mirror of
https://github.com/python/cpython.git
synced 2024-12-21 15:53:43 +08:00
523 lines
14 KiB
Python
523 lines
14 KiB
Python
"""
|
|
Tests for object finalization semantics, as outlined in PEP 442.
|
|
"""
|
|
|
|
import contextlib
|
|
import gc
|
|
import unittest
|
|
import weakref
|
|
|
|
try:
|
|
from _testcapi import with_tp_del
|
|
except ImportError:
|
|
def with_tp_del(cls):
|
|
class C(object):
|
|
def __new__(cls, *args, **kwargs):
|
|
raise TypeError('requires _testcapi.with_tp_del')
|
|
return C
|
|
|
|
from test import support
|
|
|
|
|
|
class NonGCSimpleBase:
|
|
"""
|
|
The base class for all the objects under test, equipped with various
|
|
testing features.
|
|
"""
|
|
|
|
survivors = []
|
|
del_calls = []
|
|
tp_del_calls = []
|
|
errors = []
|
|
|
|
_cleaning = False
|
|
|
|
__slots__ = ()
|
|
|
|
@classmethod
|
|
def _cleanup(cls):
|
|
cls.survivors.clear()
|
|
cls.errors.clear()
|
|
gc.garbage.clear()
|
|
gc.collect()
|
|
cls.del_calls.clear()
|
|
cls.tp_del_calls.clear()
|
|
|
|
@classmethod
|
|
@contextlib.contextmanager
|
|
def test(cls):
|
|
"""
|
|
A context manager to use around all finalization tests.
|
|
"""
|
|
with support.disable_gc():
|
|
cls.del_calls.clear()
|
|
cls.tp_del_calls.clear()
|
|
NonGCSimpleBase._cleaning = False
|
|
try:
|
|
yield
|
|
if cls.errors:
|
|
raise cls.errors[0]
|
|
finally:
|
|
NonGCSimpleBase._cleaning = True
|
|
cls._cleanup()
|
|
|
|
def check_sanity(self):
|
|
"""
|
|
Check the object is sane (non-broken).
|
|
"""
|
|
|
|
def __del__(self):
|
|
"""
|
|
PEP 442 finalizer. Record that this was called, check the
|
|
object is in a sane state, and invoke a side effect.
|
|
"""
|
|
try:
|
|
if not self._cleaning:
|
|
self.del_calls.append(id(self))
|
|
self.check_sanity()
|
|
self.side_effect()
|
|
except Exception as e:
|
|
self.errors.append(e)
|
|
|
|
def side_effect(self):
|
|
"""
|
|
A side effect called on destruction.
|
|
"""
|
|
|
|
|
|
class SimpleBase(NonGCSimpleBase):
|
|
|
|
def __init__(self):
|
|
self.id_ = id(self)
|
|
|
|
def check_sanity(self):
|
|
assert self.id_ == id(self)
|
|
|
|
|
|
class NonGC(NonGCSimpleBase):
|
|
__slots__ = ()
|
|
|
|
class NonGCResurrector(NonGCSimpleBase):
|
|
__slots__ = ()
|
|
|
|
def side_effect(self):
|
|
"""
|
|
Resurrect self by storing self in a class-wide list.
|
|
"""
|
|
self.survivors.append(self)
|
|
|
|
class Simple(SimpleBase):
|
|
pass
|
|
|
|
class SimpleResurrector(NonGCResurrector, SimpleBase):
|
|
pass
|
|
|
|
|
|
class TestBase:
|
|
|
|
def setUp(self):
|
|
self.old_garbage = gc.garbage[:]
|
|
gc.garbage[:] = []
|
|
|
|
def tearDown(self):
|
|
# None of the tests here should put anything in gc.garbage
|
|
try:
|
|
self.assertEqual(gc.garbage, [])
|
|
finally:
|
|
del self.old_garbage
|
|
gc.collect()
|
|
|
|
def assert_del_calls(self, ids):
|
|
self.assertEqual(sorted(SimpleBase.del_calls), sorted(ids))
|
|
|
|
def assert_tp_del_calls(self, ids):
|
|
self.assertEqual(sorted(SimpleBase.tp_del_calls), sorted(ids))
|
|
|
|
def assert_survivors(self, ids):
|
|
self.assertEqual(sorted(id(x) for x in SimpleBase.survivors), sorted(ids))
|
|
|
|
def assert_garbage(self, ids):
|
|
self.assertEqual(sorted(id(x) for x in gc.garbage), sorted(ids))
|
|
|
|
def clear_survivors(self):
|
|
SimpleBase.survivors.clear()
|
|
|
|
|
|
class SimpleFinalizationTest(TestBase, unittest.TestCase):
|
|
"""
|
|
Test finalization without refcycles.
|
|
"""
|
|
|
|
def test_simple(self):
|
|
with SimpleBase.test():
|
|
s = Simple()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
|
|
def test_simple_resurrect(self):
|
|
with SimpleBase.test():
|
|
s = SimpleResurrector()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors(ids)
|
|
self.assertIsNot(wr(), None)
|
|
self.clear_survivors()
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
|
|
def test_non_gc(self):
|
|
with SimpleBase.test():
|
|
s = NonGC()
|
|
self.assertFalse(gc.is_tracked(s))
|
|
ids = [id(s)]
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
|
|
def test_non_gc_resurrect(self):
|
|
with SimpleBase.test():
|
|
s = NonGCResurrector()
|
|
self.assertFalse(gc.is_tracked(s))
|
|
ids = [id(s)]
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors(ids)
|
|
self.clear_survivors()
|
|
gc.collect()
|
|
self.assert_del_calls(ids * 2)
|
|
self.assert_survivors(ids)
|
|
|
|
|
|
class SelfCycleBase:
|
|
|
|
def __init__(self):
|
|
super().__init__()
|
|
self.ref = self
|
|
|
|
def check_sanity(self):
|
|
super().check_sanity()
|
|
assert self.ref is self
|
|
|
|
class SimpleSelfCycle(SelfCycleBase, Simple):
|
|
pass
|
|
|
|
class SelfCycleResurrector(SelfCycleBase, SimpleResurrector):
|
|
pass
|
|
|
|
class SuicidalSelfCycle(SelfCycleBase, Simple):
|
|
|
|
def side_effect(self):
|
|
"""
|
|
Explicitly break the reference cycle.
|
|
"""
|
|
self.ref = None
|
|
|
|
|
|
class SelfCycleFinalizationTest(TestBase, unittest.TestCase):
|
|
"""
|
|
Test finalization of an object having a single cyclic reference to
|
|
itself.
|
|
"""
|
|
|
|
def test_simple(self):
|
|
with SimpleBase.test():
|
|
s = SimpleSelfCycle()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
|
|
def test_simple_resurrect(self):
|
|
# Test that __del__ can resurrect the object being finalized.
|
|
with SimpleBase.test():
|
|
s = SelfCycleResurrector()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors(ids)
|
|
# XXX is this desirable?
|
|
self.assertIs(wr(), None)
|
|
# When trying to destroy the object a second time, __del__
|
|
# isn't called anymore (and the object isn't resurrected).
|
|
self.clear_survivors()
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
|
|
def test_simple_suicide(self):
|
|
# Test the GC is able to deal with an object that kills its last
|
|
# reference during __del__.
|
|
with SimpleBase.test():
|
|
s = SuicidalSelfCycle()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
|
|
|
|
class ChainedBase:
|
|
|
|
def chain(self, left):
|
|
self.suicided = False
|
|
self.left = left
|
|
left.right = self
|
|
|
|
def check_sanity(self):
|
|
super().check_sanity()
|
|
if self.suicided:
|
|
assert self.left is None
|
|
assert self.right is None
|
|
else:
|
|
left = self.left
|
|
if left.suicided:
|
|
assert left.right is None
|
|
else:
|
|
assert left.right is self
|
|
right = self.right
|
|
if right.suicided:
|
|
assert right.left is None
|
|
else:
|
|
assert right.left is self
|
|
|
|
class SimpleChained(ChainedBase, Simple):
|
|
pass
|
|
|
|
class ChainedResurrector(ChainedBase, SimpleResurrector):
|
|
pass
|
|
|
|
class SuicidalChained(ChainedBase, Simple):
|
|
|
|
def side_effect(self):
|
|
"""
|
|
Explicitly break the reference cycle.
|
|
"""
|
|
self.suicided = True
|
|
self.left = None
|
|
self.right = None
|
|
|
|
|
|
class CycleChainFinalizationTest(TestBase, unittest.TestCase):
|
|
"""
|
|
Test finalization of a cyclic chain. These tests are similar in
|
|
spirit to the self-cycle tests above, but the collectable object
|
|
graph isn't trivial anymore.
|
|
"""
|
|
|
|
def build_chain(self, classes):
|
|
nodes = [cls() for cls in classes]
|
|
for i in range(len(nodes)):
|
|
nodes[i].chain(nodes[i-1])
|
|
return nodes
|
|
|
|
def check_non_resurrecting_chain(self, classes):
|
|
N = len(classes)
|
|
with SimpleBase.test():
|
|
nodes = self.build_chain(classes)
|
|
ids = [id(s) for s in nodes]
|
|
wrs = [weakref.ref(s) for s in nodes]
|
|
del nodes
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertEqual([wr() for wr in wrs], [None] * N)
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
|
|
def check_resurrecting_chain(self, classes):
|
|
N = len(classes)
|
|
with SimpleBase.test():
|
|
nodes = self.build_chain(classes)
|
|
N = len(nodes)
|
|
ids = [id(s) for s in nodes]
|
|
survivor_ids = [id(s) for s in nodes if isinstance(s, SimpleResurrector)]
|
|
wrs = [weakref.ref(s) for s in nodes]
|
|
del nodes
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors(survivor_ids)
|
|
# XXX desirable?
|
|
self.assertEqual([wr() for wr in wrs], [None] * N)
|
|
self.clear_survivors()
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_survivors([])
|
|
|
|
def test_homogenous(self):
|
|
self.check_non_resurrecting_chain([SimpleChained] * 3)
|
|
|
|
def test_homogenous_resurrect(self):
|
|
self.check_resurrecting_chain([ChainedResurrector] * 3)
|
|
|
|
def test_homogenous_suicidal(self):
|
|
self.check_non_resurrecting_chain([SuicidalChained] * 3)
|
|
|
|
def test_heterogenous_suicidal_one(self):
|
|
self.check_non_resurrecting_chain([SuicidalChained, SimpleChained] * 2)
|
|
|
|
def test_heterogenous_suicidal_two(self):
|
|
self.check_non_resurrecting_chain(
|
|
[SuicidalChained] * 2 + [SimpleChained] * 2)
|
|
|
|
def test_heterogenous_resurrect_one(self):
|
|
self.check_resurrecting_chain([ChainedResurrector, SimpleChained] * 2)
|
|
|
|
def test_heterogenous_resurrect_two(self):
|
|
self.check_resurrecting_chain(
|
|
[ChainedResurrector, SimpleChained, SuicidalChained] * 2)
|
|
|
|
def test_heterogenous_resurrect_three(self):
|
|
self.check_resurrecting_chain(
|
|
[ChainedResurrector] * 2 + [SimpleChained] * 2 + [SuicidalChained] * 2)
|
|
|
|
|
|
# NOTE: the tp_del slot isn't automatically inherited, so we have to call
|
|
# with_tp_del() for each instantiated class.
|
|
|
|
class LegacyBase(SimpleBase):
|
|
|
|
def __del__(self):
|
|
try:
|
|
# Do not invoke side_effect here, since we are now exercising
|
|
# the tp_del slot.
|
|
if not self._cleaning:
|
|
self.del_calls.append(id(self))
|
|
self.check_sanity()
|
|
except Exception as e:
|
|
self.errors.append(e)
|
|
|
|
def __tp_del__(self):
|
|
"""
|
|
Legacy (pre-PEP 442) finalizer, mapped to a tp_del slot.
|
|
"""
|
|
try:
|
|
if not self._cleaning:
|
|
self.tp_del_calls.append(id(self))
|
|
self.check_sanity()
|
|
self.side_effect()
|
|
except Exception as e:
|
|
self.errors.append(e)
|
|
|
|
@with_tp_del
|
|
class Legacy(LegacyBase):
|
|
pass
|
|
|
|
@with_tp_del
|
|
class LegacyResurrector(LegacyBase):
|
|
|
|
def side_effect(self):
|
|
"""
|
|
Resurrect self by storing self in a class-wide list.
|
|
"""
|
|
self.survivors.append(self)
|
|
|
|
@with_tp_del
|
|
class LegacySelfCycle(SelfCycleBase, LegacyBase):
|
|
pass
|
|
|
|
|
|
@support.cpython_only
|
|
class LegacyFinalizationTest(TestBase, unittest.TestCase):
|
|
"""
|
|
Test finalization of objects with a tp_del.
|
|
"""
|
|
|
|
def tearDown(self):
|
|
# These tests need to clean up a bit more, since they create
|
|
# uncollectable objects.
|
|
gc.garbage.clear()
|
|
gc.collect()
|
|
super().tearDown()
|
|
|
|
def test_legacy(self):
|
|
with SimpleBase.test():
|
|
s = Legacy()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_tp_del_calls(ids)
|
|
self.assert_survivors([])
|
|
self.assertIs(wr(), None)
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_tp_del_calls(ids)
|
|
|
|
def test_legacy_resurrect(self):
|
|
with SimpleBase.test():
|
|
s = LegacyResurrector()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_tp_del_calls(ids)
|
|
self.assert_survivors(ids)
|
|
# weakrefs are cleared before tp_del is called.
|
|
self.assertIs(wr(), None)
|
|
self.clear_survivors()
|
|
gc.collect()
|
|
self.assert_del_calls(ids)
|
|
self.assert_tp_del_calls(ids * 2)
|
|
self.assert_survivors(ids)
|
|
self.assertIs(wr(), None)
|
|
|
|
def test_legacy_self_cycle(self):
|
|
# Self-cycles with legacy finalizers end up in gc.garbage.
|
|
with SimpleBase.test():
|
|
s = LegacySelfCycle()
|
|
ids = [id(s)]
|
|
wr = weakref.ref(s)
|
|
del s
|
|
gc.collect()
|
|
self.assert_del_calls([])
|
|
self.assert_tp_del_calls([])
|
|
self.assert_survivors([])
|
|
self.assert_garbage(ids)
|
|
self.assertIsNot(wr(), None)
|
|
# Break the cycle to allow collection
|
|
gc.garbage[0].ref = None
|
|
self.assert_garbage([])
|
|
self.assertIs(wr(), None)
|
|
|
|
|
|
def test_main():
|
|
support.run_unittest(__name__)
|
|
|
|
if __name__ == "__main__":
|
|
test_main()
|