On Fri, Dec 4, 2009 at 12:05 PM, Adrian Lienhard <[email protected]> wrote:
> Hi Sheri,
>
> Sounds ok to make new: raise an exception if you adjust the tests (and
> any code that exists in the image using new: (but I assume there is
> none)).
>
> However, the actual reason why you get multiple same symbols after
> loading a segment likely is unrelated to ByteSymbol class>>new:. I
> guess it is because when creating the segment you do not hold onto
> these symbols. Like this they do not get into the outPointers ref
> stream but in the bytearray. When installing the segment again, with
> same symbols existing in the image already, then you get duplicates.
>
> The "right way" to do this is to strongly hold onto all symbols when
> creating a segment. See #createSegmentFrom:. You can reproduce this
> problem by commenting out the first line of #createSegmentFrom: and
> running #testSymbols.
>
> Let us know how it goes...
>
>
Ok...let me see if I understood you correctly.
When you are creating your root of objects and you put symbols inside, they
are not put in ourPointers but in ByteArray.
This is due to the fact that the only object who is pointing to that symbol
is inside the segment ?
What you do with this piece of code:
symbolHolder := Symbol allSymbols.
is to hold those symbols there. So, when ImageSegment uses the GC techniques
to detect which objects are ONLY pointed from inside of the segment, the
symbols is not found (because it is accessible trough that test) and thus,
it goes to outPointers instead of ByteArray.
And of course, if it is in outPointers instead of ByteArray when the segment
is loaded again, yo don't create a symbol again but use the same object (the
one of the oop).
I am correct? or I understood anything ?
Cheers,
Mariano
BTW, Mariano is also writing ImageSegment tests, so maybe you want to
> join forces (or maybe he already is the colleague you mentioned?).
>
> Cheers,
> Adrian
>
> On Dec 3, 2009, at 23:10 , Stéphane Ducasse wrote:
>
> >> From: Sheridan Mahoney <[email protected]>
> >> Date: December 3, 2009 11:04:19 PM GMT+01:00
> >> To: [email protected]
> >> Subject: Re: getting rid of Symbol >> new: ?
> >> Reply-To: [email protected]
> >>
> >>
> >> A colleague and I are investigating the ImageSegment class and its
> >> methods, we came across an issue I would like to get external
> >> opinions on. Newbie alert, BTW (at least one of us, no names
> >> mentioned...). Also, this is not a problem that will affect many
> >> users, but it is familiarizing us with the check-in process,
> >> slices, etc. While working on ImageSegment tests, we discovered a
> >> problem on trying to load segments that had Symbols in the root
> >> array. It is possible to create 2 ByteSymbols with the same
> >> sequence of characters. :( In trying to track down how this is
> >> possible, we came across a side issue, that ByteSymbol new: had
> >> the capacity to create multiple new ByteSymbols with the same
> >> number of nil characters (as in, initialized with nil). We want to
> >> dissallow Symbol new: , which would cause people to use one of
> >> the nicer methods for Symbol/ByteSymbol creation (namely, one which
> >> checks that the sequence of characters doesn't already exist, as
> >> part of the creation process). We have a fix we want to check in,
> >> but currently it breaks a test case in the SymbolTest class, which
> >> is checking that new: works. We also changed the intern:
> >> method on the class side of Symbol to use basicNew: instead
> >> of new: . Are there reasons to keep 'Symbol new:' , that
> >> outweigh the reasons to get rid of it?
> >> Many thanks,
> >> and Cheers,
> >> Sheri Mahoney
> >
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