[gnome-panel] [clock] Avoid unnecessary wakeups when monitoring non-existing files

[Vincent Untz <vuntz src gnome org>]

commit b0d742da06df69fd70fb38af927cada4cebcfca3
Author: Vincent Untz <vuntz gnome org>
Date:   Thu Jan 14 02:49:14 2010 +0100

    [clock] Avoid unnecessary wakeups when monitoring non-existing files
    
    If the parent directory of a timezone-related file doesn't exist on the
    system, then it means the file is not useful to determine the timezone
    on this system.
    
    Since gio doesn't handle well monitoring files in non-existing
    directories (it polls every other second), this should avoid unnecessary
    wakeups.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=580357

 applets/clock/system-timezone.c |   26 +++++++++++++++++++++-----
 1 files changed, 21 insertions(+), 5 deletions(-)
---
diff --git a/applets/clock/system-timezone.c b/applets/clock/system-timezone.c
index bcd7f4a..336f5a9 100644
--- a/applets/clock/system-timezone.c
+++ b/applets/clock/system-timezone.c
@@ -190,12 +190,27 @@ system_timezone_constructor (GType                  type,
         priv->env_tz = g_strdup (g_getenv ("TZ"));
 
         for (i = 0; i < CHECK_NB; i++) {
-                GFile *file;
+                GFile     *file;
+                GFile     *parent;
+                GFileType  parent_type;
 
                 file = g_file_new_for_path (files_to_check[i]);
-                priv->monitors[i] = g_file_monitor_file (file,
-                                                         G_FILE_MONITOR_NONE,
-                                                         NULL, NULL);
+
+                parent = g_file_get_parent (file);
+                parent_type = g_file_query_file_type (parent, G_FILE_QUERY_INFO_NONE, NULL);
+                g_object_unref (parent);
+
+                /* We don't try to monitor the file if the parent directory
+                 * doesn't exist: this means we're on a system where this file
+                 * is not useful to determine the system timezone.
+                 * Since gio does not monitor file in non-existing directories
+                 * in a clever way (as of gio 2.22, it just polls every other
+                 * seconds to see if the directory now exists), this avoids
+                 * unnecessary wakeups. */
+                if (parent_type == G_FILE_TYPE_DIRECTORY)
+                        priv->monitors[i] = g_file_monitor_file (file,
+                                                                 G_FILE_MONITOR_NONE,
+                                                                 NULL, NULL);
                 g_object_unref (file);
 
                 if (priv->monitors[i])
@@ -227,7 +242,8 @@ system_timezone_finalize (GObject *obj)
         }
 
         for (i = 0; i < CHECK_NB; i++) {
-                g_object_unref (priv->monitors[i]);
+                if (priv->monitors[i])
+                        g_object_unref (priv->monitors[i]);
                 priv->monitors[i] = NULL;
         }