[gegl] buffer: hold locks for tile caches only when interacting with tile cache

[Øyvind Kolås <ok src gnome org>]

commit 12375b0158e542752113fcaa0436475c37e143ab
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jan 11 02:45:42 2018 +0100

    buffer: hold locks for tile caches only when interacting with tile cache

 gegl/buffer/gegl-buffer-access.c |   18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index 136ab3e..9c9e675 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -860,8 +860,6 @@ gegl_buffer_iterate_read_simple (GeglBuffer          *buffer,
     fish = babl_fish ((gpointer) buffer->soft_format,
                       (gpointer) format);
 
-  if (gegl_config_threads()>1)
-    g_rec_mutex_lock (&buffer->tile_storage->mutex);
 
   while (bufy < height)
     {
@@ -884,10 +882,22 @@ gegl_buffer_iterate_read_simple (GeglBuffer          *buffer,
           else
             pixels = tile_width - offsetx;
 
-          tile = gegl_tile_source_get_tile ((GeglTileSource *) (buffer),
+          if (gegl_config_threads()>1)
+          {
+             g_rec_mutex_lock (&buffer->tile_storage->mutex);
+             tile = gegl_tile_source_get_tile ((GeglTileSource *) (buffer),
+                                            gegl_tile_indice (tiledx, tile_width),
+                                            gegl_tile_indice (tiledy, tile_height),
+                                            level);
+            g_rec_mutex_unlock (&buffer->tile_storage->mutex);
+          }
+          else
+          {
+             tile = gegl_tile_source_get_tile ((GeglTileSource *) (buffer),
                                             gegl_tile_indice (tiledx, tile_width),
                                             gegl_tile_indice (tiledy, tile_height),
                                             level);
+          }
 
           if (!tile)
             {
@@ -1096,8 +1106,6 @@ gegl_buffer_iterate_read_simple (GeglBuffer          *buffer,
       bufy += (tile_height - offsety);
     }
 
-  if (gegl_config_threads()>1)
-    g_rec_mutex_unlock (&buffer->tile_storage->mutex);
 }
 
 static void