Feature #571 - Closing storage objects - Removed closing(), renamed
[mediagoblin.git] / mediagoblin / process_media / __init__.py
index 27f72b65d63c8ca4cb8350b2763dc29364007efb..2b9eed6e111a051afe1001262caa85c17305a9c7 100644 (file)
@@ -1,5 +1,5 @@
 # GNU MediaGoblin -- federated, autonomous media hosting
-# Copyright (C) 2011 Free Software Foundation, Inc
+# Copyright (C) 2011 MediaGoblin contributors.  See AUTHORS.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import Image
-from mediagoblin.db.util import ObjectId
-from celery.task import task
 
+from celery.task import Task
+from celery import registry
+
+from mediagoblin.db.util import ObjectId
 from mediagoblin import mg_globals as mgg
+from mediagoblin.process_media.errors import BaseProcessingFail, BadMediaFail
 
 
 THUMB_SIZE = 180, 180
@@ -32,63 +35,145 @@ def create_pub_filepath(entry, filename):
              filename])
 
 
-@task
-def process_media_initial(media_id):
-    workbench = mgg.workbench_manager.create_workbench()
+################################
+# Media processing initial steps
+################################
+
+class ProcessMedia(Task):
+    """
+    Pass this entry off for processing.
+    """
+    def run(self, media_id):
+        """
+        Pass the media entry off to the appropriate processing function
+        (for now just process_image...)
+        """
+        entry = mgg.database.MediaEntry.one(
+            {'_id': ObjectId(media_id)})
+
+        # Try to process, and handle expected errors.
+        try:
+            process_image(entry)
+        except BaseProcessingFail, exc:
+            mark_entry_failed(entry[u'_id'], exc)
+            return
 
-    entry = mgg.database.MediaEntry.one(
-        {'_id': ObjectId(media_id)})
+        entry['state'] = u'processed'
+        entry.save()
+
+    def on_failure(self, exc, task_id, args, kwargs, einfo):
+        """
+        If the processing failed we should mark that in the database.
+
+        Assuming that the exception raised is a subclass of BaseProcessingFail,
+        we can use that to get more information about the failure and store that
+        for conveying information to users about the failure, etc.
+        """
+        entry_id = args[0]
+        mark_entry_failed(entry_id, exc)
+
+
+process_media = registry.tasks[ProcessMedia.name]
+
+
+def mark_entry_failed(entry_id, exc):
+    """
+    Mark a media entry as having failed in its conversion.
+
+    Uses the exception that was raised to mark more information.  If the
+    exception is a derivative of BaseProcessingFail then we can store extra
+    information that can be useful for users telling them why their media failed
+    to process.
+
+    Args:
+     - entry_id: The id of the media entry
+
+    """
+    # Was this a BaseProcessingFail?  In other words, was this a
+    # type of error that we know how to handle?
+    if isinstance(exc, BaseProcessingFail):
+        # Looks like yes, so record information about that failure and any
+        # metadata the user might have supplied.
+        mgg.database['media_entries'].update(
+            {'_id': entry_id},
+            {'$set': {u'state': u'failed',
+                      u'fail_error': exc.exception_path,
+                      u'fail_metadata': exc.metadata}})
+    else:
+        # Looks like no, so just mark it as failed and don't record a
+        # failure_error (we'll assume it wasn't handled) and don't record
+        # metadata (in fact overwrite it if somehow it had previous info
+        # here)
+        mgg.database['media_entries'].update(
+            {'_id': entry_id},
+            {'$set': {u'state': u'failed',
+                      u'fail_error': None,
+                      u'fail_metadata': {}}})
+
+
+def process_image(entry):
+    """
+    Code to process an image
+    """
+    workbench = mgg.workbench_manager.create_workbench()
 
     queued_filepath = entry['queued_media_file']
     queued_filename = workbench.localized_file(
         mgg.queue_store, queued_filepath,
         'source')
 
-    thumb = Image.open(queued_filename)
+    try:
+        thumb = Image.open(queued_filename)
+    except IOError:
+        raise BadMediaFail()
+
     thumb.thumbnail(THUMB_SIZE, Image.ANTIALIAS)
     # ensure color mode is compatible with jpg
     if thumb.mode != "RGB":
         thumb = thumb.convert("RGB")
 
     thumb_filepath = create_pub_filepath(entry, 'thumbnail.jpg')
-
     thumb_file = mgg.public_store.get_file(thumb_filepath, 'w')
+
     with thumb_file:
-        thumb.save(thumb_file, "JPEG")
+        thumb.save(thumb_file, "JPEG", quality=90)
 
-    """
-    Create medium file, used in `media.html`
-    """
+    # If the size of the original file exceeds the specified size of a `medium`
+    # file, a `medium.jpg` files is created and later associated with the media
+    # entry.
     medium = Image.open(queued_filename)
-    medium.thumbnail(MEDIUM_SIZE, Image.ANTIALIAS)
+    medium_processed = False
+
+    if medium.size[0] > MEDIUM_SIZE[0] or medium.size[1] > MEDIUM_SIZE[1]:
+        medium.thumbnail(MEDIUM_SIZE, Image.ANTIALIAS)
 
-    if medium.mode != "RGB":
-        medium = medium.convert("RGB")
+        if medium.mode != "RGB":
+            medium = medium.convert("RGB")
 
-    medium_filepath = create_pub_filepath(entry, 'medium.jpg')
+        medium_filepath = create_pub_filepath(entry, 'medium.jpg')
+        medium_file = mgg.public_store.get_file(medium_filepath, 'w')
 
-    medium_file = mgg.public_store.get_file(medium_filepath, 'w')
-    with medium_file:
-        medium.save(medium_file, "JPEG")
+        with medium_file:
+            medium.save(medium_file, "JPEG", quality=90)
+            medium_processed = True
 
     # we have to re-read because unlike PIL, not everything reads
     # things in string representation :)
     queued_file = file(queued_filename, 'rb')
 
     with queued_file:
-        main_filepath = create_pub_filepath(entry, queued_filepath[-1])
-        
-        with mgg.public_store.get_file(main_filepath, 'wb') as main_file:
-            main_file.write(queued_file.read())
+        original_filepath = create_pub_filepath(entry, queued_filepath[-1])
+
+        with mgg.public_store.get_file(original_filepath, 'wb') as original_file:
+            original_file.write(queued_file.read())
 
     mgg.queue_store.delete_file(queued_filepath)
     entry['queued_media_file'] = []
     media_files_dict = entry.setdefault('media_files', {})
     media_files_dict['thumb'] = thumb_filepath
-    media_files_dict['main'] = main_filepath
-    media_files_dict['medium'] = medium_filepath
-    entry['state'] = u'processed'
-    entry.save()
+    media_files_dict['original'] = original_filepath
+    if medium_processed:
+        media_files_dict['medium'] = medium_filepath
 
     # clean up workbench
     workbench.destroy_self()