mediagoblin/workbench.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011, 2012 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         try:
  51             return str(self)
  52         except AttributeError:
  53             return 'None'
  54
  55     def joinpath(self, *args):
  56         return os.path.join(self.dir, *args)
  57
  58     def localized_file(self, storage, filepath,
  59                        filename_if_copying=None,
  60                        keep_extension_if_copying=True):
  61         """
  62         Possibly localize the file from this storage system (for read-only
  63         purposes, modifications should be written to a new file.).
  64
  65         If the file is already local, just return the absolute filename of that
  66         local file.  Otherwise, copy the file locally to the workbench, and
  67         return the absolute path of the new file.
  68
  69         If it is copying locally, we might want to require a filename like
  70         "source.jpg" to ensure that we won't conflict with other filenames in
  71         our workbench... if that's the case, make sure filename_if_copying is
  72         set to something like 'source.jpg'.  Relatedly, if you set
  73         keep_extension_if_copying, you don't have to set an extension on
  74         filename_if_copying yourself, it'll be set for you (assuming such an
  75         extension can be extacted from the filename in the filepath).
  76
  77         Returns:
  78           localized_filename
  79
  80         Examples:
  81           >>> wb_manager.localized_file(
  82           ...     '/our/workbench/subdir', local_storage,
  83           ...     ['path', 'to', 'foobar.jpg'])
  84           u'/local/storage/path/to/foobar.jpg'
  85
  86           >>> wb_manager.localized_file(
  87           ...     '/our/workbench/subdir', remote_storage,
  88           ...     ['path', 'to', 'foobar.jpg'])
  89           '/our/workbench/subdir/foobar.jpg'
  90
  91           >>> wb_manager.localized_file(
  92           ...     '/our/workbench/subdir', remote_storage,
  93           ...     ['path', 'to', 'foobar.jpg'], 'source.jpeg', False)
  94           '/our/workbench/subdir/foobar.jpeg'
  95
  96           >>> wb_manager.localized_file(
  97           ...     '/our/workbench/subdir', remote_storage,
  98           ...     ['path', 'to', 'foobar.jpg'], 'source', True)
  99           '/our/workbench/subdir/foobar.jpg'
 100         """
 101         if storage.local_storage:
 102             return storage.get_local_path(filepath)
 103         else:
 104             if filename_if_copying is None:
 105                 dest_filename = filepath[-1]
 106             else:
 107                 orig_filename, orig_ext = os.path.splitext(filepath[-1])
 108                 if keep_extension_if_copying and orig_ext:
 109                     dest_filename = filename_if_copying + orig_ext
 110                 else:
 111                     dest_filename = filename_if_copying
 112
 113             full_dest_filename = os.path.join(
 114                 self.dir, dest_filename)
 115
 116             # copy it over
 117             storage.copy_locally(
 118                 filepath, full_dest_filename)
 119
 120             return full_dest_filename
 121
 122     def destroy_self(self):
 123         """
 124         Destroy this workbench!  Deletes the directory and all its contents!
 125
 126         WARNING: Does no checks for a sane value in self.dir!
 127         """
 128         # just in case
 129         workbench = os.path.abspath(self.dir)
 130
 131         shutil.rmtree(workbench)
 132
 133         del self.dir
 134
 135
 136 class WorkbenchManager(object):
 137     """
 138     A system for generating and destroying workbenches.
 139
 140     Workbenches are actually just subdirectories of a temporary storage space
 141     for during the processing stage.
 142     """
 143
 144     def __init__(self, base_workbench_dir):
 145         self.base_workbench_dir = os.path.abspath(base_workbench_dir)
 146         if not os.path.exists(self.base_workbench_dir):
 147             os.makedirs(self.base_workbench_dir)
 148
 149     def create_workbench(self):
 150         """
 151         Create and return the path to a new workbench (directory).
 152         """
 153         return Workbench(tempfile.mkdtemp(dir=self.base_workbench_dir))