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__init__.py
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# -*- coding: utf-8 -*-
##
## This file is part of Invenio.
## Copyright (C) 2013 CERN.
##
## Invenio is free software; you can redistribute it and/or
## modify it under the terms of the GNU General Public License as
## published by the Free Software Foundation; either version 2 of the
## License, or (at your option) any later version.
##
## Invenio is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Invenio; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
"""
Invenio Celery Loader
The loader's purposes is to load modules defined in invenio.*_tasks modules
"""
# Important for 'from celery import Celery' to find the right celery module.
from __future__ import absolute_import
from celery import Celery, signals
from celery.loaders.base import BaseLoader
from . import registry
from invenio.base.factory import with_app_context
class InvenioLoader(BaseLoader):
"""
The Invenio Celery loader - modeled after the Django Celery loader.
"""
def __init__(self, *args, **kwargs):
super(InvenioLoader, self).__init__(*args, **kwargs)
self._install_signal_handlers()
self.flask_app = None
self.db = None
def _install_signal_handlers(self):
# Need to close any open database connection after
# any embedded celerybeat process forks.
signals.beat_embedded_init.connect(self.close_database)
# Handlers for settings Flask request context
signals.task_prerun.connect(self.on_task_prerun)
signals.task_postrun.connect(self.on_task_postrun)
def _init_flask(self):
"""
Initialize Flask application.
The Flask application should only be created in the workers, thus
this method should not be called from the __init__ method.
"""
if not self.flask_app:
from flask import current_app
if current_app:
self.flask_app = current_app
else:
from invenio.base.factory import create_app
self.flask_app = create_app()
from invenio.ext.sqlalchemy import db
self.db = db
def on_task_init(self, task_id, task):
"""Called before every task."""
try:
is_eager = task.request.is_eager
except AttributeError:
is_eager = False
if not is_eager:
self.close_database()
def on_task_prerun(self, task=None, **dummy_kwargs):
"""
Called before a task is run - pushes a new Flask request context
for the task.
"""
app = self.flask_app
if not app:
from flask import current_app
app = current_app
task.request.flask_ctx = app.test_request_context()
task.request.flask_ctx.push()
def on_task_postrun(self, task=None, **dummy_kwargs):
"""
Called after a task is run - pops the pushed Flask request context
for the task.
"""
task.request.flask_ctx.pop()
def on_process_cleanup(self):
"""Does everything necessary for Invenio to work in a long-living,
multiprocessing environment. Called after on_task_postrun.
"""
self.close_database()
def on_worker_init(self):
"""Called when the worker starts.
Automatically discovers any ``*_tasks.py`` files in the Invenio module.
"""
self.close_database()
def on_worker_process_init(self):
self.close_database()
def read_configuration(self):
""" Read configuration defined in invenio.celery.config """
from invenio.celery.config import default_config
self._init_flask()
self.configured = True
return default_config(self.flask_app.config)
def close_database(self, **dummy_kwargs):
if self.db:
self.db.session.remove()
def import_default_modules(self):
""" Called before on_worker_init """
# First setup Flask application
self._init_flask()
# Next import all task modules with a request context (otherwise
# the SQLAlchemy models cannot be imported).
with self.flask_app.test_request_context():
super(InvenioLoader, self).import_default_modules()
self.autodiscover()
def autodiscover(self):
"""
Discover task modules named 'invenio.modules.*.tasks'
"""
from invenio.celery import tasks
self.task_modules.update(tasks.__name__)
self.task_modules.update(
mod.__name__ for mod in registry.tasks or ())
#
# Create main celery application
#
celery = Celery(
'invenio',
loader=InvenioLoader,
)

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