[mutter/wip/carlosg/input-thread: 153/160] clutter: Switch to GAsyncQueue for ClutterMainContext event queue

[Carlos Garnacho <carlosg src gnome org>]

commit 88d717c5282f4dc7b3bb05897df5ebf5672ae35c
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Aug 11 19:01:12 2020 +0200

    clutter: Switch to GAsyncQueue for ClutterMainContext event queue
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403

 clutter/clutter/clutter-event.c   | 24 +++++++++++-------------
 clutter/clutter/clutter-main.c    | 19 +++++++++++--------
 clutter/clutter/clutter-private.h |  2 +-
 3 files changed, 23 insertions(+), 22 deletions(-)
---
diff --git a/clutter/clutter/clutter-event.c b/clutter/clutter/clutter-event.c
index 75eee81df8..ae8bac4624 100644
--- a/clutter/clutter/clutter-event.c
+++ b/clutter/clutter/clutter-event.c
@@ -1525,14 +1525,17 @@ ClutterEvent *
 clutter_event_get (void)
 {
   ClutterMainContext *context = _clutter_context_get_default ();
+  ClutterEvent *event;
 
-  if (context->events_queue == NULL)
-    return NULL;
+  event = g_async_queue_try_pop (context->events_queue);
 
-  if (g_queue_is_empty (context->events_queue))
-    return NULL;
+  return event;
+}
 
-  return g_queue_pop_tail (context->events_queue);
+static gboolean
+spin_context (gpointer data)
+{
+  return G_SOURCE_REMOVE;
 }
 
 void
@@ -1543,9 +1546,6 @@ _clutter_event_push (const ClutterEvent *event,
 
   g_assert (context != NULL);
 
-  if (context->events_queue == NULL)
-    context->events_queue = g_queue_new ();
-
   if (do_copy)
     {
       ClutterEvent *copy;
@@ -1554,7 +1554,8 @@ _clutter_event_push (const ClutterEvent *event,
       event = copy;
     }
 
-  g_queue_push_head (context->events_queue, (gpointer) event);
+  g_async_queue_push (context->events_queue, (gpointer) event);
+  g_idle_add (spin_context, NULL);
 }
 
 /**
@@ -1591,10 +1592,7 @@ clutter_events_pending (void)
 
   g_return_val_if_fail (context != NULL, FALSE);
 
-  if (context->events_queue == NULL)
-    return FALSE;
-
-  return g_queue_is_empty (context->events_queue) == FALSE;
+  return g_async_queue_length (context->events_queue) > 0;
 }
 
 /**
diff --git a/clutter/clutter/clutter-main.c b/clutter/clutter/clutter-main.c
index 14b4ae8a11..0f0c21f01d 100644
--- a/clutter/clutter/clutter-main.c
+++ b/clutter/clutter/clutter-main.c
@@ -697,6 +697,8 @@ _clutter_context_get_default (void)
       ctx->settings = clutter_settings_get_default ();
       _clutter_settings_set_backend (ctx->settings, ctx->backend);
 
+      ctx->events_queue = g_async_queue_new ();
+
       ctx->last_repaint_id = 1;
     }
 
@@ -2289,15 +2291,16 @@ void
 _clutter_clear_events_queue (void)
 {
   ClutterMainContext *context = _clutter_context_get_default ();
+  ClutterEvent *event;
 
-  if (context->events_queue != NULL)
-    {
-      g_queue_foreach (context->events_queue,
-                       (GFunc) clutter_event_free,
-                       NULL);
-      g_queue_free (context->events_queue);
-      context->events_queue = NULL;
-    }
+  /* Lock the queue for as long as it lives */
+  g_async_queue_lock (context->events_queue);
+
+  while ((event = g_async_queue_try_pop_unlocked (context->events_queue)))
+    clutter_event_free (event);
+
+  g_async_queue_unref (context->events_queue);
+  context->events_queue = NULL;
 }
 
 ClutterPickMode
diff --git a/clutter/clutter/clutter-private.h b/clutter/clutter/clutter-private.h
index e4119b99fa..549c39a205 100644
--- a/clutter/clutter/clutter-private.h
+++ b/clutter/clutter/clutter-private.h
@@ -122,7 +122,7 @@ struct _ClutterMainContext
   ClutterStageManager *stage_manager;
 
   /* the main event queue */
-  GQueue *events_queue;
+  GAsyncQueue *events_queue;
 
   /* the event filters added via clutter_event_add_filter. these are
    * ordered from least recently added to most recently added */