[PATCH] window: Don't needlessly sync parent and geometry

[Ondřej Majerech]

On Sun, 14 Sep 2014 13:52:21 +0100
Daniel Stone <daniel at fooishbar.org> wrote:

> Hi,
> 
> On 13 September 2014 15:35, Ondřej Majerech <majerech.o at gmail.com>
> wrote:
> 
> > When a toytoolkit client redraws, the toolkit syncs the parent and
> > geometry. If a client redraws often (such as the terminal drawing a
> > huge amount of output), this can spam the compositor with requests
> > and may result in the client's eventual being killed.
> >
> > We don't need to send requests for changing the geometry or parent
> > if these haven't changed. So remember the last geometry and parent,
> > and update them only if needed.
> >
> 
> It looked from weston-terminal output like these happened completely
> unbounded by the frame callback; should these instead be moved
> somewhere where the requests are only issued once per frame,
> regardless of how many times they change in between?

Yes, throttling seems to be the way to go, judging from the dicussion
on IRC.

Only problem is that, so far as I can tell, idle_redraw (which is where
these two requests are indirectly sent from in this scenario) is a
place that is supposed to only be called at most once per frame. 

terminal.c seems to call window_schedule_redraw whenever it receives
and processes a chunk of data from the tty. So maybe we should make
window_schedule_redraw actually schedule a redraw for when the current
frame has been finished?

~ Ondra