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lib-python.2.7.test.test_weakref.py Maven / Gradle / Ivy
Jython is an implementation of the high-level, dynamic, object-oriented
language Python written in 100% Pure Java, and seamlessly integrated with
the Java platform. It thus allows you to run Python on any Java platform.
import gc
import sys
import unittest
import UserList
import weakref
import operator
from test import test_support
# Used in ReferencesTestCase.test_ref_created_during_del() .
ref_from_del = None
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
def create_unbound_method():
return C.method
class Object:
def __init__(self, arg):
self.arg = arg
def __repr__(self):
return "" % self.arg
def __eq__(self, other):
if isinstance(other, Object):
return self.arg == other.arg
return NotImplemented
def __ne__(self, other):
if isinstance(other, Object):
return self.arg != other.arg
return NotImplemented
def __hash__(self):
return hash(self.arg)
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
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)
self.check_basic_ref(create_unbound_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)
self.check_basic_callback(create_unbound_method)
def test_multiple_callbacks(self):
o = C()
ref1 = weakref.ref(o, self.callback)
ref2 = weakref.ref(o, self.callback)
del o
self.assertTrue(ref1() is None,
"expected reference to be invalidated")
self.assertTrue(ref2() is None,
"expected reference to be invalidated")
self.assertTrue(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_proxy_ref(self):
o = C()
o.bar = 1
ref1 = weakref.proxy(o, self.callback)
ref2 = weakref.proxy(o, self.callback)
del o
def check(proxy):
proxy.bar
self.assertRaises(weakref.ReferenceError, check, ref1)
self.assertRaises(weakref.ReferenceError, check, ref2)
self.assertRaises(weakref.ReferenceError, bool, weakref.proxy(C()))
self.assertTrue(self.cbcalled == 2)
def check_basic_ref(self, factory):
o = factory()
ref = weakref.ref(o)
self.assertTrue(ref() is not None,
"weak reference to live object should be live")
o2 = ref()
self.assertTrue(o is o2,
"[() 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
self.assertTrue(self.cbcalled == 1,
"callback did not properly set 'cbcalled'")
self.assertTrue(ref() is None,
"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.assertTrue(ref1 is 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.assertTrue(ref1 is ref2,
"reference object w/out callback should be re-used")
self.assertTrue(weakref.getweakrefcount(o) == 2,
"wrong weak ref count for object")
del proxy
self.assertTrue(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.assertTrue(proxy1 is 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 = UserList.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")
with test_support.check_py3k_warnings():
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 = UserList.UserList(L)
p2 = weakref.proxy(L2)
self.assertEqual(p, p2)
## self.assertEqual(repr(L2), repr(p2))
L3 = UserList.UserList(range(10))
p3 = weakref.proxy(L3)
with test_support.check_py3k_warnings():
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 __unicode__(self):
return u"unicode"
instance = C()
self.assertIn("__unicode__", dir(weakref.proxy(instance)))
self.assertEqual(unicode(weakref.proxy(instance)), u"unicode")
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)
# 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.assertTrue(p1 is p2, "both callbacks were None in the C API")
del p1, p2
p1 = makeref(o)
p2 = makeref(o, None)
self.assertTrue(p1 is p2, "callbacks were NULL, None in the C API")
del p1, p2
p1 = makeref(o)
p2 = makeref(o)
self.assertTrue(p1 is p2, "both callbacks were NULL in the C API")
del p1, p2
p1 = makeref(o, None)
p2 = makeref(o)
self.assertTrue(p1 is 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.assertTrue(type(ref1) is weakref.CallableProxyType,
"proxy is not of callable type")
ref1('twinkies!')
self.assertTrue(o.bar == 'twinkies!',
"call through proxy not passed through to original")
ref1(x='Splat.')
self.assertTrue(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.assertTrue(proxy.foo == 1,
"proxy does not reflect attribute addition")
o.foo = 2
self.assertTrue(proxy.foo == 2,
"proxy does not reflect attribute modification")
del o.foo
self.assertTrue(not hasattr(proxy, 'foo'),
"proxy does not reflect attribute removal")
proxy.foo = 1
self.assertTrue(o.foo == 1,
"object does not reflect attribute addition via proxy")
proxy.foo = 2
self.assertTrue(
o.foo == 2,
"object does not reflect attribute modification via proxy")
del proxy.foo
self.assertTrue(not 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_getweakrefcount(self):
o = C()
ref1 = weakref.ref(o)
ref2 = weakref.ref(o, self.callback)
self.assertTrue(weakref.getweakrefcount(o) == 2,
"got wrong number of weak reference objects")
proxy1 = weakref.proxy(o)
proxy2 = weakref.proxy(o, self.callback)
self.assertTrue(weakref.getweakrefcount(o) == 4,
"got wrong number of weak reference objects")
del ref1, ref2, proxy1, proxy2
self.assertTrue(weakref.getweakrefcount(o) == 0,
"weak reference objects not unlinked from"
" referent when discarded.")
# assumes ints do not support weakrefs
self.assertTrue(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
self.assertTrue(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
self.assertTrue(weakref.getweakrefs(o) == [ref1],
"list of refs does not match")
del ref1
self.assertTrue(weakref.getweakrefs(o) == [],
"list of refs not cleared")
# assumes ints do not support weakrefs
self.assertTrue(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.assertTrue(p + 1.0 == 3.0)
self.assertTrue(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 ]> 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.assertTrue(external_wr() is 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
# .__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 both old-style classes and new-style classes
# are weakrefable.
class A(object):
pass
class B:
pass
l = []
weakref.ref(int)
a = weakref.ref(A, l.append)
A = None
gc.collect()
self.assertEqual(a(), None)
self.assertEqual(l, [a])
b = weakref.ref(B, l.append)
B = None
gc.collect()
self.assertEqual(b(), None)
self.assertEqual(l, [a, b])
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)
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_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(object):
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()
class SubclassableWeakrefTestCase(TestBase):
def test_subclass_refs(self):
class MyRef(weakref.ref):
def __init__(self, ob, callback=None, value=42):
self.value = value
super(MyRef, self).__init__(ob, callback)
def __call__(self):
self.called = True
return super(MyRef, self).__call__()
o = Object("foo")
mr = MyRef(o, value=24)
self.assertTrue(mr() is o)
self.assertTrue(mr.called)
self.assertEqual(mr.value, 24)
del o
self.assertTrue(mr() is None)
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.assertTrue(r1 is not 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.assertTrue(r2 is 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.assertTrue(r1 is not 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):
# Bug #3110
# 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 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.iteritems()
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.iteritems()
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.assertTrue(weakref.getweakrefcount(o) == 1,
"wrong number of weak references to %r!" % o)
self.assertTrue(o is dict[o.arg],
"wrong object returned by weak dict!")
items1 = dict.items()
items2 = dict.copy().items()
items1.sort()
items2.sort()
self.assertTrue(items1 == items2,
"cloning of weak-valued dictionary did not work!")
del items1, items2
self.assertTrue(len(dict) == self.COUNT)
del objects[0]
self.assertTrue(len(dict) == (self.COUNT - 1),
"deleting object did not cause dictionary update")
del objects, o
self.assertTrue(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()
self.assertRaises(KeyError, dict.__getitem__, 2)
def test_weak_keys(self):
#
# This exercises d.copy(), d.items(), d[] = v, d[], del d[],
# len(d), in d.
#
dict, objects = self.make_weak_keyed_dict()
for o in objects:
self.assertTrue(weakref.getweakrefcount(o) == 1,
"wrong number of weak references to %r!" % o)
self.assertTrue(o.arg is dict[o],
"wrong object returned by weak dict!")
items1 = dict.items()
items2 = dict.copy().items()
self.assertTrue(set(items1) == set(items2),
"cloning of weak-keyed dictionary did not work!")
del items1, items2
self.assertTrue(len(dict) == self.COUNT)
del objects[0]
self.assertTrue(len(dict) == (self.COUNT - 1),
"deleting object did not cause dictionary update")
del objects, o
self.assertTrue(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.assertEqual(ob.arg, dict[ob])
objects2.remove(ob)
self.assertEqual(len(objects2), 0)
# Test iterkeyrefs()
objects2 = list(objects)
self.assertEqual(len(list(dict.iterkeyrefs())), len(objects))
for wr in dict.iterkeyrefs():
ob = wr()
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 = dict.items()
for item in dict.iteritems():
items.remove(item)
self.assertTrue(len(items) == 0, "iteritems() did not touch all items")
# key iterator, via __iter__():
keys = dict.keys()
for k in dict:
keys.remove(k)
self.assertTrue(len(keys) == 0, "__iter__() did not touch all keys")
# key iterator, via iterkeys():
keys = dict.keys()
for k in dict.iterkeys():
keys.remove(k)
self.assertTrue(len(keys) == 0, "iterkeys() did not touch all keys")
# value iterator:
values = dict.values()
for v in dict.itervalues():
values.remove(v)
self.assertTrue(len(values) == 0,
"itervalues() did not touch all values")
def test_make_weak_keyed_dict_from_dict(self):
o = Object(3)
dict = weakref.WeakKeyDictionary({o:364})
self.assertTrue(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.assertTrue(dict[o] == 364)
def make_weak_keyed_dict(self):
dict = weakref.WeakKeyDictionary()
objects = map(Object, range(self.COUNT))
for o in objects:
dict[o] = o.arg
return dict, objects
def make_weak_valued_dict(self):
dict = weakref.WeakValueDictionary()
objects = 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.assertTrue(len(weakdict) == 2)
k, v = weakdict.popitem()
self.assertTrue(len(weakdict) == 1)
if k is key1:
self.assertTrue(v is value1)
else:
self.assertTrue(v is value2)
k, v = weakdict.popitem()
self.assertTrue(len(weakdict) == 0)
if k is key1:
self.assertTrue(v is value1)
else:
self.assertTrue(v is 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.assertTrue(value1 is not 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(), 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()})
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.assertTrue(len(d) == 2)
del d[o1]
self.assertTrue(len(d) == 1)
self.assertTrue(d.keys() == [o2])
def test_weak_valued_delitem(self):
d = weakref.WeakValueDictionary()
o1 = Object('1')
o2 = Object('2')
d['something'] = o1
d['something else'] = o2
self.assertTrue(len(d) == 2)
del d['something']
self.assertTrue(len(d) == 1)
self.assertTrue(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 = 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 thru 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]
self.assertEqual(len(d), 0)
self.assertEqual(count, 2)
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()
libreftest = """ Doctest for examples in the library reference: weakref.rst
>>> 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
>>> print r()
None
>>> import weakref
>>> class ExtendedRef(weakref.ref):
... def __init__(self, ob, callback=None, **annotations):
... super(ExtendedRef, self).__init__(ob, callback)
... self.__counter = 0
... for k, v in annotations.iteritems():
... 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(ExtendedRef, self).__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
>>> try:
... id2obj(a_id)
... except KeyError:
... print 'OK'
... else:
... print 'WeakValueDictionary error'
OK
"""
__test__ = {'libreftest' : libreftest}
def test_main():
test_support.run_unittest(
ReferencesTestCase,
MappingTestCase,
WeakValueDictionaryTestCase,
WeakKeyDictionaryTestCase,
SubclassableWeakrefTestCase,
)
test_support.run_doctest(sys.modules[__name__])
if __name__ == "__main__":
test_main()
