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gh-85160: Reduce memory usage of singledispatchmethod when owner instances cannot be weakref'd #107706

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Merged
merged 2 commits into from
Aug 7, 2023
Merged

gh-85160: Reduce memory usage of singledispatchmethod when owner instances cannot be weakref'd #107706

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gh-85160: Reduce memory usage of `singledispatchmethod` when instance…
AlexWaygood Aug 7, 2023
3d8d4ba
Get rid of `_all_weakrefable_instances`
AlexWaygood Aug 7, 2023
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10 changes: 5 additions & 5 deletions Lib/functools.py
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Original file line number Diff line number Diff line change
Expand Up @@ -928,14 +928,14 @@ class singledispatchmethod:
"""

def __init__(self, func):
import weakref # see comment in singledispatch function
if not callable(func) and not hasattr(func, "__get__"):
raise TypeError(f"{func!r} is not callable or a descriptor")

self.dispatcher = singledispatch(func)
self.func = func

import weakref # see comment in singledispatch function
self._method_cache = weakref.WeakKeyDictionary()
self._all_weakrefable_instances = True

def register(self, cls, method=None):
"""generic_method.register(cls, func) -> func
Expand All @@ -945,11 +945,11 @@ def register(self, cls, method=None):
return self.dispatcher.register(cls, func=method)

def __get__(self, obj, cls=None):
if self._all_weakrefable_instances:
if self._method_cache is not None:
try:
_method = self._method_cache[obj]
except TypeError:
self._all_weakrefable_instances = False
self._method_cache = None
except KeyError:
pass
else:
Expand All @@ -963,7 +963,7 @@ def _method(*args, **kwargs):
_method.register = self.register
update_wrapper(_method, self.func)

if self._all_weakrefable_instances:
if self._method_cache is not None:
self._method_cache[obj] = _method

return _method
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