mediagoblin/workbench.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011 MediaGoblin contributors.  See AUTHORS.
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import os
  18 import shutil
  19 import tempfile
  20
  21
  22 DEFAULT_WORKBENCH_DIR = os.path.join(
  23     tempfile.gettempdir(), u'mgoblin_workbench')
  24
  25
  26 # Actual workbench stuff
  27 # ----------------------
  28
  29 class Workbench(object):
  30     """
  31     Represent the directory for the workbench
  32
  33     WARNING: DO NOT create Workbench objects on your own,
  34     let the WorkbenchManager do that for you!
  35     """
  36     def __init__(self, dir):
  37         """
  38         WARNING: DO NOT create Workbench objects on your own,
  39         let the WorkbenchManager do that for you!
  40         """
  41         self.dir = dir
  42
  43     def __unicode__(self):
  44         return unicode(self.dir)
  45
  46     def __str__(self):
  47         return str(self.dir)
  48
  49     def __repr__(self):
  50         return repr(self.dir)
  51
  52     def joinpath(self, *args):
  53         return os.path.join(self.dir, *args)
  54
  55     def localized_file(self, storage, filepath,
  56                        filename_if_copying=None,
  57                        keep_extension_if_copying=True):
  58         """
  59         Possibly localize the file from this storage system (for read-only
  60         purposes, modifications should be written to a new file.).
  61
  62         If the file is already local, just return the absolute filename of that
  63         local file.  Otherwise, copy the file locally to the workbench, and
  64         return the absolute path of the new file.
  65
  66         If it is copying locally, we might want to require a filename like
  67         "source.jpg" to ensure that we won't conflict with other filenames in
  68         our workbench... if that's the case, make sure filename_if_copying is
  69         set to something like 'source.jpg'.  Relatedly, if you set
  70         keep_extension_if_copying, you don't have to set an extension on
  71         filename_if_copying yourself, it'll be set for you (assuming such an
  72         extension can be extacted from the filename in the filepath).
  73
  74         Returns:
  75           localized_filename
  76
  77         Examples:
  78           >>> wb_manager.localized_file(
  79           ...     '/our/workbench/subdir', local_storage,
  80           ...     ['path', 'to', 'foobar.jpg'])
  81           u'/local/storage/path/to/foobar.jpg'
  82
  83           >>> wb_manager.localized_file(
  84           ...     '/our/workbench/subdir', remote_storage,
  85           ...     ['path', 'to', 'foobar.jpg'])
  86           '/our/workbench/subdir/foobar.jpg'
  87
  88           >>> wb_manager.localized_file(
  89           ...     '/our/workbench/subdir', remote_storage,
  90           ...     ['path', 'to', 'foobar.jpg'], 'source.jpeg', False)
  91           '/our/workbench/subdir/foobar.jpeg'
  92
  93           >>> wb_manager.localized_file(
  94           ...     '/our/workbench/subdir', remote_storage,
  95           ...     ['path', 'to', 'foobar.jpg'], 'source', True)
  96           '/our/workbench/subdir/foobar.jpg'
  97         """
  98         if storage.local_storage:
  99             return storage.get_local_path(filepath)
 100         else:
 101             if filename_if_copying is None:
 102                 dest_filename = filepath[-1]
 103             else:
 104                 orig_filename, orig_ext = os.path.splitext(filepath[-1])
 105                 if keep_extension_if_copying and orig_ext:
 106                     dest_filename = filename_if_copying + orig_ext
 107                 else:
 108                     dest_filename = filename_if_copying
 109
 110             full_dest_filename = os.path.join(
 111                 self.dir, dest_filename)
 112
 113             # copy it over
 114             storage.copy_locally(
 115                 filepath, full_dest_filename)
 116
 117             return full_dest_filename
 118
 119     def destroy_self(self):
 120         """
 121         Destroy this workbench!  Deletes the directory and all its contents!
 122
 123         WARNING: Does no checks for a sane value in self.dir!
 124         """
 125         # just in case
 126         workbench = os.path.abspath(self.dir)
 127
 128         shutil.rmtree(workbench)
 129
 130         del self.dir
 131
 132
 133 class WorkbenchManager(object):
 134     """
 135     A system for generating and destroying workbenches.
 136
 137     Workbenches are actually just subdirectories of a temporary storage space
 138     for during the processing stage.
 139     """
 140
 141     def __init__(self, base_workbench_dir):
 142         self.base_workbench_dir = os.path.abspath(base_workbench_dir)
 143         if not os.path.exists(self.base_workbench_dir):
 144             os.makedirs(self.base_workbench_dir)
 145
 146     def create_workbench(self):
 147         """
 148         Create and return the path to a new workbench (directory).
 149         """
 150         return Workbench(tempfile.mkdtemp(dir=self.base_workbench_dir))