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     def __str__(self):
  46         return str(self.dir)
  47     def __repr__(self):
  48         return repr(self.dir)
  49
  50     def joinpath(self, *args):
  51         return os.path.join(self.dir, *args)
  52
  53     def localized_file(self, storage, filepath,
  54                        filename_if_copying=None,
  55                        keep_extension_if_copying=True):
  56         """
  57         Possibly localize the file from this storage system (for read-only
  58         purposes, modifications should be written to a new file.).
  59
  60         If the file is already local, just return the absolute filename of that
  61         local file.  Otherwise, copy the file locally to the workbench, and
  62         return the absolute path of the new file.
  63
  64         If it is copying locally, we might want to require a filename like
  65         "source.jpg" to ensure that we won't conflict with other filenames in
  66         our workbench... if that's the case, make sure filename_if_copying is
  67         set to something like 'source.jpg'.  Relatedly, if you set
  68         keep_extension_if_copying, you don't have to set an extension on
  69         filename_if_copying yourself, it'll be set for you (assuming such an
  70         extension can be extacted from the filename in the filepath).
  71
  72         Returns:
  73           localized_filename
  74
  75         Examples:
  76           >>> wb_manager.localized_file(
  77           ...     '/our/workbench/subdir', local_storage,
  78           ...     ['path', 'to', 'foobar.jpg'])
  79           u'/local/storage/path/to/foobar.jpg'
  80
  81           >>> wb_manager.localized_file(
  82           ...     '/our/workbench/subdir', remote_storage,
  83           ...     ['path', 'to', 'foobar.jpg'])
  84           '/our/workbench/subdir/foobar.jpg'
  85
  86           >>> wb_manager.localized_file(
  87           ...     '/our/workbench/subdir', remote_storage,
  88           ...     ['path', 'to', 'foobar.jpg'], 'source.jpeg', False)
  89           '/our/workbench/subdir/foobar.jpeg'
  90
  91           >>> wb_manager.localized_file(
  92           ...     '/our/workbench/subdir', remote_storage,
  93           ...     ['path', 'to', 'foobar.jpg'], 'source', True)
  94           '/our/workbench/subdir/foobar.jpg'
  95         """
  96         if storage.local_storage:
  97             return storage.get_local_path(filepath)
  98         else:
  99             if filename_if_copying is None:
 100                 dest_filename = filepath[-1]
 101             else:
 102                 orig_filename, orig_ext = os.path.splitext(filepath[-1])
 103                 if keep_extension_if_copying and orig_ext:
 104                     dest_filename = filename_if_copying + orig_ext
 105                 else:
 106                     dest_filename = filename_if_copying
 107
 108             full_dest_filename = os.path.join(
 109                 self.dir, dest_filename)
 110
 111             # copy it over
 112             storage.copy_locally(
 113                 filepath, full_dest_filename)
 114
 115             return full_dest_filename
 116
 117     def destroy_self(self):
 118         """
 119         Destroy this workbench!  Deletes the directory and all its contents!
 120
 121         WARNING: Does no checks for a sane value in self.dir!
 122         """
 123         # just in case
 124         workbench = os.path.abspath(self.dir)
 125
 126         shutil.rmtree(workbench)
 127
 128         del self.dir
 129
 130
 131 class WorkbenchManager(object):
 132     """
 133     A system for generating and destroying workbenches.
 134
 135     Workbenches are actually just subdirectories of a temporary storage space
 136     for during the processing stage.
 137     """
 138
 139     def __init__(self, base_workbench_dir):
 140         self.base_workbench_dir = os.path.abspath(base_workbench_dir)
 141         if not os.path.exists(self.base_workbench_dir):
 142             os.makedirs(self.base_workbench_dir)
 143
 144     def create_workbench(self):
 145         """
 146         Create and return the path to a new workbench (directory).
 147         """
 148         return Workbench(tempfile.mkdtemp(dir=self.base_workbench_dir))