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Viewing changes to lib/lp/app/longpoll/adapters/event.py

  • Committer: Launchpad Patch Queue Manager
  • Date: 2011-07-05 17:43:37 UTC
  • mfrom: (13333.6.49 lp-app-longpoll)
  • Revision ID: launchpad@pqm.canonical.com-20110705174337-4ygi4i0soakb5cs2
[r=gmb][no-qa] New lp.app.longpoll package.

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lib/lp/app/longpoll/adapters/event.py
 
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# Copyright 2011 Canonical Ltd.  This software is licensed under the
 
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# GNU Affero General Public License version 3 (see the file LICENSE).
 
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"""Long poll adapters."""
 
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__metaclass__ = type
 
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__all__ = [
 
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    "generate_event_key",
 
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    "LongPollEvent",
 
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    ]
 
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from lp.services.messaging.queue import RabbitRoutingKey
 
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def generate_event_key(*components):
 
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    """Generate a suitable event name."""
 
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    if len(components) == 0:
 
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        raise AssertionError(
 
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            "Event keys must contain at least one component.")
 
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    return "longpoll.event.%s" % ".".join(
 
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        str(component) for component in components)
 
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class LongPollEvent:
 
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    """Base-class for event adapters.
 
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    Sub-classes need to declare something along the lines of:
 
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        adapts(Interface, Interface)
 
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        implements(ILongPollEvent)
 
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    """
 
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    def __init__(self, source, event):
 
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        self.source = source
 
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        self.event = event
 
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    @property
 
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    def event_key(self):
 
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        """See `ILongPollEvent`."""
 
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        raise NotImplementedError(self.__class__.event_key)
 
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    def emit(self, data):
 
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        """See `ILongPollEvent`."""
 
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        payload = {"event_key": self.event_key, "event_data": data}
 
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        routing_key = RabbitRoutingKey(self.event_key)
 
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        routing_key.send(payload)