From 4a774e878f1d4ea9d89b2c4a0814ef234c3a63de Mon Sep 17 00:00:00 2001
From: Seungha Yang <seungha.yang@navercorp.com>
Date: Wed, 22 Jan 2020 00:14:14 +0900
Subject: [PATCH] audiosink: Keep baseclass extensible

Add a structure for future extension.

Fixes: https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/716
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/547>
---
 gst-libs/gst/audio/gstaudiosink.c | 11 ++++++++---
 gst-libs/gst/audio/gstaudiosink.h | 22 ++++++++++++++++------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/gst-libs/gst/audio/gstaudiosink.c b/gst-libs/gst/audio/gstaudiosink.c
index c6de9e97bf..0aa44332eb 100644
--- a/gst-libs/gst/audio/gstaudiosink.c
+++ b/gst-libs/gst/audio/gstaudiosink.c
@@ -623,9 +623,9 @@ gst_audio_sink_ring_buffer_clear_all (GstAudioRingBuffer * buf)
   sink = GST_AUDIO_SINK (GST_OBJECT_PARENT (buf));
   csink = GST_AUDIO_SINK_GET_CLASS (sink);
 
-  if (csink->clear_all) {
+  if (csink->extension->clear_all) {
     GST_DEBUG_OBJECT (sink, "clear all");
-    csink->clear_all (sink);
+    csink->extension->clear_all (sink);
   }
 
   /* chain up to the parent implementation */
@@ -645,7 +645,9 @@ enum
 };
 
 #define _do_init \
-    GST_DEBUG_CATEGORY_INIT (gst_audio_sink_debug, "audiosink", 0, "audiosink element");
+    GST_DEBUG_CATEGORY_INIT (gst_audio_sink_debug, "audiosink", 0, "audiosink element"); \
+    g_type_add_class_private (g_define_type_id, \
+        sizeof (GstAudioSinkClassExtension));
 #define gst_audio_sink_parent_class parent_class
 G_DEFINE_TYPE_WITH_CODE (GstAudioSink, gst_audio_sink,
     GST_TYPE_AUDIO_BASE_SINK, _do_init);
@@ -664,6 +666,9 @@ gst_audio_sink_class_init (GstAudioSinkClass * klass)
       GST_DEBUG_FUNCPTR (gst_audio_sink_create_ringbuffer);
 
   g_type_class_ref (GST_TYPE_AUDIO_SINK_RING_BUFFER);
+
+  klass->extension = G_TYPE_CLASS_GET_PRIVATE (klass,
+      GST_TYPE_AUDIO_SINK, GstAudioSinkClassExtension);
 }
 
 static void
diff --git a/gst-libs/gst/audio/gstaudiosink.h b/gst-libs/gst/audio/gstaudiosink.h
index e54094be59..06f65ffa33 100644
--- a/gst-libs/gst/audio/gstaudiosink.h
+++ b/gst-libs/gst/audio/gstaudiosink.h
@@ -41,6 +41,7 @@ G_BEGIN_DECLS
 
 typedef struct _GstAudioSink GstAudioSink;
 typedef struct _GstAudioSinkClass GstAudioSinkClass;
+typedef struct _GstAudioSinkClassExtension GstAudioSinkClassExtension;
 
 /**
  * GstAudioSink:
@@ -76,13 +77,13 @@ struct _GstAudioSink {
  *         This vmethod is deprecated. Please provide pause and stop instead.
  * @pause: Pause the device and unblock write as fast as possible.
  *         For retro compatibility, the audio sink will fallback
- *         to calling reset if this vmethod is not provided.
- * @resume: Resume the device.
+ *         to calling reset if this vmethod is not provided. Since: 1.18
+ * @resume: Resume the device. Since: 1.18
  * @stop: Stop the device and unblock write as fast as possible.
  *        Pending samples are flushed from the device.
  *        For retro compatibility, the audio sink will fallback
- *        to calling reset if this vmethod is not provided.
- * @clear-all: Clear the device.
+ *        to calling reset if this vmethod is not provided. Since: 1.18
+ * @extension: class extension structure. Since: 1.18
  */
 struct _GstAudioSinkClass {
   GstAudioBaseSinkClass parent_class;
@@ -109,11 +110,20 @@ struct _GstAudioSinkClass {
   void     (*resume)    (GstAudioSink *sink);
   /* stop the audio device, unblock from a write */
   void     (*stop)      (GstAudioSink *sink);
+
+  GstAudioSinkClassExtension *extension;
+};
+
+/**
+ * GstAudioSinkClassExtension:
+ * @clear-all: Clear the device. Since: 1.18
+ */
+struct _GstAudioSinkClassExtension
+{
   /* clear the audio device */
   void     (*clear_all) (GstAudioSink *sink);
 
-  /*< private >*/
-  gpointer _gst_reserved[GST_PADDING - 4];
+  /* no padding needed  */
 };
 
 GST_AUDIO_API