[gimp] app: add gimp_async_remove_callback()

[Ell <ell src gnome org>]

commit 85f67e196ca060c08052bf7585356fa39e633e25
Author: Ell <ell_se yahoo com>
Date:   Sat May 26 12:06:38 2018 -0400

    app: add gimp_async_remove_callback()
    
    ... which removes a callback previously added through
    gimp_async_add_callback().

 app/core/gimpasync.c | 39 +++++++++++++++++++++++++++++++++++++++
 app/core/gimpasync.h | 42 +++++++++++++++++++++++-------------------
 2 files changed, 62 insertions(+), 19 deletions(-)
---
diff --git a/app/core/gimpasync.c b/app/core/gimpasync.c
index b86dfb61bb..7a70380fdf 100644
--- a/app/core/gimpasync.c
+++ b/app/core/gimpasync.c
@@ -328,6 +328,45 @@ gimp_async_add_callback (GimpAsync         *async,
   g_mutex_unlock (&async->priv->mutex);
 }
 
+/* removes all callbacks previously registered through
+ * 'gimp_async_add_callback()', matching 'callback' and 'data', which hasn't
+ * been called yet.
+ *
+ * may only be called on the main thread.
+ */
+void
+gimp_async_remove_callback (GimpAsync         *async,
+                            GimpAsyncCallback  callback,
+                            gpointer           data)
+{
+  GList *iter;
+
+  g_return_if_fail (GIMP_IS_ASYNC (async));
+  g_return_if_fail (callback != NULL);
+
+  g_mutex_lock (&async->priv->mutex);
+
+  iter = g_queue_peek_head_link (&async->priv->callbacks);
+
+  while (iter)
+    {
+      GimpAsyncCallbackInfo *callback_info = iter->data;
+      GList                 *next          = g_list_next (iter);
+
+      if (callback_info->callback == callback &&
+          callback_info->data     == data)
+        {
+          g_queue_delete_link (&async->priv->callbacks, iter);
+
+          g_slice_free (GimpAsyncCallbackInfo, callback_info);
+        }
+
+      iter = next;
+    }
+
+  g_mutex_unlock (&async->priv->mutex);
+}
+
 /* transitions 'async' to the "stopped" state, indicating that the task
  * completed normally, possibly providing a result.
  *
diff --git a/app/core/gimpasync.h b/app/core/gimpasync.h
index 1cd7cb23c0..b3d84dea9c 100644
--- a/app/core/gimpasync.h
+++ b/app/core/gimpasync.h
@@ -50,31 +50,35 @@ struct _GimpAsyncClass
 };
 
 
-GType       gimp_async_get_type     (void) G_GNUC_CONST;
+GType       gimp_async_get_type        (void) G_GNUC_CONST;
 
-GimpAsync * gimp_async_new          (void);
+GimpAsync * gimp_async_new             (void);
 
-gboolean    gimp_async_is_stopped   (GimpAsync         *async);
+gboolean    gimp_async_is_stopped      (GimpAsync         *async);
 
-void        gimp_async_wait         (GimpAsync         *async);
-gboolean    gimp_async_wait_until   (GimpAsync         *async,
-                                     gint64             end_time);
-void        gimp_async_add_callback (GimpAsync         *async,
-                                     GimpAsyncCallback  callback,
-                                     gpointer           data);
+void        gimp_async_wait            (GimpAsync         *async);
+gboolean    gimp_async_wait_until      (GimpAsync         *async,
+                                        gint64             end_time);
 
-void        gimp_async_finish       (GimpAsync         *async,
-                                     gpointer           result);
-void        gimp_async_finish_full  (GimpAsync         *async,
-                                     gpointer           result,
-                                     GDestroyNotify     result_destroy_func);
-gboolean    gimp_async_is_finished  (GimpAsync         *async);
-gpointer    gimp_async_get_result   (GimpAsync         *async);
+void        gimp_async_add_callback    (GimpAsync         *async,
+                                        GimpAsyncCallback  callback,
+                                        gpointer           data);
+void        gimp_async_remove_callback (GimpAsync         *async,
+                                        GimpAsyncCallback  callback,
+                                        gpointer           data);
 
-void        gimp_async_abort        (GimpAsync         *async);
+void        gimp_async_finish          (GimpAsync         *async,
+                                        gpointer           result);
+void        gimp_async_finish_full     (GimpAsync         *async,
+                                        gpointer           result,
+                                        GDestroyNotify     result_destroy_func);
+gboolean    gimp_async_is_finished     (GimpAsync         *async);
+gpointer    gimp_async_get_result      (GimpAsync         *async);
 
-void        gimp_async_cancel       (GimpAsync         *async);
-gboolean    gimp_async_is_canceled  (GimpAsync         *async);
+void        gimp_async_abort           (GimpAsync         *async);
+
+void        gimp_async_cancel          (GimpAsync         *async);
+gboolean    gimp_async_is_canceled     (GimpAsync         *async);
 
 
 #endif /* __GIMP_ASYNC_H__ */