Re: [PATCH 4/6] qom: Add object_child_foreach_type() helper function

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Oct 24, 2019 at 01:59:03PM +1100, David Gibson wrote:
> On Wed, Oct 23, 2019 at 04:52:16PM +0200, Greg Kurz wrote:
> > Calling a function for children of a certain type is a recurring pattern
> > in the QEMU code base. In order to avoid the need to setup the same boiler
> > plate again and again, introduce a variant of object_child_foreach() that
> > only considers children of the given type.
> > 
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Actually.. a couuple of caveats on that.

Reading it again the name is potentially misleading it's "for each
object of given type" not "for each type"  So maybe
"object_child_foreach_of_type()".

Also, having created these, using them to simplify hmp_info_irq() and
hmp_info_pic() seems like a good idea.

> 
> > ---
> >  include/qom/object.h |   35 +++++++++++++++++++++++++++++++++++
> >  qom/object.c         |   30 +++++++++++++++++++++++-------
> >  2 files changed, 58 insertions(+), 7 deletions(-)
> > 
> > diff --git a/include/qom/object.h b/include/qom/object.h
> > index 128d00c77fd6..e9e3c2eae8ed 100644
> > --- a/include/qom/object.h
> > +++ b/include/qom/object.h
> > @@ -1728,6 +1728,41 @@ int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
> >  int object_child_foreach_recursive(Object *obj,
> >                                     int (*fn)(Object *child, void *opaque),
> >                                     void *opaque);
> > +
> > +/**
> > + * object_child_foreach_type:
> > + * @obj: the object whose children will be navigated
> > + * @typename: the type of child objects to consider
> > + * @fn: the iterator function to be called
> > + * @opaque: an opaque value that will be passed to the iterator
> > + *
> > + * This is similar to object_child_foreach, but it only calls @fn for
> > + * child objects of the give @typename.
> > + *
> > + * Returns: The last value returned by @fn, or 0 if there is no child of
> > + * the given @typename.
> > + */
> > +int object_child_foreach_type(Object *obj, const char *typename,
> > +                              int (*fn)(Object *child, void *opaque),
> > +                              void *opaque);
> > +
> > +/**
> > + * object_child_foreach_recursive_type:
> > + * @obj: the object whose children will be navigated
> > + * @typename: the type of child objects to consider
> > + * @fn: the iterator function to be called
> > + * @opaque: an opaque value that will be passed to the iterator
> > + *
> > + * This is similar to object_child_foreach_recursive, but it only calls
> > + * @fn for child objects of the give @typename.
> > + *
> > + * Returns: The last value returned by @fn, or 0 if there is no child of
> > + * the given @typename.
> > + */
> > +int object_child_foreach_recursive_type(Object *obj, const char *typename,
> > +                                        int (*fn)(Object *child, void *opaque),
> > +                                        void *opaque);
> > +
> >  /**
> >   * container_get:
> >   * @root: root of the #path, e.g., object_get_root()
> > diff --git a/qom/object.c b/qom/object.c
> > index 6fa9c619fac4..a2dec1261ff7 100644
> > --- a/qom/object.c
> > +++ b/qom/object.c
> > @@ -986,7 +986,7 @@ void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
> >      enumerating_types = false;
> >  }
> >  
> > -static int do_object_child_foreach(Object *obj,
> > +static int do_object_child_foreach(Object *obj, const char *typename,
> >                                     int (*fn)(Object *child, void *opaque),
> >                                     void *opaque, bool recurse)
> >  {
> > @@ -999,12 +999,14 @@ static int do_object_child_foreach(Object *obj,
> >          if (object_property_is_child(prop)) {
> >              Object *child = prop->opaque;
> >  
> > -            ret = fn(child, opaque);
> > -            if (ret != 0) {
> > -                break;
> > +            if (!typename || object_dynamic_cast(child, typename)) {
> > +                ret = fn(child, opaque);
> > +                if (ret != 0) {
> > +                    break;
> > +                }
> >              }
> >              if (recurse) {
> > -                do_object_child_foreach(child, fn, opaque, true);
> > +                do_object_child_foreach(child, typename, fn, opaque, true);
> >              }
> >          }
> >      }
> > @@ -1014,14 +1016,28 @@ static int do_object_child_foreach(Object *obj,
> >  int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
> >                           void *opaque)
> >  {
> > -    return do_object_child_foreach(obj, fn, opaque, false);
> > +    return do_object_child_foreach(obj, NULL, fn, opaque, false);
> >  }
> >  
> >  int object_child_foreach_recursive(Object *obj,
> >                                     int (*fn)(Object *child, void *opaque),
> >                                     void *opaque)
> >  {
> > -    return do_object_child_foreach(obj, fn, opaque, true);
> > +    return do_object_child_foreach(obj, NULL, fn, opaque, true);
> > +}
> > +
> > +int object_child_foreach_type(Object *obj, const char *typename,
> > +                              int (*fn)(Object *child, void *opaque),
> > +                              void *opaque)
> > +{
> > +    return do_object_child_foreach(obj, typename, fn, opaque, false);
> > +}
> > +
> > +int object_child_foreach_recursive_type(Object *obj, const char *typename,
> > +                                        int (*fn)(Object *child, void *opaque),
> > +                                        void *opaque)
> > +{
> > +    return do_object_child_foreach(obj, typename, fn, opaque, true);
> >  }
> >  
> >  static void object_class_get_list_tramp(ObjectClass *klass, void *opaque)
> > 
> 



-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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