[Spice-devel] [PATCH spice-server 16/16] red-worker: Start processing commands as soon as possible

[Frediano Ziglio]

> 
> On Mon, Sep 11, 2017 at 04:03:18AM -0400, Frediano Ziglio wrote:
> > ping
> > 
> > > 
> > > When the worker is started it could take a while to start
> > > processing commands.
> > > The reason is that the dispatcher handler is called after
> > > the worker so GLib will receive a FALSE answer to both
> > > prepare and check callbacks of the RedWorkerSource causing
> > > GLib to wait till another event is received.
> 
> So we may have messages from the main thread to the worker thread
> delayed until another (non-dispatching related) event wakes up the glib
> main loop? Or do you mean something else?
> 

Time to write some documentation on terminology.
Both shortlog and message refers to commands, the main thread talk
to the worker thread through messages, not commands.

By the way, yes, quite complicated, I'll add

"Commands (from QXL interface for cursor and display) are processed
during the RedWorkerSource dispatch so if they are not processed
just when the VM is started they will be processed on next event
which could be from dispatcher (main thread requests), from 
existing connections or from pending timers. However in the case there
are no clients connected and no other requests from main thread the
worker thread won't process them."

> If that's correct, maybe makes this a bit more explicit in the log, and
> Acked-by: Christophe Fergeau <cfergeau at redhat.com>
> 
> 
> 
> > > This is a regression since the introduction of GLib event
> > > loop, before the command processing was always attempted
> > > after any events.
> > > Setting the event_timeout to 0 cause the prepare callback
> > > to return TRUE so GLib will dispatch the RedWorkerSource.
> > > This was discovered attempting to use the tests in server/tests
> > > directory to reproduce a leak in RedWorker.
> > > 
> > > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > > ---
> > >  server/red-worker.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/server/red-worker.c b/server/red-worker.c
> > > index 594dec55..c02674ba 100644
> > > --- a/server/red-worker.c
> > > +++ b/server/red-worker.c
> > > @@ -635,6 +635,7 @@ static void handle_dev_start(void *opaque, void
> > > *payload)
> > >          display_channel_wait_for_migrate_data(worker->display_channel);
> > >      }
> > >      worker->running = TRUE;
> > > +    worker->event_timeout = 0;
> > >      guest_set_client_capabilities(worker);
> > >  }
> > >