Issue #7105: Make WeakKeyDictionary and WeakValueDictionary robust against
the destruction of weakref'ed objects while iterating.
diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index ecf1976..028b418 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -4,6 +4,8 @@
import collections
import weakref
import operator
+import contextlib
+import copy
from test import support
@@ -788,6 +790,10 @@
self.arg = arg
def __repr__(self):
return "<Object %r>" % self.arg
+ def __eq__(self, other):
+ if isinstance(other, Object):
+ return self.arg == other.arg
+ return NotImplemented
def __lt__(self, other):
if isinstance(other, Object):
return self.arg < other.arg
@@ -935,6 +941,87 @@
self.assertFalse(values,
"itervalues() did not touch all values")
+ def check_weak_destroy_while_iterating(self, dict, objects, iter_name):
+ n = len(dict)
+ it = iter(getattr(dict, iter_name)())
+ next(it) # Trigger internal iteration
+ # Destroy an object
+ del objects[-1]
+ gc.collect() # just in case
+ # We have removed either the first consumed object, or another one
+ self.assertIn(len(list(it)), [len(objects), len(objects) - 1])
+ del it
+ # The removal has been committed
+ self.assertEqual(len(dict), n - 1)
+
+ def check_weak_destroy_and_mutate_while_iterating(self, dict, testcontext):
+ # Check that we can explicitly mutate the weak dict without
+ # interfering with delayed removal.
+ # `testcontext` should create an iterator, destroy one of the
+ # weakref'ed objects and then return a new key/value pair corresponding
+ # to the destroyed object.
+ with testcontext() as (k, v):
+ self.assertFalse(k in dict)
+ with testcontext() as (k, v):
+ self.assertRaises(KeyError, dict.__delitem__, k)
+ self.assertFalse(k in dict)
+ with testcontext() as (k, v):
+ self.assertRaises(KeyError, dict.pop, k)
+ self.assertFalse(k in dict)
+ with testcontext() as (k, v):
+ dict[k] = v
+ self.assertEqual(dict[k], v)
+ ddict = copy.copy(dict)
+ with testcontext() as (k, v):
+ dict.update(ddict)
+ self.assertEqual(dict, ddict)
+ with testcontext() as (k, v):
+ dict.clear()
+ 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()
+ self.check_weak_destroy_while_iterating(dict, objects, 'keys')
+ self.check_weak_destroy_while_iterating(dict, objects, 'items')
+ self.check_weak_destroy_while_iterating(dict, objects, 'values')
+ self.check_weak_destroy_while_iterating(dict, objects, 'keyrefs')
+ dict, objects = self.make_weak_keyed_dict()
+ @contextlib.contextmanager
+ def testcontext():
+ try:
+ it = iter(dict.items())
+ next(it)
+ # Schedule a key/value for removal and recreate it
+ v = objects.pop().arg
+ gc.collect() # just in case
+ yield Object(v), v
+ finally:
+ it = None # should commit all removals
+ self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
+
+ def test_weak_values_destroy_while_iterating(self):
+ # Issue #7105: iterators shouldn't crash when a key is implicitly removed
+ dict, objects = self.make_weak_valued_dict()
+ self.check_weak_destroy_while_iterating(dict, objects, 'keys')
+ self.check_weak_destroy_while_iterating(dict, objects, 'items')
+ self.check_weak_destroy_while_iterating(dict, objects, 'values')
+ self.check_weak_destroy_while_iterating(dict, objects, 'itervaluerefs')
+ self.check_weak_destroy_while_iterating(dict, objects, 'valuerefs')
+ dict, objects = self.make_weak_valued_dict()
+ @contextlib.contextmanager
+ def testcontext():
+ try:
+ it = iter(dict.items())
+ next(it)
+ # Schedule a key/value for removal and recreate it
+ k = objects.pop().arg
+ gc.collect() # just in case
+ yield k, Object(k)
+ finally:
+ it = None # should commit all removals
+ self.check_weak_destroy_and_mutate_while_iterating(dict, testcontext)
+
def test_make_weak_keyed_dict_from_dict(self):
o = Object(3)
dict = weakref.WeakKeyDictionary({o:364})