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test_weakref.py
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import gc import sys import unittest import collections import weakref import operator import contextlib import copy import threading import time import random from test import support from test.support import script_helper, ALWAYS_EQ from test.support import gc_collect # Used in ReferencesTestCase.test_ref_created_during_del() . ref_from_del = None # Used by FinalizeTestCase as a global that may be replaced by None # when the interpreter shuts down. _global_var = 'foobar' class C: def method(self): pass class Callable: bar = None def __call__(self, x): self.bar = x def create_function(): def f(): pass return f def create_bound_method(): return C().method class Object: def __init__(self, arg): 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 return NotImplemented def __hash__(self): return hash(self.arg) def some_method(self): return 4 def other_method(self): return 5 class RefCycle: def __init__(self): self.cycle = self class TestBase(unittest.TestCase): def setUp(self): self.cbcalled = 0 def callback(self, ref): self.cbcalled += 1 @contextlib.contextmanager def collect_in_thread(period=0.0001): """ Ensure GC collections happen in a different thread, at a high frequency. """ please_stop = False def collect(): while not please_stop: time.sleep(period) gc.collect() with support.disable_gc(): t = threading.Thread(target=collect) t.start() try: yield finally: please_stop = True t.join() class ReferencesTestCase(TestBase): def test_basic_ref(self): self.check_basic_ref(C) self.check_basic_ref(create_function) self.check_basic_ref(create_bound_method) # Just make sure the tp_repr handler doesn't raise an exception. # Live reference: o = C() wr = weakref.ref(o) repr(wr) # Dead reference: del o repr(wr) def test_basic_callback(self): self.check_basic_callback(C) self.check_basic_callback(create_function) self.check_basic_callback(create_bound_method) @support.cpython_only def test_cfunction(self): import _testcapi create_cfunction = _testcapi.create_cfunction f = create_cfunction() wr = weakref.ref(f) self.assertIs(wr(), f) del f self.assertIsNone(wr()) self.check_basic_ref(create_cfunction) self.check_basic_callback(create_cfunction) def test_multiple_callbacks(self): o = C() ref1 = weakref.ref(o, self.callback) ref2 = weakref.ref(o, self.callback) del o gc_collect() # For PyPy or other GCs. self.assertIsNone(ref1(), "expected reference to be invalidated") self.assertIsNone(ref2(), "expected reference to be invalidated") self.assertEqual(self.cbcalled, 2, "callback not called the right number of times") def test_multiple_selfref_callbacks(self): # Make sure all references are invalidated before callbacks are called # # What's important here is that we're using the first # reference in the callback invoked on the second reference # (the most recently created ref is cleaned up first). This # tests that all references to the object are invalidated # before any of the callbacks are invoked, so that we only # have one invocation of _weakref.c:cleanup_helper() active # for a particular object at a time. # def callback(object, self=self): self.ref() c = C() self.ref = weakref.ref(c, callback) ref1 = weakref.ref(c, callback) del c def test_constructor_kwargs(self): c = C() self.assertRaises(TypeError, weakref.ref, c, callback=None) def test_proxy_ref(self): o = C() o.bar = 1 ref1 = weakref.proxy(o, self.callback) ref2 = weakref.proxy(o, self.callback) del o gc_collect() # For PyPy or other GCs. def check(proxy): proxy.bar self.assertRaises(ReferenceError, check, ref1) self.assertRaises(ReferenceError, check, ref2) ref3 = weakref.proxy(C()) gc_collect() # For PyPy or other GCs. self.assertRaises(ReferenceError, bool, ref3) self.assertEqual(self.cbcalled, 2) def check_basic_ref(self, factory): o = factory() ref = weakref.ref(o) self.assertIsNotNone(ref(), "weak reference to live object should be live") o2 = ref() self.assertIs(o, o2, "<ref>() should return original object if live") def check_basic_callback(self, factory): self.cbcalled = 0 o = factory() ref = weakref.ref(o, self.callback) del o gc_collect() # For PyPy or other GCs. self.assertEqual(self.cbcalled, 1, "callback did not properly set 'cbcalled'") self.assertIsNone(ref(), "ref2 should be dead after deleting object reference") def test_ref_reuse(self): o = C() ref1 = weakref.ref(o) # create a proxy to make sure that there's an intervening creation # between these two; it should make no difference proxy = weakref.proxy(o) ref2 = weakref.ref(o) self.assertIs(ref1, ref2, "reference object w/out callback should be re-used") o = C() proxy = weakref.proxy(o) ref1 = weakref.ref(o) ref2 = weakref.ref(o) self.assertIs(ref1, ref2, "reference object w/out callback should be re-used") self.assertEqual(weakref.getweakrefcount(o), 2, "wrong weak ref count for object") del proxy gc_collect() # For PyPy or other GCs. self.assertEqual(weakref.getweakrefcount(o), 1, "wrong weak ref count for object after deleting proxy") def test_proxy_reuse(self): o = C() proxy1 = weakref.proxy(o) ref = weakref.ref(o) proxy2 = weakref.proxy(o) self.assertIs(proxy1, proxy2, "proxy object w/out callback should have been re-used") def test_basic_proxy(self): o = C() self.check_proxy(o, weakref.proxy(o)) L = collections.UserList() p = weakref.proxy(L) self.assertFalse(p, "proxy for empty UserList should be false") p.append(12) self.assertEqual(len(L), 1) self.assertTrue(p, "proxy for non-empty UserList should be true") p[:] = [2, 3] self.assertEqual(len(L), 2) self.assertEqual(len(p), 2) self.assertIn(3, p, "proxy didn't support __contains__() properly") p[1] = 5 self.assertEqual(L[1], 5) self.assertEqual(p[1], 5) L2 = collections.UserList(L) p2 = weakref.proxy(L2) self.assertEqual(p, p2) ## self.assertEqual(repr(L2), repr(p2)) L3 = collections.UserList(range(10)) p3 = weakref.proxy(L3) self.assertEqual(L3[:], p3[:]) self.assertEqual(L3[5:], p3[5:]) self.assertEqual(L3[:5], p3[:5]) self.assertEqual(L3[2:5], p3[2:5]) def test_proxy_unicode(self): # See bug 5037 class C(object): def __str__(self): return "string" def __bytes__(self): return b"bytes" instance = C() self.assertIn("__bytes__", dir(weakref.proxy(instance))) self.assertEqual(bytes(weakref.proxy(instance)), b"bytes") def test_proxy_index(self): class C: def __index__(self): return 10 o = C() p = weakref.proxy(o) self.assertEqual(operator.index(p), 10) def test_proxy_div(self): class C: def __floordiv__(self, other): return 42 def __ifloordiv__(self, other): return 21 o = C() p = weakref.proxy(o) self.assertEqual(p // 5, 42) p //= 5 self.assertEqual(p, 21) def test_proxy_matmul(self): class C: def __matmul__(self, other): return 1729 def __rmatmul__(self, other): return -163 def __imatmul__(self, other): return 561 o = C() p = weakref.proxy(o) self.assertEqual(p @ 5, 1729) self.assertEqual(5 @ p, -163) p @= 5 self.assertEqual(p, 561) # The PyWeakref_* C API is documented as allowing either NULL or # None as the value for the callback, where either means "no # callback". The "no callback" ref and proxy objects are supposed # to be shared so long as they exist by all callers so long as # they are active. In Python 2.3.3 and earlier, this guarantee # was not honored, and was broken in different ways for # PyWeakref_NewRef() and PyWeakref_NewProxy(). (Two tests.) def test_shared_ref_without_callback(self): self.check_shared_without_callback(weakref.ref) def test_shared_proxy_without_callback(self): self.check_shared_without_callback(weakref.proxy) def check_shared_without_callback(self, makeref): o = Object(1) p1 = makeref(o, None) p2 = makeref(o, None) self.assertIs(p1, p2, "both callbacks were None in the C API") del p1, p2 p1 = makeref(o) p2 = makeref(o, None) self.assertIs(p1, p2, "callbacks were NULL, None in the C API") del p1, p2 p1 = makeref(o) p2 = makeref(o) self.assertIs(p1, p2, "both callbacks were NULL in the C API") del p1, p2 p1 = makeref(o, None) p2 = makeref(o) self.assertIs(p1, p2, "callbacks were None, NULL in the C API") def test_callable_proxy(self): o = Callable() ref1 = weakref.proxy(o) self.check_proxy(o, ref1) self.assertIs(type(ref1), weakref.CallableProxyType, "proxy is not of callable type") ref1('twinkies!') self.assertEqual(o.bar, 'twinkies!', "call through proxy not passed through to original") ref1(x='Splat.') self.assertEqual(o.bar, 'Splat.', "call through proxy not passed through to original") # expect due to too few args self.assertRaises(TypeError, ref1) # expect due to too many args self.assertRaises(TypeError, ref1, 1, 2, 3) def check_proxy(self, o, proxy): o.foo = 1 self.assertEqual(proxy.foo, 1, "proxy does not reflect attribute addition") o.foo = 2 self.assertEqual(proxy.foo, 2, "proxy does not reflect attribute modification") del o.foo self.assertFalse(hasattr(proxy, 'foo'), "proxy does not reflect attribute removal") proxy.foo = 1 self.assertEqual(o.foo, 1, "object does not reflect attribute addition via proxy") proxy.foo = 2 self.assertEqual(o.foo, 2, "object does not reflect attribute modification via proxy") del proxy.foo self.assertFalse(hasattr(o, 'foo'), "object does not reflect attribute removal via proxy") def test_proxy_deletion(self): # Test clearing of SF bug #762891 class Foo: result = None def __delitem__(self, accessor): self.result = accessor g = Foo() f = weakref.proxy(g) del f[0] self.assertEqual(f.result, 0) def test_proxy_bool(self): # Test clearing of SF bug #1170766 class List(list): pass lyst = List() self.assertEqual(bool(weakref.proxy(lyst)), bool(lyst)) def test_proxy_iter(self): # Test fails with a debug build of the interpreter # (see bpo-38395). obj = None class MyObj: def __iter__(self): nonlocal obj del obj return NotImplemented obj = MyObj() p = weakref.proxy(obj) with self.assertRaises(TypeError): # "blech" in p calls MyObj.__iter__ through the proxy, # without keeping a reference to the real object, so it # can be killed in the middle of the call "blech" in p def test_proxy_next(self): arr = [4, 5, 6] def iterator_func(): yield from arr it = iterator_func() class IteratesWeakly: def __iter__(self): return weakref.proxy(it) weak_it = IteratesWeakly() # Calls proxy.__next__ self.assertEqual(list(weak_it), [4, 5, 6]) def test_proxy_bad_next(self): # bpo-44720: PyIter_Next() shouldn't be called if the reference # isn't an iterator. not_an_iterator = lambda: 0 class A: def __iter__(self): return weakref.proxy(not_an_iterator) a = A() msg = "Weakref proxy referenced a non-iterator" with self.assertRaisesRegex(TypeError, msg): list(a) def test_proxy_reversed(self): class MyObj: def __len__(self): return 3 def __reversed__(self): return iter('cba') obj = MyObj() self.assertEqual("".join(reversed(weakref.proxy(obj))), "cba") def test_proxy_hash(self): class MyObj: def __hash__(self): return 42 obj = MyObj() with self.assertRaises(TypeError): hash(weakref.proxy(obj)) class MyObj: __hash__ = None obj = MyObj() with self.assertRaises(TypeError): hash(weakref.proxy(obj)) def test_getweakrefcount(self): o = C() ref1 = weakref.ref(o) ref2 = weakref.ref(o, self.callback) self.assertEqual(weakref.getweakrefcount(o), 2, "got wrong number of weak reference objects") proxy1 = weakref.proxy(o) proxy2 = weakref.proxy(o, self.callback) self.assertEqual(weakref.getweakrefcount(o), 4, "got wrong number of weak reference objects") del ref1, ref2, proxy1, proxy2 gc_collect() # For PyPy or other GCs. self.assertEqual(weakref.getweakrefcount(o), 0, "weak reference objects not unlinked from" " referent when discarded.") # assumes ints do not support weakrefs self.assertEqual(weakref.getweakrefcount(1), 0, "got wrong number of weak reference objects for int") def test_getweakrefs(self): o = C() ref1 = weakref.ref(o, self.callback) ref2 = weakref.ref(o, self.callback) del ref1 gc_collect() # For PyPy or other GCs. self.assertEqual(weakref.getweakrefs(o), [ref2], "list of refs does not match") o = C() ref1 = weakref.ref(o, self.callback) ref2 = weakref.ref(o, self.callback) del ref2 gc_collect() # For PyPy or other GCs. self.assertEqual(weakref.getweakrefs(o), [ref1], "list of refs does not match") del ref1 gc_collect() # For PyPy or other GCs. self.assertEqual(weakref.getweakrefs(o), [], "list of refs not cleared") # assumes ints do not support weakrefs self.assertEqual(weakref.getweakrefs(1), [], "list of refs does not match for int") def test_newstyle_number_ops(self): class F(float): pass f = F(2.0) p = weakref.proxy(f) self.assertEqual(p + 1.0, 3.0) self.assertEqual(1.0 + p, 3.0) # this used to SEGV def test_callbacks_protected(self): # Callbacks protected from already-set exceptions? # Regression test for SF bug #478534. class BogusError(Exception): pass data = {} def remove(k): del data[k] def encapsulate(): f = lambda : () data[weakref.ref(f, remove)] = None raise BogusError try: encapsulate() except BogusError: pass else: self.fail("exception not properly restored") try: encapsulate() except BogusError: pass else: self.fail("exception not properly restored") def test_sf_bug_840829(self): # "weakref callbacks and gc corrupt memory" # subtype_dealloc erroneously exposed a new-style instance # already in the process of getting deallocated to gc, # causing double-deallocation if the instance had a weakref # callback that triggered gc. # If the bug exists, there probably won't be an obvious symptom # in a release build. In a debug build, a segfault will occur # when the second attempt to remove the instance from the "list # of all objects" occurs. import gc class C(object): pass c = C() wr = weakref.ref(c, lambda ignore: gc.collect()) del c # There endeth the first part. It gets worse. del wr c1 = C() c1.i = C() wr = weakref.ref(c1.i, lambda ignore: gc.collect()) c2 = C() c2.c1 = c1 del c1 # still alive because c2 points to it # Now when subtype_dealloc gets called on c2, it's not enough just # that c2 is immune from gc while the weakref callbacks associated # with c2 execute (there are none in this 2nd half of the test, btw). # subtype_dealloc goes on to call the base classes' deallocs too, # so any gc triggered by weakref callbacks associated with anything # torn down by a base class dealloc can also trigger double # deallocation of c2. del c2 def test_callback_in_cycle_1(self): import gc class J(object): pass class II(object): def acallback(self, ignore): self.J I = II() I.J = J I.wr = weakref.ref(J, I.acallback) # Now J and II are each in a self-cycle (as all new-style class # objects are, since their __mro__ points back to them). I holds # both a weak reference (I.wr) and a strong reference (I.J) to class # J. I is also in a cycle (I.wr points to a weakref that references # I.acallback). When we del these three, they all become trash, but # the cycles prevent any of them from getting cleaned up immediately. # Instead they have to wait for cyclic gc to deduce that they're # trash. # # gc used to call tp_clear on all of them, and the order in which # it does that is pretty accidental. The exact order in which we # built up these things manages to provoke gc into running tp_clear # in just the right order (I last). Calling tp_clear on II leaves # behind an insane class object (its __mro__ becomes NULL). Calling # tp_clear on J breaks its self-cycle, but J doesn't get deleted # just then because of the strong reference from I.J. Calling # tp_clear on I starts to clear I's __dict__, and just happens to # clear I.J first -- I.wr is still intact. That removes the last # reference to J, which triggers the weakref callback. The callback # tries to do "self.J", and instances of new-style classes look up # attributes ("J") in the class dict first. The class (II) wants to # search II.__mro__, but that's NULL. The result was a segfault in # a release build, and an assert failure in a debug build. del I, J, II gc.collect() def test_callback_in_cycle_2(self): import gc # This is just like test_callback_in_cycle_1, except that II is an # old-style class. The symptom is different then: an instance of an # old-style class looks in its own __dict__ first. 'J' happens to # get cleared from I.__dict__ before 'wr', and 'J' was never in II's # __dict__, so the attribute isn't found. The difference is that # the old-style II doesn't have a NULL __mro__ (it doesn't have any # __mro__), so no segfault occurs. Instead it got: # test_callback_in_cycle_2 (__main__.ReferencesTestCase) ... # Exception exceptions.AttributeError: # "II instance has no attribute 'J'" in <bound method II.acallback # of <?.II instance at 0x00B9B4B8>> ignored class J(object): pass class II: def acallback(self, ignore): self.J I = II() I.J = J I.wr = weakref.ref(J, I.acallback) del I, J, II gc.collect() def test_callback_in_cycle_3(self): import gc # This one broke the first patch that fixed the last two. In this # case, the objects reachable from the callback aren't also reachable # from the object (c1) *triggering* the callback: you can get to # c1 from c2, but not vice-versa. The result was that c2's __dict__ # got tp_clear'ed by the time the c2.cb callback got invoked. class C: def cb(self, ignore): self.me self.c1 self.wr c1, c2 = C(), C() c2.me = c2 c2.c1 = c1 c2.wr = weakref.ref(c1, c2.cb) del c1, c2 gc.collect() def test_callback_in_cycle_4(self): import gc # Like test_callback_in_cycle_3, except c2 and c1 have different # classes. c2's class (C) isn't reachable from c1 then, so protecting # objects reachable from the dying object (c1) isn't enough to stop # c2's class (C) from getting tp_clear'ed before c2.cb is invoked. # The result was a segfault (C.__mro__ was NULL when the callback # tried to look up self.me). class C(object): def cb(self, ignore): self.me self.c1 self.wr class D: pass c1, c2 = D(), C() c2.me = c2 c2.c1 = c1 c2.wr = weakref.ref(c1, c2.cb) del c1, c2, C, D gc.collect() def test_callback_in_cycle_resurrection(self): import gc # Do something nasty in a weakref callback: resurrect objects # from dead cycles. For this to be attempted, the weakref and # its callback must also be part of the cyclic trash (else the # objects reachable via the callback couldn't be in cyclic trash # to begin with -- the callback would act like an external root). # But gc clears trash weakrefs with callbacks early now, which # disables the callbacks, so the callbacks shouldn't get called # at all (and so nothing actually gets resurrected). alist = [] class C(object): def __init__(self, value): self.attribute = value def acallback(self, ignore): alist.append(self.c) c1, c2 = C(1), C(2) c1.c = c2 c2.c = c1 c1.wr = weakref.ref(c2, c1.acallback) c2.wr = weakref.ref(c1, c2.acallback) def C_went_away(ignore): alist.append("C went away") wr = weakref.ref(C, C_went_away) del c1, c2, C # make them all trash self.assertEqual(alist, []) # del isn't enough to reclaim anything gc.collect() # c1.wr and c2.wr were part of the cyclic trash, so should have # been cleared without their callbacks executing. OTOH, the weakref # to C is bound to a function local (wr), and wasn't trash, so that # callback should have been invoked when C went away. self.assertEqual(alist, ["C went away"]) # The remaining weakref should be dead now (its callback ran). self.assertEqual(wr(), None) del alist[:] gc.collect() self.assertEqual(alist, []) def test_callbacks_on_callback(self): import gc # Set up weakref callbacks *on* weakref callbacks. alist = [] def safe_callback(ignore): alist.append("safe_callback called") class C(object): def cb(self, ignore): alist.append("cb called") c, d = C(), C() c.other = d d.other = c callback = c.cb c.wr = weakref.ref(d, callback) # this won't trigger d.wr = weakref.ref(callback, d.cb) # ditto external_wr = weakref.ref(callback, safe_callback) # but this will self.assertIs(external_wr(), callback) # The weakrefs attached to c and d should get cleared, so that # C.cb is never called. But external_wr isn't part of the cyclic # trash, and no cyclic trash is reachable from it, so safe_callback # should get invoked when the bound method object callback (c.cb) # -- which is itself a callback, and also part of the cyclic trash -- # gets reclaimed at the end of gc. del callback, c, d, C self.assertEqual(alist, []) # del isn't enough to clean up cycles gc.collect() self.assertEqual(alist, ["safe_callback called"]) self.assertEqual(external_wr(), None) del alist[:] gc.collect() self.assertEqual(alist, []) def test_gc_during_ref_creation(self): self.check_gc_during_creation(weakref.ref) def test_gc_during_proxy_creation(self): self.check_gc_during_creation(weakref.proxy) def check_gc_during_creation(self, makeref): thresholds = gc.get_threshold() gc.set_threshold(1, 1, 1) gc.collect() class A: pass def callback(*args): pass referenced = A() a = A() a.a = a a.wr = makeref(referenced) try: # now make sure the object and the ref get labeled as # cyclic trash: a = A() weakref.ref(referenced, callback) finally: gc.set_threshold(*thresholds) def test_ref_created_during_del(self): # Bug #1377858 # A weakref created in an object's __del__() would crash the # interpreter when the weakref was cleaned up since it would refer to # non-existent memory. This test should not segfault the interpreter. class Target(object): def __del__(self): global ref_from_del ref_from_del = weakref.ref(self) w = Target() def test_init(self): # Issue 3634 # <weakref to class>.__init__() doesn't check errors correctly r = weakref.ref(Exception) self.assertRaises(TypeError, r.__init__, 0, 0, 0, 0, 0) # No exception should be raised here gc.collect() def test_classes(self): # Check that classes are weakrefable. class A(object): pass l = [] weakref.ref(int) a = weakref.ref(A, l.append) A = None gc.collect() self.assertEqual(a(), None) self.assertEqual(l, [a]) def test_equality(self): # Alive weakrefs defer equality testing to their underlying object. x = Object(1) y = Object(1) z = Object(2) a = weakref.ref(x) b = weakref.ref(y) c = weakref.ref(z) d = weakref.ref(x) # Note how we directly test the operators here, to stress both # __eq__ and __ne__. self.assertTrue(a == b) self.assertFalse(a != b) self.assertFalse(a == c) self.assertTrue(a != c) self.assertTrue(a == d) self.assertFalse(a != d) self.assertFalse(a == x) self.assertTrue(a != x) self.assertTrue(a == ALWAYS_EQ) self.assertFalse(a != ALWAYS_EQ) del x, y, z gc.collect() for r in a, b, c: # Sanity check self.assertIs(r(), None) # Dead weakrefs compare by identity: whether `a` and `d` are the # same weakref object is an implementation detail, since they pointed # to the same original object and didn't have a callback. # (see issue #16453). self.assertFalse(a == b) self.assertTrue(a != b) self.assertFalse(a == c) self.assertTrue(a != c) self.assertEqual(a == d, a is d) self.assertEqual(a != d, a is not d) def test_ordering(self): # weakrefs cannot be ordered, even if the underlying objects can. ops = [operator.lt, operator.gt, operator.le, operator.ge] x = Object(1) y = Object(1) a = weakref.ref(x) b = weakref.ref(y) for op in ops: self.assertRaises(TypeError, op, a, b) # Same when dead. del x, y gc.collect() for op in ops: self.assertRaises(TypeError, op, a, b) def test_hashing(self): # Alive weakrefs hash the same as the underlying object x = Object(42) y = Object(42) a = weakref.ref(x) b = weakref.ref(y) self.assertEqual(hash(a), hash(42)) del x, y gc.collect() # Dead weakrefs: # - retain their hash is they were hashed when alive; # - otherwise, cannot be hashed. self.assertEqual(hash(a), hash(42)) self.assertRaises(TypeError, hash, b) def test_trashcan_16602(self): # Issue #16602: when a weakref's target was part of a long # deallocation chain, the trashcan mechanism could delay clearing # of the weakref and make the target object visible from outside # code even though its refcount had dropped to 0. A crash ensued. class C: def __init__(self, parent): if not parent: return wself = weakref.ref(self) def cb(wparent): o = wself() self.wparent = weakref.ref(parent, cb) d = weakref.WeakKeyDictionary() root = c = C(None) for n in range(100): d[c] = c = C(c) del root gc.collect() def test_callback_attribute(self): x = Object(1) callback = lambda ref: None ref1 = weakref.ref(x, callback) self.assertIs(ref1.__callback__, callback) ref2 = weakref.ref(x) self.assertIsNone(ref2.__callback__) def test_callback_attribute_after_deletion(self): x = Object(1) ref = weakref.ref(x, self.callback) self.assertIsNotNone(ref.__callback__) del x support.gc_collect() self.assertIsNone(ref.__callback__) def test_set_callback_attribute(self): x = Object(1) callback = lambda ref: None ref1 = weakref.ref(x, callback) with self.assertRaises(AttributeError): ref1.__callback__ = lambda ref: None def test_callback_gcs(self): class ObjectWithDel(Object): def __del__(self): pass x = ObjectWithDel(1) ref1 = weakref.ref(x, lambda ref: support.gc_collect()) del x support.gc_collect() class SubclassableWeakrefTestCase(TestBase): def test_subclass_refs(self): class MyRef(weakref.ref): def __init__(self, ob, callback=None, value=42): self.value = value super().__init__(ob, callback) def __call__(self): self.called = True return super().__call__() o = Object("foo") mr = MyRef(o, value=24) self.assertIs(mr(), o) self.assertTrue(mr.called) self.assertEqual(mr.value, 24) del o gc_collect() # For PyPy or other GCs. self.assertIsNone(mr()) self.assertTrue(mr.called) def test_subclass_refs_dont_replace_standard_refs(self): class MyRef(weakref.ref): pass o = Object(42) r1 = MyRef(o) r2 = weakref.ref(o) self.assertIsNot(r1, r2) self.assertEqual(weakref.getweakrefs(o), [r2, r1]) self.assertEqual(weakref.getweakrefcount(o), 2) r3 = MyRef(o) self.assertEqual(weakref.getweakrefcount(o), 3) refs = weakref.getweakrefs(o) self.assertEqual(len(refs), 3) self.assertIs(r2, refs[0]) self.assertIn(r1, refs[1:]) self.assertIn(r3, refs[1:]) def test_subclass_refs_dont_conflate_callbacks(self): class MyRef(weakref.ref): pass o = Object(42) r1 = MyRef(o, id) r2 = MyRef(o, str) self.assertIsNot(r1, r2) refs = weakref.getweakrefs(o) self.assertIn(r1, refs) self.assertIn(r2, refs) def test_subclass_refs_with_slots(self): class MyRef(weakref.ref): __slots__ = "slot1", "slot2" def __new__(type, ob, callback, slot1, slot2): return weakref.ref.__new__(type, ob, callback) def __init__(self, ob, callback, slot1, slot2): self.slot1 = slot1 self.slot2 = slot2 def meth(self): return self.slot1 + self.slot2 o = Object(42) r = MyRef(o, None, "abc", "def") self.assertEqual(r.slot1, "abc") self.assertEqual(r.slot2, "def") self.assertEqual(r.meth(), "abcdef") self.assertFalse(hasattr(r, "__dict__")) def test_subclass_refs_with_cycle(self): """Confirm https://bugs.python.org/issue3100 is fixed.""" # An instance of a weakref subclass can have attributes. # If such a weakref holds the only strong reference to the object, # deleting the weakref will delete the object. In this case, # the callback must not be called, because the ref object is # being deleted. class MyRef(weakref.ref): pass # Use a local callback, for "regrtest -R::" # to detect refcounting problems def callback(w): self.cbcalled += 1 o = C() r1 = MyRef(o, callback) r1.o = o del o del r1 # Used to crash here self.assertEqual(self.cbcalled, 0) # Same test, with two weakrefs to the same object # (since code paths are different) o = C() r1 = MyRef(o, callback) r2 = MyRef(o, callback) r1.r = r2 r2.o = o del o del r2 del r1 # Used to crash here self.assertEqual(self.cbcalled, 0) class WeakMethodTestCase(unittest.TestCase): def _subclass(self): """Return an Object subclass overriding `some_method`.""" class C(Object): def some_method(self): return 6 return C def test_alive(self): o = Object(1) r = weakref.WeakMethod(o.some_method) self.assertIsInstance(r, weakref.ReferenceType) self.assertIsInstance(r(), type(o.some_method)) self.assertIs(r().__self__, o) self.assertIs(r().__func__, o.some_method.__func__) self.assertEqual(r()(), 4) def test_object_dead(self): o = Object(1) r = weakref.WeakMethod(o.some_method) del o gc.collect() self.assertIs(r(), None) def test_method_dead(self): C = self._subclass() o = C(1) r = weakref.WeakMethod(o.some_method) del C.some_method gc.collect() self.assertIs(r(), None) def test_callback_when_object_dead(self): # Test callback behaviour when object dies first. C = self._subclass() calls = [] def cb(arg): calls.append(arg) o = C(1) r = weakref.WeakMethod(o.some_method, cb) del o gc.collect() self.assertEqual(calls, [r]) # Callback is only called once. C.some_method = Object.some_method gc.collect() self.assertEqual(calls, [r]) def test_callback_when_method_dead(self): # Test callback behaviour when method dies first. C = self._subclass() calls = [] def cb(arg): calls.append(arg) o = C(1) r = weakref.WeakMethod(o.some_method, cb) del C.some_method gc.collect() self.assertEqual(calls, [r]) # Callback is only called once. del o gc.collect() self.assertEqual(calls, [r]) @support.cpython_only def test_no_cycles(self): # A WeakMethod doesn't create any reference cycle to itself. o = Object(1) def cb(_): pass r = weakref.WeakMethod(o.some_method, cb) wr = weakref.ref(r) del r self.assertIs(wr(), None) def test_equality(self): def _eq(a, b): self.assertTrue(a == b) self.assertFalse(a != b) def _ne(a, b): self.assertTrue(a != b) self.assertFalse(a == b) x = Object(1) y = Object(1) a = weakref.WeakMethod(x.some_method) b = weakref.WeakMethod(y.some_method) c = weakref.WeakMethod(x.other_method) d = weakref.WeakMethod(y.other_method) # Objects equal, same method _eq(a, b) _eq(c, d) # Objects equal, different method _ne(a, c) _ne(a, d) _ne(b, c) _ne(b, d) # Objects unequal, same or different method z = Object(2) e = weakref.WeakMethod(z.some_method) f = weakref.WeakMethod(z.other_method) _ne(a, e) _ne(a, f) _ne(b, e) _ne(b, f) # Compare with different types _ne(a, x.some_method) _eq(a, ALWAYS_EQ) del x, y, z gc.collect() # Dead WeakMethods compare by identity refs = a, b, c, d, e, f for q in refs: for r in refs: self.assertEqual(q == r, q is r) self.assertEqual(q != r, q is not r) def test_hashing(self): # Alive WeakMethods are hashable if the underlying object is # hashable. x = Object(1) y = Object(1) a = weakref.WeakMethod(x.some_method) b = weakref.WeakMethod(y.some_method) c = weakref.WeakMethod(y.other_method) # Since WeakMethod objects are equal, the hashes should be equal. self.assertEqual(hash(a), hash(b)) ha = hash(a) # Dead WeakMethods retain their old hash value del x, y gc.collect() self.assertEqual(hash(a), ha) self.assertEqual(hash(b), ha) # If it wasn't hashed when alive, a dead WeakMethod cannot be hashed. self.assertRaises(TypeError, hash, c) 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). # dict, objects = self.make_weak_valued_dict() for o in objects: self.assertEqual(weakref.getweakrefcount(o), 1) self.assertIs(o, dict[o.arg], "wrong object returned by weak dict!") items1 = list(dict.items()) items2 = list(dict.copy().items()) items1.sort() items2.sort() self.assertEqual(items1, items2, "cloning of weak-valued dictionary did not work!") del items1, items2 self.assertEqual(len(dict), self.COUNT) del objects[0] gc_collect() # For PyPy or other GCs. self.assertEqual(len(dict), self.COUNT - 1, "deleting object did not cause dictionary update") del objects, o gc_collect() # For PyPy or other GCs. self.assertEqual(len(dict), 0, "deleting the values did not clear the dictionary") # regression on SF bug #447152: dict = weakref.WeakValueDictionary() self.assertRaises(KeyError, dict.__getitem__, 1) dict[2] = C() gc_collect() # For PyPy or other GCs. self.assertRaises(KeyError, dict.__getitem__, 2) def test_weak_keys(self): # # This exercises d.copy(), d.items(), d[] = v, d[], del d[], # len(d), k in d. # dict, objects = self.make_weak_keyed_dict() for o in objects: self.assertEqual(weakref.getweakrefcount(o), 1, "wrong number of weak references to %r!" % o) self.assertIs(o.arg, dict[o], "wrong object returned by weak dict!") items1 = dict.items() items2 = dict.copy().items() self.assertEqual(set(items1), set(items2), "cloning of weak-keyed dictionary did not work!") del items1, items2 self.assertEqual(len(dict), self.COUNT) del objects[0] gc_collect() # For PyPy or other GCs. self.assertEqual(len(dict), (self.COUNT - 1), "deleting object did not cause dictionary update") del objects, o gc_collect() # For PyPy or other GCs. self.assertEqual(len(dict), 0, "deleting the keys did not clear the dictionary") o = Object(42) dict[o] = "What is the meaning of the universe?" self.assertIn(o, dict) self.assertNotIn(34, dict) def test_weak_keyed_iters(self): dict, objects = self.make_weak_keyed_dict() self.check_iters(dict) # Test keyrefs() refs = dict.keyrefs() self.assertEqual(len(refs), len(objects)) objects2 = list(objects) for wr in refs: ob = wr() self.assertIn(ob, dict) self.assertIn(ob, dict) self.assertEqual(ob.arg, dict[ob]) objects2.remove(ob) self.assertEqual(len(objects2), 0) # Test iterkeyrefs() objects2 = list(objects) self.assertEqual(len(list(dict.keyrefs())), len(objects)) for wr in dict.keyrefs(): ob = wr() self.assertIn(ob, dict) self.assertIn(ob, dict) self.assertEqual(ob.arg, dict[ob]) objects2.remove(ob) self.assertEqual(len(objects2), 0) def test_weak_valued_iters(self): dict, objects = self.make_weak_valued_dict() self.check_iters(dict) # Test valuerefs() refs = dict.valuerefs() self.assertEqual(len(refs), len(objects)) objects2 = list(objects) for wr in refs: ob = wr() self.assertEqual(ob, dict[ob.arg]) self.assertEqual(ob.arg, dict[ob.arg].arg) objects2.remove(ob) self.assertEqual(len(objects2), 0) # Test itervaluerefs() objects2 = list(objects) self.assertEqual(len(list(dict.itervaluerefs())), len(objects)) for wr in dict.itervaluerefs(): ob = wr() self.assertEqual(ob, dict[ob.arg]) self.assertEqual(ob.arg, dict[ob.arg].arg) objects2.remove(ob) self.assertEqual(len(objects2), 0) def check_iters(self, dict): # item iterator: items = list(dict.items()) for item in dict.items(): items.remove(item) self.assertFalse(items, "items() did not touch all items") # key iterator, via __iter__(): keys = list(dict.keys()) for k in dict: keys.remove(k) self.assertFalse(keys, "__iter__() did not touch all keys") # key iterator, via iterkeys(): keys = list(dict.keys()) for k in dict.keys(): keys.remove(k) self.assertFalse(keys, "iterkeys() did not touch all keys") # value iterator: values = list(dict.values()) for v in dict.values(): values.remove(v) 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.assertNotIn(k, dict) with testcontext() as (k, v): self.assertRaises(KeyError, dict.__delitem__, k) self.assertNotIn(k, dict) with testcontext() as (k, v): self.assertRaises(KeyError, dict.pop, k) self.assertNotIn(k, 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 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) # Since underlying dict is ordered, first item is popped dict.pop(next(dict.keys())) self.assertEqual(len(dict), n - 1) dict[o] = o self.assertEqual(len(dict), n) # last item in objects is removed from dict in context shutdown with testcontext(): self.assertEqual(len(dict), n - 1) # Then, (o, o) is popped dict.popitem() 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() 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 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 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 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) dict = weakref.WeakKeyDictionary({o:364}) self.assertEqual(dict[o], 364) def test_make_weak_keyed_dict_from_weak_keyed_dict(self): o = Object(3) dict = weakref.WeakKeyDictionary({o:364}) dict2 = weakref.WeakKeyDictionary(dict) self.assertEqual(dict[o], 364) def make_weak_keyed_dict(self): dict = weakref.WeakKeyDictionary() objects = list(map(Object, range(self.COUNT))) for o in objects: dict[o] = o.arg return dict, objects def test_make_weak_valued_dict_from_dict(self): o = Object(3) dict = weakref.WeakValueDictionary({364:o}) self.assertEqual(dict[364], o) def test_make_weak_valued_dict_from_weak_valued_dict(self): o = Object(3) dict = weakref.WeakValueDictionary({364:o}) dict2 = weakref.WeakValueDictionary(dict) self.assertEqual(dict[364], o) def test_make_weak_valued_dict_misc(self): # errors self.assertRaises(TypeError, weakref.WeakValueDictionary.__init__) self.assertRaises(TypeError, weakref.WeakValueDictionary, {}, {}) self.assertRaises(TypeError, weakref.WeakValueDictionary, (), ()) # special keyword arguments o = Object(3) for kw in 'self', 'dict', 'other', 'iterable': d = weakref.WeakValueDictionary(**{kw: o}) self.assertEqual(list(d.keys()), [kw]) self.assertEqual(d[kw], o) def make_weak_valued_dict(self): dict = weakref.WeakValueDictionary() objects = list(map(Object, range(self.COUNT))) for o in objects: dict[o.arg] = o return dict, objects def check_popitem(self, klass, key1, value1, key2, value2): weakdict = klass() weakdict[key1] = value1 weakdict[key2] = value2 self.assertEqual(len(weakdict), 2) k, v = weakdict.popitem() self.assertEqual(len(weakdict), 1) if k is key1: self.assertIs(v, value1) else: self.assertIs(v, value2) k, v = weakdict.popitem() self.assertEqual(len(weakdict), 0) if k is key1: self.assertIs(v, value1) else: self.assertIs(v, value2) def test_weak_valued_dict_popitem(self): self.check_popitem(weakref.WeakValueDictionary, "key1", C(), "key2", C()) def test_weak_keyed_dict_popitem(self): self.check_popitem(weakref.WeakKeyDictionary, C(), "value 1", C(), "value 2") def check_setdefault(self, klass, key, value1, value2): self.assertIsNot(value1, value2, "invalid test" " -- value parameters must be distinct objects") weakdict = klass() o = weakdict.setdefault(key, value1) self.assertIs(o, value1) self.assertIn(key, weakdict) self.assertIs(weakdict.get(key), value1) self.assertIs(weakdict[key], value1) o = weakdict.setdefault(key, value2) self.assertIs(o, value1) self.assertIn(key, weakdict) self.assertIs(weakdict.get(key), value1) self.assertIs(weakdict[key], value1) def test_weak_valued_dict_setdefault(self): self.check_setdefault(weakref.WeakValueDictionary, "key", C(), C()) def test_weak_keyed_dict_setdefault(self): self.check_setdefault(weakref.WeakKeyDictionary, C(), "value 1", "value 2") def check_update(self, klass, dict): # # This exercises d.update(), len(d), d.keys(), k in d, # d.get(), d[]. # weakdict = klass() weakdict.update(dict) self.assertEqual(len(weakdict), len(dict)) for k in weakdict.keys(): self.assertIn(k, dict, "mysterious new key appeared in weak dict") v = dict.get(k) self.assertIs(v, weakdict[k]) self.assertIs(v, weakdict.get(k)) for k in dict.keys(): self.assertIn(k, weakdict, "original key disappeared in weak dict") v = dict[k] self.assertIs(v, weakdict[k]) self.assertIs(v, weakdict.get(k)) def test_weak_valued_dict_update(self): self.check_update(weakref.WeakValueDictionary, {1: C(), 'a': C(), C(): C()}) # errors self.assertRaises(TypeError, weakref.WeakValueDictionary.update) d = weakref.WeakValueDictionary() self.assertRaises(TypeError, d.update, {}, {}) self.assertRaises(TypeError, d.update, (), ()) self.assertEqual(list(d.keys()), []) # special keyword arguments o = Object(3) for kw in 'self', 'dict', 'other', 'iterable': d = weakref.WeakValueDictionary() d.update(**{kw: o}) self.assertEqual(list(d.keys()), [kw]) self.assertEqual(d[kw], o) def test_weak_valued_union_operators(self): a = C() b = C() c = C() wvd1 = weakref.WeakValueDictionary({1: a}) wvd2 = weakref.WeakValueDictionary({1: b, 2: a}) wvd3 = wvd1.copy() d1 = {1: c, 3: b} pairs = [(5, c), (6, b)] tmp1 = wvd1 | wvd2 # Between two WeakValueDictionaries self.assertEqual(dict(tmp1), dict(wvd1) | dict(wvd2)) self.assertIs(type(tmp1), weakref.WeakValueDictionary) wvd1 |= wvd2 self.assertEqual(wvd1, tmp1) tmp2 = wvd2 | d1 # Between WeakValueDictionary and mapping self.assertEqual(dict(tmp2), dict(wvd2) | d1) self.assertIs(type(tmp2), weakref.WeakValueDictionary) wvd2 |= d1 self.assertEqual(wvd2, tmp2) tmp3 = wvd3.copy() # Between WeakValueDictionary and iterable key, value tmp3 |= pairs self.assertEqual(dict(tmp3), dict(wvd3) | dict(pairs)) self.assertIs(type(tmp3), weakref.WeakValueDictionary) tmp4 = d1 | wvd3 # Testing .__ror__ self.assertEqual(dict(tmp4), d1 | dict(wvd3)) self.assertIs(type(tmp4), weakref.WeakValueDictionary) del a self.assertNotIn(2, tmp1) self.assertNotIn(2, tmp2) self.assertNotIn(1, tmp3) self.assertNotIn(1, tmp4) def test_weak_keyed_dict_update(self): self.check_update(weakref.WeakKeyDictionary, {C(): 1, C(): 2, C(): 3}) def test_weak_keyed_delitem(self): d = weakref.WeakKeyDictionary() o1 = Object('1') o2 = Object('2') d[o1] = 'something' d[o2] = 'something' self.assertEqual(len(d), 2) del d[o1] self.assertEqual(len(d), 1) self.assertEqual(list(d.keys()), [o2]) def test_weak_keyed_union_operators(self): o1 = C() o2 = C() o3 = C() wkd1 = weakref.WeakKeyDictionary({o1: 1, o2: 2}) wkd2 = weakref.WeakKeyDictionary({o3: 3, o1: 4}) wkd3 = wkd1.copy() d1 = {o2: '5', o3: '6'} pairs = [(o2, 7), (o3, 8)] tmp1 = wkd1 | wkd2 # Between two WeakKeyDictionaries self.assertEqual(dict(tmp1), dict(wkd1) | dict(wkd2)) self.assertIs(type(tmp1), weakref.WeakKeyDictionary) wkd1 |= wkd2 self.assertEqual(wkd1, tmp1) tmp2 = wkd2 | d1 # Between WeakKeyDictionary and mapping self.assertEqual(dict(tmp2), dict(wkd2) | d1) self.assertIs(type(tmp2), weakref.WeakKeyDictionary) wkd2 |= d1 self.assertEqual(wkd2, tmp2) tmp3 = wkd3.copy() # Between WeakKeyDictionary and iterable key, value tmp3 |= pairs self.assertEqual(dict(tmp3), dict(wkd3) | dict(pairs)) self.assertIs(type(tmp3), weakref.WeakKeyDictionary) tmp4 = d1 | wkd3 # Testing .__ror__ self.assertEqual(dict(tmp4), d1 | dict(wkd3)) self.assertIs(type(tmp4), weakref.WeakKeyDictionary) del o1 self.assertNotIn(4, tmp1.values()) self.assertNotIn(4, tmp2.values()) self.assertNotIn(1, tmp3.values()) self.assertNotIn(1, tmp4.values()) def test_weak_valued_delitem(self): d = weakref.WeakValueDictionary() o1 = Object('1') o2 = Object('2') d['something'] = o1 d['something else'] = o2 self.assertEqual(len(d), 2) del d['something'] self.assertEqual(len(d), 1) self.assertEqual(list(d.items()), [('something else', o2)]) def test_weak_keyed_bad_delitem(self): d = weakref.WeakKeyDictionary() o = Object('1') # An attempt to delete an object that isn't there should raise # KeyError. It didn't before 2.3. self.assertRaises(KeyError, d.__delitem__, o) self.assertRaises(KeyError, d.__getitem__, o) # If a key isn't of a weakly referencable type, __getitem__ and # __setitem__ raise TypeError. __delitem__ should too. self.assertRaises(TypeError, d.__delitem__, 13) self.assertRaises(TypeError, d.__getitem__, 13) self.assertRaises(TypeError, d.__setitem__, 13, 13) def test_weak_keyed_cascading_deletes(self): # SF bug 742860. For some reason, before 2.3 __delitem__ iterated # over the keys via self.data.iterkeys(). If things vanished from # the dict during this (or got added), that caused a RuntimeError. d = weakref.WeakKeyDictionary() mutate = False class C(object): def __init__(self, i): self.value = i def __hash__(self): return hash(self.value) def __eq__(self, other): if mutate: # Side effect that mutates the dict, by removing the # last strong reference to a key. del objs[-1] return self.value == other.value objs = [C(i) for i in range(4)] for o in objs: d[o] = o.value del o # now the only strong references to keys are in objs # Find the order in which iterkeys sees the keys. objs = list(d.keys()) # Reverse it, so that the iteration implementation of __delitem__ # has to keep looping to find the first object we delete. objs.reverse() # Turn on mutation in C.__eq__. The first time through the loop, # under the iterkeys() business the first comparison will delete # the last item iterkeys() would see, and that causes a # RuntimeError: dictionary changed size during iteration # when the iterkeys() loop goes around to try comparing the next # key. After this was fixed, it just deletes the last object *our* # "for o in obj" loop would have gotten to. mutate = True count = 0 for o in objs: count += 1 del d[o] gc_collect() # For PyPy or other GCs. self.assertEqual(len(d), 0) self.assertEqual(count, 2) def test_make_weak_valued_dict_repr(self): dict = weakref.WeakValueDictionary() self.assertRegex(repr(dict), '<WeakValueDictionary at 0x.*>') def test_make_weak_keyed_dict_repr(self): dict = weakref.WeakKeyDictionary() self.assertRegex(repr(dict), '<WeakKeyDictionary at 0x.*>') def test_threaded_weak_valued_setdefault(self): d = weakref.WeakValueDictionary() with collect_in_thread(): for i in range(100000): x = d.setdefault(10, RefCycle()) self.assertIsNot(x, None) # we never put None in there! del x def test_threaded_weak_valued_pop(self): d = weakref.WeakValueDictionary() with collect_in_thread(): for i in range(100000): d[10] = RefCycle() x = d.pop(10, 10) self.assertIsNot(x, None) # we never put None in there! def test_threaded_weak_valued_consistency(self): # Issue #28427: old keys should not remove new values from # WeakValueDictionary when collecting from another thread. d = weakref.WeakValueDictionary() with collect_in_thread(): for i in range(200000): o = RefCycle() d[10] = o # o is still alive, so the dict can't be empty self.assertEqual(len(d), 1) o = None # lose ref def check_threaded_weak_dict_copy(self, type_, deepcopy): # `type_` should be either WeakKeyDictionary or WeakValueDictionary. # `deepcopy` should be either True or False. exc = [] class DummyKey: def __init__(self, ctr): self.ctr = ctr class DummyValue: def __init__(self, ctr): self.ctr = ctr def dict_copy(d, exc): try: if deepcopy is True: _ = copy.deepcopy(d) else: _ = d.copy() except Exception as ex: exc.append(ex) def pop_and_collect(lst): gc_ctr = 0 while lst: i = random.randint(0, len(lst) - 1) gc_ctr += 1 lst.pop(i) if gc_ctr % 10000 == 0: gc.collect() # just in case self.assertIn(type_, (weakref.WeakKeyDictionary, weakref.WeakValueDictionary)) d = type_() keys = [] values = [] # Initialize d with many entries for i in range(70000): k, v = DummyKey(i), DummyValue(i) keys.append(k) values.append(v) d[k] = v del k del v t_copy = threading.Thread(target=dict_copy, args=(d, exc,)) if type_ is weakref.WeakKeyDictionary: t_collect = threading.Thread(target=pop_and_collect, args=(keys,)) else: # weakref.WeakValueDictionary t_collect = threading.Thread(target=pop_and_collect, args=(values,)) t_copy.start() t_collect.start() t_copy.join() t_collect.join() # Test exceptions if exc: raise exc[0] def test_threaded_weak_key_dict_copy(self): # Issue #35615: Weakref keys or values getting GC'ed during dict # copying should not result in a crash. self.check_threaded_weak_dict_copy(weakref.WeakKeyDictionary, False) def test_threaded_weak_key_dict_deepcopy(self): # Issue #35615: Weakref keys or values getting GC'ed during dict # copying should not result in a crash. self.check_threaded_weak_dict_copy(weakref.WeakKeyDictionary, True) def test_threaded_weak_value_dict_copy(self): # Issue #35615: Weakref keys or values getting GC'ed during dict # copying should not result in a crash. self.check_threaded_weak_dict_copy(weakref.WeakValueDictionary, False) def test_threaded_weak_value_dict_deepcopy(self): # Issue #35615: Weakref keys or values getting GC'ed during dict # copying should not result in a crash. self.check_threaded_weak_dict_copy(weakref.WeakValueDictionary, True) @support.cpython_only def test_remove_closure(self): d = weakref.WeakValueDictionary() self.assertIsNone(d._remove.__closure__) from test import mapping_tests class WeakValueDictionaryTestCase(mapping_tests.BasicTestMappingProtocol): """Check that WeakValueDictionary conforms to the mapping protocol""" __ref = {"key1":Object(1), "key2":Object(2), "key3":Object(3)} type2test = weakref.WeakValueDictionary def _reference(self): return self.__ref.copy() class WeakKeyDictionaryTestCase(mapping_tests.BasicTestMappingProtocol): """Check that WeakKeyDictionary conforms to the mapping protocol""" __ref = {Object("key1"):1, Object("key2"):2, Object("key3"):3} type2test = weakref.WeakKeyDictionary def _reference(self): return self.__ref.copy() class FinalizeTestCase(unittest.TestCase): class A: pass def _collect_if_necessary(self): # we create no ref-cycles so in CPython no gc should be needed if sys.implementation.name != 'cpython': support.gc_collect() def test_finalize(self): def add(x,y,z): res.append(x + y + z) return x + y + z a = self.A() res = [] f = weakref.finalize(a, add, 67, 43, z=89) self.assertEqual(f.alive, True) self.assertEqual(f.peek(), (a, add, (67,43), {'z':89})) self.assertEqual(f(), 199) self.assertEqual(f(), None) self.assertEqual(f(), None) self.assertEqual(f.peek(), None) self.assertEqual(f.detach(), None) self.assertEqual(f.alive, False) self.assertEqual(res, [199]) res = [] f = weakref.finalize(a, add, 67, 43, 89) self.assertEqual(f.peek(), (a, add, (67,43,89), {})) self.assertEqual(f.detach(), (a, add, (67,43,89), {})) self.assertEqual(f(), None) self.assertEqual(f(), None) self.assertEqual(f.peek(), None) self.assertEqual(f.detach(), None) self.assertEqual(f.alive, False) self.assertEqual(res, []) res = [] f = weakref.finalize(a, add, x=67, y=43, z=89) del a self._collect_if_necessary() self.assertEqual(f(), None) self.assertEqual(f(), None) self.assertEqual(f.peek(), None) self.assertEqual(f.detach(), None) self.assertEqual(f.alive, False) self.assertEqual(res, [199]) def test_arg_errors(self): def fin(*args, **kwargs): res.append((args, kwargs)) a = self.A() res = [] f = weakref.finalize(a, fin, 1, 2, func=3, obj=4) self.assertEqual(f.peek(), (a, fin, (1, 2), {'func': 3, 'obj': 4})) f() self.assertEqual(res, [((1, 2), {'func': 3, 'obj': 4})]) with self.assertRaises(TypeError): weakref.finalize(a, func=fin, arg=1) with self.assertRaises(TypeError): weakref.finalize(obj=a, func=fin, arg=1) self.assertRaises(TypeError, weakref.finalize, a) self.assertRaises(TypeError, weakref.finalize) def test_order(self): a = self.A() res = [] f1 = weakref.finalize(a, res.append, 'f1') f2 = weakref.finalize(a, res.append, 'f2') f3 = weakref.finalize(a, res.append, 'f3') f4 = weakref.finalize(a, res.append, 'f4') f5 = weakref.finalize(a, res.append, 'f5') # make sure finalizers can keep themselves alive del f1, f4 self.assertTrue(f2.alive) self.assertTrue(f3.alive) self.assertTrue(f5.alive) self.assertTrue(f5.detach()) self.assertFalse(f5.alive) f5() # nothing because previously unregistered res.append('A') f3() # => res.append('f3') self.assertFalse(f3.alive) res.append('B') f3() # nothing because previously called res.append('C') del a self._collect_if_necessary() # => res.append('f4') # => res.append('f2') # => res.append('f1') self.assertFalse(f2.alive) res.append('D') f2() # nothing because previously called by gc expected = ['A', 'f3', 'B', 'C', 'f4', 'f2', 'f1', 'D'] self.assertEqual(res, expected) def test_all_freed(self): # we want a weakrefable subclass of weakref.finalize class MyFinalizer(weakref.finalize): pass a = self.A() res = [] def callback(): res.append(123) f = MyFinalizer(a, callback) wr_callback = weakref.ref(callback) wr_f = weakref.ref(f) del callback, f self.assertIsNotNone(wr_callback()) self.assertIsNotNone(wr_f()) del a self._collect_if_necessary() self.assertIsNone(wr_callback()) self.assertIsNone(wr_f()) self.assertEqual(res, [123]) @classmethod def run_in_child(cls): def error(): # Create an atexit finalizer from inside a finalizer called # at exit. This should be the next to be run. g1 = weakref.finalize(cls, print, 'g1') print('f3 error') 1/0 # cls should stay alive till atexit callbacks run f1 = weakref.finalize(cls, print, 'f1', _global_var) f2 = weakref.finalize(cls, print, 'f2', _global_var) f3 = weakref.finalize(cls, error) f4 = weakref.finalize(cls, print, 'f4', _global_var) assert f1.atexit == True f2.atexit = False assert f3.atexit == True assert f4.atexit == True def test_atexit(self): prog = ('from test.test_weakref import FinalizeTestCase;'+ 'FinalizeTestCase.run_in_child()') rc, out, err = script_helper.assert_python_ok('-c', prog) out = out.decode('ascii').splitlines() self.assertEqual(out, ['f4 foobar', 'f3 error', 'g1', 'f1 foobar']) self.assertTrue(b'ZeroDivisionError' in err) libreftest = """ Doctest for examples in the library reference: weakref.rst >>> from test.support import gc_collect >>> import weakref >>> class Dict(dict): ... pass ... >>> obj = Dict(red=1, green=2, blue=3) # this object is weak referencable >>> r = weakref.ref(obj) >>> print(r() is obj) True >>> import weakref >>> class Object: ... pass ... >>> o = Object() >>> r = weakref.ref(o) >>> o2 = r() >>> o is o2 True >>> del o, o2 >>> gc_collect() # For PyPy or other GCs. >>> print(r()) None >>> import weakref >>> class ExtendedRef(weakref.ref): ... def __init__(self, ob, callback=None, **annotations): ... super().__init__(ob, callback) ... self.__counter = 0 ... for k, v in annotations.items(): ... setattr(self, k, v) ... def __call__(self): ... '''Return a pair containing the referent and the number of ... times the reference has been called. ... ''' ... ob = super().__call__() ... if ob is not None: ... self.__counter += 1 ... ob = (ob, self.__counter) ... return ob ... >>> class A: # not in docs from here, just testing the ExtendedRef ... pass ... >>> a = A() >>> r = ExtendedRef(a, foo=1, bar="baz") >>> r.foo 1 >>> r.bar 'baz' >>> r()[1] 1 >>> r()[1] 2 >>> r()[0] is a True >>> import weakref >>> _id2obj_dict = weakref.WeakValueDictionary() >>> def remember(obj): ... oid = id(obj) ... _id2obj_dict[oid] = obj ... return oid ... >>> def id2obj(oid): ... return _id2obj_dict[oid] ... >>> a = A() # from here, just testing >>> a_id = remember(a) >>> id2obj(a_id) is a True >>> del a >>> gc_collect() # For PyPy or other GCs. >>> try: ... id2obj(a_id) ... except KeyError: ... print('OK') ... else: ... print('WeakValueDictionary error') OK """ __test__ = {'libreftest' : libreftest} def test_main(): support.run_unittest( ReferencesTestCase, WeakMethodTestCase, MappingTestCase, WeakValueDictionaryTestCase, WeakKeyDictionaryTestCase, SubclassableWeakrefTestCase, FinalizeTestCase, ) support.run_doctest(sys.modules[__name__]) if __name__ == "__main__": test_main()