[Qemu-devel] [RFC] qom: Sorted class enumeration

[Qemu-devel] [RFC] qom: Sorted class enumeration

[Andreas Färber]

Hello,

For listing registered CPU classes I needed a way to sort classes in a
custom (i.e., non-hashtable) order. I found it easiest to sort the classes
using the existing foreach infrastructure, on the go via GLib's binary tree.

Patch is still missing documentation, but do you think this is the right
direction, Anthony?

I've been wondering if it might make sense to replace the current filtering
mechanism (abstract and type) with another callback function or whether that
would be overkill - currently the only other filtering I needed to do was
to ignore the "host" CPU class, which can be done by simple if in the callback.

Regards,
Andreas

Andreas Färber (1):
  qom: Introduce object_class_foreach_ordered()

 include/qemu/object.h |    6 ++++++
 qom/object.c          |   43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 0 deletions(-)

-- 
1.7.7

[Qemu-devel] [PATCH RFC] qom: Introduce object_class_foreach_ordered()

[Andreas Färber]

This functions allows to walk the classes in a custom order rather than
in hashtable order.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: Peter Maydell <peter.maydell@linaro.org>
---
 include/qemu/object.h |    6 ++++++
 qom/object.c          |   43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 0 deletions(-)

diff --git a/include/qemu/object.h b/include/qemu/object.h
index 5179c0c..ab3597a 100644
--- a/include/qemu/object.h
+++ b/include/qemu/object.h
@@ -560,6 +560,12 @@ ObjectClass *object_class_by_name(const char *typename);
 void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
                           const char *implements_type, bool include_abstract,
                           void *opaque);
+
+void object_class_foreach_ordered(void (*fn)(ObjectClass *klass, void *opaque),
+                                  const char *implements_type,
+                                  bool include_abstract, void *opaque,
+                                  GCompareFunc compfn);
+
 /**
  * object_ref:
  * @obj: the object
diff --git a/qom/object.c b/qom/object.c
index 2f05ca8..dbfd6a4 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -570,6 +570,49 @@ void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
     g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, &data);
 }
 
+typedef struct OCFSData {
+    void (*fn)(ObjectClass *klass, void *opaque);
+    void *opaque;
+    GTree *classes;
+} OCFSData;
+
+static void object_class_foreach_ordered_sort(ObjectClass *klass,
+                                              void *opaque)
+{
+    OCFSData *data = opaque;
+
+    g_tree_insert(data->classes, klass, NULL);
+}
+
+static gboolean object_class_foreach_ordered_tramp(gpointer key,
+                                                   gpointer value,
+                                                   gpointer data)
+{
+    ObjectClass *klass = key;
+    OCFSData *d = data;
+
+    d->fn(klass, d->opaque);
+
+    return FALSE;
+}
+
+void object_class_foreach_ordered(void (*fn)(ObjectClass *klass, void *opaque),
+                                  const char *implements_type,
+                                  bool include_abstract, void *opaque,
+                                  GCompareFunc compfn)
+{
+    OCFSData data = {
+        .fn = fn,
+        .opaque = opaque,
+    };
+
+    data.classes = g_tree_new(compfn);
+    object_class_foreach(object_class_foreach_ordered_sort,
+                         implements_type, include_abstract, &data);
+    g_tree_foreach(data.classes, object_class_foreach_ordered_tramp, &data);
+    g_tree_destroy(data.classes);
+}
+
 void object_ref(Object *obj)
 {
     obj->ref++;
-- 
1.7.7

Re: [Qemu-devel] [RFC] qom: Sorted class enumeration

[Anthony Liguori]

On 02/22/2012 03:44 AM, Andreas Färber wrote:
> Hello,
>
> For listing registered CPU classes I needed a way to sort classes in a
> custom (i.e., non-hashtable) order. I found it easiest to sort the classes
> using the existing foreach infrastructure, on the go via GLib's binary tree.
>
> Patch is still missing documentation, but do you think this is the right
> direction, Anthony?

I think it might be better to have an object_class_search() function that acts 
like object_class_foreach() but returns a GSList.  You can then call 
g_list_sort() on the resulting data structure.

> I've been wondering if it might make sense to replace the current filtering
> mechanism (abstract and type) with another callback function or whether that
> would be overkill - currently the only other filtering I needed to do was
> to ignore the "host" CPU class, which can be done by simple if in the callback.

I'd prefer not to do callbacks because this interface gets exposed via QMP and 
callbacks can't be modeled via QMP.

Regards,

Anthony Liguori

>
> Regards,
> Andreas
>
> Andreas Färber (1):
>    qom: Introduce object_class_foreach_ordered()
>
>   include/qemu/object.h |    6 ++++++
>   qom/object.c          |   43 +++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 49 insertions(+), 0 deletions(-)
>