Source code for atmo.celery

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, you can obtain one at
import os
import random
from celery import Celery
from celery.five import string_t
from celery.utils.time import maybe_iso8601

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'atmo.settings')
os.environ.setdefault('DJANGO_CONFIGURATION', 'Dev')

import configurations  # noqa

[docs]class ExpoBackoffFullJitter: """ Implement fully jittered exponential retries. See for more infos: - - """ # Copyright 2015 Amazon # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. def __init__(self, base, cap): self.base = base self.cap = cap
[docs] def expo(self, n): """Return the exponential value for the given number.""" return min(self.cap, pow(2, n) * self.base)
[docs] def backoff(self, n): """Return the exponential backoff value for the given number.""" v = self.expo(n) return random.uniform(0, v)
[docs]class AtmoCelery(Celery): """ A custom Celery class to implement exponential backoff retries. """
[docs] def send_task(self, *args, **kwargs): # HACK: This needs to be removed once Celery > 4.0.2 is out: # see # and expires = kwargs.get('expires') if isinstance(expires, string_t): kwargs['expires'] = maybe_iso8601(expires) return super().send_task(*args, **kwargs)
[docs] def backoff(self, n, cap=60 * 60): """ Return a fully jittered backoff value for the given number. """ return ExpoBackoffFullJitter(base=1, cap=cap).backoff(n)
#: The Celery app instance used by ATMO, which auto-detects Celery #: config values from Django settings prefixed with "CELERY\_" #: and autodiscovers Celery tasks from ```` modules in #: Django apps. celery = AtmoCelery('atmo') # Using a string here means the worker don't have to serialize # the configuration object to child processes. # - namespace='CELERY' means all celery-related configuration keys # should have a `CELERY_` prefix. celery.config_from_object('django.conf:settings', namespace='CELERY') # Load task modules from all registered Django app configs. celery.autodiscover_tasks()