[gegl] mirrors: do not use gegl_buffer_sample_at - it isn't threadsafe

[Øyvind Kolås <ok src gnome org>]

commit f6b3cdd05a9d0c3e436c487fa010fb633acf9491
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Oct 12 00:45:18 2017 +0200

    mirrors: do not use gegl_buffer_sample_at - it isn't threadsafe

 operations/common-gpl3+/oilify.c |    1 +
 operations/common/mirrors.c      |   10 ++++++----
 2 files changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/operations/common-gpl3+/oilify.c b/operations/common-gpl3+/oilify.c
index 0164075..02edb63 100644
--- a/operations/common-gpl3+/oilify.c
+++ b/operations/common-gpl3+/oilify.c
@@ -472,6 +472,7 @@ gegl_op_class_init (GeglOpClass *klass)
 
   filter_class->process    = process;
   operation_class->prepare = prepare;
+  operation_class->threaded = FALSE;
 
   gegl_operation_class_set_keys (operation_class,
                                  "categories" , "artistic",
diff --git a/operations/common/mirrors.c b/operations/common/mirrors.c
index c22e689..e276efb 100644
--- a/operations/common/mirrors.c
+++ b/operations/common/mirrors.c
@@ -161,6 +161,7 @@ apply_mirror (double               mirror_angle,
               gint                 level)
 {
   gfloat *dst_buf;
+  GeglSampler *sampler;
   gint    row, col;
   gdouble cx, cy;
 
@@ -173,6 +174,8 @@ apply_mirror (double               mirror_angle,
   #ifdef DO_NOT_USE_BUFFER_SAMPLE
     src_buf = g_new0 (gfloat, boundary->width * boundary->height * 4);
     gegl_buffer_get (src, 1.0, boundary, format, src_buf, GEGL_AUTO_ROWSTRIDE);
+  #else
+    sampler = gegl_buffer_sampler_new_at_level (src, format, GEGL_SAMPLER_LINEAR, level);
   #endif
   /* Get buffer in which to place dst pixels. */
   dst_buf = g_new0 (gfloat, roi->width * roi->height * 4);
@@ -264,10 +267,8 @@ apply_mirror (double               mirror_angle,
         spx_pos = (iy * boundary->width + ix) * 4;
 #endif
 
-
-
 #ifndef DO_NOT_USE_BUFFER_SAMPLE
-        gegl_buffer_sample_at_level (src, cx, cy, NULL, &dst_buf[(row * roi->width + col) * 4], format, 
level, GEGL_SAMPLER_LINEAR, GEGL_ABYSS_NONE);
+        gegl_sampler_get (sampler, cx, cy, NULL, &dst_buf[(row * roi->width + col) * 4], GEGL_ABYSS_NONE);
 #endif
 
 #ifdef DO_NOT_USE_BUFFER_SAMPLE
@@ -280,7 +281,6 @@ apply_mirror (double               mirror_angle,
     } /* for */
   } /* for */
 
-    gegl_buffer_sample_cleanup(src);
 
   /* Store dst pixels. */
   gegl_buffer_set (dst, roi, 0, format, dst_buf, GEGL_AUTO_ROWSTRIDE);
@@ -288,6 +288,8 @@ apply_mirror (double               mirror_angle,
   /* Free acquired storage. */
 #ifdef DO_NOT_USE_BUFFER_SAMPLE
   g_free (src_buf);
+#else
+  g_object_unref (sampler);
 #endif
   g_free (dst_buf);