[tracker] rss: Be more careful about updates

[Carlos Garnacho <carlosg src gnome org>]

commit fec269ac803b37b31bddb4572548e6b7f81a6ef1
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Jul 16 02:45:25 2015 +0200

    rss: Be more careful about updates
    
    We just check all feeds on any hint from GraphUpdate, which means
    we also update everything if we dare to modify the mfo:FeedChannel,
    resulting in circular updates.
    
    Actually, we should be just inspecting additions of mfo:FeedChannel
    elements (or selected property changes in these), so modifications
    on these don't trigger the extraction of all the feeds again.
    If we happen to update all feeds on GraphUpdates, we also do so
    when modifying FeedChannels

 src/miners/rss/tracker-miner-rss.c |  112 ++++++++++++++++++++++++++++++------
 1 files changed, 95 insertions(+), 17 deletions(-)
---
diff --git a/src/miners/rss/tracker-miner-rss.c b/src/miners/rss/tracker-miner-rss.c
index e9e3a26..c4ad8c7 100644
--- a/src/miners/rss/tracker-miner-rss.c
+++ b/src/miners/rss/tracker-miner-rss.c
@@ -47,6 +47,9 @@ struct _TrackerMinerRSSPrivate {
 
        GList *item_inserts;
        GHashTable *channel_updates;
+
+       gint rdf_type_id;
+       gint mfo_feed_channel_id;
 };
 
 typedef struct {
@@ -73,7 +76,8 @@ static void         miner_started                   (TrackerMiner          *mine
 static void         miner_stopped                   (TrackerMiner          *miner);
 static void         miner_paused                    (TrackerMiner          *miner);
 static void         miner_resumed                   (TrackerMiner          *miner);
-static void         retrieve_and_schedule_feeds     (TrackerMinerRSS       *miner);
+static void         retrieve_and_schedule_feeds     (TrackerMinerRSS       *miner,
+                                                     GArray                *channel_ids);
 static gboolean     feed_channel_changed_timeout_cb (gpointer               user_data);
 static void         feed_channel_update_data_free   (FeedChannelUpdateData *fcud);
 static void         feed_item_insert_data_free      (FeedItemInsertData    *fiid);
@@ -110,6 +114,36 @@ tracker_miner_rss_finalize (GObject *object)
        G_OBJECT_CLASS (tracker_miner_rss_parent_class)->finalize (object);
 }
 
+static gint
+get_class_id (TrackerSparqlConnection *conn,
+              const gchar             *class)
+{
+       TrackerSparqlCursor *cursor;
+       GError *error = NULL;
+       gchar *query;
+       gint id = -1;
+
+       query = g_strdup_printf ("select tracker:id (%s) {}", class);
+       cursor = tracker_sparql_connection_query (conn, query, NULL, &error);
+       g_free (query);
+
+       if (error) {
+               g_critical ("Could not get class ID for '%s': %s\n",
+                           class, error->message);
+               g_error_free (error);
+               return -1;
+       }
+
+       if (tracker_sparql_cursor_next (cursor, NULL, NULL))
+               id = tracker_sparql_cursor_get_integer (cursor, 0);
+       else
+               g_critical ("'%s' didn't resolve to a known class ID", class);
+
+       g_object_unref (cursor);
+
+       return id;
+}
+
 static gboolean
 miner_connected (TrackerMinerOnline *miner,
                 TrackerNetworkType  network)
@@ -182,6 +216,29 @@ tracker_miner_rss_init (TrackerMinerRSS *object)
                                                     NULL);
 }
 
+static void
+handle_updates (TrackerMinerRSS *miner,
+                GVariantIter    *iter)
+{
+       GArray *updated = g_array_new (FALSE, FALSE, sizeof (gint));
+       gint graph, subject, pred, object;
+       TrackerMinerRSSPrivate *priv;
+
+       priv = TRACKER_MINER_RSS_GET_PRIVATE (miner);
+
+       while (g_variant_iter_next (iter, "(iiii)",
+                                   &graph, &subject, &pred, &object)) {
+               if (pred == priv->rdf_type_id &&
+                   object == priv->mfo_feed_channel_id) {
+                       g_array_append_val (updated, subject);
+               }
+       }
+
+       if (updated->len > 0)
+               retrieve_and_schedule_feeds (miner, updated);
+
+       g_array_free (updated, TRUE);
+}
 
 static void
 graph_updated_cb (GDBusConnection *connection,
@@ -193,11 +250,12 @@ graph_updated_cb (GDBusConnection *connection,
                   gpointer         user_data)
 {
        TrackerMinerRSS *miner = TRACKER_MINER_RSS (user_data);
+       GVariantIter *deletes, *updates;
 
-       g_message ("%s", signal_name);
-       g_message ("  Parameters:'%s'", g_variant_print (parameters, FALSE));
-
-       retrieve_and_schedule_feeds (miner);
+       g_variant_get (parameters, "(&sa(iiii)a(iiii))", NULL, &deletes, &updates);
+       handle_updates (miner, updates);
+       g_variant_iter_free (deletes);
+       g_variant_iter_free (updates);
 }
 
 static FeedChannelUpdateData *
@@ -758,26 +816,42 @@ feeds_retrieve_cb (GObject      *source_object,
 }
 
 static void
-retrieve_and_schedule_feeds (TrackerMinerRSS *miner)
+retrieve_and_schedule_feeds (TrackerMinerRSS *miner,
+                             GArray          *channel_ids)
 {
-       const gchar *sparql;
+       GString *sparql;
+       gint i, id;
 
        g_message ("Retrieving and scheduling feeds...");
 
-       sparql =
-               "SELECT ?url nie:title(?urn) ?interval ?urn "
-               "WHERE {"
-               "  ?urn a mfo:FeedChannel ; "
-               "         mfo:feedSettings ?settings ; "
-               "         nie:url ?url . "
-               "  ?settings mfo:updateInterval ?interval "
-               "}";
+       sparql = g_string_new ("SELECT ?url nie:title(?urn) ?interval ?urn "
+                              "WHERE {"
+                              "  ?urn a mfo:FeedChannel ; "
+                              "         mfo:feedSettings ?settings ; "
+                              "         nie:url ?url . "
+                              "  ?settings mfo:updateInterval ?interval ");
+
+       if (channel_ids && channel_ids->len > 0) {
+               g_string_append (sparql, ". FILTER (tracker:id(?urn) IN (");
+
+               for (i = 0; i < channel_ids->len; i++) {
+                       id = g_array_index (channel_ids, gint, i);
+                       if (i != 0)
+                               g_string_append (sparql, ",");
+                       g_string_append_printf (sparql, "%d", id);
+               }
+
+               g_string_append (sparql, "))");
+       }
+
+       g_string_append_printf (sparql, "}");
 
        tracker_sparql_connection_query_async (tracker_miner_get_connection (TRACKER_MINER (miner)),
-                                              sparql,
+                                              sparql->str,
                                               NULL,
                                               feeds_retrieve_cb,
                                               miner);
+       g_string_free (sparql, TRUE);
 }
 
 static const gchar *
@@ -795,11 +869,15 @@ static void
 miner_started (TrackerMiner *miner)
 {
        TrackerMinerRSSPrivate *priv;
+       TrackerSparqlConnection *conn;
 
        g_object_set (miner, "progress", 0.0, "status", "Initializing", NULL);
 
        priv = TRACKER_MINER_RSS_GET_PRIVATE (miner);
-       retrieve_and_schedule_feeds (TRACKER_MINER_RSS (miner));
+       conn = tracker_miner_get_connection (miner);
+       priv->rdf_type_id = get_class_id (conn, "rdf:type");
+       priv->mfo_feed_channel_id = get_class_id (conn, "mfo:FeedChannel");
+       retrieve_and_schedule_feeds (TRACKER_MINER_RSS (miner), NULL);
        grss_feeds_pool_switch (priv->pool, TRUE);
 }