Rework our libxfce4windowing use to be thread-safe

src/daemon/endsession.vala

@@ -135,6 +135,12 @@ namespace Budgie {
 				this.cancel_clicked();
 				return Gdk.EVENT_STOP;
 			});
+
+			GtkLayerShell.init_for_window(this);
+			GtkLayerShell.set_layer(this, GtkLayerShell.Layer.TOP);
+			GtkLayerShell.set_anchor(this, GtkLayerShell.Edge.LEFT, false);
+			GtkLayerShell.set_anchor(this, GtkLayerShell.Edge.TOP, false);
+			GtkLayerShell.set_keyboard_mode(this, GtkLayerShell.KeyboardMode.ON_DEMAND);
 		}
 
 		public void Open(uint type, uint timestamp, uint open_length, ObjectPath[] inhibiters) throws DBusError, IOError {
@@ -175,6 +181,8 @@ namespace Budgie {
 			/* Update the label */
 			this.label_end_title.set_text(title);
 
+			GtkLayerShell.set_monitor(this, new WaylandClient().gdk_monitor);
+
 			if (main_show != null) {
 				/* We have a specific type.. */
 				for (int i = 0; i < all_widgets.length; i++) {

src/daemon/manager.vala

@@ -10,6 +10,49 @@
  */
 
 namespace Budgie {
+
+	/*
+	 The underlying WaylandClient does not appear to be fully thread-safe and either
+	 repeated calls very quickly, or calls within the same process where the
+	 reference was not release will result in mutex-locks causing the daemon to spin
+	 indefinitely.
+
+	 Our use in the daemon is limited so we can initialise variable we use within
+	 a singleton to make things thread-safe.
+	 */
+	[SingleInstance]
+	public class WaylandClient : GLib.Object {
+		private unowned libxfce4windowing.Monitor? primary_monitor=null;
+
+		public bool is_initialised() { return primary_monitor != null; }
+		public unowned Gdk.Monitor gdk_monitor {get; private set; }
+		public Gdk.Rectangle monitor_res { get; private set; }
+
+		public WaylandClient() {
+			if (primary_monitor != null) return;
+			libxfce4windowing.Screen.get_default().monitors_changed.connect(on_monitors_changed);
+			on_monitors_changed();
+		}
+
+		void on_monitors_changed() {
+			int loop = 0;
+
+			/* it can take a short-time after first call for the underlying wayland client
+			   to return a reference, so lets loop until we get a reference ... but
+			   don't try indefinitely
+			*/
+			Timeout.add(200, ()=> {
+				primary_monitor = libxfce4windowing.Screen.get_default().get_primary_monitor();
+				if (primary_monitor != null || loop++ > 10) {
+					monitor_res = primary_monitor.get_logical_geometry();
+					gdk_monitor = primary_monitor.get_gdk_monitor();
+					return false;
+				}
+
+				return true;
+			});
+		}
+	}
 	/**
 	* Main lifecycle management, handle all the various session and GTK+ bits
 	*/
@@ -18,8 +61,10 @@ namespace Budgie {
 		/* Keep track of our SessionManager */
 		private LibSession.SessionClient? sclient;
 
+		// define a reference to WaylandClient once for this process
+		private WaylandClient wayland_client = new WaylandClient();
+
 		/* On Screen Display */
-		public static unowned libxfce4windowing.Monitor? primary_monitor { get; private set; }
 		Budgie.OSDManager? osd;
 		Budgie.OSDKeys? osdkeys;
 		Budgie.Notifications.Server? notifications;
@@ -38,9 +83,6 @@ namespace Budgie {
 		* Construct a new ServiceManager and initialiase appropriately
 		*/
 		public ServiceManager(bool replace) {
-			libxfce4windowing.Screen.get_default().monitors_changed.connect(on_monitors_changed);
-			on_monitors_changed();
-
 			theme_manager = new Budgie.ThemeManager();
 			status_notifier = new Budgie.StatusNotifier.FreedesktopWatcher();
 			register_with_session.begin((o, res) => {
@@ -56,6 +98,7 @@ namespace Budgie {
 
 			notifications = new Budgie.Notifications.Server();
 			notifications.setup_dbus(replace);
+
 			background = new Budgie.Background();
 
 			try {
@@ -74,9 +117,6 @@ namespace Budgie {
 			nightlight = new NightLightManager();
 		}
 
-		void on_monitors_changed() {
-			primary_monitor = libxfce4windowing.Screen.get_default().get_primary_monitor();
-		}
 		/**
 		* Attempt registration with the Session Manager
 		*/

src/daemon/notifications/dbus.vala

@@ -359,9 +359,9 @@
 		 * Configures the location of a notification popup and makes it visible on the screen.
 		 */
 		private void configure_window(Popup? popup) {
-			var primary_monitor = ServiceManager.primary_monitor;
-			if (primary_monitor == null) return;
-			Gdk.Rectangle mon_rect = primary_monitor.get_workarea();
+			if (!new WaylandClient().is_initialised()) return;
+
+			Gdk.Rectangle mon_rect = new WaylandClient().monitor_res;
 
 			GtkLayerShell.init_for_window(popup);
 			GtkLayerShell.set_layer(popup, GtkLayerShell.Layer.TOP);
@@ -376,7 +376,7 @@
 
 				/* determine the y position for the latest notification */
 				calculate_position(mon_rect.y);
-				GtkLayerShell.set_monitor(popup, primary_monitor.get_gdk_monitor());
+				GtkLayerShell.set_monitor(popup, new WaylandClient().gdk_monitor);
 				var pos = (NotificationPosition) this.panel_settings.get_enum("notification-position");
 				int edge_a, edge_b;
 

src/daemon/osd.vala

@@ -123,10 +123,12 @@ namespace Budgie {
 			resizable = false;
 			skip_pager_hint = true;
 			skip_taskbar_hint = true;
+
 			GtkLayerShell.init_for_window(this);
 			GtkLayerShell.set_layer(this, GtkLayerShell.Layer.TOP);
 			GtkLayerShell.set_margin(this, GtkLayerShell.Edge.BOTTOM, 80);
 			GtkLayerShell.set_anchor(this, GtkLayerShell.Edge.BOTTOM, true);
+
 			set_decorated(false);
 			stick();
 
@@ -153,9 +155,7 @@ namespace Budgie {
 		* Move the OSD into the correct position
 		*/
 		public void move_osd() {
-			var primary_monitor = ServiceManager.primary_monitor;
-			if (primary_monitor == null) return;
-			GtkLayerShell.set_monitor(this, primary_monitor.get_gdk_monitor());
+			GtkLayerShell.set_monitor(this, new WaylandClient().gdk_monitor);
 		}
 	}