diff options
| -rw-r--r-- | Lib/_weakrefset.py | 2 | ||||
| -rw-r--r-- | Lib/test/test_weakref.py | 60 | ||||
| -rw-r--r-- | Lib/test/test_weakset.py | 47 | ||||
| -rw-r--r-- | Lib/weakref.py | 4 | ||||
| -rw-r--r-- | Misc/NEWS | 5 |
5 files changed, 115 insertions, 3 deletions
diff --git a/Lib/_weakrefset.py b/Lib/_weakrefset.py index 4265369..f34aa86 100644 --- a/Lib/_weakrefset.py +++ b/Lib/_weakrefset.py @@ -63,7 +63,7 @@ class WeakSet: yield item def __len__(self): - return sum(x() is not None for x in self.data) + return len(self.data) - len(self._pending_removals) def __contains__(self, item): try: diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py index 8b5bbc3..74b9a87 100644 --- a/Lib/test/test_weakref.py +++ b/Lib/test/test_weakref.py @@ -812,11 +812,71 @@ class Object: def __hash__(self): return hash(self.arg) +class RefCycle: + def __init__(self): + self.cycle = self + class MappingTestCase(TestBase): COUNT = 10 + def check_len_cycles(self, dict_type, cons): + N = 20 + items = [RefCycle() for i in range(N)] + dct = dict_type(cons(o) for o in items) + # Keep an iterator alive + it = dct.items() + try: + next(it) + except StopIteration: + pass + del items + gc.collect() + n1 = len(dct) + del it + gc.collect() + n2 = len(dct) + # one item may be kept alive inside the iterator + self.assertIn(n1, (0, 1)) + self.assertEqual(n2, 0) + + def test_weak_keyed_len_cycles(self): + self.check_len_cycles(weakref.WeakKeyDictionary, lambda k: (k, 1)) + + def test_weak_valued_len_cycles(self): + self.check_len_cycles(weakref.WeakValueDictionary, lambda k: (1, k)) + + def check_len_race(self, dict_type, cons): + # Extended sanity checks for len() in the face of cyclic collection + self.addCleanup(gc.set_threshold, *gc.get_threshold()) + for th in range(1, 100): + N = 20 + gc.collect(0) + gc.set_threshold(th, th, th) + items = [RefCycle() for i in range(N)] + dct = dict_type(cons(o) for o in items) + del items + # All items will be collected at next garbage collection pass + it = dct.items() + try: + next(it) + except StopIteration: + pass + n1 = len(dct) + del it + n2 = len(dct) + self.assertGreaterEqual(n1, 0) + self.assertLessEqual(n1, N) + self.assertGreaterEqual(n2, 0) + self.assertLessEqual(n2, n1) + + def test_weak_keyed_len_race(self): + self.check_len_race(weakref.WeakKeyDictionary, lambda k: (k, 1)) + + def test_weak_valued_len_race(self): + self.check_len_race(weakref.WeakValueDictionary, lambda k: (1, k)) + def test_weak_values(self): # # This exercises d.copy(), d.items(), d[], del d[], len(d). diff --git a/Lib/test/test_weakset.py b/Lib/test/test_weakset.py index 3cddf40..35db7a6 100644 --- a/Lib/test/test_weakset.py +++ b/Lib/test/test_weakset.py @@ -17,6 +17,10 @@ import contextlib class Foo: pass +class RefCycle: + def __init__(self): + self.cycle = self + class TestWeakSet(unittest.TestCase): @@ -359,6 +363,49 @@ class TestWeakSet(unittest.TestCase): s.clear() self.assertEqual(len(s), 0) + def test_len_cycles(self): + N = 20 + items = [RefCycle() for i in range(N)] + s = WeakSet(items) + del items + it = iter(s) + try: + next(it) + except StopIteration: + pass + gc.collect() + n1 = len(s) + del it + gc.collect() + n2 = len(s) + # one item may be kept alive inside the iterator + self.assertIn(n1, (0, 1)) + self.assertEqual(n2, 0) + + def test_len_race(self): + # Extended sanity checks for len() in the face of cyclic collection + self.addCleanup(gc.set_threshold, *gc.get_threshold()) + for th in range(1, 100): + N = 20 + gc.collect(0) + gc.set_threshold(th, th, th) + items = [RefCycle() for i in range(N)] + s = WeakSet(items) + del items + # All items will be collected at next garbage collection pass + it = iter(s) + try: + next(it) + except StopIteration: + pass + n1 = len(s) + del it + n2 = len(s) + self.assertGreaterEqual(n1, 0) + self.assertLessEqual(n1, N) + self.assertGreaterEqual(n2, 0) + self.assertLessEqual(n2, n1) + def test_main(verbose=None): support.run_unittest(TestWeakSet) diff --git a/Lib/weakref.py b/Lib/weakref.py index 468f8f1..fcb6b74 100644 --- a/Lib/weakref.py +++ b/Lib/weakref.py @@ -78,7 +78,7 @@ class WeakValueDictionary(collections.MutableMapping): del self.data[key] def __len__(self): - return sum(wr() is not None for wr in self.data.values()) + return len(self.data) - len(self._pending_removals) def __contains__(self, key): try: @@ -290,7 +290,7 @@ class WeakKeyDictionary(collections.MutableMapping): return self.data[ref(key)] def __len__(self): - return len(self.data) + return len(self.data) - len(self._pending_removals) def __repr__(self): return "<WeakKeyDictionary at %s>" % id(self) @@ -127,6 +127,11 @@ Core and Builtins Library ------- +- Issue #14159: Fix the len() of weak containers (WeakSet, WeakKeyDictionary, + WeakValueDictionary) to return a better approximation when some objects + are dead or dying. Moreover, the implementation is now O(1) rather than + O(n). + - Issue #13125: Silence spurious test_lib2to3 output when in non-verbose mode. Patch by Mikhail Novikov. |