mirror of
https://github.com/storytold/storyteller-ml.git
synced 2026-10-16 00:13:07 +00:00
Brandon Thomas
40 lines
1.4 KiB
Python
40 lines
1.4 KiB
Python
# Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import threading
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class Singleton(type):
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""" Implementation of a generic, tread-safe singleton meta-class.
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Can be used as meta-class, i.e. will create
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"""
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# List of instances - one per class.
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__instances = {}
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# Lock used for accessing the instance.
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__lock = threading.Lock()
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def __call__(cls, *args, **kwargs):
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""" Returns singleton instance. A thread safe implementation. """
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if cls not in cls.__instances:
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# Enter critical section.
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with cls.__lock:
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# Check once again.
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if cls not in cls.__instances:
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# Create a new object instance - one per class.
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cls.__instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
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# Return the instance.
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return cls.__instances[cls]
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