[tracker/wip/carlosg/tracker-3.0-api-breaks: 92/100] libtracker-direct: Ensure queries get cancelled after close()

[Carlos Garnacho <carlosg src gnome org>]

commit 41d192ca17df329c05be60e7b6e3e8c2737439dc
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Feb 4 23:59:44 2020 +0100

    libtracker-direct: Ensure queries get cancelled after close()
    
    The query thread pool does not get awaited for completion, which
    means later operations should error out orderly. Ensure this
    actually happens, as documented in tracker_sparql_connection_close().

 src/libtracker-direct/tracker-direct.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
---
diff --git a/src/libtracker-direct/tracker-direct.c b/src/libtracker-direct/tracker-direct.c
index 0155a1fcc..8527f9672 100644
--- a/src/libtracker-direct/tracker-direct.c
+++ b/src/libtracker-direct/tracker-direct.c
@@ -45,6 +45,7 @@ struct _TrackerDirectConnectionPrivate
        GList *notifiers;
 
        guint initialized : 1;
+       guint closing     : 1;
 };
 
 enum {
@@ -148,12 +149,26 @@ static void
 query_thread_pool_func (gpointer data,
                         gpointer user_data)
 {
+       TrackerDirectConnection *conn = user_data;
+       TrackerDirectConnectionPrivate *priv;
        TrackerSparqlCursor *cursor;
        GTask *task = data;
        TaskData *task_data = g_task_get_task_data (task);
        GError *error = NULL;
 
        g_assert (task_data->type == TASK_TYPE_QUERY);
+
+       priv = tracker_direct_connection_get_instance_private (conn);
+
+       if (priv->closing) {
+               g_task_return_new_error (task,
+                                        G_IO_ERROR,
+                                        G_IO_ERROR_CONNECTION_CLOSED,
+                                        "Connection is closed");
+               g_object_unref (task);
+               return;
+       }
+
        cursor = tracker_sparql_connection_query (TRACKER_SPARQL_CONNECTION (g_task_get_source_object (task)),
                                                  task_data->query,
                                                  g_task_get_cancellable (task),
@@ -898,6 +913,7 @@ tracker_direct_connection_close (TrackerSparqlConnection *self)
 
        conn = TRACKER_DIRECT_CONNECTION (self);
        priv = tracker_direct_connection_get_instance_private (conn);
+       priv->closing = TRUE;
 
        if (priv->update_thread) {
                g_thread_pool_free (priv->update_thread, TRUE, TRUE);