From 6397d2f910a2ef9160abcc51acbc2dfd4c165a3f Mon Sep 17 00:00:00 2001
From: Matthew Waters <matthew@centricular.com>
Date: Mon, 23 Mar 2020 14:02:22 +1100
Subject: [PATCH] qmlgloverlay: don't leak resources freed on a different GL
 thread

deleting a QOpenGLFrameBufferObject needs to occur on the same thread it
was created on in order to actually free the relevant resources
immediately.  Otherwise, they will be queued for deletion and not freed
until the associated QOpenGLContext is destroyed.
---
 ext/qt/qtglrenderer.cc | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/ext/qt/qtglrenderer.cc b/ext/qt/qtglrenderer.cc
index e78bcdf465..75ed10f309 100644
--- a/ext/qt/qtglrenderer.cc
+++ b/ext/qt/qtglrenderer.cc
@@ -170,11 +170,26 @@ GstQuickRenderer::activateContext ()
 {
 }
 
-static void
-delete_cxx (QOpenGLFramebufferObject * cxx)
+struct FBOUserData
 {
-  GST_TRACE ("freeing Qfbo %p", cxx);
-  delete cxx;
+  GstGLContext * context;
+  QOpenGLFramebufferObject * fbo;
+};
+
+static void
+delete_cxx_gl_context (GstGLContext * context, struct FBOUserData * data)
+{
+  GST_TRACE ("freeing Qfbo %p", data->fbo);
+  delete data->fbo;
+}
+
+static void
+notify_fbo_delete (struct FBOUserData * data)
+{
+  gst_gl_context_thread_add (data->context,
+      (GstGLContextThreadFunc) delete_cxx_gl_context, data);
+  gst_object_unref (data->context);
+  g_free (data);
 }
 
 GstQuickRenderer::GstQuickRenderer()
@@ -294,7 +309,7 @@ bool GstQuickRenderer::init (GstGLContext * context, GError ** error)
     gl_params = (GstGLAllocationParams *)
         gst_gl_video_allocation_params_new_wrapped_texture (gl_context,
             NULL, &this->v_info, 0, NULL, GST_GL_TEXTURE_TARGET_2D, GST_GL_RGBA8,
-            0, NULL, (GDestroyNotify) delete_cxx);
+            0, NULL, (GDestroyNotify) notify_fbo_delete);
 
     /* This is a gross hack relying on the internals of Qt and GStreamer
      * however it's the only way to remove this warning on shutdown of all
@@ -435,7 +450,10 @@ GstQuickRenderer::renderGstGL ()
     m_renderControl->render();
 
     GST_DEBUG ("wrapping Qfbo %p with texture %u", m_fbo, m_fbo->texture());
-    gl_params->user_data = static_cast<gpointer> (m_fbo);
+    struct FBOUserData *data = g_new0 (struct FBOUserData, 1);
+    data->context = (GstGLContext *) gst_object_ref (gl_context);
+    data->fbo = m_fbo;
+    gl_params->user_data = static_cast<gpointer> (data);
     gl_params->gl_handle = GINT_TO_POINTER (m_fbo->texture());
     gl_mem = (GstGLMemory *) gst_gl_base_memory_alloc (gl_allocator, gl_params);