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https://github.com/grillazz/fastapi-sqlalchemy-asyncpg.git
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36 lines
865 B
Python
36 lines
865 B
Python
from threading import Lock
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class SingletonMeta(type):
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"""
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This is a thread-safe implementation of Singleton.
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"""
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_instances = {}
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_lock: Lock = Lock()
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def __call__(cls, *args, **kwargs):
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with cls._lock:
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if cls not in cls._instances:
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instance = super().__call__(*args, **kwargs)
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cls._instances[cls] = instance
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return cls._instances[cls]
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class SingletonMetaNoArgs(type):
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"""
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Singleton metaclass for classes without parameters on constructor,
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for compatibility with FastApi Depends() function.
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"""
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_instances = {}
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_lock: Lock = Lock()
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def __call__(cls):
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with cls._lock:
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if cls not in cls._instances:
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instance = super().__call__()
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cls._instances[cls] = instance
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return cls._instances[cls] |