[tracker/wip/carlosg/tracker-3.0-api-breaks] libtracker-sparql: Cancel info query on notifier finalization

[Carlos Garnacho <carlosg src gnome org>]

commit 922ac3b4e2401983acfe08f06667f25e07d6c308
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Feb 11 17:05:17 2020 +0100

    libtracker-sparql: Cancel info query on notifier finalization
    
    We are indirectly safe here as the event cache holds a ref to the
    notifier, but seems sensible to ensure that TrackerNotifier finalization
    would result in async queries bailing out.

 src/libtracker-sparql/tracker-notifier.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)
---
diff --git a/src/libtracker-sparql/tracker-notifier.c b/src/libtracker-sparql/tracker-notifier.c
index 332483cd3..3859fb667 100644
--- a/src/libtracker-sparql/tracker-notifier.c
+++ b/src/libtracker-sparql/tracker-notifier.c
@@ -85,6 +85,7 @@ struct _TrackerNotifierPrivate {
        TrackerSparqlConnection *connection;
        TrackerNotifierFlags flags;
        GHashTable *subscriptions; /* guint -> TrackerNotifierSubscription */
+       GCancellable *cancellable;
 };
 
 struct _TrackerNotifierEventCache {
@@ -368,12 +369,25 @@ query_extra_info_cb (GObject      *object,
        TrackerSparqlCursor *cursor;
        TrackerNotifierEvent *event;
        GSequenceIter *iter;
+       GError *error = NULL;
        gint col;
        gint64 id;
 
        priv = tracker_notifier_get_instance_private (cache->notifier);
        conn = TRACKER_SPARQL_CONNECTION (object);
-       cursor = tracker_sparql_connection_query_finish (conn, res, NULL);
+       cursor = tracker_sparql_connection_query_finish (conn, res, &error);
+
+       if (!cursor) {
+               if (!g_error_matches (error,
+                                     G_IO_ERROR,
+                                     G_IO_ERROR_CANCELLED)) {
+                       g_critical ("Could not get cursor: %s\n", error->message);
+               }
+
+               _tracker_notifier_event_cache_free (cache);
+               g_clear_error (&error);
+               return;
+       }
 
        iter = g_sequence_get_begin_iter (cache->sequence);
 
@@ -416,7 +430,7 @@ tracker_notifier_query_extra_info (TrackerNotifier           *notifier,
 
        priv = tracker_notifier_get_instance_private (notifier);
        tracker_sparql_connection_query_async (priv->connection, sparql,
-                                              NULL,
+                                              priv->cancellable,
                                               query_extra_info_cb,
                                               cache);
        g_free (sparql);
@@ -518,6 +532,9 @@ tracker_notifier_finalize (GObject *object)
 
        priv = tracker_notifier_get_instance_private (TRACKER_NOTIFIER (object));
 
+       g_cancellable_cancel (priv->cancellable);
+       g_clear_object (&priv->cancellable);
+
        if (priv->connection)
                g_object_unref (priv->connection);
 
@@ -594,6 +611,7 @@ tracker_notifier_init (TrackerNotifier *notifier)
        priv = tracker_notifier_get_instance_private (notifier);
        priv->subscriptions = g_hash_table_new_full (NULL, NULL, NULL,
                                                     (GDestroyNotify) tracker_notifier_subscription_free);
+       priv->cancellable = g_cancellable_new ();
 }
 
 guint