malcontent-control: Refactor bus initialisation

Get the system bus higher up in the application, so the same system bus
connection can be shared between different parts of the application if
needed in future.

This also means the synchronous I/O needed to connect to the bus is done
before the application UI is shown, which prevents it unnecessarily
blocking initialisation of the `MctUserControls` widget.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

libmalcontent-ui/user-controls.c

@@ -97,6 +97,7 @@ struct _MctUserControls
   GPermission *permission;  /* (owned) (nullable) */
   gulong permission_allowed_id;
 
+  GDBusConnection *dbus_connection;  /* (owned) */
   GCancellable *cancellable; /* (owned) */
   MctManager   *manager; /* (owned) */
   MctAppFilter *filter; /* (owned) (nullable) */
@@ -149,9 +150,10 @@ typedef enum
   PROP_USER_ACCOUNT_TYPE,
   PROP_USER_LOCALE,
   PROP_USER_DISPLAY_NAME,
+  PROP_DBUS_CONNECTION,
 } MctUserControlsProperty;
 
-static GParamSpec *properties[PROP_USER_DISPLAY_NAME + 1];
+static GParamSpec *properties[PROP_DBUS_CONNECTION + 1];
 
 static const GActionEntry actions[] = {
   { "set-age", on_set_age_action_activated, "u", NULL, NULL, { 0, }}
@@ -718,6 +720,18 @@ list_box_header_func (GtkListBoxRow *row,
 
 /* GObject overrides */
 
+static void
+mct_user_controls_constructed (GObject *object)
+{
+  MctUserControls *self = MCT_USER_CONTROLS (object);
+
+  /* Chain up. */
+  G_OBJECT_CLASS (mct_user_controls_parent_class)->constructed (object);
+
+  g_assert (self->dbus_connection != NULL);
+  self->manager = mct_manager_new (self->dbus_connection);
+}
+
 static void
 mct_user_controls_finalize (GObject *object)
 {
@@ -744,6 +758,7 @@ mct_user_controls_finalize (GObject *object)
 
   g_clear_pointer (&self->filter, mct_app_filter_unref);
   g_clear_object (&self->manager);
+  g_clear_object (&self->dbus_connection);
 
   /* Hopefully we don’t have data loss. */
   g_assert (self->flushed_on_dispose);
@@ -802,6 +817,10 @@ mct_user_controls_get_property (GObject    *object,
       g_value_set_string (value, self->user_display_name);
       break;
 
+    case PROP_DBUS_CONNECTION:
+      g_value_set_object (value, self->dbus_connection);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
     }
@@ -841,6 +860,12 @@ mct_user_controls_set_property (GObject      *object,
       mct_user_controls_set_user_display_name (self, g_value_get_string (value));
       break;
 
+    case PROP_DBUS_CONNECTION:
+      /* Construct only. */
+      g_assert (self->dbus_connection == NULL);
+      self->dbus_connection = g_value_dup_object (value);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
     }
@@ -852,6 +877,7 @@ mct_user_controls_class_init (MctUserControlsClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
+  object_class->constructed = mct_user_controls_constructed;
   object_class->finalize = mct_user_controls_finalize;
   object_class->dispose = mct_user_controls_dispose;
   object_class->get_property = mct_user_controls_get_property;
@@ -958,6 +984,24 @@ mct_user_controls_class_init (MctUserControlsClass *klass)
                            G_PARAM_STATIC_STRINGS |
                            G_PARAM_EXPLICIT_NOTIFY);
 
+  /**
+   * MctUserControls:dbus-connection: (not nullable)
+   *
+   * A connection to the system bus. This will be used for retrieving details
+   * of user accounts, and must be provided at construction time.
+   *
+   * Since: 0.7.0
+   */
+  properties[PROP_DBUS_CONNECTION] =
+      g_param_spec_object ("dbus-connection",
+                           "D-Bus Connection",
+                           "A connection to the system bus.",
+                           G_TYPE_DBUS_CONNECTION,
+                           G_PARAM_READWRITE |
+                           G_PARAM_CONSTRUCT_ONLY |
+                           G_PARAM_STATIC_STRINGS |
+                           G_PARAM_EXPLICIT_NOTIFY);
+
   g_object_class_install_properties (object_class, G_N_ELEMENTS (properties), properties);
 
   gtk_widget_class_set_template_from_resource (widget_class, "/org/freedesktop/MalcontentUi/ui/user-controls.ui");
@@ -987,7 +1031,6 @@ mct_user_controls_class_init (MctUserControlsClass *klass)
 static void
 mct_user_controls_init (MctUserControls *self)
 {
-  g_autoptr(GDBusConnection) system_bus = NULL;
   g_autoptr(GError) error = NULL;
   g_autoptr(GtkCssProvider) provider = NULL;
 
@@ -1007,16 +1050,6 @@ mct_user_controls_init (MctUserControls *self)
 
   self->cancellable = g_cancellable_new ();
 
-  /* FIXME: should become asynchronous */
-  system_bus = g_bus_get_sync (G_BUS_TYPE_SYSTEM, self->cancellable, &error);
-  if (system_bus == NULL)
-    {
-      g_warning ("Error getting system bus while setting up app permissions: %s", error->message);
-      return;
-    }
-
-  self->manager = mct_manager_new (system_bus);
-
   self->action_group = g_simple_action_group_new ();
   g_action_map_add_action_entries (G_ACTION_MAP (self->action_group),
                                    actions,

malcontent-control/application.c

@@ -64,6 +64,7 @@ struct _MctApplication
 
   GCancellable *cancellable;  /* (owned) */
 
+  GDBusConnection *dbus_connection;  /* (owned) */
   ActUserManager *user_manager;  /* (owned) */
 
   GPermission *permission;  /* (owned) */
@@ -125,6 +126,7 @@ mct_application_dispose (GObject *object)
       g_clear_object (&self->permission);
     }
 
+  g_clear_object (&self->dbus_connection);
   g_clear_error (&self->permission_error);
   g_clear_object (&self->cancellable);
 
@@ -161,11 +163,20 @@ mct_application_activate (GApplication *application)
 
       builder = gtk_builder_new ();
 
+      g_assert (self->dbus_connection == NULL);
+      self->dbus_connection = g_bus_get_sync (G_BUS_TYPE_SYSTEM, self->cancellable, &local_error);
+      if (self->dbus_connection == NULL)
+        {
+          g_error ("Error getting system bus: %s", local_error->message);
+          return;
+        }
+
       g_assert (self->user_manager == NULL);
       self->user_manager = g_object_ref (act_user_manager_get_default ());
 
       gtk_builder_set_translation_domain (builder, "malcontent");
       gtk_builder_expose_object (builder, "user_manager", G_OBJECT (self->user_manager));
+      gtk_builder_expose_object (builder, "dbus_connection", G_OBJECT (self->dbus_connection));
 
       gtk_builder_add_from_resource (builder, "/org/freedesktop/MalcontentControl/ui/main.ui", &local_error);
       g_assert (local_error == NULL);

malcontent-control/main.ui

@@ -36,6 +36,7 @@
                   <object class="MctUserControls" id="user_controls">
                     <property name="visible">True</property>
                     <property name="margin">12</property>
+                    <property name="dbus-connection">dbus_connection</property>
                   </object>
                 </child>
               </object>