[Spice-devel] [PATCH 4/9] worker: avoid server hanging when no client are connected.

[Frediano Ziglio]

> 
> I've been staring at this patch for a while and I honestly can't figure out
> how
> this change would avoid the server hanging when no clients are connected.
> Hopefully somebody more perceptive than me can step in and review this one...
> 

As I said I think this patch is moving the problem from client to server
which is IMHO bad.

Frediano

Note: this patch is part of changes we'll merge next year

> 
> On Wed, 2015-12-09 at 12:17 +0000, Frediano Ziglio wrote:
> > From: Marc-André Lureau <marcandre.lureau at gmail.com>
> > 
> > ---
> >  server/red-worker.c | 27 ++++++++++++++++++---------
> >  1 file changed, 18 insertions(+), 9 deletions(-)
> > 
> > diff --git a/server/red-worker.c b/server/red-worker.c
> > index 9f2aba1..a57301c 100644
> > --- a/server/red-worker.c
> > +++ b/server/red-worker.c
> > @@ -227,7 +227,6 @@ static int red_process_display(RedWorker *worker,
> > uint32_t
> > max_pipe_size, int *r
> >  {
> >      QXLCommandExt ext_cmd;
> >      int n = 0;
> > -    uint64_t start = red_get_monotonic_time();
> >  
> >      if (!worker->running) {
> >          *ring_is_empty = TRUE;
> > @@ -236,8 +235,23 @@ static int red_process_display(RedWorker *worker,
> > uint32_t max_pipe_size, int *r
> >  
> >      worker->process_display_generation++;
> >      *ring_is_empty = FALSE;
> > -    while (!display_is_connected(worker) ||
> > -           red_channel_max_pipe_size(RED_CHANNEL(worker->display_channel))
> > <=
> > max_pipe_size) {
> > +    for (;;) {
> > +
> > +        if (display_is_connected(worker)) {
> > +
> > +            if (red_channel_all_blocked(RED_CHANNEL(worker
> > ->display_channel))) {
> > +                spice_info("all display clients are blocking");
> > +                return n;
> > +            }
> > +
> > +
> > +            // TODO: change to average pipe size?
> > +            if (red_channel_max_pipe_size(RED_CHANNEL(worker
> > ->display_channel)) > max_pipe_size) {
> > +                spice_info("too many items in the display clients pipe
> > already");
> > +                return n;
> > +            }
> > +        }
> > +
> >          if (!worker->qxl->st->qif->get_command(worker->qxl, &ext_cmd)) {
> >              *ring_is_empty = TRUE;;
> >              if (worker->display_poll_tries < CMD_RING_POLL_RETRIES) {
> > @@ -327,13 +341,8 @@ static int red_process_display(RedWorker *worker,
> > uint32_t max_pipe_size, int *r
> >              spice_error("bad command type");
> >          }
> >          n++;
> > -        if ((worker->display_channel &&
> > -
> > red_channel_all_blocked(&worker->display_channel->common.base))
> > -            || red_get_monotonic_time() - start > 10 * 1000 * 1000) {
> > -            worker->event_timeout = 0;
> > -            return n;
> > -        }
> >      }
> > +
> >      return n;
> >  }
> >  
>