Created
August 27, 2012 03:10
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Dead letter exchange based celery countdown implementation
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class FrealCountdownTask(task.Task): | |
abstract = True | |
@classmethod | |
def apply_async(self, args=None, kwargs=None, | |
task_id=None, producer=None, connection=None, router=None, | |
link=None, link_error=None, publisher=None, add_to_parent=True, | |
**options): | |
try: | |
countdown = options.pop('countdown') | |
except KeyError: | |
# no countdown, call super as normal | |
return super(FrealCountdownTask, self).apply_async(args=args, | |
kwargs=kwargs, task_id=task_id, producer=producer, | |
connection=connection, router=router, link=link, | |
link_error=link_error, publisher=publisher, | |
add_to_parent=add_to_parent, **options) | |
# resolve full list of options (taken from Task.apply_async) | |
app = self._get_app() | |
router = router or self.app.amqp.router | |
options = dict(extract_exec_options(self), **options) | |
options = router.route(options, self.name, args, kwargs) | |
# add the queue to the app so celery knows about it and use that queue | |
# for this task | |
task_id = task_id or gen_unique_id() | |
app.amqp.queues.add(task_id, exchange=settings.COUNTDOWN_EXCHANGE.name, | |
exchange_type=settings.COUNTDOWN_EXCHANGE.type, | |
routing_key=options['routing_key'], queue_arguments={ | |
'x-message-ttl': countdown * 1000, | |
'x-dead-letter-exchange': options['queue'], | |
'x-expires': (countdown + 1) * 1000, | |
}) | |
options.update({ | |
'queue': task_id, | |
'exchange': settings.COUNTDOWN_EXCHANGE, | |
}) | |
return super(FrealCountdownTask, self).apply_async(args=args, | |
kwargs=kwargs, task_id=task_id, producer=producer, | |
connection=connection, router=router, link=link, | |
link_error=link_error, publisher=publisher, | |
add_to_parent=add_to_parent, **options) |
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