When Celery CachedFileBackend used with filesystem storage (django.core.files.storage.FileSystemStorage), everything works fine.
But there are issues with storages.backends.s3boto3.S3Boto3Storage (and it's fix from #391), as well as with django_s3_storage.storage.S3Storage.
Exception was:
```
Traceback (most recent call last):
...
File "/src/django-imagekit/imagekit/cachefiles/__init__.py", line 131, in __bool__
existence_required.send(sender=self, file=self)
...
File "/libs/utils.py", line 380, in on_existence_required
file.generate()
File "/src/django-imagekit/imagekit/cachefiles/__init__.py", line 94, in generate
self.cachefile_backend.generate(self, force)
File "/src/django-imagekit/imagekit/cachefiles/backends.py", line 136, in generate
self.schedule_generation(file, force=force)
File "/src/django-imagekit/imagekit/cachefiles/backends.py", line 165, in schedule_generation
_celery_task.delay(self, file.generator, force=force)
...
File "/lib/python3.6/site-packages/kombu/serialization.py", line 221, in dumps
payload = encoder(data)
File "/lib/python3.6/site-packages/kombu/serialization.py", line 350, in pickle_dumps
return dumper(obj, protocol=pickle_protocol)
kombu.exceptions.EncodeError: can't pickle _thread._local objects
```
Cachefile strategy may be configured to generate file when file existance required.
To generate images, async backends passes `ImageCacheFile` instance to worker.
Both celery and RQ calls `__repr__` method for each argument to enque call.
And if `__repr__` of object will send `existnace_required` signal, we will get endless recursion.
Issue: #434
The Lenna image used in image processing tests is considered problematic due to
its unclear copyright status. Right now it is considered to be "overlooked" by
the copyright holder Playboy.
A suitable replacement image is already provided in the libav sources which is
licensed under the Expat (MIT) license and thus truly free.
This replaces the Lenna image with the one from the libav project.
This prevents extra IO. Different defaults are used for async backends
since we can’t assume that `existence_required` resulted in existence
synchronously.
* 'python3' of https://github.com/vstoykov/django-imagekit:
Add Venelin Stoykov to AUTHORS
Improve logic of contributing ImageSpecFields to Models
Use force_bytes from imagekit.lib in test_cachefiles
Remove @vstoykov's note. Seems like the right place to me (:
Move force_bytes into lib module
Don't use a raw string with \u escapes
Fix sanitizing cache key under Python 3
Add module to sys.modules
Test for Python 3
Insert importer at beginning of list
Delay Django import until needed
Add Python 3 suport and drop support for Python 2.5
Conflicts:
imagekit/cachefiles/__init__.py
As discussed in #214, source_created and source_changed didn't really
have clear definitions. In truth, their names and separation betray
their origins as model receivers in earlier versions. The "source group"
abstraction helped us get away from thinking about things exclusively in
terms of models, but these remained as an artifact.
Differentiating between when the generated file content is required and
when the generated file is just required to exist gives us more
flexibility with strategies.
