gsk: Add GskRenderTree

A render tree owns all the nodes that are created during a frame,
and they are allocated with a custom allocator. All the resources
allocated for the tree are kept until destruction, and then
it is all released at the same time.

Allocation happes in chunks which makes both allocation and
freeing very efficient, and also quite cache efficient.

This somewhat changes the memory management of GskRenderNode. All
nodes created by the tree are owned by the tree, and normally you
don't need to ref them. If you want to keep them around you can still
ref them, but that actually refs the entire tree.

gsk/gskrenderer.c

@@ -688,38 +688,38 @@ gsk_renderer_render_texture (GskRenderer           *renderer,
 /**
  * gsk_renderer_render:
  * @renderer: a #GskRenderer
- * @root: a #GskRenderNode
+ * @root_node: a #GskRenderNode
  * @context: The drawing context created via gsk_renderer_begin_draw_frame()
  *
  * Renders the scene graph, described by a tree of #GskRenderNode instances,
  * using the given #GdkDrawingContext.
  *
- * The @renderer will acquire a reference on the #GskRenderNode tree while
+ * The @renderer will acquire a reference on the #GskRenderNode while
  * the rendering is in progress.
  *
  * Since: 3.90
  */
 void
 gsk_renderer_render (GskRenderer       *renderer,
-                     GskRenderNode     *root,
+                     GskRenderNode     *root_node,
                      GdkDrawingContext *context)
 {
   GskRendererPrivate *priv = gsk_renderer_get_instance_private (renderer);
 
   g_return_if_fail (GSK_IS_RENDERER (renderer));
   g_return_if_fail (priv->is_realized);
-  g_return_if_fail (GSK_IS_RENDER_NODE (root));
+  g_return_if_fail (GSK_IS_RENDER_NODE (root_node));
   g_return_if_fail (priv->root_node == NULL);
   g_return_if_fail (GDK_IS_DRAWING_CONTEXT (context));
   g_return_if_fail (context == priv->drawing_context);
 
-  priv->root_node = gsk_render_node_ref (root);
+  priv->root_node = gsk_render_node_ref (root_node);
 
 #ifdef G_ENABLE_DEBUG
   gsk_profiler_reset (priv->profiler);
 #endif
 
-  GSK_RENDERER_GET_CLASS (renderer)->render (renderer, root);
+  GSK_RENDERER_GET_CLASS (renderer)->render (renderer, root_node);
 
 #ifdef G_ENABLE_DEBUG
   if (GSK_DEBUG_CHECK (RENDERER))

gsk/gskrenderer.h

@@ -75,7 +75,7 @@ GdkDrawingContext *     gsk_renderer_begin_draw_frame           (GskRenderer
                                                                  const cairo_region_t    *region);
 GDK_AVAILABLE_IN_3_90
 void                    gsk_renderer_render                     (GskRenderer             *renderer,
-                                                                 GskRenderNode           *root,
+                                                                 GskRenderNode           *root_node,
                                                                  GdkDrawingContext       *context);
 GDK_AVAILABLE_IN_3_90
 void                    gsk_renderer_end_draw_frame             (GskRenderer             *renderer,

gsk/gskrendernode.c

@@ -53,6 +53,113 @@
 
 #include <gobject/gvaluecollector.h>
 
+#define ALLOCATE_CHUNK_SIZE (16*1024 - 2*sizeof(gsize))
+
+#define ALIGN(size, base)       ((base) * (gsize) (((size) + (base) - 1) / (base)))
+
+struct _GskRenderTree
+{
+  GObject parent_instance;
+
+  guint8 *chunk;
+  gsize chunk_offset;
+  int chunk_count;
+
+  GPtrArray *destroy_list;
+};
+
+G_DEFINE_TYPE (GskRenderTree, gsk_render_tree, G_TYPE_OBJECT)
+G_DEFINE_QUARK (gsk-serialization-error-quark, gsk_serialization_error)
+
+static void
+gsk_render_tree_finalize (GObject *gobject)
+{
+  GskRenderTree *self = GSK_RENDER_TREE (gobject);
+  int i;
+
+  /* We free in reverse order, because the notify may touch
+     something allocated before it */
+  for (i = self->destroy_list->len - 2; i >= 0 ; i -= 2)
+    {
+      GDestroyNotify notify = g_ptr_array_index (self->destroy_list, i);
+      gpointer data = g_ptr_array_index (self->destroy_list, i + 1);
+      notify (data);
+    }
+
+  g_ptr_array_free (self->destroy_list, TRUE);
+
+  G_OBJECT_CLASS (gsk_render_tree_parent_class)->finalize (gobject);
+}
+
+static void
+gsk_render_tree_class_init (GskRenderTreeClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->finalize = gsk_render_tree_finalize;
+}
+
+static void
+gsk_render_tree_init (GskRenderTree *self)
+{
+  self->destroy_list = g_ptr_array_new ();
+}
+
+void
+gsk_render_tree_add_cleanup (GskRenderTree  *self,
+                             GDestroyNotify notify,
+                             gpointer data)
+{
+  g_ptr_array_add (self->destroy_list, notify);
+  g_ptr_array_add (self->destroy_list, data);
+}
+
+/* Note: Align-size must be a power of two */
+gpointer
+gsk_render_tree_allocate (GskRenderTree *self, gsize n_bytes, gsize align_size)
+{
+  gpointer data = NULL;
+
+  if (n_bytes >= ALLOCATE_CHUNK_SIZE / 4)
+    {
+      data = g_malloc0 (n_bytes);
+      gsk_render_tree_add_cleanup (self, g_free, data);
+    }
+  else
+    {
+      self->chunk_offset = (self->chunk_offset + align_size - 1) & ~(align_size - 1);
+      if (self->chunk == NULL || (ALLOCATE_CHUNK_SIZE - self->chunk_offset) < n_bytes)
+        {
+          self->chunk = g_malloc (ALLOCATE_CHUNK_SIZE);
+          gsk_render_tree_add_cleanup (self, g_free, self->chunk);
+          self->chunk_offset = 0;
+        }
+
+      data = self->chunk + self->chunk_offset;
+      self->chunk_offset += n_bytes;
+      memset (data, 0, n_bytes);
+    }
+
+  return data;
+}
+
+GskRenderNode *
+gsk_render_tree_ref_foreign (GskRenderTree  *tree, GskRenderNode *node)
+{
+  if (node->tree != tree)
+    gsk_render_tree_add_cleanup (tree, (GDestroyNotify)gsk_render_node_unref, gsk_render_node_ref (node));
+
+  return node;
+}
+
+
+GskRenderTree *
+gsk_render_tree_new ()
+{
+  return g_object_new (GSK_TYPE_RENDER_TREE,
+                       NULL);
+}
+
 /**
  * GskRenderNode: (ref-func gsk_render_node_ref) (unref-func gsk_render_node_unref)
  *
@@ -65,42 +172,34 @@ G_DEFINE_BOXED_TYPE (GskRenderNode, gsk_render_node,
                      gsk_render_node_ref,
                      gsk_render_node_unref)
 
-G_DEFINE_QUARK (gsk-serialization-error-quark, gsk_serialization_error)
-
-static void
-gsk_render_node_finalize (GskRenderNode *self)
-{
-  self->node_class->finalize (self);
-
-  g_clear_pointer (&self->name, g_free);
-
-  g_free (self);
-}
-
 /*< private >
- * gsk_render_node_new:
+ * gsk_render_tree_new_node:
  * @node_class: class structure for this node
  *
  * Returns: (transfer full): the newly created #GskRenderNode
  */
 GskRenderNode *
-gsk_render_node_new (const GskRenderNodeClass *node_class, gsize extra_size)
+gsk_render_tree_new_node (GskRenderTree *self, const GskRenderNodeClass *node_class, gsize extra_size)
 {
-  GskRenderNode *self;
+  GskRenderNode *node;
 
   g_return_val_if_fail (node_class != NULL, NULL);
   g_return_val_if_fail (node_class->node_type != GSK_NOT_A_RENDER_NODE, NULL);
 
-  self = g_malloc0 (node_class->struct_size + extra_size);
+  node = gsk_render_tree_allocate (self, node_class->struct_size + extra_size, 2*sizeof(gsize));
 
-  self->node_class = node_class;
+  node->node_class = node_class;
+  node->tree = self;
+  node->min_filter = GSK_SCALING_FILTER_NEAREST;
+  node->mag_filter = GSK_SCALING_FILTER_NEAREST;
 
-  self->ref_count = 1;
+  return node;
+}
 
-  self->min_filter = GSK_SCALING_FILTER_NEAREST;
-  self->mag_filter = GSK_SCALING_FILTER_NEAREST;
-
-  return self;
+GskRenderTree *
+gsk_render_node_get_tree (GskRenderNode *self)
+{
+  return self->tree;
 }
 
 /**
@@ -108,6 +207,10 @@ gsk_render_node_new (const GskRenderNodeClass *node_class, gsize extra_size)
  * @node: a #GskRenderNode
  *
  * Acquires a reference on the given #GskRenderNode.
+ * All nodes are owned by the tree they are part of, so normally you don't
+ * need to ref individual nodes.
+ *
+ * Note: This keeps the whole tree alive for the lifetime of the node.
  *
  * Returns: (transfer none): the #GskRenderNode with an additional reference
  *
@@ -116,9 +219,12 @@ gsk_render_node_new (const GskRenderNodeClass *node_class, gsize extra_size)
 GskRenderNode *
 gsk_render_node_ref (GskRenderNode *node)
 {
+  GskRenderTree *tree;
+
   g_return_val_if_fail (GSK_IS_RENDER_NODE (node), NULL);
 
-  g_atomic_int_inc (&node->ref_count);
+  tree = gsk_render_node_get_tree (node);
+  g_object_ref (tree);
 
   return node;
 }
@@ -137,10 +243,12 @@ gsk_render_node_ref (GskRenderNode *node)
 void
 gsk_render_node_unref (GskRenderNode *node)
 {
+  GskRenderTree *tree;
+
   g_return_if_fail (GSK_IS_RENDER_NODE (node));
 
-  if (g_atomic_int_dec_and_test (&node->ref_count))
-    gsk_render_node_finalize (node);
+  tree = gsk_render_node_get_tree (node);
+  g_object_unref (tree);
 }
 
 /**
@@ -209,10 +317,16 @@ void
 gsk_render_node_set_name (GskRenderNode *node,
                           const char    *name)
 {
+  GskRenderTree *tree;
+  char *new_name;
+
   g_return_if_fail (GSK_IS_RENDER_NODE (node));
 
-  g_free (node->name);
-  node->name = g_strdup (name);
+  tree = gsk_render_node_get_tree (node);
+
+  new_name = gsk_render_tree_allocate (tree, strlen (name) + 1, 1);
+  strcpy (new_name, name);
+  node->name = new_name;
 }
 
 /**
@@ -391,6 +505,7 @@ gsk_render_node_deserialize (GBytes  *bytes,
   guint32 version, node_type;
   GVariant *variant, *node_variant;
   GskRenderNode *node = NULL;
+  GskRenderTree *tree;
 
   variant = g_variant_new_from_bytes (G_VARIANT_TYPE ("(suuv)"), bytes, FALSE);
 
@@ -410,7 +525,10 @@ gsk_render_node_deserialize (GBytes  *bytes,
       goto out;
     }
 
-  node = gsk_render_node_deserialize_node (node_type, node_variant, error);
+  tree = gsk_render_tree_new ();
+  node = gsk_render_node_deserialize_node (tree, node_type, node_variant, error);
+  gsk_render_node_ref (node);
+  g_object_unref (tree);
 
 out:
   g_free (id_string);

gsk/gskrendernode.h

@@ -28,12 +28,17 @@
 
 G_BEGIN_DECLS
 
-#define GSK_TYPE_RENDER_NODE (gsk_render_node_get_type ())
+#define GSK_TYPE_RENDER_TREE (gsk_render_tree_get_type ())
 
+GDK_AVAILABLE_IN_3_90
+G_DECLARE_FINAL_TYPE (GskRenderTree, gsk_render_tree, GSK, RENDER_TREE, GObject)
+
+#define GSK_TYPE_RENDER_NODE (gsk_render_node_get_type ())
 #define GSK_IS_RENDER_NODE(obj) ((obj) != NULL)
 
 #define GSK_SERIALIZATION_ERROR       (gsk_serialization_error_quark ())
 
+typedef struct _GskRenderTree           GskRenderTree;
 typedef struct _GskRenderNode           GskRenderNode;
 typedef struct _GskColorStop            GskColorStop;
 typedef struct _GskShadow               GskShadow;
@@ -53,10 +58,11 @@ struct _GskShadow
 };
 
 GDK_AVAILABLE_IN_3_90
-GType                   gsk_render_node_get_type                (void) G_GNUC_CONST;
+GQuark                  gsk_serialization_error_quark           (void);
+GskRenderTree * gsk_render_tree_new (void);
 
 GDK_AVAILABLE_IN_3_90
-GQuark                  gsk_serialization_error_quark           (void);
+GType gsk_render_node_get_type (void) G_GNUC_CONST;
 
 GDK_AVAILABLE_IN_3_90
 GskRenderNode *         gsk_render_node_ref                     (GskRenderNode *node);
@@ -67,40 +73,47 @@ GDK_AVAILABLE_IN_3_90
 GskRenderNodeType       gsk_render_node_get_node_type           (GskRenderNode *node);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_color_node_new                      (const GdkRGBA            *rgba,
+GskRenderNode *         gsk_color_node_new                      (GskRenderTree            *tree,
+                                                                 const GdkRGBA            *rgba,
                                                                  const graphene_rect_t    *bounds);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_texture_node_new                    (GskTexture               *texture,
+GskRenderNode *         gsk_texture_node_new                    (GskRenderTree            *tree,
+                                                                 GskTexture               *texture,
                                                                  const graphene_rect_t    *bounds);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_linear_gradient_node_new            (const graphene_rect_t    *bounds,
+GskRenderNode *         gsk_linear_gradient_node_new            (GskRenderTree            *tree,
+                                                                 const graphene_rect_t    *bounds,
                                                                  const graphene_point_t   *start,
                                                                  const graphene_point_t   *end,
                                                                  const GskColorStop       *color_stops,
                                                                  gsize                     n_color_stops);
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_repeating_linear_gradient_node_new  (const graphene_rect_t    *bounds,
+GskRenderNode *         gsk_repeating_linear_gradient_node_new  (GskRenderTree            *tree,
+                                                                 const graphene_rect_t    *bounds,
                                                                  const graphene_point_t   *start,
                                                                  const graphene_point_t   *end,
                                                                  const GskColorStop       *color_stops,
                                                                  gsize                     n_color_stops);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_border_node_new                     (const GskRoundedRect     *outline,
+GskRenderNode *         gsk_border_node_new                     (GskRenderTree            *tree,
+                                                                 const GskRoundedRect     *outline,
                                                                  const float               border_width[4],
                                                                  const GdkRGBA             border_color[4]);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_inset_shadow_node_new               (const GskRoundedRect     *outline,
+GskRenderNode *         gsk_inset_shadow_node_new               (GskRenderTree            *tree,
+                                                                 const GskRoundedRect     *outline,
                                                                  const GdkRGBA            *color,
                                                                  float                     dx,
                                                                  float                     dy,
                                                                  float                     spread,
                                                                  float                     blur_radius);
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_outset_shadow_node_new              (const GskRoundedRect     *outline,
+GskRenderNode *         gsk_outset_shadow_node_new              (GskRenderTree            *tree,
+                                                                 const GskRoundedRect     *outline,
                                                                  const GdkRGBA            *color,
                                                                  float                     dx,
                                                                  float                     dy,
@@ -108,13 +121,15 @@ GskRenderNode *         gsk_outset_shadow_node_new              (const GskRounde
                                                                  float                     blur_radius);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_cairo_node_new                      (const graphene_rect_t    *bounds);
+GskRenderNode *         gsk_cairo_node_new                      (GskRenderTree            *tree,
+                                                                 const graphene_rect_t    *bounds);
 GDK_AVAILABLE_IN_3_90
 cairo_t *               gsk_cairo_node_get_draw_context         (GskRenderNode            *node,
                                                                  GskRenderer              *renderer);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_container_node_new                  (GskRenderNode           **children,
+GskRenderNode *         gsk_container_node_new                  (GskRenderTree            *tree,
+                                                                 GskRenderNode           **children,
                                                                  guint                     n_children);
 GDK_AVAILABLE_IN_3_90
 guint                   gsk_container_node_get_n_children       (GskRenderNode            *node);
@@ -123,51 +138,60 @@ GskRenderNode *         gsk_container_node_get_child            (GskRenderNode
                                                                  guint                     idx);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_transform_node_new                  (GskRenderNode            *child,
+GskRenderNode *         gsk_transform_node_new                  (GskRenderTree            *tree,
+                                                                 GskRenderNode            *child,
                                                                  const graphene_matrix_t  *transform);
 GDK_AVAILABLE_IN_3_90
 GskRenderNode *         gsk_transform_node_get_child            (GskRenderNode            *node);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_opacity_node_new                    (GskRenderNode            *child,
+GskRenderNode *         gsk_opacity_node_new                    (GskRenderTree            *tree,
+                                                                 GskRenderNode            *child,
                                                                  double                    opacity);
 GDK_AVAILABLE_IN_3_90
 GskRenderNode *         gsk_opacity_node_get_child              (GskRenderNode            *node);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_color_matrix_node_new               (GskRenderNode            *child,
+GskRenderNode *         gsk_color_matrix_node_new               (GskRenderTree            *tree,
+                                                                 GskRenderNode            *child,
                                                                  const graphene_matrix_t  *color_matrix,
                                                                  const graphene_vec4_t    *color_offset);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_repeat_node_new                     (const graphene_rect_t    *bounds,
+GskRenderNode *         gsk_repeat_node_new                     (GskRenderTree            *tree,
+                                                                 const graphene_rect_t    *bounds,
                                                                  GskRenderNode            *child,
                                                                  const graphene_rect_t    *child_bounds);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_clip_node_new                       (GskRenderNode            *child,
+GskRenderNode *         gsk_clip_node_new                       (GskRenderTree            *tree,
+                                                                 GskRenderNode            *child,
                                                                  const graphene_rect_t    *clip);
 GDK_AVAILABLE_IN_3_90
 GskRenderNode *         gsk_clip_node_get_child                 (GskRenderNode            *node);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_rounded_clip_node_new               (GskRenderNode            *child,
+GskRenderNode *         gsk_rounded_clip_node_new               (GskRenderTree            *tree,
+                                                                 GskRenderNode            *child,
                                                                  const GskRoundedRect     *clip);
 GDK_AVAILABLE_IN_3_90
 GskRenderNode *         gsk_rounded_clip_node_get_child         (GskRenderNode            *node);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_shadow_node_new                     (GskRenderNode            *child,
+GskRenderNode *         gsk_shadow_node_new                     (GskRenderTree            *tree,
+                                                                 GskRenderNode            *child,
                                                                  const GskShadow          *shadows,
                                                                  gsize                     n_shadows);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_blend_node_new                      (GskRenderNode            *bottom,
+GskRenderNode *         gsk_blend_node_new                      (GskRenderTree            *tree,
+                                                                 GskRenderNode            *bottom,
                                                                  GskRenderNode            *top,
                                                                  GskBlendMode              blend_mode);
 
 GDK_AVAILABLE_IN_3_90
-GskRenderNode *         gsk_cross_fade_node_new                 (GskRenderNode            *start,
+GskRenderNode *         gsk_cross_fade_node_new                 (GskRenderTree            *tree,
+                                                                 GskRenderNode            *start,
                                                                  GskRenderNode            *end,
                                                                  double                    progress);
 

gsk/gskrendernodeprivate.h

@@ -13,8 +13,7 @@ typedef struct _GskRenderNodeClass GskRenderNodeClass;
 struct _GskRenderNode
 {
   const GskRenderNodeClass *node_class;
-
-  volatile int ref_count;
+  GskRenderTree *tree;
 
   /* Use for debugging */
   char *name;
@@ -31,19 +30,23 @@ struct _GskRenderNodeClass
   GskRenderNodeType node_type;
   gsize struct_size;
   const char *type_name;
-  void (* finalize) (GskRenderNode *node);
   void (* draw) (GskRenderNode *node,
                  cairo_t       *cr);
   GVariant * (* serialize) (GskRenderNode *node);
-  GskRenderNode * (* deserialize) (GVariant  *variant,
+  GskRenderNode * (* deserialize) (GskRenderTree *tree,
+                                   GVariant  *variant,
                                    GError   **error);
 };
 
-GskRenderNode *gsk_render_node_new (const GskRenderNodeClass *node_class, gsize extra_size);
+GskRenderNode *gsk_render_tree_new_node (GskRenderTree  *tree, const GskRenderNodeClass *node_class, gsize extra_size);
+gpointer gsk_render_tree_allocate (GskRenderTree *self, gsize n_bytes, gsize align_size);
+void gsk_render_tree_add_cleanup (GskRenderTree  *tree, GDestroyNotify notify, gpointer data);
+GskRenderNode *gsk_render_tree_ref_foreign (GskRenderTree  *tree, GskRenderNode *node);
 
 GVariant * gsk_render_node_serialize_node (GskRenderNode *node);
-GskRenderNode * gsk_render_node_deserialize_node (GskRenderNodeType type, GVariant *variant, GError **error);
+GskRenderNode * gsk_render_node_deserialize_node (GskRenderTree *tree, GskRenderNodeType type, GVariant *variant, GError **error);
 
+GskRenderTree *gsk_render_node_get_tree (GskRenderNode *self);
 double gsk_opacity_node_get_opacity (GskRenderNode *node);
 
 GskRenderNode * gsk_color_matrix_node_get_child (GskRenderNode *node);
@@ -62,7 +65,7 @@ const GskRoundedRect * gsk_border_node_peek_outline (GskRenderNode *node);
 float gsk_border_node_get_width (GskRenderNode *node, guint i);
 const GdkRGBA * gsk_border_node_peek_color (GskRenderNode *node, guint i);
 
-GskRenderNode *gsk_cairo_node_new_for_surface (const graphene_rect_t *bounds, cairo_surface_t *surface);
+GskRenderNode *gsk_cairo_node_new_for_surface (GskRenderTree *tree, const graphene_rect_t *bounds, cairo_surface_t *surface);
 cairo_surface_t *gsk_cairo_node_get_surface (GskRenderNode *node);
 
 GskTexture *gsk_texture_node_get_texture (GskRenderNode *node);

gtk/gtkcssimagecrossfade.c

@@ -139,29 +139,23 @@ gtk_css_image_cross_fade_snapshot (GtkCssImage *image,
 
       if (start_node && end_node)
         {
-          GskRenderNode *node = gsk_cross_fade_node_new (start_node, end_node, cross_fade->progress);
+          GskRenderNode *node = gsk_cross_fade_node_new (gtk_snapshot_get_tree (snapshot), start_node, end_node, cross_fade->progress);
 
           if (snapshot->record_names)
             gsk_render_node_set_name (node, "CrossFade");
           gtk_snapshot_append_node (snapshot, node);
-
-          gsk_render_node_unref (node);
-          gsk_render_node_unref (start_node);
-          gsk_render_node_unref (end_node);
         }
       else if (start_node)
         {
           gtk_snapshot_push_opacity (snapshot, 1.0 - cross_fade->progress, "CrossFadeStart");
           gtk_snapshot_append_node (snapshot, start_node);
           gtk_snapshot_pop_and_append (snapshot);
-          gsk_render_node_unref (start_node);
         }
       else if (end_node)
         {
           gtk_snapshot_push_opacity (snapshot, cross_fade->progress, "CrossFadeEnd");
           gtk_snapshot_append_node (snapshot, end_node);
           gtk_snapshot_pop_and_append (snapshot);
-          gsk_render_node_unref (end_node);
         }
     }
 }

gtk/gtkcssimagelinear.c

@@ -238,6 +238,7 @@ gtk_css_image_linear_snapshot (GtkCssImage        *image,
   if (linear->repeating)
     {
       node = gsk_repeating_linear_gradient_node_new (
+          gtk_snapshot_get_tree (snapshot),
           &GRAPHENE_RECT_INIT (off_x, off_y, width, height),
           &GRAPHENE_POINT_INIT (off_x + width / 2 + x * (start - 0.5), off_y + height / 2 + y * (start - 0.5)),
           &GRAPHENE_POINT_INIT (off_x + width / 2 + x * (end - 0.5),   off_y + height / 2 + y * (end - 0.5)),
@@ -247,6 +248,7 @@ gtk_css_image_linear_snapshot (GtkCssImage        *image,
   else
     {
       node = gsk_linear_gradient_node_new (
+          gtk_snapshot_get_tree (snapshot),
           &GRAPHENE_RECT_INIT (off_x, off_y, width, height),
           &GRAPHENE_POINT_INIT (off_x + width / 2 + x * (start - 0.5), off_y + height / 2 + y * (start - 0.5)),
           &GRAPHENE_POINT_INIT (off_x + width / 2 + x * (end - 0.5),   off_y + height / 2 + y * (end - 0.5)),
@@ -262,8 +264,6 @@ gtk_css_image_linear_snapshot (GtkCssImage        *image,
     }
 
   gtk_snapshot_append_node (snapshot, node);
-
-  gsk_render_node_unref (node);
 }
 
 

gtk/gtkcssshadowvalue.c

@@ -1051,7 +1051,8 @@ gtk_css_shadow_value_snapshot_outset (const GtkCssValue    *shadow,
   gsk_rounded_rect_init_copy (&outline, border_box);
   gsk_rounded_rect_offset (&outline, off_x, off_y);
 
-  node = gsk_outset_shadow_node_new (&outline, 
+  node = gsk_outset_shadow_node_new (gtk_snapshot_get_tree (snapshot),
+                                     &outline,
                                      _gtk_css_rgba_value_get_rgba (shadow->color),
                                      _gtk_css_number_value_get (shadow->hoffset, 0),
                                      _gtk_css_number_value_get (shadow->voffset, 0),
@@ -1060,7 +1061,6 @@ gtk_css_shadow_value_snapshot_outset (const GtkCssValue    *shadow,
   if (snapshot->record_names)
     gsk_render_node_set_name (node, "Outset Shadow");
   gtk_snapshot_append_node (snapshot, node);
-  gsk_render_node_unref (node);
 }
 
 void
@@ -1082,7 +1082,8 @@ gtk_css_shadow_value_snapshot_inset (const GtkCssValue   *shadow,
   gsk_rounded_rect_init_copy (&outline, padding_box);
   gsk_rounded_rect_offset (&outline, off_x, off_y);
 
-  node = gsk_inset_shadow_node_new (&outline, 
+  node = gsk_inset_shadow_node_new (gtk_snapshot_get_tree (snapshot),
+                                     &outline,
                                     _gtk_css_rgba_value_get_rgba (shadow->color),
                                     _gtk_css_number_value_get (shadow->hoffset, 0),
                                     _gtk_css_number_value_get (shadow->voffset, 0),
@@ -1091,6 +1092,5 @@ gtk_css_shadow_value_snapshot_inset (const GtkCssValue   *shadow,
   if (snapshot->record_names)
     gsk_render_node_set_name (node, "Inset Shadow");
   gtk_snapshot_append_node (snapshot, node);
-  gsk_render_node_unref (node);
 }
 

gtk/gtkiconview.c

@@ -7024,6 +7024,8 @@ gtk_icon_view_create_drag_icon (GtkIconView *icon_view,
           gsk_render_node_draw (node, cr);
 	  cairo_destroy (cr);
 
+          gsk_render_node_unref (node);
+
 	  return surface;
 	}
     }

gtk/gtkrenderbackground.c

@@ -676,20 +676,16 @@ gtk_css_style_snapshot_background (GtkCssStyle      *style,
 
               /* XXX: Is this necessary? Do we need a NULL node? */
               if (top == NULL)
-                top = gsk_container_node_new (NULL, 0);
+                top = gsk_container_node_new (gtk_snapshot_get_tree (snapshot), NULL, 0);
               if (bottom == NULL)
-                bottom = gsk_container_node_new (NULL, 0);
+                bottom = gsk_container_node_new (gtk_snapshot_get_tree (snapshot), NULL, 0);
 
-              blend = gsk_blend_node_new (bottom, top, blend_mode);
+              blend = gsk_blend_node_new (gtk_snapshot_get_tree (snapshot), bottom, top, blend_mode);
               if (snapshot->record_names)
                 gsk_render_node_set_name (blend, "BackgroundBlend");
 
               gtk_snapshot_push (snapshot, TRUE, "BackgroundBlendGroup");
               gtk_snapshot_append_node (snapshot, blend);
-
-              gsk_render_node_unref (blend);
-              gsk_render_node_unref (top);
-              gsk_render_node_unref (bottom);
             }
         }
 

gtk/gtkrenderborder.c

@@ -437,11 +437,10 @@ snapshot_frame_fill (GtkSnapshot          *snapshot,
   gsk_rounded_rect_init_copy (&offset_outline, outline);
   gsk_rounded_rect_offset (&offset_outline, off_x, off_y);
   
-  node = gsk_border_node_new (&offset_outline, border_width, colors);
+  node = gsk_border_node_new (snapshot->tree, &offset_outline, border_width, colors);
   if (snapshot->record_names)
     gsk_render_node_set_name (node, "Border");
   gtk_snapshot_append_node (snapshot, node);
-  gsk_render_node_unref (node);
 }
 
 static void

gtk/gtksnapshot.c

@@ -62,11 +62,11 @@ gtk_snapshot_collect_default (GtkSnapshotState *state,
     }
   else if (n_nodes == 1)
     {
-      node = gsk_render_node_ref (nodes[0]);
+      node = nodes[0];
     }
   else
     {
-      node = gsk_container_node_new (nodes, n_nodes);
+      node = gsk_container_node_new (state->tree, nodes, n_nodes);
       if (name)
         gsk_render_node_set_name (node, name);
     }
@@ -77,6 +77,7 @@ gtk_snapshot_collect_default (GtkSnapshotState *state,
 static GtkSnapshotState *
 gtk_snapshot_state_new (GtkSnapshotState       *parent,
                         char                   *name,
+                        GskRenderTree          *tree,
                         cairo_region_t         *clip,
                         int                     translate_x,
                         int                     translate_y,
@@ -92,11 +93,12 @@ gtk_snapshot_state_new (GtkSnapshotState       *parent,
   else
     {
       state = g_slice_new0 (GtkSnapshotState);
-      state->nodes = g_ptr_array_new_with_free_func ((GDestroyNotify) gsk_render_node_unref);
+      state->nodes = g_ptr_array_new ();
       state->parent = parent;
     }
 
   state->name = name;
+  state->tree = tree;
   if (clip)
     state->clip_region = cairo_region_reference (clip);
   state->translate_x = translate_x;
@@ -137,6 +139,7 @@ gtk_snapshot_init (GtkSnapshot          *snapshot,
   snapshot->state = NULL;
   snapshot->record_names = record_names;
   snapshot->renderer = renderer;
+  snapshot->tree = gsk_render_tree_new ();
 
   if (name && record_names)
     {
@@ -151,6 +154,7 @@ gtk_snapshot_init (GtkSnapshot          *snapshot,
 
   snapshot->state = gtk_snapshot_state_new (NULL,
                                             str,
+                                            snapshot->tree,
                                             (cairo_region_t *) clip,
                                             0, 0,
                                             gtk_snapshot_collect_default);
@@ -160,7 +164,7 @@ GskRenderNode *
 gtk_snapshot_finish (GtkSnapshot *snapshot)
 {
   GskRenderNode *result;
-  
+
   result = gtk_snapshot_pop (snapshot);
 
   if (snapshot->state != NULL)
@@ -168,6 +172,9 @@ gtk_snapshot_finish (GtkSnapshot *snapshot)
       g_warning ("Too many gtk_snapshot_push() calls.");
     }
 
+  gsk_render_node_ref (result);
+  g_clear_object (&snapshot->tree);
+
   return result;
 }
 
@@ -208,6 +215,7 @@ gtk_snapshot_push (GtkSnapshot           *snapshot,
     {
       snapshot->state = gtk_snapshot_state_new (snapshot->state,
                                                 str,
+                                                snapshot->state->tree,
                                                 snapshot->state->clip_region,
                                                 snapshot->state->translate_x,
                                                 snapshot->state->translate_y,
@@ -217,6 +225,7 @@ gtk_snapshot_push (GtkSnapshot           *snapshot,
     {
       snapshot->state = gtk_snapshot_state_new (snapshot->state,
                                                 str,
+                                                snapshot->state->tree,
                                                 NULL,
                                                 0, 0,
                                                 gtk_snapshot_collect_default);
@@ -235,12 +244,10 @@ gtk_snapshot_collect_transform (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  transform_node = gsk_transform_node_new (node, &state->data.transform.transform);
+  transform_node = gsk_transform_node_new (state->tree, node, &state->data.transform.transform);
   if (name)
     gsk_render_node_set_name (transform_node, name);
 
-  gsk_render_node_unref (node);
-
   return transform_node;
 }
 
@@ -267,6 +274,7 @@ gtk_snapshot_push_transform (GtkSnapshot             *snapshot,
 
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   NULL,
                                   0, 0,
                                   gtk_snapshot_collect_transform);
@@ -295,12 +303,10 @@ gtk_snapshot_collect_opacity (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  opacity_node = gsk_opacity_node_new (node, state->data.opacity.opacity);
+  opacity_node = gsk_opacity_node_new (state->tree, node, state->data.opacity.opacity);
   if (name)
     gsk_render_node_set_name (opacity_node, name);
 
-  gsk_render_node_unref (node);
-
   return opacity_node;
 }
 
@@ -326,6 +332,7 @@ gtk_snapshot_push_opacity (GtkSnapshot *snapshot,
 
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   snapshot->state->clip_region,
                                   snapshot->state->translate_x,
                                   snapshot->state->translate_y,
@@ -346,14 +353,12 @@ gtk_snapshot_collect_color_matrix (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  color_matrix_node = gsk_color_matrix_node_new (node,
+  color_matrix_node = gsk_color_matrix_node_new (state->tree, node,
                                                  &state->data.color_matrix.matrix,
                                                  &state->data.color_matrix.offset);
   if (name)
     gsk_render_node_set_name (color_matrix_node, name);
 
-  gsk_render_node_unref (node);
-
   return color_matrix_node;
 }
 
@@ -380,6 +385,7 @@ gtk_snapshot_push_color_matrix (GtkSnapshot             *snapshot,
 
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   snapshot->state->clip_region,
                                   snapshot->state->translate_x,
                                   snapshot->state->translate_y,
@@ -414,14 +420,12 @@ gtk_snapshot_collect_repeat (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  repeat_node = gsk_repeat_node_new (bounds,
+  repeat_node = gsk_repeat_node_new (state->tree, bounds,
                                      node,
                                      child_bounds->size.width > 0 ? child_bounds : NULL);
   if (name)
     gsk_render_node_set_name (repeat_node, name);
 
-  gsk_render_node_unref (node);
-
   return repeat_node;
 }
 
@@ -458,6 +462,7 @@ gtk_snapshot_push_repeat (GtkSnapshot           *snapshot,
 
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   clip,
                                   snapshot->state->translate_x,
                                   snapshot->state->translate_y,
@@ -484,12 +489,10 @@ gtk_snapshot_collect_clip (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  clip_node = gsk_clip_node_new (node, &state->data.clip.bounds);
+  clip_node = gsk_clip_node_new (state->tree, node, &state->data.clip.bounds);
   if (name)
     gsk_render_node_set_name (clip_node, name);
 
-  gsk_render_node_unref (node);
-
   return clip_node;
 }
 
@@ -530,6 +533,7 @@ gtk_snapshot_push_clip (GtkSnapshot           *snapshot,
     }
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   clip,
                                   snapshot->state->translate_x,
                                   snapshot->state->translate_y,
@@ -554,12 +558,10 @@ gtk_snapshot_collect_rounded_clip (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  clip_node = gsk_rounded_clip_node_new (node, &state->data.rounded_clip.bounds);
+  clip_node = gsk_rounded_clip_node_new (state->tree, node, &state->data.rounded_clip.bounds);
   if (name)
     gsk_render_node_set_name (clip_node, name);
 
-  gsk_render_node_unref (node);
-
   return clip_node;
 }
 
@@ -602,6 +604,7 @@ gtk_snapshot_push_rounded_clip (GtkSnapshot          *snapshot,
 
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   clip,
                                   snapshot->state->translate_x,
                                   snapshot->state->translate_y,
@@ -626,11 +629,10 @@ gtk_snapshot_collect_shadow (GtkSnapshotState *state,
   if (node == NULL)
     return NULL;
 
-  shadow_node = gsk_shadow_node_new (node, state->data.shadow.shadows, state->data.shadow.n_shadows);
+  shadow_node = gsk_shadow_node_new (state->tree, node, state->data.shadow.shadows, state->data.shadow.n_shadows);
   if (name)
     gsk_render_node_set_name (shadow_node, name);
 
-  gsk_render_node_unref (node);
   if (state->data.shadow.shadows != &state->data.shadow.a_shadow)
     g_free (state->data.shadow.shadows);
 
@@ -661,6 +663,7 @@ gtk_snapshot_push_shadow (GtkSnapshot            *snapshot,
 
   state = gtk_snapshot_state_new (snapshot->state,
                                   str,
+                                  snapshot->state->tree,
                                   snapshot->state->clip_region,
                                   snapshot->state->translate_x,
                                   snapshot->state->translate_y,
@@ -736,10 +739,7 @@ gtk_snapshot_pop_and_append (GtkSnapshot *snapshot)
 
   node = gtk_snapshot_pop (snapshot);
   if (node)
-    {
-      gtk_snapshot_append_node (snapshot, node);
-      gsk_render_node_unref (node);
-    }
+    gtk_snapshot_append_node (snapshot, node);
 }
 
 /**
@@ -807,6 +807,12 @@ gtk_snapshot_get_offset (GtkSnapshot *snapshot,
     *y = snapshot->state->translate_y;
 }
 
+GskRenderTree *
+gtk_snapshot_get_tree (GtkSnapshot *snapshot)
+{
+  return snapshot->tree;
+}
+
 /**
  * gtk_snapshot_append_node:
  * @snapshot: a #GtkSnapshot
@@ -826,7 +832,7 @@ gtk_snapshot_append_node (GtkSnapshot   *snapshot,
 
   if (snapshot->state)
     {
-      g_ptr_array_add (snapshot->state->nodes, gsk_render_node_ref (node));
+      g_ptr_array_add (snapshot->state->nodes, node);
     }
   else
     {
@@ -863,7 +869,7 @@ gtk_snapshot_append_cairo_node (GtkSnapshot           *snapshot,
   g_return_val_if_fail (bounds != NULL, NULL);
 
   graphene_rect_offset_r (bounds, snapshot->state->translate_x, snapshot->state->translate_y, &real_bounds);
-  node = gsk_cairo_node_new (&real_bounds);
+  node = gsk_cairo_node_new (snapshot->tree, &real_bounds);
 
   if (name && snapshot->record_names)
     {
@@ -880,7 +886,6 @@ gtk_snapshot_append_cairo_node (GtkSnapshot           *snapshot,
     }
 
   gtk_snapshot_append_node (snapshot, node);
-  gsk_render_node_unref (node);
 
   cr = gsk_cairo_node_get_draw_context (node, snapshot->renderer);
 
@@ -915,7 +920,7 @@ gtk_snapshot_append_texture_node (GtkSnapshot            *snapshot,
   g_return_if_fail (bounds != NULL);
 
   graphene_rect_offset_r (bounds, snapshot->state->translate_x, snapshot->state->translate_y, &real_bounds);
-  node = gsk_texture_node_new (texture, &real_bounds);
+  node = gsk_texture_node_new (snapshot->tree, texture, &real_bounds);
 
   if (name && snapshot->record_names)
     {
@@ -932,7 +937,6 @@ gtk_snapshot_append_texture_node (GtkSnapshot            *snapshot,
     }
 
   gtk_snapshot_append_node (snapshot, node);
-  gsk_render_node_unref (node);
 }
 
 /**
@@ -963,7 +967,7 @@ gtk_snapshot_append_color_node (GtkSnapshot           *snapshot,
   g_return_if_fail (bounds != NULL);
 
   graphene_rect_offset_r (bounds, snapshot->state->translate_x, snapshot->state->translate_y, &real_bounds);
-  node = gsk_color_node_new (color, &real_bounds);
+  node = gsk_color_node_new (snapshot->tree, color, &real_bounds);
 
   if (name && snapshot->record_names)
     {
@@ -980,7 +984,6 @@ gtk_snapshot_append_color_node (GtkSnapshot           *snapshot,
     }
 
   gtk_snapshot_append_node (snapshot, node);
-  gsk_render_node_unref (node);
 }
 
 /**

gtk/gtksnapshot.h

@@ -92,6 +92,8 @@ GDK_AVAILABLE_IN_3_90
 void            gtk_snapshot_get_offset                 (GtkSnapshot            *snapshot,
                                                          int                    *x,
                                                          int                    *y);
+GDK_AVAILABLE_IN_3_90
+GskRenderTree *gtk_snapshot_get_tree                   (GtkSnapshot            *snapshot);
 
 GDK_AVAILABLE_IN_3_90
 void            gtk_snapshot_append_node                (GtkSnapshot            *snapshot,

gtk/gtksnapshotprivate.h

@@ -34,6 +34,7 @@ struct _GtkSnapshotState {
   GtkSnapshotState      *cached_state; /* A cleared state object we can (re)use */
 
   char                  *name;
+  GskRenderTree         *tree;
   GPtrArray             *nodes;
 
   cairo_region_t        *clip_region;
@@ -74,6 +75,7 @@ struct _GtkSnapshot {
   GtkSnapshotState      *state;
   gboolean               record_names;
   GskRenderer           *renderer;
+  GskRenderTree         *tree;
 };
 
 void            gtk_snapshot_init               (GtkSnapshot             *state,

gtk/gtkstack.c

@@ -1933,12 +1933,11 @@ gtk_stack_snapshot_crossfade (GtkWidget   *widget,
       gtk_snapshot_push_transform (snapshot, &identity, "CrossFadeStart");
       gtk_snapshot_append_node (snapshot, priv->last_visible_node);
       start_node = gtk_snapshot_pop (snapshot);
-      node = gsk_cross_fade_node_new (start_node, end_node, progress);
-      gsk_render_node_unref (start_node);
+      node = gsk_cross_fade_node_new (gtk_snapshot_get_tree (snapshot), start_node, end_node, progress);
     }
   else
     {
-      node = gsk_opacity_node_new (end_node, 1.0 - progress);
+      node = gsk_opacity_node_new (gtk_snapshot_get_tree (snapshot), end_node, 1.0 - progress);
     }
 
   if (snapshot->record_names)
@@ -1949,9 +1948,6 @@ gtk_stack_snapshot_crossfade (GtkWidget   *widget,
     }
 
   gtk_snapshot_append_node (snapshot, node);
-
-  gsk_render_node_unref (node);
-  gsk_render_node_unref (end_node);
 }
 
 static void