selfprivacy-rest-api/selfprivacy_api/utils/singleton_metaclass.py

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"""
Singleton is a creational design pattern, which ensures that only
one object of its kind exists and provides a single point of access
to it for any other code.
"""
from threading import Lock
class SingletonMetaclass(type):
"""
This is a thread-safe implementation of Singleton.
"""
_instances = {}
_lock: Lock = Lock()
def __call__(cls, *args, **kwargs):
with cls._lock:
if cls not in cls._instances:
cls._instances[cls] = super(SingletonMetaclass, cls).__call__(
*args, **kwargs
)
return cls._instances[cls]