[mutter/wip/carlosg/group-text-input-events] wayland: Defer text_input.done on an idle

[Carlos Garnacho <carlosg src gnome org>]

commit e783778faa490512576c40a9531763566a6af1f8
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Oct 18 02:08:24 2018 +0200

    wayland: Defer text_input.done on an idle
    
    With the right priority so we hopefully group events properly.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/499
    https://gitlab.gnome.org/GNOME/gtk/issues/1365

 src/wayland/meta-wayland-text-input.c | 60 +++++++++++++++++++++++++++++++----
 1 file changed, 54 insertions(+), 6 deletions(-)
---
diff --git a/src/wayland/meta-wayland-text-input.c b/src/wayland/meta-wayland-text-input.c
index d9e1e36b1..d63f489bd 100644
--- a/src/wayland/meta-wayland-text-input.c
+++ b/src/wayland/meta-wayland-text-input.c
@@ -72,6 +72,8 @@ struct _MetaWaylandTextInput
   uint32_t content_type_purpose;
   uint32_t text_change_cause;
   gboolean enabled;
+
+  guint done_idle_id;
 };
 
 struct _MetaWaylandTextInputFocus
@@ -116,6 +118,52 @@ increment_serial (MetaWaylandTextInput *text_input,
                        GUINT_TO_POINTER (serial + 1));
 }
 
+static gboolean
+done_idle_cb (gpointer user_data)
+{
+  ClutterInputFocus *focus = user_data;
+  MetaWaylandTextInput *text_input;
+  struct wl_resource *resource;
+
+  text_input = META_WAYLAND_TEXT_INPUT_FOCUS (focus)->text_input;
+
+  wl_resource_for_each (resource, &text_input->focus_resource_list)
+    {
+      zwp_text_input_v3_send_done (resource,
+                                   lookup_serial (text_input, resource));
+    }
+
+  text_input->done_idle_id = 0;
+  return G_SOURCE_REMOVE;
+}
+
+static void
+meta_wayland_text_input_focus_defer_done (ClutterInputFocus *focus)
+{
+  MetaWaylandTextInput *text_input;
+
+  text_input = META_WAYLAND_TEXT_INPUT_FOCUS (focus)->text_input;
+
+  if (text_input->done_idle_id != 0)
+    return;
+
+  /* This operates on 3 principles:
+   * - GDBus uses G_PRIORITY_DEFAULT to put messages in the thread default main
+   *   context.
+   * - All relevant ClutterInputFocus methods are ultimately backed by
+   *   DBus methods inside IBus.
+   * - We want to run .done after them all. The slightly lower
+   *   G_PRIORITY_DEFAULT + 1 priority should ensure we at least group
+   *   all messages seen so far.
+   *
+   * FIXME: .done may be delayed indefinitely if there's a high enough
+   *        priority idle source in the main loop. It's unlikely that
+   *        recurring idles run at this high priority though.
+   */
+  text_input->done_idle_id = g_idle_add_full (G_PRIORITY_DEFAULT + 1,
+                                              done_idle_cb, focus, NULL);
+}
+
 static void
 meta_wayland_text_input_focus_delete_surrounding (ClutterInputFocus *focus,
                                                   guint              cursor,
@@ -129,9 +177,9 @@ meta_wayland_text_input_focus_delete_surrounding (ClutterInputFocus *focus,
   wl_resource_for_each (resource, &text_input->focus_resource_list)
     {
       zwp_text_input_v3_send_delete_surrounding_text (resource, cursor, len);
-      zwp_text_input_v3_send_done (resource,
-                                   lookup_serial (text_input, resource));
     }
+
+  meta_wayland_text_input_focus_defer_done (focus);
 }
 
 static void
@@ -147,9 +195,9 @@ meta_wayland_text_input_focus_commit_text (ClutterInputFocus *focus,
     {
       zwp_text_input_v3_send_preedit_string (resource, NULL, 0, 0);
       zwp_text_input_v3_send_commit_string (resource, text);
-      zwp_text_input_v3_send_done (resource,
-                                   lookup_serial (text_input, resource));
     }
+
+  meta_wayland_text_input_focus_defer_done (focus);
 }
 
 static void
@@ -165,9 +213,9 @@ meta_wayland_text_input_focus_set_preedit_text (ClutterInputFocus *focus,
   wl_resource_for_each (resource, &text_input->focus_resource_list)
     {
       zwp_text_input_v3_send_preedit_string (resource, text, cursor, cursor);
-      zwp_text_input_v3_send_done (resource,
-                                   lookup_serial (text_input, resource));
     }
+
+  meta_wayland_text_input_focus_defer_done (focus);
 }
 
 static void