[gnome-photos/wip/rishi/double-buffering: 7/7] base-item: Modify and process the pipeline in batches

[Debarshi Ray <debarshir src gnome org>]

commit 49f2817b0a8ad326dc387c952c40b9dba58231b3
Author: Debarshi Ray <debarshir gnome org>
Date:   Fri Jan 20 15:01:16 2017 +0100

    base-item: Modify and process the pipeline in batches
    
    There is a drawback to modifying the GEGL graph and processing it as
    soon as photos_base_item_operation_{add, remove} are called.
    
    GEGL might already be processing it in chunks in an idle handler.
    Interrupting it will lead to GeglNode::invalidated being emitted,
    which will mislead PhotosImageView into thinking that processing has
    been restarted. If this happens too often, with a high enough number
    of pixels or a graph that is noticeably slow, the view won't get
    updated for a long time since it will keep waiting for the processing
    to complete.
    
    Therefore, instead of interrupting the graph we buffer all pending
    edits. Once the previous run is over, we apply everything that's been
    queued and process it afresh. This ensures that the view gets a chance
    to update itself after every batch.

 src/photos-base-item.c |  165 +++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 155 insertions(+), 10 deletions(-)
---
diff --git a/src/photos-base-item.c b/src/photos-base-item.c
index 4cdca26..c5c9832 100644
--- a/src/photos-base-item.c
+++ b/src/photos-base-item.c
@@ -76,6 +76,7 @@ struct _PhotosBaseItemPrivate
   GQuark equipment;
   GQuark flash;
   GQuark orientation;
+  GQueue *operation_queue;
   PhotosCollectionIconWatcher *watcher;
   PhotosPipeline *pipeline;
   PhotosSelectionController *sel_cntrlr;
@@ -83,6 +84,7 @@ struct _PhotosBaseItemPrivate
   gboolean collection;
   gboolean failed_thumbnailing;
   gboolean favorite;
+  gboolean operation_running;
   gchar *author;
   gchar *default_app_name;
   gchar *filename;
@@ -142,7 +144,14 @@ G_DEFINE_ABSTRACT_TYPE_WITH_CODE (PhotosBaseItem, photos_base_item, G_TYPE_OBJEC
 EGG_DEFINE_COUNTER (instances, "PhotosBaseItem", "Instances", "Number of PhotosBaseItem instances")
 
 
+typedef enum
+{
+  PHOTOS_BASE_ITEM_OPERATION_ADD,
+  PHOTOS_BASE_ITEM_OPERATION_REMOVE
+} PhotosBaseItemOperationType;
+
 typedef struct _PhotosBaseItemMetadataAddSharedData PhotosBaseItemMetadataAddSharedData;
+typedef struct _PhotosBaseItemOperationData PhotosBaseItemOperationData;
 typedef struct _PhotosBaseItemSaveData PhotosBaseItemSaveData;
 typedef struct _PhotosBaseItemSaveBufferData PhotosBaseItemSaveBufferData;
 typedef struct _PhotosBaseItemSaveToStreamData PhotosBaseItemSaveToStreamData;
@@ -154,6 +163,13 @@ struct _PhotosBaseItemMetadataAddSharedData
   gchar *shared_id;
 };
 
+struct _PhotosBaseItemOperationData
+{
+  GList *parameters;
+  PhotosBaseItemOperationType type;
+  gchar *name;
+};
+
 struct _PhotosBaseItemSaveData
 {
   GFile *dir;
@@ -183,6 +199,7 @@ static GThreadPool *create_thumbnail_pool;
 static const gint PIXEL_SIZES[] = {2048, 1024};
 
 
+static void photos_base_item_operation_queue_check (PhotosBaseItem *self);
 static void photos_base_item_populate_from_cursor (PhotosBaseItem *self, TrackerSparqlCursor *cursor);
 
 
@@ -212,6 +229,28 @@ photos_base_item_metadata_add_shared_data_free (PhotosBaseItemMetadataAddSharedD
 }
 
 
+static PhotosBaseItemOperationData *
+photos_base_item_operation_data_new (PhotosBaseItemOperationType type, const gchar *name)
+{
+  PhotosBaseItemOperationData *data;
+
+  data = g_slice_new0 (PhotosBaseItemOperationData);
+  data->type = type;
+  data->name = g_strdup (name);
+
+  return data;
+}
+
+
+static void
+photos_base_item_operation_data_free (PhotosBaseItemOperationData *data)
+{
+  g_free (data->name);
+  g_list_free_full (data->parameters, (GDestroyNotify) photos_utils_parameter_free);
+  g_slice_free (PhotosBaseItemOperationData, data);
+}
+
+
 static PhotosBaseItemSaveData *
 photos_base_item_save_data_new (GFile *dir, GeglBuffer *buffer, const gchar *type, gdouble zoom)
 {
@@ -1556,6 +1595,105 @@ photos_base_item_metadata_add_shared_in_thread_func (GTask *task,
 
 
 static void
+photos_base_item_operation_queue_collector (GObject *source_object, GAsyncResult *res, gpointer user_data)
+{
+  PhotosBaseItem *self = PHOTOS_BASE_ITEM (source_object);
+  PhotosBaseItemPrivate *priv;
+  GList *l;
+  GList *tasks = NULL;
+  GTask *batched_task = G_TASK (user_data);
+  GError *error;
+
+  priv = photos_base_item_get_instance_private (self);
+  tasks = (GList *) g_task_get_task_data (batched_task);
+
+  error = NULL;
+  photos_base_item_process_finish (self, res, &error);
+  for (l = tasks; l != NULL; l = l->next)
+    {
+      GTask *task = G_TASK (l->data);
+
+      if (error != NULL)
+        g_task_return_error (task, g_error_copy (error));
+      else
+        g_task_return_boolean (task, TRUE);
+    }
+
+  g_clear_error (&error);
+
+  priv->operation_running = FALSE;
+  photos_base_item_operation_queue_check (self);
+
+  g_object_unref (batched_task);
+}
+
+
+static void
+photos_base_item_operation_queue_check (PhotosBaseItem *self)
+{
+  PhotosBaseItemPrivate *priv;
+  GList *l;
+  GList *tasks = NULL;
+  GTask *batched_task = NULL;
+
+  priv = photos_base_item_get_instance_private (self);
+
+  if (priv->operation_running)
+    goto out;
+
+  if (priv->operation_queue->length == 0)
+    goto out;
+
+  priv->operation_running = TRUE;
+
+  for (l = priv->operation_queue->head; l != NULL; l = l->next)
+    {
+      GTask *task = G_TASK (l->data);
+      PhotosBaseItemOperationData *data;
+
+      data = (PhotosBaseItemOperationData *) g_task_get_task_data (task);
+
+      if (data->type == PHOTOS_BASE_ITEM_OPERATION_ADD)
+        {
+          photos_pipeline_addl (priv->pipeline, data->name, data->parameters);
+        }
+      else if (data->type == PHOTOS_BASE_ITEM_OPERATION_REMOVE)
+        {
+          g_assert_null (data->parameters);
+
+          if (!photos_pipeline_remove (priv->pipeline, data->name))
+            {
+              g_task_return_new_error (task, PHOTOS_ERROR, 0, "Failed to find a GeglNode for %s", 
data->name);
+              continue;
+            }
+        }
+      else
+        {
+          g_assert_not_reached ();
+        }
+
+      tasks = g_list_prepend (tasks, g_object_ref (task));
+    }
+
+  batched_task = g_task_new (self, NULL, NULL, NULL);
+  g_task_set_task_data (batched_task, tasks, (GDestroyNotify) photos_utils_object_list_free_full);
+  tasks = NULL;
+
+  photos_base_item_process_async (self,
+                                  NULL,
+                                  photos_base_item_operation_queue_collector,
+                                  g_object_ref (batched_task));
+
+  g_queue_foreach (priv->operation_queue, (GFunc) g_object_unref, NULL);
+  g_queue_clear (priv->operation_queue);
+
+ out:
+  g_list_free_full (tasks, g_object_unref);
+  g_clear_object (&batched_task);
+}
+
+
+static void
 photos_base_item_pipeline_save_save (GObject *source_object, GAsyncResult *res, gpointer user_data)
 {
   GTask *task = G_TASK (user_data);
@@ -2464,6 +2602,8 @@ photos_base_item_finalize (GObject *object)
   g_mutex_clear (&priv->mutex_download);
   g_mutex_clear (&priv->mutex_save_metadata);
 
+  g_queue_free_full (priv->operation_queue, g_object_unref);
+
   G_OBJECT_CLASS (photos_base_item_parent_class)->finalize (object);
 
   EGG_COUNTER_DEC (instances);
@@ -2554,6 +2694,8 @@ photos_base_item_init (PhotosBaseItem *self)
   g_mutex_init (&priv->mutex_download);
   g_mutex_init (&priv->mutex_save_metadata);
 
+  priv->operation_queue = g_queue_new ();
+
   priv->sel_cntrlr = photos_selection_controller_dup_singleton ();
 }
 
@@ -3408,6 +3550,7 @@ photos_base_item_operation_add_async (PhotosBaseItem *self,
 {
   PhotosBaseItemPrivate *priv;
   GTask *task;
+  PhotosBaseItemOperationData *data;
   va_list ap;
 
   g_return_if_fail (PHOTOS_IS_BASE_ITEM (self));
@@ -3415,14 +3558,18 @@ photos_base_item_operation_add_async (PhotosBaseItem *self,
 
   g_return_if_fail (!priv->collection);
 
+  data = photos_base_item_operation_data_new (PHOTOS_BASE_ITEM_OPERATION_ADD, operation);
+
   va_start (ap, first_property_name);
-  photos_pipeline_add_valist (priv->pipeline, operation, first_property_name, ap);
+  data->parameters = photos_utils_create_operation_parameters_from_valist (operation, first_property_name, 
ap);
   va_end (ap);
 
   task = g_task_new (self, cancellable, callback, user_data);
   g_task_set_source_tag (task, photos_base_item_operation_add_async);
+  g_task_set_task_data (task, data, (GDestroyNotify) photos_base_item_operation_data_free);
 
-  photos_base_item_process_async (self, cancellable, photos_base_item_common_process, g_object_ref (task));
+  g_queue_push_tail (priv->operation_queue, g_object_ref (task));
+  photos_base_item_operation_queue_check (self);
 
   g_object_unref (task);
 }
@@ -3471,24 +3618,22 @@ photos_base_item_operation_remove_async (PhotosBaseItem *self,
 {
   PhotosBaseItemPrivate *priv;
   GTask *task;
+  PhotosBaseItemOperationData *data;
 
   g_return_if_fail (PHOTOS_IS_BASE_ITEM (self));
   priv = photos_base_item_get_instance_private (self);
 
   g_return_if_fail (!priv->collection);
 
+  data = photos_base_item_operation_data_new (PHOTOS_BASE_ITEM_OPERATION_REMOVE, operation);
+
   task = g_task_new (self, cancellable, callback, user_data);
   g_task_set_source_tag (task, photos_base_item_operation_remove_async);
+  g_task_set_task_data (task, data, (GDestroyNotify) photos_base_item_operation_data_free);
 
-  if (!photos_pipeline_remove (priv->pipeline, operation))
-    {
-      g_task_return_new_error (task, PHOTOS_ERROR, 0, "Failed to find a GeglNode for %s", operation);
-      goto out;
-    }
-
-  photos_base_item_process_async (self, cancellable, photos_base_item_common_process, g_object_ref (task));
+  g_queue_push_tail (priv->operation_queue, g_object_ref (task));
+  photos_base_item_operation_queue_check (self);
 
- out:
   g_object_unref (task);
 }