#13447: Make libsingular multivariate polynomial rings collectable
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Reporter: nbruin |
Owner:
Type: defect |
Status: needs_work
Priority: major |
Milestone: sage-5.4
Component: memleak |
Resolution:
Keywords: | Work
issues: Understand why sometimes `new_RingWrap` needs an incref and sometimes
not
Report Upstream: None of the above - read trac for reasoning. |
Reviewers: Simon King
Authors: Nils Bruin, Simon King | Merged
in:
Dependencies: #11521 |
Stopgaps:
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Comment (by SimonKing):
Some suggestions:
The singular function `rKill` seems to do what we want in
`singular_ring_delete`. Hence, to keep it simple, `singular_ring_delete`
should call `rKill`, and nothing more (unless we want a sanity test, such
as printing a warning if `singular_ring_delete` is called on NULL).
`rKill` only takes action if `r->ref` is zero when it is called. Indeed,
according to Hans, `r->ref` is the number of interpreter variables
pointing to a ring, minus one. In order to avoid confusion, we should
follow the same idea.
So, what means "interpreter variables" for us? I think this should be "any
Sage object whose deallocation needs the libsingular ring being alive".
This is every polynomial ring, every Gröbner strategy, and any element of
a polynomial ring.
Since ref is -1 based, when a Sage ring R is created then ref shall be
zero, so that the underlying libsingular ring can be properly deleted if R
is deallocated. And if any element or Gröbner strategy on that ring is
created, ref needs to be incremented. The deallocation of an element or
Gröbner strategy must involve a call to `singular_ring_delete`.
A complication arises when calling a singular_function. When we call a
Singular interpreter function, then we should have ref>0, again according
to Hans. Hence, at the begin of a call, ref must be incremented, and
decremented when leaving it.
Special care needs to be taken on `currRingHdl`. According to Hans,
`rKill` can make it NULL, and it should be NULL if and only if `currRing`
is NULL. Currently, we create `currRingHdl` when we ''create'' a Singular
function, but we only use it when we ''call'' a Singular function. That's
asking for trouble. Hence, we should move the creation of currRingHdl to
`SingularFunction.__call__`, where we also set the correct `currRing`.
`SingularFunction.__init__` is not the right place.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13447#comment:69>
Sage <http://www.sagemath.org>
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