[gnome-desktop] idle-monitor: Check if a monitor exists before creating a proxy for it

[Rui Matos <rtcm src gnome org>]

commit fff5475f4c320025e5bda847951cb478cd57982c
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Nov 26 00:55:23 2013 +0100

    idle-monitor: Check if a monitor exists before creating a proxy for it
    
    The fact that we know about a given device doesn't mean that mutter
    also knows about it nor that it has created an idle monitor object on
    the bus for it.
    
    To fix this race, instead of immediately trying to create a proxy for
    the bus object, we instantiate an object manager and ask it whether
    the object we want already exists and if it doesn't we wait
    (indefinitely) until it shows up.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706229

 libgnome-desktop/gnome-idle-monitor.c |  107 ++++++++++++++++++++++-----------
 1 files changed, 72 insertions(+), 35 deletions(-)
---
diff --git a/libgnome-desktop/gnome-idle-monitor.c b/libgnome-desktop/gnome-idle-monitor.c
index 6af1343..539c99b 100644
--- a/libgnome-desktop/gnome-idle-monitor.c
+++ b/libgnome-desktop/gnome-idle-monitor.c
@@ -40,10 +40,12 @@ struct _GnomeIdleMonitorPrivate
 {
        GCancellable        *cancellable;
        MetaDBusIdleMonitor *proxy;
+       MetaDBusObjectManagerClient *om;
        int                  name_watch_id;
        GHashTable          *watches;
        GHashTable          *watches_by_upstream_id;
        GdkDevice           *device;
+       gchar               *path;
 };
 
 typedef struct
@@ -163,8 +165,10 @@ gnome_idle_monitor_dispose (GObject *object)
        }
 
        g_clear_object (&monitor->priv->proxy);
+       g_clear_object (&monitor->priv->om);
        g_clear_pointer (&monitor->priv->watches, g_hash_table_destroy);
        g_clear_object (&monitor->priv->device);
+       g_clear_pointer (&monitor->priv->path, g_free);
 
        G_OBJECT_CLASS (gnome_idle_monitor_parent_class)->dispose (object);
 }
@@ -198,6 +202,15 @@ gnome_idle_monitor_set_property (GObject      *object,
        {
        case PROP_DEVICE:
                monitor->priv->device = g_value_dup_object (value);
+
+               g_free (monitor->priv->path);
+               if (monitor->priv->device) {
+                       monitor->priv->path = g_strdup_printf ("/org/gnome/Mutter/IdleMonitor/Device%d",
+                                                              gdk_x11_device_get_id (monitor->priv->device));
+               } else {
+                       monitor->priv->path = g_strdup ("/org/gnome/Mutter/IdleMonitor/Core");
+               }
+
                break;
        default:
                G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -220,57 +233,74 @@ add_known_watch (gpointer key,
 }
 
 static void
-on_proxy_acquired (GObject      *object,
-                  GAsyncResult *result,
-                  gpointer      user_data)
+connect_proxy (GDBusObject     *object,
+              GnomeIdleMonitor *monitor)
 {
-       GnomeIdleMonitor *monitor = user_data;
-       GError *error;
        MetaDBusIdleMonitor *proxy;
 
-       error = NULL;
-       proxy = meta_dbus_idle_monitor_proxy_new_finish (result, &error);
+       proxy = meta_dbus_object_get_idle_monitor (META_DBUS_OBJECT (object));
        if (!proxy) {
-               if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED)) {
-                       g_error_free (error);
-                       return;
-               }
-
-               g_warning ("Failed to acquire idle monitor proxy: %s", error->message);
-               g_error_free (error);
+               g_critical ("Unable to get idle monitor from object at %s",
+                           g_dbus_object_get_object_path (object));
                return;
        }
 
        monitor->priv->proxy = proxy;
-
        g_signal_connect_object (proxy, "watch-fired", G_CALLBACK (on_watch_fired), monitor, 0);
        g_hash_table_foreach (monitor->priv->watches, add_known_watch, monitor);
 }
 
 static void
-connect_proxy (GnomeIdleMonitor *monitor,
-              GDBusConnection  *connection,
-              const char       *unique_name)
-{
-       char *path;
-       int device_id;
-
-       if (monitor->priv->device) {
-               /* FIXME! Gdk! WTF? */
-               device_id = gdk_x11_device_get_id (monitor->priv->device);
-       path = g_strdup_printf ("/org/gnome/Mutter/IdleMonitor/Device%d", device_id);
-       } else {
-               path = g_strdup ("/org/gnome/Mutter/IdleMonitor/Core");
+on_object_added (GDBusObjectManager    *manager,
+                GDBusObject            *object,
+                gpointer                user_data)
+{
+       GnomeIdleMonitor *monitor = user_data;
+
+       if (!g_str_equal (monitor->priv->path, g_dbus_object_get_object_path (object)))
+               return;
+
+       connect_proxy (object, monitor);
+
+       g_signal_handlers_disconnect_by_func (manager, on_object_added, user_data);
+}
+
+static void
+get_proxy (GnomeIdleMonitor *monitor)
+{
+       GDBusObject *object;
+
+       object = g_dbus_object_manager_get_object (G_DBUS_OBJECT_MANAGER (monitor->priv->om),
+                                                  monitor->priv->path);
+       if (object) {
+               connect_proxy (object, monitor);
+               g_object_unref (object);
+               return;
        }
 
-       meta_dbus_idle_monitor_proxy_new (connection,
-                                         G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES,
-                                         unique_name, path,
-                                         monitor->priv->cancellable,
-                                         on_proxy_acquired,
-                                         monitor);
+       g_signal_connect_object (monitor->priv->om, "object-added",
+                                G_CALLBACK (on_object_added), monitor, 0);
+}
+
+static void
+on_object_manager_ready (GObject       *source,
+                        GAsyncResult   *res,
+                        gpointer        user_data)
+{
+       GnomeIdleMonitor *monitor = user_data;
+       GDBusObjectManager *om;
+       GError *error = NULL;
+
+       om = meta_dbus_object_manager_client_new_finish (res, &error);
+       if (!om) {
+               if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+                       g_warning ("Failed to acquire idle monitor object manager: %s", error->message);
+               g_error_free (error);
+               return;
+       }
 
-       g_free (path);
+       monitor->priv->om = META_DBUS_OBJECT_MANAGER_CLIENT (om);
+       get_proxy (monitor);
 }
 
 static void
@@ -281,7 +311,13 @@ on_name_appeared (GDBusConnection *connection,
 {
        GnomeIdleMonitor *monitor = user_data;
 
-       connect_proxy (monitor, connection, name_owner);
+       meta_dbus_object_manager_client_new (connection,
+                                            G_DBUS_OBJECT_MANAGER_CLIENT_FLAGS_NONE,
+                                            name_owner,
+                                            "/org/gnome/Mutter/IdleMonitor",
+                                            monitor->priv->cancellable,
+                                            on_object_manager_ready,
+                                            monitor);
 }
 
 static void
@@ -305,6 +341,7 @@ on_name_vanished (GDBusConnection *connection,
 
        g_hash_table_foreach (monitor->priv->watches, clear_watch, monitor);
        g_clear_object (&monitor->priv->proxy);
+       g_clear_object (&monitor->priv->om);
 }
 
 static gboolean