[PD-dev] Improving PD for multi-instances and multithreading.

[Miller Puckette]

HI Pierre -

Maybe I'm missing something but I don't think this would work.  Objects like
pipe and makenote call clock_new on teh fly (and I can't see how to get pd_this
to them safely).

cheers
Miller

On Thu, Sep 10, 2015 at 11:22:47AM +0200, Pierre Guillot wrote:
> Since few weeks, I work on a plugin that dynamically loads Pure Data
> patches, creates a GUI depending on the graphical objects of the patch and
> retrieves their parameters to link them with the automation system of the
> host. Everything works fine, but I had some issues to manage several PD
> instances with multiple threads (pdlib doesn't manage multiple instances).
> 
> I made my own implementation that solved the problem and I found 2 small
> things that could really improve the development of applications with Pure
> Data.
> 
> I try to explain :
> The main problem isn't the loading of patches that can be managed using
> locks but  running the pacthes in parallele. For what I've seen, attack
> ships on fire off the shoulder of Orion... sorry I digress. For what I've
> seen, there are only 2 things that cause problems : the dsp chains and the
> clocks. Here my solutions :
> 
> 1 - "t_pdinstance*" in the prototypes of the functions "sched_tick()" and
>  "dsp_tick()". This way, we don't need to call "pd_setinstance" at each dsp
> tick so it is thread safe.
> (we could have something like "pdinstance_sched_tick(t_pdinstance* x)" and
> "pdinstance_dsp_tick(t_pdinstance* x)" to ensure the good working of
> previous applications)
> 
> 2 -  "t_pdinstance*" in the structure of the clock. All the clock_new
> functions seem to be called in the "creation" methods of the objects. If
> when we load a patch and we create objects, "pd_this" is well defined, we
> can initialize the reference "t_pdinstance*" of the clock with "pd_this"
> and later when we'll call "clock_set" the clock will use its reference
> instead of "pd_this". In this case, imagine that we send a  bang to a
> [delay] in one instance during the loading of a pacth in another instance,
> even if "pd_this" is not the good one, the clock will be added to the
> clocks list of its instance.
> 
> For the moment, I don't use this updates (I manage everything with locks)
> because I want to be compatible with future versions of Pure Data. But if
> you think that can be a good thing, I can submit the code. Can I use GitHub
> for this ?
> 
> Cheers

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