5a657dd947
__metaclass__ cannot be used in python3. six be used in general for python 3 compatibility. Change-Id: I1d9909d70bb614c9d1c336d0c492027f5b6b5088 Closes-Bug: #1236648
103 lines
3.2 KiB
Python
103 lines
3.2 KiB
Python
# -*- encoding: utf-8 -*-
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#
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# Copyright © 2012 New Dream Network, LLC (DreamHost)
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#
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# Author: Doug Hellmann <doug.hellmann@dreamhost.com>
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Base class for plugins.
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"""
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import abc
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import collections
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import fnmatch
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from oslo.config import cfg
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import six
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# Import this option so every Notification plugin can use it freely.
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cfg.CONF.import_opt('notification_topics',
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'ceilometer.openstack.common.notifier.rpc_notifier')
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ExchangeTopics = collections.namedtuple('ExchangeTopics',
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['exchange', 'topics'])
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class PluginBase(object):
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"""Base class for all plugins.
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"""
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@six.add_metaclass(abc.ABCMeta)
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class NotificationBase(PluginBase):
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"""Base class for plugins that support the notification API."""
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@abc.abstractproperty
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def event_types(self):
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"""Return a sequence of strings defining the event types to be
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given to this plugin.
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"""
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@abc.abstractmethod
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def get_exchange_topics(self, conf):
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"""Return a sequence of ExchangeTopics defining the exchange and
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topics to be connected for this plugin.
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:param conf: Configuration.
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"""
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@abc.abstractmethod
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def process_notification(self, message):
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"""Return a sequence of Counter instances for the given message.
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:param message: Message to process.
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"""
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@staticmethod
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def _handle_event_type(event_type, event_type_to_handle):
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"""Check whether event_type should be handled according to
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event_type_to_handle.
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"""
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return any(map(lambda e: fnmatch.fnmatch(event_type, e),
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event_type_to_handle))
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def to_samples(self, notification):
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"""Return samples produced by *process_notification* for the given
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notification, if it's handled by this notification handler.
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:param notification: The notification to process.
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"""
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if self._handle_event_type(notification['event_type'],
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self.event_types):
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return self.process_notification(notification)
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return []
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@six.add_metaclass(abc.ABCMeta)
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class PollsterBase(PluginBase):
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"""Base class for plugins that support the polling API."""
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@abc.abstractmethod
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def get_samples(self, manager, cache):
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"""Return a sequence of Counter instances from polling the resources.
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:param manager: The service manager class invoking the plugin.
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:param cache: A dictionary to allow pollsters to pass data
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between themselves when recomputing it would be
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expensive (e.g., asking another service for a
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list of objects).
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"""
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