[Spice-devel] [PATCH spice] Provide thread safety between spice_server_playback_put_samples and snd_set_playback_latency.

[Jeremy White]

>
> Is this difficult to solve? It seems the thread is reading from a fd and
> pushing to spice server. Couldn't this be done from X main loop?

Yes, that may be possible.  There are some tricks with the timing that 
may make that challenging (e.g. we need to feed audio at regular 
intervals).  I also have the sense that the original implementation was 
done that way, and we changed to this approach for some good reason that 
I can not currently recall :-/.

I will dig a bit deeper and report back.

>
>     This patch uses a mutex to prevent such collisions.
>
>
> Is the mutex supposed to protect the whole SndChannel struct?It seems
> there are various code path that could be called with or without the
> lock held (snd_playback_send callback, for example). I would rather move
> the protected bits into a substructure, and make sure only access is
> made with the lock.

Fair enough; the patch as written was arguably more a proof of concept 
than a full implementation.  It did patch the known risk area, but is 
arguably not fully rigorous.

>
> But I think we are going in a dangerous place if we start making spice
> server MT-safe api

I think that was the key question I was trying to get at.  I see some 
evidence that there has been some effort made, and I wanted to get a 
sense for the longer term plans in this respect.

Cheers,

Jeremy