Re: [Qemu-devel] [PATCH] Add 'query-events' command to QMP to query async events

[Anthony Liguori]

On 05/16/2012 11:04 AM, Eric Blake wrote:
> On 05/16/2012 06:55 AM, Daniel P. Berrange wrote:
> > From: "Daniel P. Berrange"<address@hidden>
> >
> > Sometimes it is neccessary for an application to determine
> > whether a particular QMP event is available, so they can
> > decide whether to use compatibility code instead. This
> > introduces a new 'query-events' command to QMP todo just
>
> s/todo/to do/
>
> > that
> >
> >   { "execute": "query-events" }
> >   {"return": [{"name": "WAKEUP"},
> >               {"name": "SUSPEND"},
> >               {"name": "DEVICE_TRAY_MOVED"},
> >               {"name": "BLOCK_JOB_CANCELLED"},
> >               {"name": "BLOCK_JOB_COMPLETED"},
> >               ...snip...
> >               {"name": "SHUTDOWN"}]}
> >
> > * monitor.c: Split out MonitorEvent ->  string conversion
> >    into monitor_protocol_event_name() API. Add impl of
> >    qmp_query_events monitor command handler
> > * qapi-schema.json, qmp-commands.hx: Define contract of
> >    query-events command
>
> Definitely useful for libvirt.
>
>
> > +static const char *monitor_protocol_event_name(MonitorEvent event)
> > +{
> >       switch (event) {
> >           case QEVENT_SHUTDOWN:
> > -            event_name = "SHUTDOWN";
> > +            return "SHUTDOWN";
> >               break;
>
> These 'break' statements are now unreachable; does this matter in qemu
> coding style?

Seems like we should just take the opportunity to kill off the function entirely 
and replace it with a table:

static const char *monitor_event_names[] = {
 [QEVENT_SHUTDOWN] = "SHUTDOWN",
 ...
};

Regards,

Anthony Liguori