Re: [PATCH v4 30/34] qapi: Implement deprecated-output=hide for QMP event data

[Eric Blake]

On 3/17/20 6:54 AM, Markus Armbruster wrote:
> This policy suppresses deprecated bits in output, and thus permits
> "testing the future".  Implement it for QMP event data: suppress
> deprecated members.
>
> No QMP event data is deprecated right now.
>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---

> +static void test_event_deprecated_data(TestEventData *data, const void *unused)
> +{
> +    memset(&compat_policy, 0, sizeof(compat_policy));
> +
> +    data->expect = qdict_from_jsonf_nofail("{ 'event': 'TEST-EVENT-FEATURES0',"
> +                                           " 'data': { 'foo': 42 } }");
> +    qapi_event_send_test_event_features0(42);
> +    g_assert(data->emitted);
> +
> +    qobject_unref(data->expect);
> +
> +    compat_policy.deprecated_output = COMPAT_POLICY_OUTPUT_HIDE;

Again, playing fast-and-loose with compat_policy.has_deprecated_output.


> +++ b/scripts/qapi/events.py
> @@ -104,7 +104,7 @@ def gen_event_send(name, arg_type, features, boxed,
>   
>       if have_args:
>           ret += mcgen('''
> -    v = qobject_output_visitor_new(&obj);
> +    v = qobject_output_visitor_new_qmp(&obj);
>   ''')
>           if not arg_type.is_implicit():
>               ret += mcgen('''
> @@ -123,7 +123,11 @@ def gen_event_send(name, arg_type, features, boxed,
>           ret += mcgen('''
>   
>       visit_complete(v, &obj);
> -    qdict_put_obj(qmp, "data", obj);
> +    if (qdict_size(qobject_to(QDict, obj))) {
> +        qdict_put_obj(qmp, "data", obj);
> +    } else {
> +        qobject_unref(obj);
> +    }

So you'd rather omit data altogether than emit "data":{} when all 
deprecated members disappear.  Fair enough; both approaches work.

Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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