pysize/core/deletion.py

   1 # This program is free software; you can redistribute it and/or modify
   2 # it under the terms of the GNU General Public License as published by
   3 # the Free Software Foundation; either version 2 of the License, or
   4 # (at your option) any later version.
   5 #
   6 # This program is distributed in the hope that it will be useful,
   7 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 # GNU Library General Public License for more details.
  10 #
  11 # You should have received a copy of the GNU General Public License
  12 # along with this program; if not, write to the Free Software
  13 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  14 #
  15 # See the COPYING file for license information.
  16 #
  17 # Copyright (c) 2006, 2007 Guillaume Chazarain <guichaz@yahoo.fr>
  18
  19 import os
  20
  21 from pysize.core.pysize_global_fs_cache import get_dev_ino
  22
  23 # ['/path/to/file1', '/path/to/file2']
  24 TO_DELETE = []
  25
  26 # {device: {inode: (size_to_subtract|DELETED)}}
  27 DEV_INO_TO_SUBTRACT = {}
  28
  29 DELETED = 'deleted'
  30
  31 def _get_subtracted(path):
  32     dev, ino = get_dev_ino(path)
  33     return DEV_INO_TO_SUBTRACT.setdefault(dev, {}).get(ino, None)
  34
  35 def _iter_to_the_root(path):
  36     while path not in ('/', ''):
  37         yield get_dev_ino(path), path
  38         path = os.path.dirname(path)
  39
  40 def get_subtracted(path):
  41     if DEV_INO_TO_SUBTRACT:
  42         for dev_ino, tmp_path in _iter_to_the_root(path):
  43             if _get_subtracted(tmp_path) is DELETED:
  44                 return DELETED
  45         subtracted = _get_subtracted(path)
  46         if subtracted is not None:
  47             return subtracted
  48     return 0
  49
  50 def _add_hash(path):
  51     from pysize.core import compute_size
  52     size = compute_size.slow(path)
  53     dev, ino = get_dev_ino(path)
  54     DEV_INO_TO_SUBTRACT.setdefault(dev, {})[ino] = DELETED
  55     for (dev, ino), path in _iter_to_the_root(os.path.dirname(path)):
  56         inodes = DEV_INO_TO_SUBTRACT.setdefault(dev, {})
  57         subtract = inodes.get(ino, 0)
  58         subtract += size
  59         inodes[ino] = subtract
  60
  61 # TODO: Deletion of hard links
  62 def schedule(nodes):
  63     for node in nodes:
  64         for path in node.get_fullpaths():
  65             subtract = get_subtracted(path)
  66             if subtract is not DELETED:
  67                 TO_DELETE.append(path)
  68                 _add_hash(path)
  69     _prune_list()
  70     _rebuild_hash()
  71
  72 def _prune_list():
  73     """Remove children if we have the parent"""
  74     while True:
  75         for i in xrange(len(TO_DELETE)):
  76             parent = os.path.dirname(TO_DELETE[i])
  77             if get_subtracted(parent) is DELETED:
  78                 del TO_DELETE[i]
  79                 break
  80         else:
  81             break
  82
  83 def _rebuild_hash():
  84     DEV_INO_TO_SUBTRACT.clear()
  85     for path in TO_DELETE:
  86         _add_hash(path)
  87
  88 def filter_deleted(paths):
  89     if DEV_INO_TO_SUBTRACT:
  90         def is_not_deleted(path):
  91             return get_subtracted(path) is not DELETED
  92         return filter(is_not_deleted, paths)
  93     return paths
  94
  95 def get_deleted():
  96     return TO_DELETE[:]
  97
  98 def restore(path):
  99     from pysize.core import compute_size
 100     TO_DELETE.remove(path)
 101     dev, ino = get_dev_ino(path)
 102     del DEV_INO_TO_SUBTRACT[dev][ino]
 103     size = compute_size.slow(path, account_deletion=False)
 104     for (dev, ino), path in _iter_to_the_root(os.path.dirname(path)):
 105         inodes = DEV_INO_TO_SUBTRACT[dev]
 106         if inodes[ino] == size:
 107             del inodes[ino]
 108         else:
 109             inodes[ino] -= size