136 lines
4.9 KiB
Python
136 lines
4.9 KiB
Python
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"""Event receiver implementation."""
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import time
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from operator import itemgetter
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from kombu import Queue
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from kombu.connection import maybe_channel
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from kombu.mixins import ConsumerMixin
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from celery import uuid
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from celery.app import app_or_default
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from celery.utils.time import adjust_timestamp
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from .event import get_exchange
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__all__ = ('EventReceiver',)
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CLIENT_CLOCK_SKEW = -1
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_TZGETTER = itemgetter('utcoffset', 'timestamp')
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class EventReceiver(ConsumerMixin):
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"""Capture events.
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Arguments:
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connection (kombu.Connection): Connection to the broker.
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handlers (Mapping[Callable]): Event handlers.
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This is a map of event type names and their handlers.
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The special handler `"*"` captures all events that don't have a
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handler.
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"""
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app = None
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def __init__(self, channel, handlers=None, routing_key='#',
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node_id=None, app=None, queue_prefix=None,
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accept=None, queue_ttl=None, queue_expires=None):
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self.app = app_or_default(app or self.app)
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self.channel = maybe_channel(channel)
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self.handlers = {} if handlers is None else handlers
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self.routing_key = routing_key
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self.node_id = node_id or uuid()
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self.queue_prefix = queue_prefix or self.app.conf.event_queue_prefix
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self.exchange = get_exchange(
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self.connection or self.app.connection_for_write(),
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name=self.app.conf.event_exchange)
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if queue_ttl is None:
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queue_ttl = self.app.conf.event_queue_ttl
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if queue_expires is None:
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queue_expires = self.app.conf.event_queue_expires
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self.queue = Queue(
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'.'.join([self.queue_prefix, self.node_id]),
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exchange=self.exchange,
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routing_key=self.routing_key,
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auto_delete=True, durable=False,
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message_ttl=queue_ttl,
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expires=queue_expires,
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)
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self.clock = self.app.clock
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self.adjust_clock = self.clock.adjust
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self.forward_clock = self.clock.forward
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if accept is None:
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accept = {self.app.conf.event_serializer, 'json'}
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self.accept = accept
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def process(self, type, event):
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"""Process event by dispatching to configured handler."""
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handler = self.handlers.get(type) or self.handlers.get('*')
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handler and handler(event)
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def get_consumers(self, Consumer, channel):
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return [Consumer(queues=[self.queue],
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callbacks=[self._receive], no_ack=True,
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accept=self.accept)]
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def on_consume_ready(self, connection, channel, consumers,
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wakeup=True, **kwargs):
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if wakeup:
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self.wakeup_workers(channel=channel)
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def itercapture(self, limit=None, timeout=None, wakeup=True):
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return self.consume(limit=limit, timeout=timeout, wakeup=wakeup)
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def capture(self, limit=None, timeout=None, wakeup=True):
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"""Open up a consumer capturing events.
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This has to run in the main process, and it will never stop
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unless :attr:`EventDispatcher.should_stop` is set to True, or
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forced via :exc:`KeyboardInterrupt` or :exc:`SystemExit`.
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"""
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for _ in self.consume(limit=limit, timeout=timeout, wakeup=wakeup):
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pass
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def wakeup_workers(self, channel=None):
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self.app.control.broadcast('heartbeat',
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connection=self.connection,
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channel=channel)
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def event_from_message(self, body, localize=True,
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now=time.time, tzfields=_TZGETTER,
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adjust_timestamp=adjust_timestamp,
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CLIENT_CLOCK_SKEW=CLIENT_CLOCK_SKEW):
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type = body['type']
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if type == 'task-sent':
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# clients never sync so cannot use their clock value
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_c = body['clock'] = (self.clock.value or 1) + CLIENT_CLOCK_SKEW
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self.adjust_clock(_c)
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else:
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try:
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clock = body['clock']
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except KeyError:
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body['clock'] = self.forward_clock()
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else:
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self.adjust_clock(clock)
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if localize:
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try:
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offset, timestamp = tzfields(body)
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except KeyError:
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pass
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else:
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body['timestamp'] = adjust_timestamp(timestamp, offset)
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body['local_received'] = now()
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return type, body
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def _receive(self, body, message, list=list, isinstance=isinstance):
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if isinstance(body, list): # celery 4.0+: List of events
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process, from_message = self.process, self.event_from_message
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[process(*from_message(event)) for event in body]
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else:
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self.process(*self.event_from_message(body))
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@property
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def connection(self):
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return self.channel.connection.client if self.channel else None
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