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List:       kfm-devel
Subject:    Re: KJS crashes
From:       Harri Porten <porten () trolltech ! com>
Date:       2001-08-01 11:10:10
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On Wed, 1 Aug 2001, Dirk Mueller wrote:

> On Die, 31 Jul 2001, Dirk Mueller wrote:
> 
> > > This patch should fix the problem.
> > The patch makes obviously sense, please apply (calling a virtual method 
> > without a full constructor run before can't work).  
> 
> Actually, after having slept a night over it I don't understand anymore why 
> it is supposed to work.

Heh. Now *I* don't feel so stupid anymore :) There is no "virtual method"
involved as far as I see it btw.

> I think "new Classname" is an atomic operation ?
> how can there be another allocation before the constructor ran ?
> 
> Isn't the actual problem that we allocate another Imp derivative during 
> executing an Imp derived constructor ?

That certainly happens in many cases but I don't understand why this
causes a problem. The crash happened in the memory managment but the
allocation is done before the respective ctor is run. And why didn't the
following code in Collector::allocate() already help if there is a
problem with the gc ?

 // hack to ensure obj is protected from GC before any constructors are
run
  // (prev = marked, next = gcallowed)
  static_cast<Imp*>(m)->prev = 0;
  static_cast<Imp*>(m)->next = 0;

Harri (happy that a crash is gone but curious to know what is was about)

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