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Re: [Qemu-devel] [PATCH 1/9] qom/user-creatable: add a few helper macros
From: |
Igor Mammedov |
Subject: |
Re: [Qemu-devel] [PATCH 1/9] qom/user-creatable: add a few helper macros |
Date: |
Mon, 29 Oct 2018 10:56:57 +0100 |
On Fri, 26 Oct 2018 12:13:21 -0300
Eduardo Habkost <address@hidden> wrote:
> On Mon, Oct 22, 2018 at 03:33:30PM +0100, Igor Mammedov wrote:
> > On Wed, 12 Sep 2018 16:55:23 +0400
> > Marc-André Lureau <address@hidden> wrote:
> >
> > > Improve a bit code readability.
> > >
> > > Signed-off-by: Marc-André Lureau <address@hidden>
> > > ---
> > > include/qom/object_interfaces.h | 4 ++++
> > > qom/object.c | 4 ++--
> > > qom/object_interfaces.c | 9 +++------
> > > 3 files changed, 9 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/include/qom/object_interfaces.h
> > > b/include/qom/object_interfaces.h
> > > index 4d513fb329..46b0861457 100644
> > > --- a/include/qom/object_interfaces.h
> > > +++ b/include/qom/object_interfaces.h
> > > @@ -9,9 +9,13 @@
> > > #define USER_CREATABLE_CLASS(klass) \
> > > OBJECT_CLASS_CHECK(UserCreatableClass, (klass), \
> > > TYPE_USER_CREATABLE)
> > > +#define IS_USER_CREATABLE_CLASS(klass) \
> > > + object_class_dynamic_cast(OBJECT_CLASS(oc), TYPE_USER_CREATABLE)
> > > #define USER_CREATABLE_GET_CLASS(obj) \
> > > OBJECT_GET_CLASS(UserCreatableClass, (obj), \
> > > TYPE_USER_CREATABLE)
> > > +#define IS_USER_CREATABLE(obj) \
> > > + object_dynamic_cast(OBJECT(obj), TYPE_USER_CREATABLE)
> > > #define USER_CREATABLE(obj) \
> > > INTERFACE_CHECK(UserCreatable, (obj), \
> > > TYPE_USER_CREATABLE)
> > > diff --git a/qom/object.c b/qom/object.c
> > > index 75d1d48944..0703e8e4ff 100644
> > > --- a/qom/object.c
> > > +++ b/qom/object.c
> > > @@ -424,7 +424,7 @@ void object_initialize_childv(Object *parentobj,
> > > const char *propname,
> > > goto out;
> > > }
> > >
> > > - if (object_dynamic_cast(obj, TYPE_USER_CREATABLE)) {
> > > + if (IS_USER_CREATABLE(obj)) {
> > > user_creatable_complete(obj, &local_err);
> > > if (local_err) {
> > > object_unparent(obj);
> > > @@ -605,7 +605,7 @@ Object *object_new_with_propv(const char *typename,
> > > goto error;
> > > }
> > >
> > > - if (object_dynamic_cast(obj, TYPE_USER_CREATABLE)) {
> > > + if (IS_USER_CREATABLE(obj)) {
> > > user_creatable_complete(obj, &local_err);
> > > if (local_err) {
> > > object_unparent(obj);
> > > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
> > > index 72b97a8bed..e3084bc04a 100644
> > > --- a/qom/object_interfaces.c
> > > +++ b/qom/object_interfaces.c
> > > @@ -10,18 +10,15 @@
> > >
> > > void user_creatable_complete(Object *obj, Error **errp)
> > > {
> > > -
> > > UserCreatableClass *ucc;
> > > - UserCreatable *uc =
> > > - (UserCreatable *)object_dynamic_cast(obj, TYPE_USER_CREATABLE);
> > >
> > > - if (!uc) {
> > > + if (!IS_USER_CREATABLE(obj)) {
> > > return;
> > > }
> > >
> > > - ucc = USER_CREATABLE_GET_CLASS(uc);
> > > + ucc = USER_CREATABLE_GET_CLASS(obj);
> > > if (ucc->complete) {
> > > - ucc->complete(uc, errp);
> > > + ucc->complete(USER_CREATABLE(obj), errp);
> > ^^^
> > even though function becomes more concise,
> > this will call expensive dynamic cast 2nd time (IS_USER_CREATABLE was the
> > 1st and discarded)
> > so I'm not sure is a good idea to regress startup time for readability.
>
> (INTERFACE_CHECK is a nop if CONFIG_QOM_CAST_DEBUG is not
> enabled, so I don't understand how it would regress startup time.
Isn't it enabled by default though?
Maybe we should flip default to disabled then cast should be ok and enable it
when generic '--debug' is enabled.