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96 lines
2.5 KiB
Python
96 lines
2.5 KiB
Python
3 months ago
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# ext/asyncio/base.py
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# Copyright (C) 2020-2022 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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import abc
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import functools
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import weakref
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from . import exc as async_exc
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class ReversibleProxy:
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# weakref.ref(async proxy object) -> weakref.ref(sync proxied object)
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_proxy_objects = {}
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__slots__ = ("__weakref__",)
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def _assign_proxied(self, target):
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if target is not None:
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target_ref = weakref.ref(target, ReversibleProxy._target_gced)
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proxy_ref = weakref.ref(
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self,
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functools.partial(ReversibleProxy._target_gced, target_ref),
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)
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ReversibleProxy._proxy_objects[target_ref] = proxy_ref
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return target
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@classmethod
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def _target_gced(cls, ref, proxy_ref=None):
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cls._proxy_objects.pop(ref, None)
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@classmethod
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def _regenerate_proxy_for_target(cls, target):
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raise NotImplementedError()
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@classmethod
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def _retrieve_proxy_for_target(cls, target, regenerate=True):
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try:
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proxy_ref = cls._proxy_objects[weakref.ref(target)]
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except KeyError:
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pass
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else:
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proxy = proxy_ref()
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if proxy is not None:
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return proxy
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if regenerate:
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return cls._regenerate_proxy_for_target(target)
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else:
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return None
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class StartableContext(abc.ABC):
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__slots__ = ()
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@abc.abstractmethod
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async def start(self, is_ctxmanager=False):
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pass
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def __await__(self):
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return self.start().__await__()
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async def __aenter__(self):
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return await self.start(is_ctxmanager=True)
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@abc.abstractmethod
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async def __aexit__(self, type_, value, traceback):
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pass
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def _raise_for_not_started(self):
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raise async_exc.AsyncContextNotStarted(
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"%s context has not been started and object has not been awaited."
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% (self.__class__.__name__)
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)
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class ProxyComparable(ReversibleProxy):
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__slots__ = ()
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def __hash__(self):
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return id(self)
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def __eq__(self, other):
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return (
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isinstance(other, self.__class__)
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and self._proxied == other._proxied
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)
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def __ne__(self, other):
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return (
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not isinstance(other, self.__class__)
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or self._proxied != other._proxied
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)
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