Re: D-Bus

[Alexander Larsson <alexl redhat com>]

On 3 Mar 2003, Michael Meeks wrote:

> 	Nonetheless - these comments are particularly egregious:
> 
> On Fri, 2003-02-28 at 18:05, Havoc Pennington wrote:
> > Also, there are a couple of serious problems with our current IPC
> > setup (uncontrolled reentrancy and refcount-based lifecycle) that are
> > not really fixable without ABI breakage.
> 
> 	I do believe you're talking rubbish again. But for the fact that you
> have a vested interest to do so I'd believe that was just an error:
> 
> 	So - you're idea for 'fixing' the 'uncontrollable' re-enterancy is to
> queue everything until idle: well, that's really tough to do. If -
> instead of re-writing this stuff in GConf / nautilus / etc. people had
> bothered to do the right thing and implement a 'delay till idle' POA
> policy - this would have been trivially fixed once. It's a comparatively
> tiny amount of API addition.

A 'delay till idle' POA policy, should such a beast be written, can't be 
introduced without a great amount of care. Its very easy to get a 
back-call which means you will deadlock with a 'delay till idle' policy, 
since outgoing CORBA calls are blocking. 

Furthermore the Bonobo APIs have one global POA used by all BonoboObjects, 
so having several types of POAs in gnome is very hard.

You are the maintainer and main proponent of Bonobo. Why haven't you 
fixed this, if you say it is so easy? I know we pointed this problem out 
for you a long time ago, and we even discussed this recently and you 
seemed to understand that it is a problem[1].

> 	As for the lifecycle issue - you can do connection lifetime based
> lifecycle already, and produce a reliable daemon / bus that doesn't use
> reference counting with the existing infrastructure.

Yes, it is true that by using ORBit-specific non-CORBA functionallity you 
can in fact get connection-based lifetime handling for a simple 
daemon-style setup (such as a message bus). However, it is much less 
useful when handling for instance embedded UI components, or any other 
case where object ownership is "interesting". 

[1] http://mail.gnome.org/archives/gnome-vfs-list/2002-December/msg00053.html

-- 
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 Alexander Larsson                                            Red Hat, Inc 
                   alexl redhat com    alla lysator liu se 
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