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gdbus-codegen: Don't send out PropertiesChanged if value ends up not changing

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A fairly typical pattern is to have code that does

 foo_set_bar (object, "");
 if (some_condition)
   {
     foo_set_bar (object, "yes");
   }

where some_condition is often true every time @object is updated.

With this code, bar is essentially always "yes" but because of how
gdbus-codegen works, useless PropertiesChanged events got scheduled
and sent out. With this patch, we avoid that by always keeping the
original value around and comparing it only when we deem it's time to
send out the ::PropertiesChanged signal (typically in an idle but can
be forced by the user via flush()).

Also add a test case for this.

Signed-off-by: David Zeuthen <davidz@redhat.com>
This commit is contained in:
David Zeuthen
2011-04-15 15:53:28 -04:00
parent cade3cb1da
commit 6bccc46d15
3 changed files with 93 additions and 17 deletions
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49
gio/gdbus-codegen/codegen.py
View File

@@ -96,14 +96,14 @@ class CodeGenerator:
self.c.write('typedef struct\n'
'{\n'
' const _ExtendedGDBusPropertyInfo *info;\n'
' GParamSpec *pspec;\n'
' GValue value;\n'
' guint prop_id;\n'
' GValue orig_value; /* the value before the change */\n'
'} ChangedProperty;\n'
'\n'
'static void\n'
'_changed_property_free (ChangedProperty *data)\n'
'{\n'
' g_value_unset (&data->value);\n'
' g_value_unset (&data->orig_value);\n'
' g_free (data);\n'
'}\n'
'\n')
@@ -1685,6 +1685,18 @@ class CodeGenerator:
self.c.write('}\n'
'\n')
if len(i.properties) > 0:
# if property is already scheduled then re-use entry.. though it could be
# that the user did
#
# foo_set_prop_bar (object, "");
# foo_set_prop_bar (object, "blah");
#
# say, every update... In this case, where nothing happens, we obviously
# don't want a PropertiesChanged() event. We can easily check for this
# by comparing against the _original value_ recorded before the first
# change event. If the latest value is not different from the original
# one, we can simply ignore the ChangedProperty
#
self.c.write('static gboolean\n'
'_%s_emit_changed (gpointer user_data)\n'
'{\n'
@@ -1699,9 +1711,15 @@ class CodeGenerator:
' {\n'
' ChangedProperty *cp = l->data;\n'
' GVariant *variant;\n'
' variant = g_dbus_gvalue_to_gvariant (&cp->value, G_VARIANT_TYPE (cp->info->parent_struct.signature));\n'
' g_variant_builder_add (&builder, "{sv}", cp->info->parent_struct.name, variant);\n'
' g_variant_unref (variant);\n'
' const GValue *cur_value;\n'
'\n'
' cur_value = &skeleton->priv->properties->values[cp->prop_id - 1];\n'
' if (!_g_value_equal (cur_value, &cp->orig_value))\n'
' {\n'
' variant = g_dbus_gvalue_to_gvariant (cur_value, G_VARIANT_TYPE (cp->info->parent_struct.signature));\n'
' g_variant_builder_add (&builder, "{sv}", cp->info->parent_struct.name, variant);\n'
' g_variant_unref (variant);\n'
' }\n'
' }\n'
' g_dbus_connection_emit_signal (g_dbus_interface_skeleton_get_connection (G_DBUS_INTERFACE_SKELETON (skeleton)),\n'
' NULL, g_dbus_interface_skeleton_get_object_path (G_DBUS_INTERFACE_SKELETON (skeleton)),\n'
@@ -1719,9 +1737,8 @@ class CodeGenerator:
self.c.write(' return FALSE;\n'
'}\n'
'\n')
# if property is already scheduled then re-use entry
self.c.write('static void\n'
'_%s_schedule_emit_changed (%sSkeleton *skeleton, const _ExtendedGDBusPropertyInfo *info, GParamSpec *pspec, const GValue *value)\n'
'_%s_schedule_emit_changed (%sSkeleton *skeleton, const _ExtendedGDBusPropertyInfo *info, guint prop_id, const GValue *orig_value)\n'
'{\n'
' ChangedProperty *cp;\n'
' GList *l;\n'
@@ -1732,19 +1749,19 @@ class CodeGenerator:
' if (i_cp->info == info)\n'
' {\n'
' cp = i_cp;\n'
' g_value_unset (&cp->value);\n'
' break;\n'
' }\n'
' }\n'
' if (cp == NULL)\n'
%(i.name_lower, i.camel_name))
self.c.write(' if (cp == NULL)\n'
' {\n'
' cp = g_new0 (ChangedProperty, 1);\n'
' cp->pspec = pspec;\n'
' cp->prop_id = prop_id;\n'
' cp->info = info;\n'
' skeleton->priv->changed_properties = g_list_prepend (skeleton->priv->changed_properties, cp);\n'
' g_value_init (&cp->orig_value, G_VALUE_TYPE (orig_value));\n'
' g_value_copy (orig_value, &cp->orig_value);\n'
' }\n'
' g_value_init (&cp->value, G_VALUE_TYPE (value));\n'
' g_value_copy (value, &cp->value);\n'
' if (skeleton->priv->changed_properties_idle_source == NULL)\n'
' {\n'
' skeleton->priv->changed_properties_idle_source = g_idle_source_new ();\n'
@@ -1755,7 +1772,7 @@ class CodeGenerator:
' }\n'
'}\n'
'\n'
%(i.name_lower, i.camel_name, i.name_lower))
%(i.name_lower))
self.c.write('static void\n'
'%s_skeleton_set_property (GObject *object,\n'
' guint prop_id,\n'
@@ -1767,10 +1784,10 @@ class CodeGenerator:
' g_assert (prop_id - 1 >= 0 && prop_id - 1 < %d);\n'
' if (!_g_value_equal (value, &skeleton->priv->properties->values[prop_id - 1]))\n'
' {\n'
' if (g_dbus_interface_skeleton_get_connection (G_DBUS_INTERFACE_SKELETON (skeleton)) != NULL)\n'
' _%s_schedule_emit_changed (skeleton, _%s_property_info_pointers[prop_id - 1], prop_id, &skeleton->priv->properties->values[prop_id - 1]);\n'
' g_value_copy (value, &skeleton->priv->properties->values[prop_id - 1]);\n'
' g_object_notify_by_pspec (object, pspec);\n'
' if (g_dbus_interface_skeleton_get_connection (G_DBUS_INTERFACE_SKELETON (skeleton)) != NULL)\n'
' _%s_schedule_emit_changed (skeleton, _%s_property_info_pointers[prop_id - 1], pspec, value);\n'
' }\n'
%(i.camel_name, i.ns_upper, i.name_upper, len(i.properties), i.name_lower, i.name_lower))
self.c.write('}\n'