[glib/wip/hadess/gapp-restart-data] GApplication: Add RestartData property, and setter

[Bastien Nocera <hadess src gnome org>]

commit e18007fa2fb19ded7a0a29f0f5cac22ff788145d
Author: Bastien Nocera <hadess hadess net>
Date:   Wed Feb 20 01:39:10 2019 +0100

    GApplication: Add RestartData property, and setter
    
    The RestartData property on the org.gtk.Application interface can be
    used by session services to save some data to disk should the
    application disappear.
    
    The application would call g_application_set_restart_data() when the
    state of the application changes, with enough information for the
    application to restart itself in the same "position".
    
    FIXME:
     [ ] API docs
     [ ] note about restart data size
     [ ] have one example implementation of the session side
    
    One idea would be for xdg-desktop-portal to save a stringified
    RestartData to ~/.var/app/$ID/config/state.gvariant if none empty when
    the application disappears from the bus.
    
    Questions:
    - Can we enforce to only do this for unique applications?
    - Can we detect applications leaving the bus suddenly, or do we
      want to rely on them clearing RestartData if they're "done" (or should
      they always save state, *some* state)
    - Should we implement this via org.gnome.SessionManager.Client and the
      app calling out to gnome-session instead?
    - Or is this API fine, and gnome-session can do what xdg-desktop-portal
      does above?

 gio/gapplication.c          | 18 ++++++++++++++++++
 gio/gapplication.h          |  4 ++++
 gio/gapplicationimpl-dbus.c | 20 +++++++++++++++++---
 gio/gapplicationimpl.h      |  2 ++
 4 files changed, 41 insertions(+), 3 deletions(-)
---
diff --git a/gio/gapplication.c b/gio/gapplication.c
index 2d2ab48e3..6cb378d7a 100644
--- a/gio/gapplication.c
+++ b/gio/gapplication.c
@@ -3069,5 +3069,23 @@ g_application_unbind_busy_property (GApplication *application,
   g_signal_handler_disconnect (object, handler_id);
 }
 
+/* Session handling {{{1 */
+
+/**
+ * g_application_set_restart_data:
+ * @application:
+ * @data:
+ *
+ */
+void
+g_application_set_restart_data (GApplication *application,
+                                GVariant     *data)
+{
+  g_return_if_fail (G_IS_APPLICATION (application));
+  g_return_if_fail (!(application->priv->flags & G_APPLICATION_NON_UNIQUE));
+
+  g_application_impl_set_restart_data (application->priv->impl, data);
+}
+
 /* Epilogue {{{1 */
 /* vim:set foldmethod=marker: */
diff --git a/gio/gapplication.h b/gio/gapplication.h
index adc32ed44..489c9125e 100644
--- a/gio/gapplication.h
+++ b/gio/gapplication.h
@@ -229,6 +229,10 @@ void                    g_application_unmark_busy                       (GApplic
 GLIB_AVAILABLE_IN_2_44
 gboolean                g_application_get_is_busy                       (GApplication             
*application);
 
+GLIB_AVAILABLE_IN_2_60
+void                    g_application_set_restart_data                  (GApplication             
*application,
+                                                                         GVariant                 *data);
+
 GLIB_AVAILABLE_IN_2_40
 void                    g_application_send_notification                 (GApplication             
*application,
                                                                          const gchar              *id,
diff --git a/gio/gapplicationimpl-dbus.c b/gio/gapplicationimpl-dbus.c
index 76d67eec8..40a61888a 100644
--- a/gio/gapplicationimpl-dbus.c
+++ b/gio/gapplicationimpl-dbus.c
@@ -66,6 +66,7 @@ static const gchar org_gtk_Application_xml[] =
         "<arg type='i' name='exit-status' direction='out'/>"
       "</method>"
     "<property name='Busy' type='b' access='read'/>"
+    "<property name='RestartData' type='v' access='read'/>"
     "</interface>"
   "</node>";
 
@@ -121,6 +122,7 @@ struct _GApplicationImpl
   gboolean         properties_live;
   gboolean         primary;
   gboolean         busy;
+  GVariant        *restart_data;
   gboolean         registered;
   GApplication    *app;
 };
@@ -149,14 +151,16 @@ g_application_impl_get_property (GDBusConnection *connection,
 }
 
 static void
-send_property_change (GApplicationImpl *impl)
+send_property_change (GApplicationImpl *impl,
+                      const char       *property_name,
+                      GVariant         *value)
 {
   GVariantBuilder builder;
 
   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
   g_variant_builder_add (&builder,
                          "{sv}",
-                         "Busy", g_variant_new_boolean (impl->busy));
+                         property_name, value);
 
   g_dbus_connection_emit_signal (impl->session_bus,
                                  NULL,
@@ -558,10 +562,20 @@ g_application_impl_set_busy_state (GApplicationImpl *impl,
   if (impl->busy != busy)
     {
       impl->busy = busy;
-      send_property_change (impl);
+      send_property_change (impl, "Busy", g_variant_new_boolean (impl->busy));
     }
 }
 
+void
+g_application_impl_set_restart_data (GApplicationImpl *impl,
+                                     GVariant         *variant)
+{
+  g_clear_pointer (&impl->restart_data, g_variant_unref);
+  if (variant)
+    impl->restart_data = g_variant_ref (variant);
+  send_property_change (impl, "RestartData", impl->restart_data);
+}
+
 void
 g_application_impl_destroy (GApplicationImpl *impl)
 {
diff --git a/gio/gapplicationimpl.h b/gio/gapplicationimpl.h
index 1e6a718db..80e93d58a 100644
--- a/gio/gapplicationimpl.h
+++ b/gio/gapplicationimpl.h
@@ -42,3 +42,5 @@ const gchar *           g_application_impl_get_dbus_object_path         (GApplic
 
 void                    g_application_impl_set_busy_state               (GApplicationImpl   *impl,
                                                                          gboolean            busy);
+void                    g_application_impl_set_restart_data             (GApplicationImpl   *impl,
+                                                                         GVariant           *variant);