[gegl] buffer: don't damage pyramid when inserting new tile to cache

[Ell <ell src gnome org>]

commit 4aa710faa747c7a3885f607d6810ed3bded08057
Author: Ell <ell_se yahoo com>
Date:   Wed Nov 28 09:08:38 2018 -0500

    buffer: don't damage pyramid when inserting new tile to cache
    
    In gegl_tile_handler_cache_insert(), when there's already a cached
    tile at the same coordinates as the new tile, merely remove the old
    tile from the cache, but don't damage the corresponding area of the
    pyramid.  We already explicitly damage the pyramid at all the
    relevant points, so doing this again in cache_insert() is
    superfluous.  Moreover, the code in gegl_tile_handler_cache_void()
    that is responsible for the damaging is erroneous, and fixing it
    (as done in the next few commits) would make damaging the pyramid
    in cache_insert() excessive, breaking a few tests.
    
            .mtsync.log

 gegl/buffer/gegl-tile-handler-cache.c | 57 ++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 17 deletions(-)
---
diff --git a/gegl/buffer/gegl-tile-handler-cache.c b/gegl/buffer/gegl-tile-handler-cache.c
index f57e5b65b..ce1395405 100644
--- a/gegl/buffer/gegl-tile-handler-cache.c
+++ b/gegl/buffer/gegl-tile-handler-cache.c
@@ -745,6 +745,44 @@ gegl_tile_handler_cache_copy (GeglTileHandlerCache     *cache,
 }
 
 
+static void
+gegl_tile_handler_cache_remove_item (GeglTileHandlerCache *cache,
+                                     CacheItem            *item)
+{
+  if (g_atomic_int_dec_and_test (gegl_tile_n_cached_clones (item->tile)))
+    g_atomic_pointer_add (&cache_total, -item->tile->size);
+  g_atomic_pointer_add (&cache_total_uncloned, -item->tile->size);
+
+  g_queue_unlink (&cache->queue, &item->link);
+  g_hash_table_remove (cache->items, item);
+
+  if (g_queue_is_empty (&cache->queue))
+    cache->time = cache->stamp = 0;
+
+  item->tile->tile_storage = NULL;
+  gegl_tile_unref (item->tile);
+
+  g_slice_free (CacheItem, item);
+}
+
+static void
+gegl_tile_handler_cache_remove (GeglTileHandlerCache *cache,
+                                gint                  x,
+                                gint                  y,
+                                gint                  z)
+{
+  CacheItem *item;
+
+  item = cache_lookup (cache, x, y, z);
+
+  if (item)
+    {
+      drop_hot_tile (item->tile);
+
+      gegl_tile_handler_cache_remove_item (cache, item);
+    }
+}
+
 static void
 gegl_tile_handler_cache_void (GeglTileHandlerCache *cache,
                               gint                  x,
@@ -760,22 +798,7 @@ gegl_tile_handler_cache_void (GeglTileHandlerCache *cache,
       drop_hot_tile (item->tile);
 
       if (gegl_tile_damage (item->tile, damage))
-        {
-          if (g_atomic_int_dec_and_test (gegl_tile_n_cached_clones (item->tile)))
-            g_atomic_pointer_add (&cache_total, -item->tile->size);
-          g_atomic_pointer_add (&cache_total_uncloned, -item->tile->size);
-
-          g_queue_unlink (&cache->queue, &item->link);
-          g_hash_table_remove (cache->items, item);
-
-          if (g_queue_is_empty (&cache->queue))
-            cache->time = cache->stamp = 0;
-
-          item->tile->tile_storage = NULL;
-          gegl_tile_unref (item->tile);
-
-          g_slice_free (CacheItem, item);
-        }
+        gegl_tile_handler_cache_remove_item (cache, item);
     }
 }
 
@@ -797,7 +820,7 @@ gegl_tile_handler_cache_insert (GeglTileHandlerCache *cache,
   item->z         = z;
 
   // XXX : remove entry if it already exists
-  gegl_tile_handler_cache_void (cache, x, y, z, ~(guint64) 0);
+  gegl_tile_handler_cache_remove (cache, x, y, z);
 
   tile->x = x;
   tile->y = y;