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, 2008  Guillaume Chazarain <guichaz@gmail.com>
  18
  19 import os
  20
  21 from pysize.core.pysize_global_fs_cache import get_dev_ino
  22 from pysize.core.exception_propagation import catches, unexpect
  23
  24 # ['/path/to/file1', '/path/to/file2']
  25 TO_DELETE = []
  26
  27 # {device: {inode: (size_to_subtract|DELETED)}}
  28 DEV_INO_TO_SUBTRACT = {}
  29
  30 # Deleted inodes are marked as such, instead of subtracting their whole size
  31 # as the latter may change
  32 class deleted(object):
  33     pass
  34 DELETED = deleted()
  35
  36 @unexpect(OSError)
  37 def _iter_from_the_root(fullpath):
  38     """If path is /a/b/c, iterates over /, /a, /a/b, /a/b/c and returns also
  39     for each path the inodes dictionary in DEV_INO_TO_SUBTRACT as well as the
  40     inode number"""
  41     rebuilt = '/'
  42     for element in [''] + fullpath.strip('/').split('/'):
  43         rebuilt = os.path.join(rebuilt, element)
  44         dev, ino = get_dev_ino(rebuilt)
  45         yield DEV_INO_TO_SUBTRACT.setdefault(dev, {}), ino, rebuilt
  46
  47 @catches(OSError)
  48 def get_deletion_info(fullpath):
  49     """Get the size to subtract to the size of the given path, the returned
  50     value can be:
  51       o The size to subtract
  52       o DELETED if the given path has been deleted"""
  53     subtracted = 0
  54     if DEV_INO_TO_SUBTRACT:
  55         try:
  56             for inodes, ino, prefix in _iter_from_the_root(fullpath):
  57                 subtracted = inodes.get(ino, 0)
  58                 if subtracted == 0:
  59                     # Nothing to delete
  60                     break
  61                 if subtracted is DELETED:
  62                     # The prefix is deleted, so the complete path too
  63                     break
  64                 # Otherwise the prefix contains some deleted items, so we must
  65                 # continue
  66         except OSError, e:
  67             print e
  68             return DELETED
  69     return subtracted
  70
  71 def _add_to_hash(fullpath):
  72     """Add the path to the hash table, including its parents"""
  73     from pysize.core import compute_size
  74     size = compute_size.slow(fullpath)
  75     dev, ino = get_dev_ino(fullpath)
  76     DEV_INO_TO_SUBTRACT.setdefault(dev, {})[ino] = DELETED
  77     for inodes, ino, prefix in _iter_from_the_root(os.path.dirname(fullpath)):
  78         inodes[ino] = inodes.get(ino, 0) + size
  79
  80 # TODO: Deletion of hard links
  81 @catches(OSError)
  82 def schedule(nodes):
  83     """Simulate the deletion of some files"""
  84     for node in nodes:
  85         for fullpath in node.get_fullpaths():
  86             to_delete = False
  87             try:
  88                 subtract = get_deletion_info(fullpath)
  89                 if subtract is not DELETED:
  90                     _add_to_hash(fullpath)
  91                     to_delete = True
  92             except OSError, e:
  93                 print e
  94             if to_delete:
  95                 TO_DELETE.append(fullpath)
  96
  97     _prune_list()
  98     _rebuild_hash()
  99
 100 def _prune_list():
 101     """Remove children if we have the parent"""
 102     while True:
 103         for i in xrange(len(TO_DELETE)):
 104             parent = os.path.dirname(TO_DELETE[i])
 105             if get_deletion_info(parent) is DELETED:
 106                 del TO_DELETE[i]
 107                 break
 108         else:
 109             break
 110
 111 def _rebuild_hash():
 112     """Rebuild the hash table from the list of deleted files"""
 113     DEV_INO_TO_SUBTRACT.clear()
 114     for fullpath in TO_DELETE:
 115         _add_to_hash(fullpath)
 116
 117 def filter_deleted(dirname, basenames):
 118     """Basenames are files in the current directory"""
 119     if not DEV_INO_TO_SUBTRACT:
 120         return basenames
 121     subtracted_prefix = get_deletion_info(dirname)
 122     if subtracted_prefix is DELETED:
 123         return []
 124     if not subtracted_prefix:
 125         return basenames
 126     @catches(OSError)
 127     def is_not_deleted(basename):
 128         try:
 129             dev, ino = get_dev_ino(dirname + '/' + basename)
 130             return DEV_INO_TO_SUBTRACT.get(dev, {}).get(ino, 0) is not DELETED
 131         except OSError, e:
 132             print e
 133             return False
 134     return filter(is_not_deleted, basenames)
 135
 136 def get_deleted():
 137     """Return a copy to permit modifications while iterating"""
 138     return TO_DELETE[:]
 139
 140 @catches(OSError)
 141 def restore(fullpath):
 142     """Cancel the deletion of the given path"""
 143     from pysize.core import compute_size
 144     try:
 145         dev, ino = get_dev_ino(fullpath)
 146     except OSError, e:
 147         print e
 148         return
 149     TO_DELETE.remove(fullpath)
 150     del DEV_INO_TO_SUBTRACT[dev][ino]
 151     size = compute_size.slow(fullpath, account_deletion=False)
 152     for inodes, ino, prefix in _iter_from_the_root(os.path.dirname(fullpath)):
 153         if inodes[ino] == size:
 154             del inodes[ino]
 155         else:
 156             inodes[ino] -= size