2 from __future__ import absolute_import
3 import cPickle, errno, os, tempfile
7 class Error(Exception):
11 def __init__(self, filename):
12 # Map a "dev:ino" node to a list of paths associated with that node.
14 # Map a path to a "dev:ino" node.
16 self._filename = filename
17 self._save_prepared = None
21 f = open(filename, 'r')
23 if e.errno == errno.ENOENT:
29 self._node_paths = cPickle.load(f)
33 # Set up the reverse hard link index.
34 for node, paths in compat.items(self._node_paths):
36 self._path_node[path] = node
38 def prepare_save(self):
39 """ Commit all of the relevant data to disk. Do as much work
40 as possible without actually making the changes visible."""
41 if self._save_prepared:
42 raise Error('save of %r already in progress' % self._filename)
44 (dir, name) = os.path.split(self._filename)
45 (ffd, self._tmpname) = tempfile.mkstemp('.tmp', name, dir)
48 f = os.fdopen(ffd, 'wb', 65536)
53 cPickle.dump(self._node_paths, f, 2)
58 tmpname = self._tmpname
62 self._save_prepared = True
64 def commit_save(self):
65 if not self._save_prepared:
66 raise Error('cannot commit save of %r; no save prepared'
69 os.rename(self._tmpname, self._filename)
71 else: # No data -- delete _filename if it exists.
73 os.unlink(self._filename)
75 if e.errno == errno.ENOENT:
79 self._save_prepared = None
83 os.unlink(self._tmpname)
89 def add_path(self, path, dev, ino):
91 node = '%s:%s' % (dev, ino)
92 self._path_node[path] = node
93 link_paths = self._node_paths.get(node)
94 if link_paths and path not in link_paths:
95 link_paths.append(path)
97 self._node_paths[node] = [path]
99 def _del_node_path(self, node, path):
100 link_paths = self._node_paths[node]
101 link_paths.remove(path)
103 del self._node_paths[node]
105 def change_path(self, path, new_dev, new_ino):
106 prev_node = self._path_node.get(path)
108 self._del_node_path(prev_node, path)
109 self.add_path(new_dev, new_ino, path)
111 def del_path(self, path):
112 # Path may not be in db (if updating a pre-hardlink support index).
113 node = self._path_node.get(path)
115 self._del_node_path(node, path)
116 del self._path_node[path]
118 def node_paths(self, dev, ino):
119 node = '%s:%s' % (dev, ino)
120 return self._node_paths[node]