Re: [Qemu-devel] [PATCH 2/9] qom: add object_property_add_unnamed_child

[Paolo Bonzini <pbonzini@redhat.com>]

Il 03/05/2013 18:03, Michael Roth ha scritto:
> This interface allows us to add a child property without specifying a
> name. Instead, a unique name is created and passed back after adding
> the property.
> 
> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> ---
>  include/qom/object.h |   16 ++++++++++++++++
>  qom/object.c         |   25 +++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/include/qom/object.h b/include/qom/object.h
> index 86f1e2e..ca0fce8 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -1041,6 +1041,22 @@ void object_property_add_child(Object *obj, const char *name,
>                                 Object *child, struct Error **errp);
>  
>  /**
> + * object_property_add_unnamed_child:
> + *
> + * @obj: the object to add a property to
> + * @name: the name of the property
> + * @child: the child object
> + * @errp: if an error occurs, a pointer to an area to store the area
> + *
> + * Same as object_property_add_child, but will allocate a unique name to
> + * identify the child property.
> + *
> + * Returns: The name assigned to the child property, or NULL on failure.
> + */
> +char *object_property_add_unnamed_child(Object *obj, Object *child,
> +                                        struct Error **errp);
> +
> +/**
>   * object_property_add_link:
>   * @obj: the object to add a property to
>   * @name: the name of the property
> diff --git a/qom/object.c b/qom/object.c
> index c932f64..229a9a7 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -926,6 +926,31 @@ static void object_finalize_child_property(Object *obj, const char *name,
>      object_unref(child);
>  }
>  
> +char *object_property_add_unnamed_child(Object *obj, Object *child, Error **errp)
> +{
> +    int idx = 0;
> +    bool next_idx_found = false;
> +    char name[64];
> +    ObjectProperty *prop;
> +
> +    while (!next_idx_found) {
> +        sprintf(name, "unnamed[%d]", idx);
> +        QTAILQ_FOREACH(prop, &obj->properties, node) {
> +            if (strcmp(name, prop->name) == 0) {
> +                idx++;
> +                break;
> +            }
> +        }
> +        if (!prop) {
> +            next_idx_found = true;
> +        }
> +    }
> +
> +    object_property_add_child(obj, name, child, errp);
> +
> +    return error_is_set(errp) ? NULL : g_strdup(name);
> +}

This is O(n^3) for adding N children.  O(n^2) would be not-that-great
but fine; can you take the occasion to convert the properties list to a
hashtable?

Paolo

> +
>  void object_property_add_child(Object *obj, const char *name,
>                                 Object *child, Error **errp)
>  {
>