mediagoblin/processing/__init__.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 import os
  19
  20 from mediagoblin.db.util import atomic_update
  21 from mediagoblin import mg_globals as mgg
  22
  23 from mediagoblin.tools.translate import lazy_pass_to_ugettext as _
  24
  25 _log = logging.getLogger(__name__)
  26
  27
  28 class ProgressCallback(object):
  29     def __init__(self, entry):
  30         self.entry = entry
  31
  32     def __call__(self, progress):
  33         if progress:
  34             self.entry.transcoding_progress = progress
  35             self.entry.save()
  36
  37
  38 def create_pub_filepath(entry, filename):
  39     return mgg.public_store.get_unique_filepath(
  40             ['media_entries',
  41              unicode(entry.id),
  42              filename])
  43
  44
  45 class FilenameBuilder(object):
  46     """Easily slice and dice filenames.
  47
  48     Initialize this class with an original file path, then use the fill()
  49     method to create new filenames based on the original.
  50
  51     """
  52     MAX_FILENAME_LENGTH = 255  # VFAT's maximum filename length
  53
  54     def __init__(self, path):
  55         """Initialize a builder from an original file path."""
  56         self.dirpath, self.basename = os.path.split(path)
  57         self.basename, self.ext = os.path.splitext(self.basename)
  58         self.ext = self.ext.lower()
  59
  60     def fill(self, fmtstr):
  61         """Build a new filename based on the original.
  62
  63         The fmtstr argument can include the following:
  64         {basename} -- the original basename, with the extension removed
  65         {ext} -- the original extension, always lowercase
  66
  67         If necessary, {basename} will be truncated so the filename does not
  68         exceed this class' MAX_FILENAME_LENGTH in length.
  69
  70         """
  71         basename_len = (self.MAX_FILENAME_LENGTH -
  72                         len(fmtstr.format(basename='', ext=self.ext)))
  73         return fmtstr.format(basename=self.basename[:basename_len],
  74                              ext=self.ext)
  75
  76
  77 class ProcessingState(object):
  78     """
  79     The first and only argument to the "processor" of a media type
  80
  81     This could be thought of as a "request" to the processor
  82     function. It has the main info for the request (media entry)
  83     and a bunch of tools for the request on it.
  84     It can get more fancy without impacting old media types.
  85     """
  86     def __init__(self, entry):
  87         self.entry = entry
  88         self.workbench = None
  89         self.orig_filename = None
  90
  91     def set_workbench(self, wb):
  92         self.workbench = wb
  93
  94     def get_orig_filename(self):
  95         """
  96         Get the a filename for the original, on local storage
  97
  98         If the media entry has a queued_media_file, use that, otherwise
  99         use the original.
 100
 101         In the future, this will return the highest quality file available
 102         if neither the original or queued file are available
 103         """
 104         if self.orig_filename is not None:
 105             return self.orig_filename
 106
 107         if self.entry.queued_media_file:
 108             orig_filepath = self.entry.queued_media_file
 109         else:
 110             orig_filepath = self.entry.media_files['original']
 111
 112         orig_filename = self.workbench.localized_file(
 113             mgg.queue_store, orig_filepath,
 114             'source')
 115         self.orig_filename = orig_filename
 116         return orig_filename
 117
 118     def copy_original(self, target_name, keyname=u"original"):
 119         self.store_public(keyname, self.get_orig_filename(), target_name)
 120
 121     def store_public(self, keyname, local_file, target_name=None):
 122         if target_name is None:
 123             target_name = os.path.basename(local_file)
 124         target_filepath = create_pub_filepath(self.entry, target_name)
 125         if keyname in self.entry.media_files:
 126             _log.warn("store_public: keyname %r already used for file %r, "
 127                       "replacing with %r", keyname,
 128                       self.entry.media_files[keyname], target_filepath)
 129         mgg.public_store.copy_local_to_storage(local_file, target_filepath)
 130         self.entry.media_files[keyname] = target_filepath
 131
 132     def delete_queue_file(self):
 133         # Remove queued media file from storage and database.
 134         # queued_filepath is in the task_id directory which should
 135         # be removed too, but fail if the directory is not empty to be on
 136         # the super-safe side.
 137         queued_filepath = self.entry.queued_media_file
 138         mgg.queue_store.delete_file(queued_filepath)      # rm file
 139         mgg.queue_store.delete_dir(queued_filepath[:-1])  # rm dir
 140         self.entry.queued_media_file = []
 141
 142
 143 def mark_entry_failed(entry_id, exc):
 144     """
 145     Mark a media entry as having failed in its conversion.
 146
 147     Uses the exception that was raised to mark more information.  If
 148     the exception is a derivative of BaseProcessingFail then we can
 149     store extra information that can be useful for users telling them
 150     why their media failed to process.
 151
 152     Args:
 153      - entry_id: The id of the media entry
 154
 155     """
 156     # Was this a BaseProcessingFail?  In other words, was this a
 157     # type of error that we know how to handle?
 158     if isinstance(exc, BaseProcessingFail):
 159         # Looks like yes, so record information about that failure and any
 160         # metadata the user might have supplied.
 161         atomic_update(mgg.database.MediaEntry,
 162             {'id': entry_id},
 163             {u'state': u'failed',
 164              u'fail_error': unicode(exc.exception_path),
 165              u'fail_metadata': exc.metadata})
 166     else:
 167         _log.warn("No idea what happened here, but it failed: %r", exc)
 168         # Looks like no, so just mark it as failed and don't record a
 169         # failure_error (we'll assume it wasn't handled) and don't record
 170         # metadata (in fact overwrite it if somehow it had previous info
 171         # here)
 172         atomic_update(mgg.database.MediaEntry,
 173             {'id': entry_id},
 174             {u'state': u'failed',
 175              u'fail_error': None,
 176              u'fail_metadata': {}})
 177
 178
 179 class BaseProcessingFail(Exception):
 180     """
 181     Base exception that all other processing failure messages should
 182     subclass from.
 183
 184     You shouldn't call this itself; instead you should subclass it
 185     and provid the exception_path and general_message applicable to
 186     this error.
 187     """
 188     general_message = u''
 189
 190     @property
 191     def exception_path(self):
 192         return u"%s:%s" % (
 193             self.__class__.__module__, self.__class__.__name__)
 194
 195     def __init__(self, **metadata):
 196         self.metadata = metadata or {}
 197
 198
 199 class BadMediaFail(BaseProcessingFail):
 200     """
 201     Error that should be raised when an inappropriate file was given
 202     for the media type specified.
 203     """
 204     general_message = _(u'Invalid file given for media type.')