#13394: Write a WeakValueDictionary with safer key removal
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Reporter: nbruin | Owner: rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.13
Component: memleak | Resolution:
Keywords: | Merged in:
Authors: Simon King, Nils | Reviewers: Simon King
Bruin | Work issues:
Report Upstream: None of the above | Commit:
- read trac for reasoning. | 851cc9522dde332561101f1c84182a0a84b8eed4
Branch: | Stopgaps:
u/SimonKing/ticket/13394 |
Dependencies: |
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Comment (by SimonKing):
Replying to [comment:61 nbruin]:
> OK, we don't have a doctest for `del_dictitem_by_exact_value`. Given
that we absolutely want to know if somehow python changes something about
their dicts so that our implementation needs adapting, we should include a
stress test (perhaps `#long`?). Something along the lines of:
> {{{
> sage: from sage.misc.weak_dict import del_dictitem_by_exact_value
> B=1000
> L=list(range(B))
> D1=dict()
> D2=dict()
> for i in range(100000):
> ki=L[floor(random()*B)]
> vi=L[floor(random()*B)]
> D1[ki]=vi
> D2[ki]=vi
> ko=L[floor(random()*B)]
> if ko in D1:
> vo=D1[ko]
> del D1[ko]
> del_dictitem_by_exact_value(D2,vo,hash(ko))
> assert D1 == D2
> }}}
I think, for an indirect doctest, one should modify it so that
`del_dictitem_by_exact_value` is executed because a callback happens. I'll
try to create an example accordingly. Roughly: We have two equal dicts; we
explicitly delete an item in the first dict, and implicitly delete the
same item in the second dict, by allowing the value to become garbage
collected.
For a weak value dictionary we can of course not use a list `L` of ints.
What I don't understand: Is it essential in your example that keys and
values come from the same list? Otherwise, I would simply have a list and
two weak value dictionaries keeping track of the same key-value pairs, so
that a callback is triggered if one deletes a value from the list.
--
Ticket URL: <http://trac.sagemath.org/ticket/13394#comment:71>
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