Closes #21173: Fix len() on a WeakKeyDictionary when .clear() was called with an iterator alive.
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@ -1298,6 +1298,36 @@ class MappingTestCase(TestBase):
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dict.clear()
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self.assertEqual(len(dict), 0)
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def check_weak_del_and_len_while_iterating(self, dict, testcontext):
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# Check that len() works when both iterating and removing keys
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# explicitly through various means (.pop(), .clear()...), while
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# implicit mutation is deferred because an iterator is alive.
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# (each call to testcontext() should schedule one item for removal
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# for this test to work properly)
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o = Object(123456)
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with testcontext():
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n = len(dict)
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dict.popitem()
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self.assertEqual(len(dict), n - 1)
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dict[o] = o
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self.assertEqual(len(dict), n)
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with testcontext():
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self.assertEqual(len(dict), n - 1)
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dict.pop(next(dict.keys()))
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self.assertEqual(len(dict), n - 2)
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with testcontext():
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self.assertEqual(len(dict), n - 3)
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del dict[next(dict.keys())]
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self.assertEqual(len(dict), n - 4)
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with testcontext():
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self.assertEqual(len(dict), n - 5)
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dict.popitem()
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self.assertEqual(len(dict), n - 6)
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with testcontext():
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dict.clear()
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self.assertEqual(len(dict), 0)
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self.assertEqual(len(dict), 0)
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def test_weak_keys_destroy_while_iterating(self):
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# Issue #7105: iterators shouldn't crash when a key is implicitly removed
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dict, objects = self.make_weak_keyed_dict()
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@ -1319,6 +1349,10 @@ class MappingTestCase(TestBase):
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it = None # should commit all removals
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gc.collect()
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self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
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# Issue #21173: len() fragile when keys are both implicitly and
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# explicitly removed.
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dict, objects = self.make_weak_keyed_dict()
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self.check_weak_del_and_len_while_iterating(dict, testcontext)
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def test_weak_values_destroy_while_iterating(self):
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# Issue #7105: iterators shouldn't crash when a key is implicitly removed
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@ -1342,6 +1376,8 @@ class MappingTestCase(TestBase):
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it = None # should commit all removals
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gc.collect()
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self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
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dict, objects = self.make_weak_valued_dict()
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self.check_weak_del_and_len_while_iterating(dict, testcontext)
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def test_make_weak_keyed_dict_from_dict(self):
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o = Object(3)
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@ -322,6 +322,7 @@ class WeakKeyDictionary(collections.MutableMapping):
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# A list of dead weakrefs (keys to be removed)
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self._pending_removals = []
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self._iterating = set()
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self._dirty_len = False
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if dict is not None:
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self.update(dict)
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@ -338,13 +339,23 @@ class WeakKeyDictionary(collections.MutableMapping):
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except KeyError:
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pass
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def _scrub_removals(self):
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d = self.data
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self._pending_removals = [k for k in self._pending_removals if k in d]
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self._dirty_len = False
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def __delitem__(self, key):
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self._dirty_len = True
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del self.data[ref(key)]
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def __getitem__(self, key):
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return self.data[ref(key)]
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def __len__(self):
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if self._dirty_len and self._pending_removals:
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# self._pending_removals may still contain keys which were
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# explicitly removed, we have to scrub them (see issue #21173).
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self._scrub_removals()
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return len(self.data) - len(self._pending_removals)
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def __repr__(self):
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@ -417,6 +428,7 @@ class WeakKeyDictionary(collections.MutableMapping):
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return list(self.data)
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def popitem(self):
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self._dirty_len = True
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while True:
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key, value = self.data.popitem()
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o = key()
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@ -424,6 +436,7 @@ class WeakKeyDictionary(collections.MutableMapping):
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return o, value
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def pop(self, key, *args):
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self._dirty_len = True
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return self.data.pop(ref(key), *args)
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def setdefault(self, key, default=None):
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