Closes #21173: Fix len() on a WeakKeyDictionary when .clear() was called with an iterator alive.

This commit is contained in:
Antoine Pitrou 2014-10-05 20:02:28 +02:00
parent bed04a77ee
commit 1bf974dc6e
3 changed files with 52 additions and 0 deletions

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@ -1298,6 +1298,36 @@ class MappingTestCase(TestBase):
dict.clear()
self.assertEqual(len(dict), 0)
def check_weak_del_and_len_while_iterating(self, dict, testcontext):
# Check that len() works when both iterating and removing keys
# explicitly through various means (.pop(), .clear()...), while
# implicit mutation is deferred because an iterator is alive.
# (each call to testcontext() should schedule one item for removal
# for this test to work properly)
o = Object(123456)
with testcontext():
n = len(dict)
dict.popitem()
self.assertEqual(len(dict), n - 1)
dict[o] = o
self.assertEqual(len(dict), n)
with testcontext():
self.assertEqual(len(dict), n - 1)
dict.pop(next(dict.keys()))
self.assertEqual(len(dict), n - 2)
with testcontext():
self.assertEqual(len(dict), n - 3)
del dict[next(dict.keys())]
self.assertEqual(len(dict), n - 4)
with testcontext():
self.assertEqual(len(dict), n - 5)
dict.popitem()
self.assertEqual(len(dict), n - 6)
with testcontext():
dict.clear()
self.assertEqual(len(dict), 0)
self.assertEqual(len(dict), 0)
def test_weak_keys_destroy_while_iterating(self):
# Issue #7105: iterators shouldn't crash when a key is implicitly removed
dict, objects = self.make_weak_keyed_dict()
@ -1319,6 +1349,10 @@ class MappingTestCase(TestBase):
it = None # should commit all removals
gc.collect()
self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
# Issue #21173: len() fragile when keys are both implicitly and
# explicitly removed.
dict, objects = self.make_weak_keyed_dict()
self.check_weak_del_and_len_while_iterating(dict, testcontext)
def test_weak_values_destroy_while_iterating(self):
# Issue #7105: iterators shouldn't crash when a key is implicitly removed
@ -1342,6 +1376,8 @@ class MappingTestCase(TestBase):
it = None # should commit all removals
gc.collect()
self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
dict, objects = self.make_weak_valued_dict()
self.check_weak_del_and_len_while_iterating(dict, testcontext)
def test_make_weak_keyed_dict_from_dict(self):
o = Object(3)

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@ -322,6 +322,7 @@ class WeakKeyDictionary(collections.MutableMapping):
# A list of dead weakrefs (keys to be removed)
self._pending_removals = []
self._iterating = set()
self._dirty_len = False
if dict is not None:
self.update(dict)
@ -338,13 +339,23 @@ class WeakKeyDictionary(collections.MutableMapping):
except KeyError:
pass
def _scrub_removals(self):
d = self.data
self._pending_removals = [k for k in self._pending_removals if k in d]
self._dirty_len = False
def __delitem__(self, key):
self._dirty_len = True
del self.data[ref(key)]
def __getitem__(self, key):
return self.data[ref(key)]
def __len__(self):
if self._dirty_len and self._pending_removals:
# self._pending_removals may still contain keys which were
# explicitly removed, we have to scrub them (see issue #21173).
self._scrub_removals()
return len(self.data) - len(self._pending_removals)
def __repr__(self):
@ -417,6 +428,7 @@ class WeakKeyDictionary(collections.MutableMapping):
return list(self.data)
def popitem(self):
self._dirty_len = True
while True:
key, value = self.data.popitem()
o = key()
@ -424,6 +436,7 @@ class WeakKeyDictionary(collections.MutableMapping):
return o, value
def pop(self, key, *args):
self._dirty_len = True
return self.data.pop(ref(key), *args)
def setdefault(self, key, default=None):

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@ -22,6 +22,9 @@ Core and Builtins
Library
-------
- Issue #21173: Fix len() on a WeakKeyDictionary when .clear() was called
with an iterator alive.
- Issue #11866: Eliminated race condition in the computation of names
for new threads.