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Date: Tue, 24 Apr 2012 13:30:11 +0300
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Subject: Re: [PATCH] ruby: make sure the database is closed
From: Felipe Contreras <felipe.contreras@gmail.com>
To: Austin Clements <amdragon@mit.edu>
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Cc: Ali Polatel <alip@exherbo.org>, notmuch@notmuchmail.org
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On Tue, Apr 24, 2012 at 4:15 AM, Austin Clements <amdragon@mit.edu> wrote:
> Quoth Felipe Contreras on Apr 24 at =C2=A03:45 am:
>> On Tue, Apr 24, 2012 at 2:46 AM, Ali Polatel <alip@exherbo.org> wrote:
>> > 2012/4/24 Felipe Contreras <felipe.contreras@gmail.com>:
>>
>> >> Personally I don't see why an object, like say a query would remain
>> >> working correctly after the database is gone, either by calling
>> >> .close() directly, or just loosing the pointer to the original object=
.
>> >> I don't think users would expect that, or, even if they somehow found
>> >> it useful, that most likely would be very seldom, and hardly worth
>> >> worrying about it.
>> >
>> > Working correctly is not expected but wouldn't it be more appropriate
>> > to throw an exception rather than dumping core or printing on standard=
 error?
>>
>> Sure, if that was possible.
>>
>> > I wonder whether we can make both work somehow.
>> > Maybe by using talloc explicitly and keeping reference pointers?
>> > I don't know whether it's worth bothering.
>>
>> Maybe, I don't see how, that's just not how C works. Maybe talloc does
>> have some way to figure out if a pointer has been freed, but I doubt
>> that, and I can't find it by grepping through the API.
>>
>> Another option would be hook into talloc's destructor so we know when
>> an object is freed and taint it, but then we would be overriding
>> notmuch's destructor, and there's no way around that (unless we tap
>> into talloc's internal structures). A way to workaround that would be
>> to modify notmuch's API so that we can specify a destructor for
>> notmuch objects, but that would be tedious, and I doubt a lof people
>> beside us would benefit from that.
>
> I believe (though I might be wrong) that bindings could simply
> maintain their own talloc references to C objects returned by
> libnotmuch to prevent them from being freed until the wrapper object
> is garbage collected. =C2=A0This would require modifying all of the
> library's _destroy functions to use talloc_find_parent_bytype and
> talloc_unlink instead of simply calling talloc_free, but I don't think
> this change would be particularly invasive and it certainly wouldn't
> affect the library interface.

That might work, but still, I don't see why this patch can't be applied.

Cheers.

--=20
Felipe Contreras