[gegl/threaded-base-classes: 3/22] buffer: use tile-indice based mutexes for tile-writing

[Øyvind Kolås <ok src gnome org>]

commit c8319988d6e8679b060cb3ce1f2952708eda2ddc
Author: Massimo Valentini <mvalentini src gnome org>
Date:   Thu Jun 26 18:48:54 2014 +0200

    buffer: use tile-indice based mutexes for tile-writing
    
    This changes both gegl_buffer_set and gegl_buffer_iterator.

 gegl/buffer/gegl-buffer-access.c   |   13 ++++++++++---
 gegl/buffer/gegl-buffer-iterator.c |    3 +++
 2 files changed, 13 insertions(+), 3 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index c2cf098..9a88b49 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -303,6 +303,8 @@ gegl_buffer_flush (GeglBuffer *buffer)
                             GEGL_TILE_FLUSH, 0,0,0,NULL);
 }
 
+static GMutex mutexes[256];
+
 static inline void
 gegl_buffer_iterate_write (GeglBuffer          *buffer,
                            const GeglRectangle *roi,
@@ -375,6 +377,8 @@ gegl_buffer_iterate_write (GeglBuffer          *buffer,
           gint      tiledx  = buffer_x + bufx;
           gint      offsetx = gegl_tile_offset (tiledx, tile_width);
           gint      y       = bufy;
+          gint index_x;
+          gint index_y;
           gint      lskip, rskip, pixels, row;
           guchar   *bp, *tile_base, *tp;
           GeglTile *tile;
@@ -386,10 +390,13 @@ gegl_buffer_iterate_write (GeglBuffer          *buffer,
           else
             pixels = tile_width - offsetx;
 
+          index_x = gegl_tile_indice (tiledx, tile_width);
+          index_y = gegl_tile_indice (tiledy, tile_height);
+
+          g_mutex_lock (&mutexes[ABS (index_x) % 256]);
           tile = gegl_tile_source_get_tile ((GeglTileSource *) (buffer),
-                                            gegl_tile_indice (tiledx, tile_width),
-                                            gegl_tile_indice (tiledy, tile_height),
-                                            level);
+                                            index_x, index_y, level);
+          g_mutex_unlock (&mutexes[ABS (index_x) % 256]);
 
           lskip = (buffer_abyss_x) - (buffer_x + bufx);
           /* gap between left side of tile, and abyss */
diff --git a/gegl/buffer/gegl-buffer-iterator.c b/gegl/buffer/gegl-buffer-iterator.c
index 456e805..9a90e5c 100644
--- a/gegl/buffer/gegl-buffer-iterator.c
+++ b/gegl/buffer/gegl-buffer-iterator.c
@@ -285,6 +285,7 @@ increment_rects (GeglBufferIterator *iter)
   return TRUE;
 }
 
+static GMutex mutexes[256];
 static void
 get_tile (GeglBufferIterator *iter,
           int        index)
@@ -313,8 +314,10 @@ get_tile (GeglBufferIterator *iter,
       int tile_x = gegl_tile_indice (iter->roi[index].x + shift_x, tile_width);
       int tile_y = gegl_tile_indice (iter->roi[index].y + shift_y, tile_height);
 
+      g_mutex_lock (&mutexes[ABS (tile_x) % 256]);
       sub->current_tile = gegl_tile_source_get_tile ((GeglTileSource *)(buf),
                                                      tile_x, tile_y, 0);
+      g_mutex_unlock (&mutexes[ABS (tile_x) % 256]);
 
       if (sub->flags & GEGL_BUFFER_WRITE)
         gegl_tile_lock (sub->current_tile);