kms/result-listener: Let listeners own a feedback ref

Dispatch results via a helper, and let each result hold a reference to
the feedback. This allows for more asynchronous feedback management.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2854>

src/backends/native/meta-kms-private.h

@@ -25,6 +25,7 @@
 #include <gudev/gudev.h>
 
 #include "backends/native/meta-kms-types.h"
+#include "backends/native/meta-kms-types-private.h"
 
 typedef void (* MetaKmsCallback) (MetaKms  *kms,
                                   gpointer  user_data);
@@ -38,6 +39,9 @@ void meta_kms_queue_callback (MetaKms         *kms,
                               gpointer         user_data,
                               GDestroyNotify   user_data_destroy);
 
+void meta_kms_queue_result_callback (MetaKms               *kms,
+                                     MetaKmsResultListener *listener);
+
 gpointer meta_kms_run_impl_task_sync (MetaKms              *kms,
                                       MetaKmsImplTaskFunc   func,
                                       gpointer              user_data,

src/backends/native/meta-kms-types-private.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2022 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#ifndef META_KMS_TYPES_PRIVATE_H
+#define META_KMS_TYPES_PRIVATE_H
+
+typedef struct _MetaKmsResultListener MetaKmsResultListener;
+
+#endif /* META_KMS_TYPES_PRIVATE_H */

src/backends/native/meta-kms-update-private.h

@@ -26,6 +26,7 @@
 #include "backends/native/meta-kms-crtc.h"
 #include "backends/native/meta-kms-plane-private.h"
 #include "backends/native/meta-kms-types.h"
+#include "backends/native/meta-kms-types-private.h"
 #include "backends/native/meta-kms-update.h"
 
 typedef struct _MetaKmsCrtcColorUpdate
@@ -113,11 +114,13 @@ typedef struct _MetaKmsPageFlipListener
   GDestroyNotify destroy_notify;
 } MetaKmsPageFlipListener;
 
-typedef struct _MetaKmsResultListener
+struct _MetaKmsResultListener
 {
   MetaKmsResultListenerFunc func;
   gpointer user_data;
-} MetaKmsResultListener;
+
+  MetaKmsFeedback *feedback;
+};
 
 typedef struct _MetaKmsCustomPageFlip
 {
@@ -185,8 +188,10 @@ META_EXPORT_TEST
 void meta_kms_update_merge_from (MetaKmsUpdate *update,
                                  MetaKmsUpdate *other_update);
 
-void meta_kms_result_listener_notify (MetaKmsResultListener *listener,
-                                      const MetaKmsFeedback *feedback);
+void meta_kms_result_listener_set_feedback (MetaKmsResultListener *listener,
+                                            MetaKmsFeedback       *feedback);
+
+void meta_kms_result_listener_notify (MetaKmsResultListener *listener);
 
 void meta_kms_result_listener_free (MetaKmsResultListener *listener);
 

src/backends/native/meta-kms-update.c

@@ -27,6 +27,7 @@
 #include "backends/native/meta-kms-crtc.h"
 #include "backends/native/meta-kms-mode-private.h"
 #include "backends/native/meta-kms-plane.h"
+#include "backends/native/meta-kms-private.h"
 
 struct _MetaKmsUpdate
 {
@@ -149,6 +150,23 @@ meta_kms_feedback_get_error (const MetaKmsFeedback *feedback)
   return feedback->error;
 }
 
+void
+meta_kms_feedback_dispatch_result (MetaKmsFeedback *feedback,
+                                   MetaKms         *kms,
+                                   GList           *result_listeners)
+{
+  GList *l;
+
+  for (l = result_listeners; l; l = l->next)
+    {
+      MetaKmsResultListener *listener = l->data;
+
+      meta_kms_result_listener_set_feedback (listener, feedback);
+      meta_kms_queue_result_callback (kms, listener);
+    }
+  g_list_free (result_listeners);
+}
+
 static void
 meta_kms_fb_damage_free (MetaKmsFbDamage *fb_damage)
 {
@@ -549,15 +567,26 @@ meta_kms_update_take_result_listeners (MetaKmsUpdate *update)
 }
 
 void
-meta_kms_result_listener_notify (MetaKmsResultListener *listener,
-                                 const MetaKmsFeedback *feedback)
+meta_kms_result_listener_set_feedback (MetaKmsResultListener *listener,
+                                       MetaKmsFeedback       *feedback)
 {
-  listener->func (feedback, listener->user_data);
+  g_return_if_fail (!listener->feedback);
+
+  listener->feedback = meta_kms_feedback_ref (feedback);
+}
+
+void
+meta_kms_result_listener_notify (MetaKmsResultListener *listener)
+{
+  g_return_if_fail (listener->feedback);
+
+  listener->func (listener->feedback, listener->user_data);
 }
 
 void
 meta_kms_result_listener_free (MetaKmsResultListener *listener)
 {
+  g_clear_pointer (&listener->feedback, meta_kms_feedback_unref);
   g_free (listener);
 }
 

src/backends/native/meta-kms-update.h

@@ -91,6 +91,10 @@ GList * meta_kms_feedback_get_failed_planes (const MetaKmsFeedback *feedback);
 
 const GError * meta_kms_feedback_get_error (const MetaKmsFeedback *feedback);
 
+void meta_kms_feedback_dispatch_result (MetaKmsFeedback *feedback,
+                                        MetaKms         *kms,
+                                        GList           *result_listeners);
+
 META_EXPORT_TEST
 MetaKmsUpdate * meta_kms_update_new (MetaKmsDevice *device);
 

src/backends/native/meta-kms.c

@@ -247,6 +247,25 @@ meta_kms_take_pending_update (MetaKms       *kms,
   return NULL;
 }
 
+static void
+invoke_result_listener (MetaKms  *kms,
+                        gpointer  user_data)
+{
+  MetaKmsResultListener *listener = user_data;
+
+  meta_kms_result_listener_notify (listener);
+}
+
+void
+meta_kms_queue_result_callback (MetaKms               *kms,
+                                MetaKmsResultListener *listener)
+{
+  meta_kms_queue_callback  (kms,
+                            invoke_result_listener,
+                            listener,
+                            (GDestroyNotify) meta_kms_result_listener_free);
+}
+
 MetaKmsFeedback *
 meta_kms_post_pending_update_sync (MetaKms           *kms,
                                    MetaKmsDevice     *device,
@@ -255,7 +274,6 @@ meta_kms_post_pending_update_sync (MetaKms           *kms,
   MetaKmsUpdate *update;
   MetaKmsFeedback *feedback;
   GList *result_listeners;
-  GList *l;
 
   COGL_TRACE_BEGIN_SCOPED (MetaKmsPostUpdateSync,
                            "KMS (post update)");
@@ -270,14 +288,7 @@ meta_kms_post_pending_update_sync (MetaKms           *kms,
 
   meta_kms_update_free (update);
 
-  for (l = result_listeners; l; l = l->next)
-    {
-      MetaKmsResultListener *listener = l->data;
-
-      meta_kms_result_listener_notify (listener, feedback);
-      meta_kms_result_listener_free (listener);
-    }
-  g_list_free (result_listeners);
+  meta_kms_feedback_dispatch_result (feedback, kms, result_listeners);
 
   return feedback;
 }

src/meson.build

@@ -788,6 +788,7 @@ if have_native_backend
     'backends/native/meta-kms-plane-private.h',
     'backends/native/meta-kms-plane.h',
     'backends/native/meta-kms-private.h',
+    'backends/native/meta-kms-types-private.h',
     'backends/native/meta-kms-types.h',
     'backends/native/meta-kms-update-private.h',
     'backends/native/meta-kms-update.c',