[PD-dev] long lasting operations

[Miller Puckette]

Sure... just allocate a whole new array in the low priority thread, and
then grab the lock only when you're done and ready to switch the new
array in place of the old one.

cheers
Miller

On Sun, Dec 21, 2003 at 11:51:12AM +0100, Thomas Grill wrote:
> Hi all,
> the other day i had to compare Max and PD again, and it seems that one of
> PDs core weaknesses is the fact that all messaged operations are happening
> synchronously, that is, with no respect whether they'll fit into the
> real-time schedule.
> A good example is soundfiler, where reading and writing of large files is
> done in one piece which inevitable leads to audio cracks.
> In Max for these kind of operations there exists a low-priority message
> queue (using so-called qelems) which can be used to retrigger an operation
> that is executed in chunks. These qelems can also be dropped if they are
> occuring more than once in a queue, or postponed if audio timing needs it.
> This can't really be done equally in PD by using clock_delay as an
> alternative.
> Since PD has a global thread lock now, the other (probably more comfortable)
> way would be to use threading for longer-lasting operations, and i'd really
> like to adapt soundfiler and other objects accordingly.
> The problem with any asynchronous array operation is that there has to be a
> mechanism to avoid concurrent changing of table sizes by two separate
> objects (e.g. when one soundfiler is reading data into the array, another
> one must not resize the same array)... consequently there has to be some
> kind of "array lock" or even a queue of operations scheduled for execution,
> because i don't think that operations should just fail... or are there any
> other ideas how to do it?
> 
> best greetings,
> Thomas
> 
> 
> 
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