1 import cPickle, errno, os, tempfile
3 class Error(Exception):
7 def __init__(self, filename):
8 # Map a "dev:ino" node to a list of paths associated with that node.
10 # Map a path to a "dev:ino" node.
12 self._filename = filename
13 self._save_prepared = None
17 f = open(filename, 'r')
19 if e.errno == errno.ENOENT:
25 self._node_paths = cPickle.load(f)
29 # Set up the reverse hard link index.
30 for node, paths in self._node_paths.iteritems():
32 self._path_node[path] = node
34 def prepare_save(self):
35 """ Commit all of the relevant data to disk. Do as much work
36 as possible without actually making the changes visible."""
37 if self._save_prepared:
38 raise Error('save of %r already in progress' % self._filename)
40 (dir, name) = os.path.split(self._filename)
41 (ffd, self._tmpname) = tempfile.mkstemp('.tmp', name, dir)
44 f = os.fdopen(ffd, 'wb', 65536)
49 cPickle.dump(self._node_paths, f, 2)
54 tmpname = self._tmpname
58 self._save_prepared = True
60 def commit_save(self):
61 if not self._save_prepared:
62 raise Error('cannot commit save of %r; no save prepared'
65 os.rename(self._tmpname, self._filename)
67 else: # No data -- delete _filename if it exists.
69 os.unlink(self._filename)
71 if e.errno == errno.ENOENT:
75 self._save_prepared = None
79 os.unlink(self._tmpname)
85 def add_path(self, path, dev, ino):
87 node = '%s:%s' % (dev, ino)
88 self._path_node[path] = node
89 link_paths = self._node_paths.get(node)
90 if link_paths and path not in link_paths:
91 link_paths.append(path)
93 self._node_paths[node] = [path]
95 def _del_node_path(self, node, path):
96 link_paths = self._node_paths[node]
97 link_paths.remove(path)
99 del self._node_paths[node]
101 def change_path(self, path, new_dev, new_ino):
102 prev_node = self._path_node.get(path)
104 self._del_node_path(prev_node, path)
105 self.add_path(new_dev, new_ino, path)
107 def del_path(self, path):
108 # Path may not be in db (if updating a pre-hardlink support index).
109 node = self._path_node.get(path)
111 self._del_node_path(node, path)
112 del self._path_node[path]
114 def node_paths(self, dev, ino):
115 node = '%s:%s' % (dev, ino)
116 return self._node_paths[node]