mediagoblin/processing.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 logging
  18
  19 from celery.task import Task
  20
  21 from mediagoblin.db.util import ObjectId
  22 from mediagoblin import mg_globals as mgg
  23
  24 from mediagoblin.tools.translate import lazy_pass_to_ugettext as _
  25
  26 from mediagoblin.media_types import get_media_manager
  27
  28 _log = logging.getLogger(__name__)
  29
  30 THUMB_SIZE = 180, 180
  31 MEDIUM_SIZE = 640, 640
  32
  33
  34 def create_pub_filepath(entry, filename):
  35     return mgg.public_store.get_unique_filepath(
  36             ['media_entries',
  37              unicode(entry._id),
  38              filename])
  39
  40
  41 ################################
  42 # Media processing initial steps
  43 ################################
  44
  45 class ProcessMedia(Task):
  46     """
  47     DEPRECATED -- This now resides in the individual media plugins
  48
  49     Pass this entry off for processing.
  50     """
  51     def run(self, media_id):
  52         """
  53         Pass the media entry off to the appropriate processing function
  54         (for now just process_image...)
  55         """
  56         entry = mgg.database.MediaEntry.one(
  57             {'_id': ObjectId(media_id)})
  58
  59         # Try to process, and handle expected errors.
  60         try:
  61             #__import__(entry.media_type)
  62             manager = get_media_manager(entry.media_type)
  63             _log.debug('Processing {0}'.format(entry))
  64             manager['processor'](entry)
  65         except BaseProcessingFail, exc:
  66             mark_entry_failed(entry._id, exc)
  67             return
  68         except ImportError, exc:
  69             _log.error(
  70                 'Entry {0} failed to process due to an import error: {1}'\
  71                     .format(
  72                     entry.title,
  73                     exc))
  74
  75             mark_entry_failed(entry._id, exc)
  76
  77         entry.state = u'processed'
  78         entry.save()
  79
  80     def on_failure(self, exc, task_id, args, kwargs, einfo):
  81         """
  82         If the processing failed we should mark that in the database.
  83
  84         Assuming that the exception raised is a subclass of
  85         BaseProcessingFail, we can use that to get more information
  86         about the failure and store that for conveying information to
  87         users about the failure, etc.
  88         """
  89         entry_id = args[0]
  90         mark_entry_failed(entry_id, exc)
  91
  92
  93 def mark_entry_failed(entry_id, exc):
  94     """
  95     Mark a media entry as having failed in its conversion.
  96
  97     Uses the exception that was raised to mark more information.  If
  98     the exception is a derivative of BaseProcessingFail then we can
  99     store extra information that can be useful for users telling them
 100     why their media failed to process.
 101
 102     Args:
 103      - entry_id: The id of the media entry
 104
 105     """
 106     # Was this a BaseProcessingFail?  In other words, was this a
 107     # type of error that we know how to handle?
 108     if isinstance(exc, BaseProcessingFail):
 109         # Looks like yes, so record information about that failure and any
 110         # metadata the user might have supplied.
 111         mgg.database['media_entries'].update(
 112             {'_id': entry_id},
 113             {'$set': {u'state': u'failed',
 114                       u'fail_error': exc.exception_path,
 115                       u'fail_metadata': exc.metadata}})
 116     else:
 117         # Looks like no, so just mark it as failed and don't record a
 118         # failure_error (we'll assume it wasn't handled) and don't record
 119         # metadata (in fact overwrite it if somehow it had previous info
 120         # here)
 121         mgg.database['media_entries'].update(
 122             {'_id': entry_id},
 123             {'$set': {u'state': u'failed',
 124                       u'fail_error': None,
 125                       u'fail_metadata': {}}})
 126
 127
 128 class BaseProcessingFail(Exception):
 129     """
 130     Base exception that all other processing failure messages should
 131     subclass from.
 132
 133     You shouldn't call this itself; instead you should subclass it
 134     and provid the exception_path and general_message applicable to
 135     this error.
 136     """
 137     general_message = u''
 138
 139     @property
 140     def exception_path(self):
 141         return u"%s:%s" % (
 142             self.__class__.__module__, self.__class__.__name__)
 143
 144     def __init__(self, **metadata):
 145         self.metadata = metadata or {}
 146
 147
 148 class BadMediaFail(BaseProcessingFail):
 149     """
 150     Error that should be raised when an inappropriate file was given
 151     for the media type specified.
 152     """
 153     general_message = _(u'Invalid file given for media type.')