[Spice-devel] [RFC] server: add main_dispatcher

[Alon Levy]

On Thu, Sep 08, 2011 at 09:31:33AM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> >>simple object system, not unions). Just an idea, could be changed
> >>later perhaps. socketpair is probably fine.
> >
> >First of all I see I forgot to add a mutex, since I said "any non main thread", right
> >now we only have one, so no need to lock, but the idea is that it can also be called from
> >others, and so we will need it later. (unless that write can be considered atomic, but
> >I don't think it can)
> 
> A single write system call is atomic.

ok, I'll add a comment to this effect.

> 
> >To answer your question - infrequently. So I don't want / think we need to invest in
> >optimizing this. Right now the only usage is the channel event (core->channel_event)
> >calls, which have to happen in the main thread, and are currently done also from the
> >worker thread.
> >
> >Thanks for the reference, I'll definitely check it. We already use a single socketpair
> >btw in red_dispatcher, this is a simple copy from there, I didn't actually create a
> >base "dispatcher" class because there are some differences and there isn't that much
> >shared code
> 
> It makes sense to use the same mechanism everythere in spice.

Is this a vote for creating a base/shared struct? but then we have the existing send+ack behavior
that can't be copied because of the mentioned deadlock, so either I make it so it can be used
in both ways, i.e. messaging is left for the user, or what, check for deadlocks?

> 
> We might want to look out for something else, I guess the pipe /
> socketpair isn't exactly the most efficient way to do inter-thread
> communication.  But I don't think that is a bottle-neck in spice,
> there isn't that much communication going on between red_dispatcher
> and red_worker.
> 

So - I was going to send this patch as a PATCH and to 0.8 as well (I have it ready, tested) - is
further work required? do you want to try to create a base class?

> cheers,
>   Gerd
> 
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