[grilo-plugins/wip/trackernotifier: 18/18] tracker: Rewrite tracker GrlSource notification to use TrackerNotifier

[Bastien Nocera <hadess src gnome org>]

commit 27d8a48a2657dce513abe0de9f953172444dfeb6
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Nov 20 17:55:39 2016 +0100

    tracker: Rewrite tracker GrlSource notification to use TrackerNotifier
    
    This is a new facility in Tracker abstracting usage of the GraphUpdated
    dbus signal, so is a perfect fit to use here. The event resources are
    rather plainly translated to GrlMedias so they are emitted.
    
    Events are also grouped so the tracker source makes use of the
    grl_source_notify_change_list(), which will avoid high signal emission
    overhead if there's many changes to notify about.
    
    Closes: #14

 src/tracker/grl-tracker-source-notif.c | 336 ++++++---------------------------
 1 file changed, 53 insertions(+), 283 deletions(-)
---
diff --git a/src/tracker/grl-tracker-source-notif.c b/src/tracker/grl-tracker-source-notif.c
index cca2071..83c9d82 100644
--- a/src/tracker/grl-tracker-source-notif.c
+++ b/src/tracker/grl-tracker-source-notif.c
@@ -41,18 +41,8 @@ G_DECLARE_FINAL_TYPE (GrlTrackerSourceNotify, grl_tracker_source_notify, GRL_TRA
 
 struct _GrlTrackerSourceNotify {
   GObject parent;
-
-  GDBusConnection *conn;
-
-  /* subject id -> GrlSourceChangeType */
-  GHashTable *updates;
-  /* Number of updates being queried */
-  guint updates_count;
-  /* subject id -> MediaInfo (NULL means it's being queried) */
-  GHashTable *cache;
-
-  guint graph_updated_id;
-  gint rdf_type_id;
+  TrackerNotifier *notifier;
+  guint events_signal_id;
 };
 
 static void grl_tracker_source_notify_initable_iface_init (GInitableIface *iface);
@@ -62,258 +52,70 @@ G_DEFINE_TYPE_WITH_CODE (GrlTrackerSourceNotify, grl_tracker_source_notify, G_TY
 
 static GrlTrackerSourceNotify *singleton = NULL;
 
-typedef struct {
-  gchar *type;
-  gchar *datasource;
-  gchar *url;
-} MediaInfo;
-
-static MediaInfo *
-media_info_new (const gchar *type,
-                const gchar *datasource,
-                const gchar *url)
+static GrlMedia *
+media_for_event (GrlTrackerSourceNotify *self,
+                 TrackerNotifierEvent   *event)
 {
-  MediaInfo *info;
+  gchar *id_str;
+  GrlMedia *media;
 
-  info = g_slice_new (MediaInfo);
-  info->type = g_strdup (type);
-  info->datasource = g_strdup (datasource);
-  info->url = g_strdup (url);
-
-  return info;
-}
-
-static void
-media_info_free (MediaInfo *info)
-{
-  if (info == NULL)
-    return;
+  id_str = g_strdup_printf ("%" G_GINT64_FORMAT, tracker_notifier_event_get_id (event));
+  media = grl_tracker_build_grilo_media (tracker_notifier_event_get_type (event),
+                                         GRL_TYPE_FILTER_NONE);
+  grl_media_set_id (media, id_str);
+  grl_media_set_url (media, tracker_notifier_event_get_location (event));
 
-  g_free (info->type);
-  g_free (info->datasource);
-  g_free (info->url);
+  g_free (id_str);
 
-  g_slice_free (MediaInfo, info);
+  return media;
 }
 
 static void
-notify_change (GrlTrackerSourceNotify *self,
-               gint                    id,
-               GrlSourceChangeType     change_type)
+handle_changes (GrlTrackerSourceNotify   *self,
+                GPtrArray                *events,
+                TrackerNotifierEventType  tracker_type,
+                GrlSourceChangeType       change_type)
 {
   GrlTrackerSource *source = NULL;
-  gchar *id_str = NULL;
-  GrlMedia *media = NULL;
-  MediaInfo *info;
-
-  info = g_hash_table_lookup (self->cache, GINT_TO_POINTER (id));
-  if (info == NULL)
-    goto out;
+  TrackerNotifierEvent *event;
+  GPtrArray *change_list;
+  GrlMedia *media;
+  gint i;
 
   source = grl_tracker_source_find ("");
 
   if (!source || !grl_tracker_source_can_notify (source))
-    goto out;
-
-  id_str = g_strdup_printf ("%i", id);
-  media = grl_tracker_build_grilo_media (info->type, GRL_TYPE_FILTER_NONE);
-  grl_media_set_id (media, id_str);
-  grl_media_set_url (media, info->url);
-
-  GRL_DEBUG ("Notify: source=%s, change_type=%d, url=%s",
-             grl_source_get_name (GRL_SOURCE (source)),
-             change_type, info->url);
-
-  grl_source_notify_change (GRL_SOURCE (source), media, change_type, FALSE);
-
-out:
-  if (change_type == GRL_CONTENT_REMOVED)
-    g_hash_table_remove (self->cache, GINT_TO_POINTER (id));
-  g_clear_object (&media);
-  g_free (id_str);
-}
-
-static void
-update_query_done (GrlTrackerSourceNotify *self)
-{
-  GHashTableIter iter;
-  gpointer key, value;
-
-  /* If more updates came while we were querying, wait for them so we can
-   * aggregate notifications. */
-  self->updates_count--;
-  if (self->updates_count > 0)
-    return;
-
-  g_hash_table_iter_init (&iter, self->updates);
-  while (g_hash_table_iter_next (&iter, &key, &value)) {
-    gint id = GPOINTER_TO_INT (key);
-    GrlSourceChangeType change_type = GPOINTER_TO_INT (value);
-
-    notify_change (self, id, change_type);
-  }
-
-  g_hash_table_remove_all (self->updates);
-}
-
-static void
-update_cursor_next_cb (GObject      *source_object,
-                       GAsyncResult *result,
-                       gpointer      user_data)
-{
-  GrlTrackerSourceNotify *self = user_data;
-  TrackerSparqlCursor *cursor = (TrackerSparqlCursor *) source_object;
-  const gchar *type;
-  const gchar *datasource;
-  const gchar *url;
-  gint id;
-  GError *error = NULL;
-
-  if (!tracker_sparql_cursor_next_finish (cursor, result, &error)) {
-    if (error != NULL) {
-      GRL_WARNING ("Error: %s", error->message);
-      g_clear_error (&error);
-    }
-    update_query_done (self);
-    g_object_unref (self);
     return;
-  }
 
-  type = tracker_sparql_cursor_get_string (cursor, 0, NULL);
-  id = tracker_sparql_cursor_get_integer (cursor, 1);
-  datasource = tracker_sparql_cursor_get_string (cursor, 2, NULL);
-  url = tracker_sparql_cursor_get_string (cursor, 3, NULL);
+  change_list = g_ptr_array_new ();
 
-  g_hash_table_insert (self->cache,
-                       GINT_TO_POINTER (id),
-                       media_info_new (type, datasource, url));
-
-  tracker_sparql_cursor_next_async (cursor,
-                                    NULL,
-                                    update_cursor_next_cb,
-                                    self);
-}
+  for (i = 0; i < events->len; i++) {
+    event = g_ptr_array_index (events, i);
+    if (tracker_notifier_event_get_event_type (event) != tracker_type)
+      continue;
 
-static void
-update_query_cb (GObject      *source,
-                 GAsyncResult *result,
-                 gpointer      user_data)
-{
-  GrlTrackerSourceNotify *self = user_data;
-  TrackerSparqlCursor *cursor;
-  GError *error = NULL;
-
-  cursor = tracker_sparql_connection_query_finish (grl_tracker_connection,
-                                                   result,
-                                                   &error);
-  if (cursor == NULL) {
-    if (error != NULL) {
-      GRL_WARNING ("Error: %s", error->message);
-      g_clear_error (&error);
-    }
-    update_query_done (self);
-    g_object_unref (self);
-    return;
+    media = media_for_event (self, event);
+    g_ptr_array_add (change_list, media);
   }
 
-  tracker_sparql_cursor_next_async (cursor,
-                                    NULL,
-                                    update_cursor_next_cb,
-                                    self);
+  grl_source_notify_change_list (GRL_SOURCE (source), change_list,
+                                 change_type, FALSE);
 }
 
-#define CHANGED GINT_TO_POINTER (GRL_CONTENT_CHANGED)
-#define ADDED   GINT_TO_POINTER (GRL_CONTENT_ADDED)
-#define REMOVED GINT_TO_POINTER (GRL_CONTENT_REMOVED)
-
 static void
-graph_updated_cb (GDBusConnection *connection,
-                  const gchar     *sender_name,
-                  const gchar     *object_path,
-                  const gchar     *interface_name,
-                  const gchar     *signal_name,
-                  GVariant        *parameters,
-                  gpointer         user_data)
-
+notifier_event_cb (GrlTrackerSourceNotify *self,
+                   GPtrArray              *events,
+                   gpointer                user_data)
 {
-  GrlTrackerSourceNotify *self = user_data;
-  const gchar *class_name;
-  GVariantIter *iter1, *iter2;
-  gint graph, subject, predicate, object;
-  GString *query;
-
-  g_variant_get (parameters, "(&sa(iiii)a(iiii))", &class_name, &iter1, &iter2);
-
-  GRL_DEBUG ("Tracker update event for class=%s ins=%"G_GSIZE_FORMAT" del=%"G_GSIZE_FORMAT,
-             class_name,
-             g_variant_iter_n_children (iter2),
-             g_variant_iter_n_children (iter1));
-
-  query = g_string_new (NULL);
-
-  /* DELETE */
-  while (g_variant_iter_loop (iter1, "(iiii)", &graph, &subject, &predicate, &object)) {
-    gpointer key = GINT_TO_POINTER (subject);
-
-    /* If a rdf:type is removed, it probably means everything is going to be
-     * removed. The media has been deleted. If some other property is deleted
-     * it means the media already existed but changed.
-     */
-
-    if (predicate == self->rdf_type_id) {
-      g_hash_table_insert (self->updates, key, REMOVED);
-    } else if (g_hash_table_lookup (self->updates, key) != REMOVED) {
-      g_hash_table_insert (self->updates, key, CHANGED);
-    }
-  }
-
-  /* UPDATE */
-  while (g_variant_iter_loop (iter2, "(iiii)", &graph, &subject, &predicate, &object)) {
-    gpointer key = GINT_TO_POINTER (subject);
-
-    /* If a rdf:type is added it means it's a new media, otherwise it's an
-     * update of an existing media
-     */
-
-    if (predicate == self->rdf_type_id) {
-      g_hash_table_insert (self->updates, key, ADDED);
-    } else if (g_hash_table_lookup (self->updates, key) != ADDED) {
-      g_hash_table_insert (self->updates, key, CHANGED);
-    }
-
-    /* If we don't yet have info about this subject query it and add NULL in
-     * the table so we won't query it twice. */
-    if (!g_hash_table_contains (self->cache, key)) {
-      g_string_append_printf (query, "%d,", subject);
-      g_hash_table_insert (self->cache, key, NULL);
-    }
-  }
-
-  self->updates_count++;
-
-  if (query->len > 0) {
-    /* Remove trailing coma */
-    g_string_truncate (query, query->len - 1);
-
-    g_string_prepend (query,
-      "SELECT rdf:type(?urn) tracker:id(?urn) nie:dataSource(?urn) nie:url(?urn) "
-      "WHERE { ?urn a nfo:FileDataObject . "
-      "FILTER (tracker:id(?urn) IN (");
-    g_string_append (query, "))}");
-
-    GRL_DEBUG ("Query: %s", query->str);
-    tracker_sparql_connection_query_async (grl_tracker_connection,
-                                           query->str,
-                                           NULL,
-                                           update_query_cb,
-                                           g_object_ref (self));
-  } else {
-    update_query_done (self);
-  }
-
-  g_variant_iter_free (iter1);
-  g_variant_iter_free (iter2);
-  g_string_free (query, TRUE);
+  handle_changes (self, events,
+                  TRACKER_NOTIFIER_EVENT_CREATE,
+                  GRL_CONTENT_ADDED);
+  handle_changes (self, events,
+                  TRACKER_NOTIFIER_EVENT_UPDATE,
+                  GRL_CONTENT_CHANGED);
+  handle_changes (self, events,
+                  TRACKER_NOTIFIER_EVENT_DELETE,
+                  GRL_CONTENT_REMOVED);
 }
 
 static gboolean
@@ -322,40 +124,16 @@ grl_tracker_source_notify_initable_init (GInitable    *initable,
                                          GError      **error)
 {
   GrlTrackerSourceNotify *self = GRL_TRACKER_SOURCE_NOTIFY (initable);
-  TrackerSparqlCursor *cursor;
-
-  self->conn = g_bus_get_sync (G_BUS_TYPE_SESSION, cancellable, error);
-  if (self->conn == NULL)
-    return FALSE;
 
-  self->graph_updated_id = g_dbus_connection_signal_subscribe (
-      self->conn,
-      TRACKER_DBUS_SERVICE,
-      TRACKER_DBUS_INTERFACE_RESOURCES,
-      "GraphUpdated",
-      TRACKER_DBUS_OBJECT_RESOURCES,
-      NULL,
-      G_DBUS_SIGNAL_FLAGS_NONE,
-      graph_updated_cb,
-      self, NULL);
-
-  /* Query tracker to know the id of the rdf:type predicate so we can easily
-   * identify them in graph_updated_cb(). */
-  cursor = tracker_sparql_connection_query (grl_tracker_connection,
-      "select tracker:id(rdf:type) tracker:id(nfo:FileDataObject) {}",
-      NULL, error);
-  if (cursor == NULL)
+  self->notifier = tracker_notifier_new (NULL,
+                                        TRACKER_NOTIFIER_FLAG_QUERY_LOCATION,
+                                        cancellable, error);
+  if (!self->notifier)
     return FALSE;
 
-  if (!tracker_sparql_cursor_next (cursor, NULL, error)) {
-    g_object_unref (cursor);
-    return FALSE;
-  }
-
-  self->rdf_type_id = tracker_sparql_cursor_get_integer (cursor, 0);
-
-  g_object_unref (cursor);
-
+  self->events_signal_id =
+    g_signal_connect_swapped (self->notifier, "events",
+                              G_CALLBACK (notifier_event_cb), initable);
   return TRUE;
 }
 
@@ -364,13 +142,9 @@ grl_tracker_source_notify_finalize (GObject *object)
 {
   GrlTrackerSourceNotify *self = GRL_TRACKER_SOURCE_NOTIFY (object);
 
-  if (self->conn && self->graph_updated_id)
-    g_dbus_connection_signal_unsubscribe (self->conn, self->graph_updated_id);
-
-  g_clear_object (&self->conn);
-  g_clear_pointer (&self->updates, g_hash_table_unref);
-  g_clear_pointer (&self->cache, g_hash_table_unref);
-
+  if (self->events_signal_id)
+    g_signal_handler_disconnect (self->notifier, self->events_signal_id);
+  g_clear_object (&self->notifier);
   G_OBJECT_CLASS (grl_tracker_source_notify_parent_class)->finalize (object);
 }
 
@@ -386,10 +160,6 @@ grl_tracker_source_notify_class_init (GrlTrackerSourceNotifyClass *klass)
 static void
 grl_tracker_source_notify_init (GrlTrackerSourceNotify *self)
 {
-  self->updates = g_hash_table_new (NULL, NULL);
-  self->cache = g_hash_table_new_full (NULL, NULL,
-      NULL,
-      (GDestroyNotify) media_info_free);
 }
 
 static void