53bd946ff7
- Add collectd_ceilometer.ceilometer dir
- Add collectd_ceilometer.common dir
- Move test files to collectd_ceilometer/tests/{ceilometer,common}
- Add base code to collectd_ceilometer/tests
Change-Id: I5bd0a8cfe8eb55407f3d6827c0bb4b509dae8c8c
41 lines
1.3 KiB
Python
41 lines
1.3 KiB
Python
# -*- coding: utf-8 -*-
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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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"""Generic singleton implementation"""
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from __future__ import unicode_literals
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import threading
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class Singleton(object):
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"""Generic singleton"""
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def __init__(self, decorated):
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self._decorated = decorated
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self._lock = threading.Lock()
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def __call__(self, *args, **kwargs):
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raise TypeError('Singleton must be accessed through instance() method')
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def instance(self):
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"""Return singleton instance"""
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# pylint: disable=attribute-defined-outside-init
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try:
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return self._instance
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except AttributeError:
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with self._lock:
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if not hasattr(self, '_instance'):
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self._instance = self._decorated()
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return self._instance
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