Re: [PATCH 1/3] jackaudio: use ifdefs to hide unavailable functions

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Sonntag, 26. Dezember 2021 16:40:15 CET Volker Rümelin wrote:
> On Windows the jack_set_thread_creator() function and on MacOS the
> pthread_setname_np() function with a thread pointer paramater is
> not available. Use #ifdefs to remove the jack_set_thread_creator()
> function call and the qjack_thread_creator() function in both
> cases.
> 
> The qjack_thread_creator() function just sets the name of the
> created thread for debugging purposes and isn't really necessary.

As far as Windows is concerned, right, there is no jack_set_thread_creator().

I find it actually very useful to have named threads for debugging purposes, 
especially for processes that have a load of threads, but I see there would be 
no easy solution to preserve this for macOS, as on macOS pthread_setname_np() 
must be called from the to be named thread itself, and the thread's entry 
point is on JACK server side, so for now ...

Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

> From the jack_set_thread_creator() documentation:
> (...)
> 
> No normal application/client should consider calling this. (...)
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/785
> Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
> ---
>  audio/jackaudio.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/audio/jackaudio.c b/audio/jackaudio.c
> index e7de6d5433..317009e936 100644
> --- a/audio/jackaudio.c
> +++ b/audio/jackaudio.c
> @@ -622,6 +622,7 @@ static void qjack_enable_in(HWVoiceIn *hw, bool enable)
>      ji->c.enabled = enable;
>  }
> 
> +#if !defined(WIN32) && defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
>  static int qjack_thread_creator(jack_native_thread_t *thread,
>      const pthread_attr_t *attr, void *(*function)(void *), void *arg)
>  {
> @@ -635,6 +636,7 @@ static int qjack_thread_creator(jack_native_thread_t
> *thread,
> 
>      return ret;
>  }
> +#endif
> 
>  static void *qjack_init(Audiodev *dev)
>  {
> @@ -687,7 +689,9 @@ static void register_audio_jack(void)
>  {
>      qemu_mutex_init(&qjack_shutdown_lock);
>      audio_driver_register(&jack_driver);
> +#if !defined(WIN32) && defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
>      jack_set_thread_creator(qjack_thread_creator);
> +#endif
>      jack_set_error_function(qjack_error);
>      jack_set_info_function(qjack_info);
>  }