Re: AOO plugin for PD on SGI Irix

> All works now,
Great!

> I love clean solutions!
Me too :)

In the next AOO version I might use sync::shared_spinlock for the update 
lock resp. provide a compile time option to choose between mutex and 
spinlock. The reason is that a mutex try-lock is not guaranteed to be 
realtime safe because the *unlock* operation might have to wake up 
waiting threads, which requires calling into the kernel.

(In practice, I think unlocking a mutex should be comparable to 
signalling a semaphore, which is a pretty common thing in audio apps. 
Nevertheless, I want to give people a 100% realtime safe option.)

Christof

On 8/13/2026 5:27 PM, Wolfgang Gaggl via Pd-list wrote:
>>> As I said, you just need to replace the shared_mutex with a shared_spinlock.
> Yes, that was the best solution all along!
>
> In sink.hpp
> #if defined(__sgi) && defined(__mips__)
> using sink_update_lock = sync::shared_spinlock;
> #else
> using sink_update_lock = sync::shared_mutex;
> #endif
> And further down:
> private:
>      using shared_lock = sync::shared_lock<sink_update_lock>; // sink_update_lock, not shared_mutex
>      using unique_lock = sync::unique_lock<sink_update_lock>;
>      using scoped_lock = sync::scoped_lock<sink_update_lock>;
>      using scoped_shared_lock = sync::scoped_shared_lock<sink_update_lock>;
>
> In source.hpp
> #if defined(__sgi) && defined(__mips__)
> using source_update_lock = sync::shared_spinlock;
> #else
> using source_update_lock = sync::shared_mutex;
> #endif
> and further down:
>   private:
>      using shared_lock = sync::shared_lock<source_update_lock>;  // source_update_lock, not shared_mutex
>      using unique_lock = sync::unique_lock<source_update_lock>;
>      using scoped_lock = sync::scoped_lock<source_update_lock>;
>      using scoped_shared_lock = sync::scoped_shared_lock<source_update_lock>;
>      using scoped_spinlock = sync::scoped_lock<sync::spinlock>;
>
> Or maybe just once in sync.hpp...
>
> No changes in source.cpp or sink.cpp needed (even the try_to_lock works fine as is).
>
> All works now, I love clean solutions!
>
> Thank you!
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