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.queued_filename = None
  90
  91     def set_workbench(self, wb):
  92         self.workbench = wb
  93
  94     def get_queued_filename(self):
  95         """
  96         Get the a filename for the original, on local storage
  97         """
  98         if self.queued_filename is not None:
  99             return self.queued_filename
 100         queued_filepath = self.entry.queued_media_file
 101         queued_filename = self.workbench.localized_file(
 102             mgg.queue_store, queued_filepath,
 103             'source')
 104         self.queued_filename = queued_filename
 105         return queued_filename
 106
 107     def copy_original(self, target_name, keyname=u"original"):
 108         self.store_public(keyname, self.get_queued_filename(), target_name)
 109
 110     def store_public(self, keyname, local_file, target_name=None):
 111         if target_name is None:
 112             target_name = os.path.basename(local_file)
 113         target_filepath = create_pub_filepath(self.entry, target_name)
 114         if keyname in self.entry.media_files:
 115             _log.warn("store_public: keyname %r already used for file %r, "
 116                       "replacing with %r", keyname,
 117                       self.entry.media_files[keyname], target_filepath)
 118         mgg.public_store.copy_local_to_storage(local_file, target_filepath)
 119         self.entry.media_files[keyname] = target_filepath
 120
 121     def delete_queue_file(self):
 122         # Remove queued media file from storage and database.
 123         # queued_filepath is in the task_id directory which should
 124         # be removed too, but fail if the directory is not empty to be on
 125         # the super-safe side.
 126         queued_filepath = self.entry.queued_media_file
 127         mgg.queue_store.delete_file(queued_filepath)      # rm file
 128         mgg.queue_store.delete_dir(queued_filepath[:-1])  # rm dir
 129         self.entry.queued_media_file = []
 130
 131
 132 def mark_entry_failed(entry_id, exc):
 133     """
 134     Mark a media entry as having failed in its conversion.
 135
 136     Uses the exception that was raised to mark more information.  If
 137     the exception is a derivative of BaseProcessingFail then we can
 138     store extra information that can be useful for users telling them
 139     why their media failed to process.
 140
 141     Args:
 142      - entry_id: The id of the media entry
 143
 144     """
 145     # Was this a BaseProcessingFail?  In other words, was this a
 146     # type of error that we know how to handle?
 147     if isinstance(exc, BaseProcessingFail):
 148         # Looks like yes, so record information about that failure and any
 149         # metadata the user might have supplied.
 150         atomic_update(mgg.database.MediaEntry,
 151             {'id': entry_id},
 152             {u'state': u'failed',
 153              u'fail_error': unicode(exc.exception_path),
 154              u'fail_metadata': exc.metadata})
 155     else:
 156         _log.warn("No idea what happened here, but it failed: %r", exc)
 157         # Looks like no, so just mark it as failed and don't record a
 158         # failure_error (we'll assume it wasn't handled) and don't record
 159         # metadata (in fact overwrite it if somehow it had previous info
 160         # here)
 161         atomic_update(mgg.database.MediaEntry,
 162             {'id': entry_id},
 163             {u'state': u'failed',
 164              u'fail_error': None,
 165              u'fail_metadata': {}})
 166
 167
 168 class BaseProcessingFail(Exception):
 169     """
 170     Base exception that all other processing failure messages should
 171     subclass from.
 172
 173     You shouldn't call this itself; instead you should subclass it
 174     and provid the exception_path and general_message applicable to
 175     this error.
 176     """
 177     general_message = u''
 178
 179     @property
 180     def exception_path(self):
 181         return u"%s:%s" % (
 182             self.__class__.__module__, self.__class__.__name__)
 183
 184     def __init__(self, **metadata):
 185         self.metadata = metadata or {}
 186
 187 class BadMediaFail(BaseProcessingFail):
 188     """
 189     Error that should be raised when an inappropriate file was given
 190     for the media type specified.
 191     """
 192     general_message = _(u'Invalid file given for media type.')