[gnome-settings-daemon] GsdDeviceMapper: use an async constructor for GnomeRRScreen

[Giovanni Campagna <gcampagna src gnome org>]

commit a73c5903ac45b66d0899610036bdedb5f0ac167e
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Thu Feb 13 23:19:03 2014 +0100

    GsdDeviceMapper: use an async constructor for GnomeRRScreen
    
    GnomeRRScreen depends on mutter, so it cannot be created synchronously,
    because doing so blocks gnome-settings-daemon from registering with
    gnome-session, and thus blocks mutter/gnome-shell from being
    spawned. Which triggers a timeout and fails.
    Instead, do the init asynchronously. We lose the error reporting,
    but in practice the call should never fail. Also, this creates
    a small window of time in which GsdDeviceMapper sees no outputs,
    but that's ok, because we recompute everything when the screen
    is ready.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=724323

 plugins/common/gsd-device-mapper.c |   71 +++++++++++++++---------------------
 1 files changed, 29 insertions(+), 42 deletions(-)
---
diff --git a/plugins/common/gsd-device-mapper.c b/plugins/common/gsd-device-mapper.c
index 5f777f3..0a94e7b 100644
--- a/plugins/common/gsd-device-mapper.c
+++ b/plugins/common/gsd-device-mapper.c
@@ -122,11 +122,7 @@ enum {
 
 static guint signals[N_SIGNALS] = { 0 };
 
-static void gsd_device_mapper_initable_iface_init (GInitableIface *iface);
-
-G_DEFINE_TYPE_WITH_CODE (GsdDeviceMapper, gsd_device_mapper, G_TYPE_OBJECT,
-                        G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
-                                               gsd_device_mapper_initable_iface_init))
+G_DEFINE_TYPE (GsdDeviceMapper, gsd_device_mapper, G_TYPE_OBJECT)
 
 static XDevice *
 open_device (GdkDevice *device)
@@ -192,6 +188,10 @@ find_output_by_edid (GnomeRRScreen *rr_screen,
        GnomeRROutput *retval = NULL;
        guint i;
 
+        /* possible during async initialization */
+       if (rr_screen == NULL)
+               return NULL;
+
        outputs = gnome_rr_screen_list_outputs (rr_screen);
 
        for (i = 0; outputs[i] != NULL; i++) {
@@ -986,47 +986,41 @@ _device_mapper_update_outputs (GsdDeviceMapper *mapper)
 }
 
 static void
-outputs_changed_cb (GnomeRRScreen   *rr_screen,
-                   GnomeRROutput   *output,
-                   GsdDeviceMapper *mapper)
-{
-       _device_mapper_update_outputs (mapper);
-}
-
-static void
 screen_changed_cb (GnomeRRScreen   *rr_screen,
                   GsdDeviceMapper *mapper)
 {
        _device_mapper_update_outputs (mapper);
 }
 
-static gboolean
-gsd_device_mapper_initable_init (GInitable     *initable,
-                                GCancellable  *cancellable,
-                                GError       **error)
+static void
+on_rr_screen_ready (GObject      *object,
+                   GAsyncResult *result,
+                   gpointer      user_data)
 {
-       GsdDeviceMapper *mapper;
+       GError *error;
+       GsdDeviceMapper *mapper = user_data;
 
-       mapper = GSD_DEVICE_MAPPER (initable);
-       mapper->rr_screen = gnome_rr_screen_new (mapper->screen, error);
+       error = NULL;
+       mapper->rr_screen = gnome_rr_screen_new_finish (result, &error);
 
-       if (!mapper->rr_screen)
-               return FALSE;
+       if (!mapper->rr_screen) {
+               g_warning ("Failed to construct RR screen: %s", error->message);
+               g_error_free (error);
+               return;
+       }
 
        g_signal_connect (mapper->rr_screen, "changed",
-                         G_CALLBACK (screen_changed_cb), initable);
-       g_signal_connect (mapper->rr_screen, "output-connected",
-                         G_CALLBACK (outputs_changed_cb), initable);
-       g_signal_connect (mapper->rr_screen, "output-disconnected",
-                         G_CALLBACK (outputs_changed_cb), initable);
-       _device_mapper_update_outputs (GSD_DEVICE_MAPPER (initable));
-       return TRUE;
+                         G_CALLBACK (screen_changed_cb), mapper);
+       _device_mapper_update_outputs (mapper);
 }
 
 static void
-gsd_device_mapper_initable_iface_init (GInitableIface *iface)
+gsd_device_mapper_constructed (GObject *object)
 {
-       iface->init = gsd_device_mapper_initable_init;
+       GsdDeviceMapper *mapper;
+
+       mapper = GSD_DEVICE_MAPPER (object);
+       gnome_rr_screen_new_async (mapper->screen, on_rr_screen_ready, mapper);
 }
 
 static void
@@ -1071,6 +1065,7 @@ gsd_device_mapper_class_init (GsdDeviceMapperClass *klass)
        object_class->set_property = gsd_device_mapper_set_property;
        object_class->get_property = gsd_device_mapper_get_property;
        object_class->finalize = gsd_device_mapper_finalize;
+       object_class->constructed = gsd_device_mapper_constructed;
 
        g_object_class_install_property (object_class,
                                         PROP_SCREEN,
@@ -1110,17 +1105,9 @@ gsd_device_mapper_get (void)
        mapper = g_object_get_data (G_OBJECT (screen), "gsd-device-mapper-data");
 
        if (!mapper) {
-               GError *error = NULL;
-
-               mapper = g_initable_new (GSD_TYPE_DEVICE_MAPPER, NULL, &error,
-                                        "screen", screen, NULL);
-               if (error) {
-                       g_critical ("Could not create device mapper: %s", error->message);
-                       g_error_free (error);
-               } else {
-                       g_object_set_data_full (G_OBJECT (screen), "gsd-device-mapper-data",
-                                               mapper, (GDestroyNotify) g_object_unref);
-               }
+               mapper = g_object_new (GSD_TYPE_DEVICE_MAPPER, "screen", screen, NULL);
+               g_object_set_data_full (G_OBJECT (screen), "gsd-device-mapper-data",
+                                        mapper, (GDestroyNotify) g_object_unref);
        }
 
        return mapper;