Repository navigation
Expand file tree
/
Copy pathtest_weakref.py
More file actions
2316 lines (1997 loc) · 77 KB
/
Copy pathtest_weakref.py
File metadata and controls
2316 lines (1997 loc) · 77 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
import gc
import sys
import doctest
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, suppress_immortalization
from test.support import gc_collect
from test.support import import_helper
from test.support import threading_helper
# 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)
@support.cpython_only
def test_ref_repr(self):
obj = C()
ref = weakref.ref(obj)
self.assertRegex(repr(ref),
rf"<weakref at 0x[0-9a-fA-F]+; "
rf"to '{C.__module__}.{C.__qualname__}' "
rf"at 0x[0-9a-fA-F]+>")
obj = None
gc_collect()
self.assertRegex(repr(ref),
rf'<weakref at 0x[0-9a-fA-F]+; dead>')
# test type with __name__
class WithName:
@property
def __name__(self):
return "custom_name"
obj2 = WithName()
ref2 = weakref.ref(obj2)
self.assertRegex(repr(ref2),
rf"<weakref at 0x[0-9a-fA-F]+; "
rf"to '{WithName.__module__}.{WithName.__qualname__}' "
rf"at 0x[0-9a-fA-F]+ \(custom_name\)>")
def test_repr_failure_gh99184(self):
class MyConfig(dict):
def __getattr__(self, x):
return self[x]
obj = MyConfig(offset=5)
obj_weakref = weakref.ref(obj)
self.assertIn('MyConfig', repr(obj_weakref))
self.assertIn('MyConfig', str(obj_weakref))
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):
_testcapi = import_helper.import_module("_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)
@support.cpython_only
def test_proxy_repr(self):
obj = C()
ref = weakref.proxy(obj, self.callback)
self.assertRegex(repr(ref),
rf"<weakproxy at 0x[0-9a-fA-F]+; "
rf"to '{C.__module__}.{C.__qualname__}' "
rf"at 0x[0-9a-fA-F]+>")
obj = None
gc_collect()
self.assertRegex(repr(ref),
rf'<weakproxy at 0x[0-9a-fA-F]+; dead>')
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
@suppress_immortalization()
def test_callback_in_cycle(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_reachable_one_way(self):
import gc
# This one broke the first patch that fixed the previous test. 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_different_classes(self):
import gc
# Like test_callback_reachable_one_way, 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()
@suppress_immortalization()
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()
@suppress_immortalization()
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):