[gegl] sampler: make gegl_buffer_sample_cleanup() thread safe

[N/A <ell src gnome org>]

commit 651e5eecacbaa720d82558a23574b5c3df1f3078
Author: Ell <ell_se yahoo com>
Date:   Thu Jun 29 03:54:35 2017 -0400

    sampler: make gegl_buffer_sample_cleanup() thread safe
    
    ... w.r.t. gegl_buffer_sample_foo()
    
    Use the same mutex that guards gegl_buffer_sample(_at_level) in
    gegl_buffer_sample_cleanup(), so that they can be safely called
    concurrently.  This currently happens in certain ops when using
    multithreading; this is probably not a very good thing to begin
    with, but at least it doesn't crash anymore.

 gegl/buffer/gegl-buffer-access.c |   12 ------------
 gegl/buffer/gegl-sampler.c       |   32 +++++++++++++++++++++++++++++---
 2 files changed, 29 insertions(+), 15 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index 8c3473e..2c02d44 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -1559,18 +1559,6 @@ gegl_buffer_get (GeglBuffer          *buffer,
   gegl_buffer_unlock (buffer);
 }
 
-void
-gegl_buffer_sample_cleanup (GeglBuffer *buffer)
-{
-  g_return_if_fail (GEGL_IS_BUFFER (buffer));
-
-  if (buffer->sampler)
-    {
-      g_object_unref (buffer->sampler);
-      buffer->sampler = NULL;
-    }
-}
-
 static void
 gegl_buffer_copy2 (GeglBuffer          *src,
                    const GeglRectangle *src_rect,
diff --git a/gegl/buffer/gegl-sampler.c b/gegl/buffer/gegl-sampler.c
index 2364380..aa47a9a 100644
--- a/gegl/buffer/gegl-sampler.c
+++ b/gegl/buffer/gegl-sampler.c
@@ -519,6 +519,8 @@ gegl_sampler_gtype_from_enum (GeglSamplerType sampler_type)
     }
 }
 
+static GMutex gegl_buffer_sampler_mutex = {0,};
+
 void
 gegl_buffer_sample_at_level (GeglBuffer       *buffer,
                              gdouble           x,
@@ -539,7 +541,6 @@ gegl_buffer_sample_at_level (GeglBuffer       *buffer,
     return;
   }*/
 
-  static GMutex mutex = {0,};
   gboolean threaded =  gegl_config_threads ()>1;
 
 
@@ -553,7 +554,7 @@ gegl_buffer_sample_at_level (GeglBuffer       *buffer,
   }
 
   if (threaded)
-    g_mutex_lock (&mutex);
+    g_mutex_lock (&gegl_buffer_sampler_mutex);
 
   /* unset the cached sampler if it dosn't match the needs */
   if (buffer->sampler != NULL &&
@@ -582,7 +583,7 @@ gegl_buffer_sample_at_level (GeglBuffer       *buffer,
 
   buffer->sampler->get(buffer->sampler, x, y, scale, dest, repeat_mode);
   if (threaded)
-    g_mutex_unlock (&mutex);
+    g_mutex_unlock (&gegl_buffer_sampler_mutex);
 }
 
 
@@ -599,6 +600,31 @@ gegl_buffer_sample (GeglBuffer       *buffer,
   gegl_buffer_sample_at_level (buffer, x, y, scale, dest, format, 0, sampler_type, repeat_mode);
 }
 
+void
+gegl_buffer_sample_cleanup (GeglBuffer *buffer)
+{
+  gboolean threaded;
+
+  g_return_if_fail (GEGL_IS_BUFFER (buffer));
+
+  if (! buffer->sampler)
+    return;
+
+  threaded = gegl_config_threads ()>1;
+
+  if (threaded)
+    g_mutex_lock (&gegl_buffer_sampler_mutex);
+
+  if (buffer->sampler)
+    {
+      g_object_unref (buffer->sampler);
+      buffer->sampler = NULL;
+    }
+
+  if (threaded)
+    g_mutex_unlock (&gegl_buffer_sampler_mutex);
+}
+
 GeglSampler *
 gegl_buffer_sampler_new_at_level (GeglBuffer      *buffer,
                                   const Babl      *format,