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

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

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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>

> ---
>  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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