From: Derek Lewis <lewisd@...00f.net>
Date: 2003-12-14T03:23:10+09:00
Subject: Re: strange rb_gc_mark error


I don't know if it makes a difference, but in my libxosd-ruby code I'm
doing something similar, but it seems to work fine:

xosd *osd;
VALUE r_osd;

osd = xosd_create(lines);
r_osd = INT2FIX( (int)osd );

rb_iv_set(self, "@osd", r_osd);

Two major differences I notice:
1. I'm using INT2FIX instead of casting to VALUE
2. I'm using an "@" on my variable name in rv_iv_set

Also, a quick question.  Am I creating objects that won't be GC'd by using
INT2FIX like that?


On Sun, 14 Dec 2003, Elias Athanasopoulos wrote:

> On Sun, Dec 14, 2003 at 12:02:27AM +0900, Elias Athanasopoulos wrote:
> > On Sat, Dec 13, 2003 at 10:11:12PM +0900, Yukihiro Matsumoto wrote:
> > > Hi,
> > >
> > > In message "strange rb_gc_mark error"
> > >     on 03/12/13, Elias Athanasopoulos <elathan@phys.uoa.gr> writes:
> > >
> > > |I have a pure C function, which may be called arbitrary
> > > |sequential times. If I call any rb_* function inside, including
> > > |the simple rb_warn(), I get:
> > > |
> > > |BUG] rb_gc_mark(): unknown data type 0x28(0x89965b0) non object
> > > |ruby 1.8.0 (2003-08-04) [i586-linux]
> > > |
> > > |The error occures after a lot of calls; it reminds me the
> > > |behaviour of a stack overflow, or something.
> > >
> > > Show us whole program, if possible, to reproduce your error.
> >
> > I will try, but it is a little bit hard because the C func is called
> > from a C++ method deeply inside a complex inheritance tree.
> >
> > Things that I can verify now are:
> >
> > (a) The C func is called with no problem 8000 times.
> > (b) The C func is called for 3000+ and segfaults if I put a
> >     simple rb_warn() inside. Ruby 1.8.0
> > (c) The C func is called for 6000+ and segfaults if I put a
> >     simple rb_warn() inside. Ruby 1.8.1 preview 3.
>
> Okay, it is my fault. :-(
>
> While writting a C++ extension for Ruby, I do (almost everywhere):
>
> static VALUE foo_init (...)
> {
>     Foo *f = new Foo();
>     rb_iv_set (self, "__ptr__", (VALUE) f);
>     return self;
> }
>
> static VALUE foo_bar (...)
> {
>     Foo *f = (Foo *) rb_iv_get (self, "__ptr__");
>     f->Bar();
>     return self;
> }
>
> The error ruby reports is on an address of a Foo created pointer.
> If I remove the rb_iv_set() call, ruby executes correctly. But, I
> have to keep the pointer somewhere in order to execute methods of
> the specific class.
>
> Any ideas?
>
> Regards,
> --
> University of Athens			I bet the human brain
> Physics Department				is a kludge --Marvin Minsky
>
>
>

Derek Lewis

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