[gnome-shell] shell/tray-manager: Only create resources when needed

[Florian Müllner <fmuellner src gnome org>]

commit 07bbcb1b4805510b3dc7ab4df507ae878407b762
Author: Florian Müllner <fmuellner gnome org>
Date:   Wed Mar 4 23:12:29 2020 +0100

    shell/tray-manager: Only create resources when needed
    
    NaTrayManager in particular is deeply tied to X11. We currently assume
    that X11 support is always available, but that is already not true
    anymore - Xwayland startup is now asynchronous.
    
    It will be even less true once we handle Xwayland crashes gracefully.
    
    Start addressing that by not creating the corresponding resources once
    and assume they exist for the lifetime of Shell.TrayManager, but make
    sure they exist when actually needed.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/2308

 src/shell-tray-manager.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)
---
diff --git a/src/shell-tray-manager.c b/src/shell-tray-manager.c
index 6503cc3c45..269682bcff 100644
--- a/src/shell-tray-manager.c
+++ b/src/shell-tray-manager.c
@@ -58,6 +58,8 @@ static guint shell_tray_manager_signals [LAST_SIGNAL] = { 0 };
 
 static const ClutterColor default_color = { 0x00, 0x00, 0x00, 0xff };
 
+static void shell_tray_manager_release_resources (ShellTrayManager *manager);
+
 static void na_tray_icon_added (NaTrayManager *na_manager, GtkWidget *child, gpointer manager);
 static void na_tray_icon_removed (NaTrayManager *na_manager, GtkWidget *child, gpointer manager);
 
@@ -125,16 +127,7 @@ shell_tray_manager_init (ShellTrayManager *manager)
 {
   manager->priv = shell_tray_manager_get_instance_private (manager);
 
-  manager->priv->na_manager = na_tray_manager_new ();
-
-  manager->priv->icons = g_hash_table_new_full (NULL, NULL,
-                                                NULL, free_tray_icon);
   manager->priv->bg_color = default_color;
-
-  g_signal_connect (manager->priv->na_manager, "tray-icon-added",
-                    G_CALLBACK (na_tray_icon_added), manager);
-  g_signal_connect (manager->priv->na_manager, "tray-icon-removed",
-                    G_CALLBACK (na_tray_icon_removed), manager);
 }
 
 static void
@@ -142,8 +135,7 @@ shell_tray_manager_finalize (GObject *object)
 {
   ShellTrayManager *manager = SHELL_TRAY_MANAGER (object);
 
-  g_object_unref (manager->priv->na_manager);
-  g_hash_table_destroy (manager->priv->icons);
+  shell_tray_manager_release_resources (manager);
 
   G_OBJECT_CLASS (shell_tray_manager_parent_class)->finalize (object);
 }
@@ -193,6 +185,30 @@ shell_tray_manager_new (void)
   return g_object_new (SHELL_TYPE_TRAY_MANAGER, NULL);
 }
 
+static void
+shell_tray_manager_ensure_resources (ShellTrayManager *manager)
+{
+  if (manager->priv->na_manager != NULL)
+    return;
+
+  manager->priv->icons = g_hash_table_new_full (NULL, NULL,
+                                                NULL, free_tray_icon);
+
+  manager->priv->na_manager = na_tray_manager_new ();
+
+  g_signal_connect (manager->priv->na_manager, "tray-icon-added",
+                    G_CALLBACK (na_tray_icon_added), manager);
+  g_signal_connect (manager->priv->na_manager, "tray-icon-removed",
+                    G_CALLBACK (na_tray_icon_removed), manager);
+}
+
+static void
+shell_tray_manager_release_resources (ShellTrayManager *manager)
+{
+  g_clear_object (&manager->priv->na_manager);
+  g_clear_pointer (&manager->priv->icons, g_hash_table_destroy);
+}
+
 static void
 shell_tray_manager_style_changed (StWidget *theme_widget,
                                   gpointer  user_data)
@@ -212,6 +228,8 @@ void
 shell_tray_manager_manage_screen (ShellTrayManager *manager,
                                   StWidget         *theme_widget)
 {
+  shell_tray_manager_ensure_resources (manager);
+
   na_tray_manager_manage_screen (manager->priv->na_manager);
 
   g_signal_connect_object (theme_widget, "style-changed",