[vlc-devel] commit: atmo filter: disable until it is fixed ( Rémi Denis-Courmont )

[Rémi Denis-Courmont]

Le mardi 25 août 2009 17:53:47 git version control, vous avez écrit :
> atmo filter: disable until it is fixed
>
> > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=b59d0081f056925f90
> >e9f5b850f13ad416904617
(...)
>  #if defined(_ATMO_VLC_PLUGIN_)
> +#error This makes no sense!
>     vlc_mutex_lock( &m_WakeupLock );
>     vlc_cond_signal( &m_WakeupCond );
>     vlc_mutex_unlock( &m_WakeupLock );

A thread condition variable is always associated with a piece of state. There 
are no memory access within the lock, so this simply cannot be right. No 
wonder there were deadlocks and race conditions in the waiting thread.

> @@ -173,8 +174,10 @@ DWORD CAtmoExternalCaptureInput::Execute(void) {
>  void CAtmoExternalCaptureInput::WaitForNextFrame(DWORD timeout)
>  {
>      this->m_FrameArrived = ATMO_FALSE;
> +#error m_FrameArrived is not protected (no, volatile does not work)

volatile protects against compiler optimization. However it does not provide 
atomicity nor memory cache flushes.

>      for(DWORD i=0;(i<timeout) && !m_FrameArrived;i++)
>  #if defined (_ATMO_VLC_PLUGIN_)
> +#error A condition variable or a semaphore is needed.
>          msleep(1000);

This is inefficient.

-- 
Rémi Denis-Courmont
http://www.remlab.net/