Re: [Rubydotnet-developer] GC ideas

[Thomas S. <th...@th...>]

I don't really understand how reference counting is error prone? Speaking 
for my own implementation I use a System.Runtime.InteropServices.GCHandle in 
the ruby-proxy-object to keep the .net object reference. The GCHandle 
mechanism is a reference counting scheme for referencing .net objects 
outside of the .net runtime. Similary, I use  rb_gc_register_address in 
the .net-proxy constructor to tell ruby that there is an external reference 
to that object. I don't see any significant potential for forgetting to 
update the reference count, the major problem is the circular references 
problem. 

Cheers,

Thomas

---------- Original Message -----------
From: Tim Sutherland <ti...@ih...>
To: rub...@li...
Sent: Fri, 9 Jan 2004 00:40:10 +1300
Subject: [Rubydotnet-developer] GC ideas

> Hello. I changed the way I deal with the GC in my rubydotnetproxy
> object. (I haven't uploaded a version using these new changes.)
> 
> I was previously using reference counting[*]. This was error prone 
> and ugly. (It was not easy to be sure that I hadn't made a mistake 
> somewhere.)
> 
> [*] This would all be easy if I had a rule like "for each VALUE, 
> there is at most one RbType wrapping it", but then I couldn't use implicit
> constructors for type conversions.
> 
> Now for .NET calling Ruby:
> 	In .NET I have a collection of weakreferences of RbTypes. (I add
> 	to it whenever a RbType is constructed.)
> 
> 	Whenever Ruby's GC is running, I call rb_gc_mark for each VALUE
> 	where the RbType has not yet been collected. (And remove those
> 	which have been collected.)
> 
> 	In this way, as long as .NET has access to the RbType, Ruby will
> 	not collect the associated VALUE.
> 
> For Ruby calling .NET
> 	In .NET I have a hashtable from .NET OBJ id => object.
> 	
> 	Roughly as often as the .NET GC is run, I create a C array of
> 	OBJs, assign it to a global variable and then rb_gc_start().
> 
> 	My mark_DotNetData() function adds its type_id/instance_id to
> 	the array.
> 
> 	Then I pass this array to .NET and it removes all objects from
> 	the hashtable whose ids don't appear in the array.
> 	
> This still suffers from the circular references memory leak that
> reference counting had.
> 
> BTW: I saw (on a webpage somewhere? I seem to recall it was Thomas')
> someone say they added a feature to allow you to do things like the
> following Ruby
> 	require 'dotnet'
> 
> 	class Foo
> 	end
> 	foo = Foo.new
> 
> 	h = Hashtable.new
> 	h[foo] = 12345
> 
> i.e. have arbitrary Ruby objects as arguments to .NET methods by
> wrapping them up as `.NET wrapper around Ruby object` and unwrapping 
> on the other end.
> 
> This seems like a really great idea. It does raise issues like 
> "should we still convert arguments which are Ruby strings into .NET strings
> automatically. Similarly for integers etc.
> 
> -- 
> Q: What is normed, complete, and yellow?
> A: A Bananach space... 
> 
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------- End of Original Message -------