[gtk/wip/chergert/gtk4-gtk-main-sync: 2/2] gtkmain: be deterministic in source removal

[Christian Hergert <chergert src gnome org>]

commit 2f3518c80dc08aeddfd65273b79d39b325664e3f
Author: Christian Hergert <chergert redhat com>
Date:   Fri Jan 10 15:04:44 2020 -0800

    gtkmain: be deterministic in source removal
    
    Fixes gtk_main_sync() to only remove a source if it has not
    already executed (and been removed). The previous code was
    using gtk_main_quit() directly which would be non-determinstic
    based on the previous value in the return register.

 gtk/gtkmain.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)
---
diff --git a/gtk/gtkmain.c b/gtk/gtkmain.c
index 93fea8540a..37ee557c48 100644
--- a/gtk/gtkmain.c
+++ b/gtk/gtkmain.c
@@ -1044,6 +1044,7 @@ gtk_main (void)
 typedef struct {
   GMainLoop *store_loop;
   guint n_clipboards;
+  guint timeout_id;
 } ClipboardStore;
 
 static void
@@ -1071,13 +1072,20 @@ clipboard_store_finished (GObject      *source,
     g_main_loop_quit (store->store_loop);
 }
 
+static gboolean
+sync_timed_out_cb (ClipboardStore *store)
+{
+  store->timeout_id = 0;
+  g_main_loop_quit (store->store_loop);
+  return G_SOURCE_REMOVE;
+}
+
 void
 gtk_main_sync (void)
 {
   ClipboardStore store = { NULL, };
   GSList *displays, *l;
   GCancellable *cancel;
-  guint store_timeout;
   
   /* Try storing all clipboard data we have */
   displays = gdk_display_manager_list_displays (gdk_display_manager_get ());
@@ -1101,17 +1109,16 @@ gtk_main_sync (void)
   g_slist_free (displays);
 
   store.store_loop = g_main_loop_new (NULL, TRUE);
-  store_timeout = g_timeout_add_seconds (10, (GSourceFunc) g_main_loop_quit, store.store_loop);
-  g_source_set_name_by_id (store_timeout, "[gtk] gtk_main_sync clipboard store timeout");
+  store.timeout_id = g_timeout_add_seconds (10, (GSourceFunc) sync_timed_out_cb, &store);
+  g_source_set_name_by_id (store.timeout_id, "[gtk] gtk_main_sync clipboard store timeout");
 
   if (g_main_loop_is_running (store.store_loop))
     g_main_loop_run (store.store_loop);
   
   g_cancellable_cancel (cancel);
   g_object_unref (cancel);
-  g_source_remove (store_timeout);
-  g_main_loop_unref (store.store_loop);
-  store.store_loop = NULL;
+  g_clear_handle_id (&store.timeout_id, g_source_remove);
+  g_clear_pointer (&store.store_loop, g_main_loop_unref);
   
   /* Synchronize the recent manager singleton */
   _gtk_recent_manager_sync ();