[gnome-photos/wip/rishi/misc-fixes: 10/22] base-item, pipeline: Construct Pipeline asynchronously

[Debarshi Ray <debarshir src gnome org>]

commit 8466b027078757d8b5734fafe338332fd7ffa1cb
Author: Debarshi Ray <debarshir gnome org>
Date:   Fri Dec 18 15:47:40 2015 +0100

    base-item, pipeline: Construct Pipeline asynchronously
    
    We want to restore any saved Pipeline by reading the XML from disk
    during construction. Since there is no guarantee that the user's home
    directory will be on a local filesystem, we have to do it
    asynchronously.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=759363

 src/photos-base-item.c |   56 +++++++++++++++++++++++++++----------
 src/photos-pipeline.c  |   72 +++++++++++++++++++++++++++++++++++++++++++++--
 src/photos-pipeline.h  |    9 +++++-
 3 files changed, 117 insertions(+), 20 deletions(-)
---
diff --git a/src/photos-base-item.c b/src/photos-base-item.c
index 682b878..f14f168 100644
--- a/src/photos-base-item.c
+++ b/src/photos-base-item.c
@@ -799,17 +799,6 @@ photos_base_item_load_buffer_async (PhotosBaseItem *self,
       gegl_node_link_many (priv->load, orientation, priv->buffer_sink, NULL);
     }
 
-  if (priv->edit_graph == NULL)
-    {
-      GeglNode *graph;
-
-      priv->edit_graph = gegl_node_new ();
-      priv->buffer_source = gegl_node_new_child (priv->edit_graph, "operation", "gegl:buffer-source", NULL);
-      priv->pipeline = photos_pipeline_new (priv->edit_graph);
-      graph = photos_pipeline_get_graph (priv->pipeline);
-      gegl_node_link (priv->buffer_source, graph);
-    }
-
   task = g_task_new (self, cancellable, callback, user_data);
   g_task_set_source_tag (task, photos_base_item_load_buffer_async);
 
@@ -900,6 +889,39 @@ photos_base_item_load_load_buffer (GObject *source_object, GAsyncResult *res, gp
 
 
 static void
+photos_base_item_load_pipeline (GObject *source_object, GAsyncResult *res, gpointer user_data)
+{
+  GTask *task = G_TASK (user_data);
+  PhotosBaseItem *self;
+  PhotosBaseItemPrivate *priv;
+  GeglNode *graph;
+  GCancellable *cancellable;
+  GError *error;
+
+  self = PHOTOS_BASE_ITEM (g_task_get_source_object (task));
+  priv = self->priv;
+
+  cancellable = g_task_get_cancellable (task);
+
+  error = NULL;
+  priv->pipeline = photos_pipeline_new_finish (res, &error);
+  if (error != NULL)
+    {
+      g_task_return_error (task, error);
+      goto out;
+    }
+
+  graph = photos_pipeline_get_graph (priv->pipeline);
+  gegl_node_link (priv->buffer_source, graph);
+
+  photos_base_item_load_buffer_async (self, cancellable, photos_base_item_load_load_buffer, g_object_ref 
(task));
+
+ out:
+  g_object_unref (task);
+}
+
+
+static void
 photos_base_item_pipeline_save_save (GObject *source_object, GAsyncResult *res, gpointer user_data)
 {
   GTask *task = G_TASK (user_data);
@@ -1788,6 +1810,8 @@ photos_base_item_load_async (PhotosBaseItem *self,
   g_return_if_fail (PHOTOS_IS_BASE_ITEM (self));
   priv = self->priv;
 
+  g_return_if_fail (priv->edit_graph == NULL || priv->pipeline != NULL);
+
   task = g_task_new (self, cancellable, callback, user_data);
   g_task_set_source_tag (task, photos_base_item_load_async);
 
@@ -1802,10 +1826,12 @@ photos_base_item_load_async (PhotosBaseItem *self,
     }
   else
     {
-      photos_base_item_load_buffer_async (self,
-                                          cancellable,
-                                          photos_base_item_load_load_buffer,
-                                          g_object_ref (task));
+      priv->edit_graph = gegl_node_new ();
+      priv->buffer_source = gegl_node_new_child (priv->edit_graph, "operation", "gegl:buffer-source", NULL);
+      photos_pipeline_new_async (priv->edit_graph,
+                                 cancellable,
+                                 photos_base_item_load_pipeline,
+                                 g_object_ref (task));
     }
 
   g_object_unref (task);
diff --git a/src/photos-pipeline.c b/src/photos-pipeline.c
index 150d858..c938cbb 100644
--- a/src/photos-pipeline.c
+++ b/src/photos-pipeline.c
@@ -24,7 +24,6 @@
 #include <string.h>
 
 #include <glib.h>
-#include <gio/gio.h>
 
 #include "egg-counter.h"
 #include "photos-debug.h"
@@ -52,8 +51,11 @@ enum
   PROP_PARENT,
 };
 
+static void photos_pipeline_async_initable_iface_init (GAsyncInitableIface *iface);
 
-G_DEFINE_TYPE (PhotosPipeline, photos_pipeline, G_TYPE_OBJECT);
+
+G_DEFINE_TYPE_EXTENDED (PhotosPipeline, photos_pipeline, G_TYPE_OBJECT, 0,
+                        G_IMPLEMENT_INTERFACE (G_TYPE_ASYNC_INITABLE, 
photos_pipeline_async_initable_iface_init));
 EGG_DEFINE_COUNTER (instances, "PhotosPipeline", "Instances", "Number of PhotosPipeline instances");
 
 
@@ -200,10 +202,72 @@ photos_pipeline_class_init (PhotosPipelineClass *class)
 }
 
 
+static void
+photos_pipeline_async_initable_init_async (GAsyncInitable *initable,
+                                           gint io_priority,
+                                           GCancellable *cancellable,
+                                           GAsyncReadyCallback callback,
+                                           gpointer user_data)
+{
+  PhotosPipeline *self = PHOTOS_PIPELINE (initable);
+  GTask *task;
+
+  task = g_task_new (self, cancellable, callback, user_data);
+  g_task_set_source_tag (task, photos_pipeline_async_initable_init_async);
+
+  g_task_return_boolean (task, TRUE);
+  g_object_unref (task);
+}
+
+
+static gboolean
+photos_pipeline_async_initable_init_finish (GAsyncInitable *initable, GAsyncResult *res, GError **error)
+{
+  PhotosPipeline *self = PHOTOS_PIPELINE (initable);
+  GTask *task = G_TASK (res);
+
+  g_return_val_if_fail (g_task_is_valid (res, self), FALSE);
+  g_return_val_if_fail (g_task_get_source_tag (task) == photos_pipeline_async_initable_init_async, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
+  return g_task_propagate_boolean (task, error);
+}
+
+
+static void
+photos_pipeline_async_initable_iface_init (GAsyncInitableIface *iface)
+{
+  iface->init_async = photos_pipeline_async_initable_init_async;
+  iface->init_finish = photos_pipeline_async_initable_init_finish;
+}
+
+
+void
+photos_pipeline_new_async (GeglNode *parent,
+                           GCancellable *cancellable,
+                           GAsyncReadyCallback callback,
+                           gpointer user_data)
+{
+  g_async_initable_new_async (PHOTOS_TYPE_PIPELINE,
+                              G_PRIORITY_DEFAULT,
+                              cancellable,
+                              callback,
+                              user_data,
+                              "parent", parent,
+                              NULL);
+}
+
+
 PhotosPipeline *
-photos_pipeline_new (GeglNode *parent)
+photos_pipeline_new_finish (GAsyncResult *res, GError **error)
 {
-  return g_object_new (PHOTOS_TYPE_PIPELINE, "parent", parent, NULL);
+  GObject *ret_val;
+  GObject *source_object;
+
+  source_object = g_async_result_get_source_object (res);
+  ret_val = g_async_initable_new_finish (G_ASYNC_INITABLE (source_object), res, error);
+  g_object_unref (source_object);
+  return PHOTOS_PIPELINE (ret_val);
 }
 
 
diff --git a/src/photos-pipeline.h b/src/photos-pipeline.h
index 69dd81a..d0a6577 100644
--- a/src/photos-pipeline.h
+++ b/src/photos-pipeline.h
@@ -24,6 +24,7 @@
 #include <stdarg.h>
 
 #include <gegl.h>
+#include <gio/gio.h>
 
 G_BEGIN_DECLS
 
@@ -54,7 +55,13 @@ typedef struct _PhotosPipelineClass PhotosPipelineClass;
 
 GType                  photos_pipeline_get_type          (void) G_GNUC_CONST;
 
-PhotosPipeline        *photos_pipeline_new               (GeglNode *parent);
+void                   photos_pipeline_new_async         (GeglNode *parent,
+                                                          GCancellable *cancellable,
+                                                          GAsyncReadyCallback callback,
+                                                          gpointer user_data);
+
+PhotosPipeline        *photos_pipeline_new_finish        (GAsyncResult *res,
+                                                          GError **error);
 
 void                   photos_pipeline_add               (PhotosPipeline *self,
                                                           const gchar *operation,