[gegl] buffer: do not do memcpy for uncloning empty tiles

[Øyvind Kolås <ok src gnome org>]

commit 4e3c942a55da9ded6488de399e8a06fabdc24cb4
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Apr 8 23:15:10 2013 +0200

    buffer: do not do memcpy for uncloning empty tiles

 gegl/buffer/gegl-buffer-private.h     |    1 +
 gegl/buffer/gegl-tile-handler-empty.c |    1 +
 gegl/buffer/gegl-tile.c               |   20 ++++++++++++++++----
 gegl/gegl-utils.c                     |    9 +++++++++
 gegl/gegl-utils.h                     |    1 +
 5 files changed, 28 insertions(+), 4 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-private.h b/gegl/buffer/gegl-buffer-private.h
index b41516d..5a72a99 100644
--- a/gegl/buffer/gegl-buffer-private.h
+++ b/gegl/buffer/gegl-buffer-private.h
@@ -169,6 +169,7 @@ struct _GeglTile
   gchar            lock;        /* number of times the tile is write locked
                                  * should in theory just have the values 0/1
                                  */
+  gint             is_zero_tile:1;
 
   /* the shared list is a doubly linked circular list */
   GeglTile        *next_shared;
diff --git a/gegl/buffer/gegl-tile-handler-empty.c b/gegl/buffer/gegl-tile-handler-empty.c
index c5d2614..6b0f9d7 100644
--- a/gegl/buffer/gegl-tile-handler-empty.c
+++ b/gegl/buffer/gegl-tile-handler-empty.c
@@ -63,6 +63,7 @@ get_tile (GeglTileSource *gegl_tile_source,
       gint tile_size = gegl_tile_backend_get_tile_size (empty->backend);
       empty->tile    = gegl_tile_new (tile_size);
       memset (gegl_tile_get_data (empty->tile), 0x00, tile_size);
+      empty->tile->is_zero_tile = 1;
     }
 
   return gegl_tile_handler_dup_tile (GEGL_TILE_HANDLER (empty),
diff --git a/gegl/buffer/gegl-tile.c b/gegl/buffer/gegl-tile.c
index 1be57b7..b9c43e4 100644
--- a/gegl/buffer/gegl-tile.c
+++ b/gegl/buffer/gegl-tile.c
@@ -110,9 +110,10 @@ gegl_tile_dup (GeglTile *src)
 {
   GeglTile *tile = gegl_tile_new_bare ();
 
-  tile->tile_storage    = src->tile_storage;
-  tile->data       = src->data;
-  tile->size       = src->size;
+  tile->tile_storage = src->tile_storage;
+  tile->data         = src->data;
+  tile->size         = src->size;
+  tile->is_zero_tile = src->is_zero_tile;
 
   tile->destroy_notify      = src->destroy_notify;
   tile->destroy_notify_data = src->destroy_notify_data;
@@ -165,13 +166,24 @@ gegl_tile_unclone (GeglTile *tile)
        * create a local copy
        */
       g_mutex_lock (&cowmutex);
-      tile->data                     = gegl_memdup (tile->data, tile->size);
+
+      if (tile->is_zero_tile)
+        {
+          tile->data = gegl_memdup (tile->data, tile->size);
+          tile->is_zero_tile = 0;
+        }
+      else
+        {
+          tile->data                     = gegl_memdup (tile->data, tile->size);
+        }
       tile->destroy_notify           = (void*)&free_data_directly;
       tile->destroy_notify_data      = NULL;
       tile->prev_shared->next_shared = tile->next_shared;
       tile->next_shared->prev_shared = tile->prev_shared;
       tile->prev_shared              = tile;
       tile->next_shared              = tile;
+
+
       g_mutex_unlock (&cowmutex);
     }
 }
diff --git a/gegl/gegl-utils.c b/gegl/gegl-utils.c
index 812a9e8..39f1b4b 100644
--- a/gegl/gegl-utils.c
+++ b/gegl/gegl-utils.c
@@ -18,6 +18,7 @@
 
 #include "config.h"
 
+#include <string.h>
 #include <glib-object.h>
 
 #include "gegl.h"
@@ -249,6 +250,14 @@ gpointer gegl_malloc (gsize size)
   return (gpointer) ret;
 }
 
+gpointer gegl_calloc (gsize size, int n_memb);
+gpointer gegl_calloc (gsize size, int n_memb)
+{
+  gchar *ret = gegl_malloc (size * n_memb);
+  memset (ret, 0, size * n_memb);
+  return ret;
+}
+
 void
 gegl_free (gpointer buf);
 void
diff --git a/gegl/gegl-utils.h b/gegl/gegl-utils.h
index aea6eb5..039c969 100644
--- a/gegl/gegl-utils.h
+++ b/gegl/gegl-utils.h
@@ -196,6 +196,7 @@ gpointer gegl_malloc                  (gsize    n_bytes);
  */
 void     gegl_free                    (gpointer mem);
 
+gpointer gegl_calloc (gsize size, int n_memb);
 
 #define GEGL_FLOAT_EPSILON            (1e-5)
 #define GEGL_FLOAT_IS_ZERO(value)     (_gegl_float_epsilon_zero ((value)))