Re: [Qemu-devel] [PATCH 3/9] qapi: remove error checks for event emission

[Markus Armbruster]

Peter Xu <address@hidden> writes:

> In the whole QAPI event emission code we're passing in an Error* object
> along the whole stack.  That's never useful since it never fails after
> all.  Remove that.
>
> Then, remove that parameter from all the callers to send an event.
>
> Suggested-by: Eric Blake <address@hidden>
> Suggested-by: Markus Armbruster <address@hidden>
> Signed-off-by: Peter Xu <address@hidden>
[...]
> diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
> index 5657524688..3953dc9837 100644
> --- a/scripts/qapi/events.py
> +++ b/scripts/qapi/events.py
> @@ -18,7 +18,7 @@ from qapi.common import *
>  def build_event_send_proto(name, arg_type, boxed):
>      return 'void qapi_event_send_%(c_name)s(%(param)s)' % {
>          'c_name': c_name(name.lower()),
> -        'param': build_params(arg_type, boxed, 'Error **errp')}
> +        'param': build_params(arg_type, boxed, "")}

Use ' instead of " for consistency.

But let's make @extra optional in the previous patch (default it to
None), so this spot becomes simpler.

>  
>  
>  def gen_event_send_decl(name, arg_type, boxed):
> @@ -70,7 +70,6 @@ def gen_event_send(name, arg_type, boxed, event_enum_name):
>  %(proto)s
>  {
>      QDict *qmp;
> -    Error *err = NULL;
>      QMPEventFuncEmit emit;
>  ''',
>                  proto=build_event_send_proto(name, arg_type, boxed))
> @@ -103,45 +102,35 @@ def gen_event_send(name, arg_type, boxed, 
> event_enum_name):
>  ''')
>          if not arg_type.is_implicit():
>              ret += mcgen('''
> -    visit_type_%(c_name)s(v, "%(name)s", &arg, &err);
> +    visit_type_%(c_name)s(v, "%(name)s", &arg, NULL);

&error_abort, please.  This should never fail, and when it does,
something's seriously wrong.

>  ''',
>                           name=name, c_name=arg_type.c_name())
>          else:
>              ret += mcgen('''
>  
> -    visit_start_struct(v, "%(name)s", NULL, 0, &err);
> -    if (err) {
> -        goto out;
> -    }
> -    visit_type_%(c_name)s_members(v, &param, &err);
> -    if (!err) {
> -        visit_check_struct(v, &err);
> -    }
> +    visit_start_struct(v, "%(name)s", NULL, 0, NULL);
> +    visit_type_%(c_name)s_members(v, &param, NULL);
> +    visit_check_struct(v, NULL);

Likewise.

>      visit_end_struct(v, NULL);
>  ''',
>                           name=name, c_name=arg_type.c_name())
>          ret += mcgen('''
> -    if (err) {
> -        goto out;
> -    }
>  
>      visit_complete(v, &obj);
>      qdict_put_obj(qmp, "data", obj);
>  ''')
>  
>      ret += mcgen('''
> -    emit(%(c_enum)s, qmp, &err);
> +    emit(%(c_enum)s, qmp);
>  
>  ''',
>                   c_enum=c_enum_const(event_enum_name, name))
>  
>      if arg_type and not arg_type.is_empty():
>          ret += mcgen('''
> -out:
>      visit_free(v);
>  ''')
>      ret += mcgen('''
> -    error_propagate(errp, err);
>      qobject_unref(qmp);
>  }
>  ''')