[tracker-miners/wip/carlosg/delay-monitors: 8/19] libtracker-miner: Disable monitors during crawling

[Carlos Garnacho <carlosg src gnome org>]

commit 7cc9fce3e0da3761c65c8d659d5bccee66f02cc5
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Oct 31 11:43:32 2020 +0100

    libtracker-miner: Disable monitors during crawling
    
    Adding these as the directories are traversed incurs in a fair
    amount of GSource overhead, as every monitor adds one to the
    glib worker thread, thus its main context is iterated often.
    
    Waiting to do this at once is a performance improvement, since
    the main loop is not that much busy during traversal, and adding
    all monitors collectively in one go isn't nearly as bad as adding
    them in small groups.
    
    This however means we increase the room for race conditions if
    files or directories were modified between traversal and monitor
    enablement. This is slightly racy already, and eventually the
    indexed state will mirror the filesystem's, so perhaps it's not
    that bad.

 src/libtracker-miner/tracker-file-notifier.c | 43 ++--------------------------
 1 file changed, 3 insertions(+), 40 deletions(-)
---
diff --git a/src/libtracker-miner/tracker-file-notifier.c b/src/libtracker-miner/tracker-file-notifier.c
index 7317ed93e..6092ab087 100644
--- a/src/libtracker-miner/tracker-file-notifier.c
+++ b/src/libtracker-miner/tracker-file-notifier.c
@@ -1369,43 +1369,6 @@ tracker_file_notifier_finalize (GObject *object)
        G_OBJECT_CLASS (tracker_file_notifier_parent_class)->finalize (object);
 }
 
-static void
-check_disable_monitor (TrackerFileNotifier *notifier)
-{
-       TrackerFileNotifierPrivate *priv;
-       TrackerSparqlCursor *cursor;
-       gint64 folder_count = 0;
-       GError *error = NULL;
-
-       priv = tracker_file_notifier_get_instance_private (notifier);
-       cursor = tracker_sparql_connection_query (priv->connection,
-                                                 "SELECT COUNT(?f) { ?f a nfo:Folder }",
-                                                 NULL, &error);
-
-       if (!error && tracker_sparql_cursor_next (cursor, NULL, &error)) {
-               folder_count = tracker_sparql_cursor_get_integer (cursor, 0);
-               tracker_sparql_cursor_close (cursor);
-       }
-
-       if (error) {
-               g_warning ("Could not get folder count: %s\n", error->message);
-               g_error_free (error);
-       } else if (folder_count > tracker_monitor_get_limit (priv->monitor)) {
-               /* If the folder count exceeds the monitor limit, there's
-                * nothing we can do anyway to prevent possibly out of date
-                * content. As it is the case no matter what we try, fully
-                * embrace it instead, and disable monitors until after crawling
-                * has been performed. This dramatically improves crawling time
-                * as monitors are inherently expensive.
-                */
-               g_info ("Temporarily disabling monitors until crawling is "
-                       "completed. Too many folders to monitor anyway");
-               tracker_monitor_set_enabled (priv->monitor, FALSE);
-       }
-
-       g_clear_object (&cursor);
-}
-
 static gboolean
 crawler_check_func (TrackerCrawler           *crawler,
                     TrackerCrawlerCheckFlags  flags,
@@ -1460,7 +1423,8 @@ tracker_file_notifier_constructed (GObject *object)
                                        object, NULL);
        tracker_crawler_set_file_attributes (priv->crawler, priv->file_attributes);
 
-       check_disable_monitor (TRACKER_FILE_NOTIFIER (object));
+       g_info ("Temporarily disabling monitors until crawling is completed.");
+       tracker_monitor_set_enabled (priv->monitor, FALSE);
 }
 
 static void
@@ -1471,8 +1435,7 @@ tracker_file_notifier_real_finished (TrackerFileNotifier *notifier)
        priv = tracker_file_notifier_get_instance_private (notifier);
 
        if (!tracker_monitor_get_enabled (priv->monitor)) {
-               /* If the monitor was disabled on ::constructed (see
-                * check_disable_monitor()), enable it back again.
+               /* Enable monitors back again.
                 * This will lazily create all missing directory
                 * monitors.
                 */