[gegl] gegl:gegl use per op user_data for caching info

[Øyvind Kolås <ok src gnome org>]

commit 41b9cd42ecbeddcce0cb79ab8063424268e8e280
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat Apr 16 01:52:12 2016 +0100

    gegl:gegl use per op user_data for caching info

 operations/common/gegl.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/operations/common/gegl.c b/operations/common/gegl.c
index 4532d5e..743c58c 100644
--- a/operations/common/gegl.c
+++ b/operations/common/gegl.c
@@ -35,6 +35,8 @@ property_string (error, _("error"), "")
 
 #include "gegl-op.h"
 
+/* XXX: leaking o->user_data */
+
 static void
 attach (GeglOperation *operation)
 {
@@ -61,11 +63,11 @@ prepare (GeglOperation *operation)
 
   gegl = operation->node;
 
-  if (!cached || !g_str_equal (cached, o->string))
+  if (!o->user_data || !g_str_equal (cached, o->user_data))
   {
-    if (cached)
-      g_free (cached);
-    cached = g_strdup (o->string);
+    if (o->user_data)
+      g_free (o->user_data);
+    o->user_data = g_strdup (o->string);
 
   input    = gegl_node_get_input_proxy (gegl, "input");
   output   = gegl_node_get_output_proxy (gegl, "output");