[gtk+/wip/otte/vulkan: 27/28] vulkan: Don't create more than one render object

[Benjamin Otte <otte src gnome org>]

commit afc3e58abc60130428c8d1f068339913e04753f8
Author: Benjamin Otte <otte redhat com>
Date:   Fri Dec 9 06:13:14 2016 +0100

    vulkan: Don't create more than one render object
    
    By creating unlimited render objects, we would never wait on the GPU.
    
    This would mean that if the GPU was the bottleneck, we would fill its
    queue with render commands faster than it could process them.
    
    And because the nvidia binary driver and my code work surprisingly well
    and bugfree, this lead to exhaustion of RAM. I had 50GB of swap
    configured and my hard disk was quicker as swap storage than my GPU was
    at processing the commands, so stuff still filled up.
    
    At that point my computer became rather unresponsive and I decided to
    reboot it, so I that could write this patch.

 gsk/gskvulkanrenderer.c |   24 ++++--------------------
 1 files changed, 4 insertions(+), 20 deletions(-)
---
diff --git a/gsk/gskvulkanrenderer.c b/gsk/gskvulkanrenderer.c
index 488b8f4..2f71dc0 100644
--- a/gsk/gskvulkanrenderer.c
+++ b/gsk/gskvulkanrenderer.c
@@ -33,7 +33,7 @@ struct _GskVulkanRenderer
 
   VkSampler sampler;
 
-  GSList *renders;
+  GskVulkanRender *render;
 
 #ifdef G_ENABLE_DEBUG
   ProfileTimers profile_timers;
@@ -123,8 +123,7 @@ gsk_vulkan_renderer_realize (GskRenderer  *renderer,
                     self);
   gsk_vulkan_renderer_update_images_cb (self->vulkan, self);
 
-  /* We will need at least one render object, so create it early where we can still fail fine */
-  self->renders = g_slist_prepend (self->renders, gsk_vulkan_render_new (renderer, self->vulkan));
+  self->render = gsk_vulkan_render_new (renderer, self->vulkan);
 
   return TRUE;
 }
@@ -135,8 +134,7 @@ gsk_vulkan_renderer_unrealize (GskRenderer *renderer)
   GskVulkanRenderer *self = GSK_VULKAN_RENDERER (renderer);
   VkDevice device;
 
-  g_slist_free_full (self->renders, (GDestroyNotify) gsk_vulkan_render_free);
-  self->renders = NULL;
+  g_clear_pointer (&self->render, gsk_vulkan_render_free);
 
   device = gdk_vulkan_context_get_device (self->vulkan);
 
@@ -159,7 +157,6 @@ gsk_vulkan_renderer_render (GskRenderer   *renderer,
 {
   GskVulkanRenderer *self = GSK_VULKAN_RENDERER (renderer);
   GskVulkanRender *render;
-  GSList *l;
 #ifdef G_ENABLE_DEBUG
   GskProfiler *profiler;
   gint64 cpu_time;
@@ -170,20 +167,7 @@ gsk_vulkan_renderer_render (GskRenderer   *renderer,
   gsk_profiler_timer_begin (profiler, self->profile_timers.cpu_time);
 #endif
 
-  for (l = self->renders; l; l = l->next)
-    {
-      if (!gsk_vulkan_render_is_busy (l->data))
-        break;
-    }
-  if (l)
-    {
-      render = l->data;
-    }
-  else
-    {
-      render = gsk_vulkan_render_new (renderer, self->vulkan);
-      self->renders = g_slist_prepend (self->renders, render);
-    }
+  render = self->render;
 
   gsk_vulkan_render_reset (render, self->targets[gdk_vulkan_context_get_draw_index (self->vulkan)]);