+    absolute = os.path.relpath(tar_info.name.decode('utf-8'), './')
+
+    # Skip metadata.
+    if is_aufs_metadata(absolute):
+      continue
+
+    # Add prefixes of removed paths to the collector.
+    deleted_prefix = get_deleted_prefix(absolute)
+    if deleted_prefix is not None:
+      removed_prefix_collector.add(deleted_prefix)
+      continue
+
+    # Otherwise, yield the path if it is in the allowed types.
+    if tar_info.type in ALLOWED_TYPES:
+      yield '/' + absolute
+
+
+def __compute_removed(base_trie, removed_prefixes):
+  for prefix in removed_prefixes:
+    for filename in base_trie.keys(prefix):
+      yield filename
+
+
+def __compute_added_changed(base_trie, delta_trie):
+  added = set()
+  changed = set()
+
+  for filename in delta_trie.keys():
+    if filename not in base_trie:
+      added.add(filename)
+    else:
+      changed.add(filename)
+
+  return added, changed
+
+
+def __new_fs(base_trie, added, removed):
+  for filename in base_trie.keys():
+    if filename not in removed:
+      yield filename
+
+  for filename in added:
+    yield filename
+
+
+def empty_fs():
+  return marisa_trie.Trie()
+
+
+def compute_new_diffs_and_fs(base_trie, filename_source,
+                             removed_prefix_collector):
+  new_trie = marisa_trie.Trie(filename_source)
+  (new_added, new_changed) = __compute_added_changed(base_trie, new_trie)
+
+  new_removed = marisa_trie.Trie(__compute_removed(base_trie,
+                                                   removed_prefix_collector))
+
+  new_fs = marisa_trie.Trie(__new_fs(base_trie, new_added, new_removed))
+
+  return (new_fs, new_added, new_changed, new_removed.keys())