Add GPowerProfileMonitor

docs/reference/gio/gio-docs.xml

@@ -238,6 +238,7 @@
         <xi:include href="xml/gmenuexporter.xml"/>
         <xi:include href="xml/gdbusmenumodel.xml"/>
         <xi:include href="xml/gnotification.xml"/>
+        <xi:include href="xml/gpowerprofilemonitor.xml"/>
     </chapter>
     <chapter id="extending">
         <title>Extending GIO</title>

docs/reference/gio/gio-sections-common.txt

@@ -4247,6 +4247,24 @@ G_NETWORK_MONITOR_GET_INTERFACE
 g_network_connectivity_get_type
 </SECTION>
 
+<SECTION>
+<FILE>gpowerprofilemonitor</FILE>
+<TITLE>GPowerProfileMonitor</TITLE>
+GPowerProfileMonitor
+GPowerProfileMonitorInterface
+G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME
+g_power_profile_monitor_dup_default
+g_power_profile_monitor_get_power_saver_enabled
+<SUBSECTION Standard>
+g_power_profile_monitor_get_type
+G_TYPE_POWER_PROFILE_MONITOR
+G_POWER_PROFILE_MONITOR
+G_IS_POWER_PROFILE_MONITOR
+G_POWER_PROFILE_MONITOR_GET_INTERFACE
+G_TYPE_POWER_PROFILE_LEVEL
+g_power_profile_level_get_type
+</SECTION>
+
 <SECTION>
 <FILE>gmenuexporter</FILE>
 g_dbus_connection_export_menu_model

docs/reference/gio/meson.build

@@ -65,6 +65,7 @@ if get_option('gtk_doc')
     'gopenuriportal.h',
     'gpollfilemonitor.h',
     'gportalsupport.h',
+    'gpowerprofilemonitordbus.h',
     'gproxyresolverportal.h',
     'gregistrysettingsbackend.h',
     'gresourcefile.h',

gio/gio.h

@@ -120,6 +120,7 @@
 #include <gio/gpollableinputstream.h>
 #include <gio/gpollableoutputstream.h>
 #include <gio/gpollableutils.h>
+#include <gio/gpowerprofilemonitor.h>
 #include <gio/gpropertyaction.h>
 #include <gio/gproxy.h>
 #include <gio/gproxyaddress.h>

gio/giomodule.c

@@ -48,6 +48,8 @@
 #include "gmemorymonitor.h"
 #include "gmemorymonitorportal.h"
 #include "gmemorymonitordbus.h"
+#include "gpowerprofilemonitor.h"
+#include "gpowerprofilemonitordbus.h"
 #ifdef G_OS_WIN32
 #include "gregistrysettingsbackend.h"
 #include "giowin32-priv.h"
@@ -1077,6 +1079,7 @@ extern GType _g_network_monitor_nm_get_type (void);
 
 extern GType g_memory_monitor_dbus_get_type (void);
 extern GType g_memory_monitor_portal_get_type (void);
+extern GType g_power_profile_monitor_dbus_get_type (void);
 
 #ifdef G_OS_UNIX
 extern GType g_fdo_notification_backend_get_type (void);
@@ -1187,6 +1190,9 @@ _g_io_modules_ensure_extension_points_registered (void)
 
       ep = g_io_extension_point_register (G_MEMORY_MONITOR_EXTENSION_POINT_NAME);
       g_io_extension_point_set_required_type (ep, G_TYPE_MEMORY_MONITOR);
+
+      ep = g_io_extension_point_register (G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME);
+      g_io_extension_point_set_required_type (ep, G_TYPE_POWER_PROFILE_MONITOR);
     }
   
   G_UNLOCK (registered_extensions);
@@ -1272,6 +1278,7 @@ _g_io_modules_ensure_loaded (void)
       g_type_ensure (g_null_settings_backend_get_type ());
       g_type_ensure (g_memory_settings_backend_get_type ());
       g_type_ensure (g_keyfile_settings_backend_get_type ());
+      g_type_ensure (g_power_profile_monitor_dbus_get_type ());
 #if defined(HAVE_INOTIFY_INIT1)
       g_type_ensure (g_inotify_file_monitor_get_type ());
 #endif

gio/gpowerprofilemonitor.c

@@ -0,0 +1,141 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2019 Red Hat, Inc
+ * Copyright 2021 Igalia S.L.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include "glib.h"
+#include "glibintl.h"
+
+#include "gpowerprofilemonitor.h"
+#include "ginetaddress.h"
+#include "ginetsocketaddress.h"
+#include "ginitable.h"
+#include "gioenumtypes.h"
+#include "giomodule-priv.h"
+#include "gtask.h"
+
+/**
+ * SECTION:gpowerprofilemonitor
+ * @title: GPowerProfileMonitor
+ * @short_description: Power profile monitor
+ * @include: gio/gio.h
+ *
+ * #GPowerProfileMonitor makes it possible for applications as well as OS components
+ * to monitor system power profiles and act upon them. It currently only exports
+ * whether the system is in “Power Saver” mode (known as “Low Power” mode on
+ * some systems).
+ *
+ * When in “Low Power” mode, it is recommended that applications:
+ * - disabling automatic downloads
+ * - reduce the rate of refresh from online sources such as calendar or
+ *   email synchronisation
+ * - if the application has expensive visual effects, reduce them
+ *
+ * It is also likely that OS components providing services to applications will
+ * lower their own background activity, for the sake of the system.
+ *
+ * There are a variety of tools that exist for power consumption analysis, but those
+ * usually depend on the OS and hardware used. On Linux, one could use `upower` to
+ * monitor the battery discharge rate, `powertop` to check on the background activity
+ * or activity at all), `sysprof` to inspect CPU usage, and `intel_gpu_time` to
+ * profile GPU usage.
+ *
+ * Don't forget to disconnect the #GPowerProfileMonitor::notify::power-saver-enabled
+ * signal, and unref the #GPowerProfileMonitor itself when exiting.
+ *
+ * Since: 2.70
+ */
+
+/**
+ * GPowerProfileMonitor:
+ *
+ * #GPowerProfileMonitor monitors system power profile and notifies on
+ * changes.
+ *
+ * Since: 2.70
+ */
+
+/**
+ * GPowerProfileMonitorInterface:
+ * @g_iface: The parent interface.
+ *
+ * The virtual function table for #GPowerProfileMonitor.
+ *
+ * Since: 2.70
+ */
+
+G_DEFINE_INTERFACE_WITH_CODE (GPowerProfileMonitor, g_power_profile_monitor, G_TYPE_OBJECT,
+                              g_type_interface_add_prerequisite (g_define_type_id, G_TYPE_INITABLE))
+
+
+/**
+ * g_power_profile_monitor_dup_default:
+ *
+ * Gets a reference to the default #GPowerProfileMonitor for the system.
+ *
+ * Returns: (not nullable) (transfer full): a new reference to the default #GPowerProfileMonitor
+ *
+ * Since: 2.70
+ */
+GPowerProfileMonitor *
+g_power_profile_monitor_dup_default (void)
+{
+  return g_object_ref (_g_io_module_get_default (G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME,
+                                                 "GIO_USE_POWER_PROFILE_MONITOR",
+                                                 NULL));
+}
+
+/**
+ * g_power_profile_monitor_get_power_saver_enabled:
+ * @monitor: a #GPowerProfileMonitor
+ *
+ * Gets whether the system is in “Power Saver” mode.
+ *
+ * You are expected to listen to the
+ * #GPowerProfileMonitor::notify::power-saver-enabled signal to know when the profile has
+ * changed.
+ *
+ * Returns: Whether the system is in “Power Saver” mode.
+ *
+ * Since: 2.70
+ */
+gboolean
+g_power_profile_monitor_get_power_saver_enabled (GPowerProfileMonitor *monitor)
+{
+  gboolean enabled;
+  g_object_get (monitor, "power-saver-enabled", &enabled, NULL);
+  return enabled;
+}
+
+static void
+g_power_profile_monitor_default_init (GPowerProfileMonitorInterface *iface)
+{
+  /**
+   * GPowerProfileMonitor:power-saver-enabled:
+   *
+   * Whether “Power Saver” mode is enabled on the system.
+   *
+   * Since: 2.70
+   */
+  g_object_interface_install_property (iface,
+                                       g_param_spec_boolean ("power-saver-enabled",
+                                                             "power-saver-enabled",
+                                                             "Power Saver Enabled",
+                                                             FALSE,
+                                                             G_PARAM_READABLE | G_PARAM_STATIC_STRINGS | G_PARAM_EXPLICIT_NOTIFY));
+}

gio/gpowerprofilemonitor.h

@@ -0,0 +1,63 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2019 Red Hat, Inc.
+ * Copyright 2021 Igalia S.L.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __G_POWER_PROFILE_MONITOR_H__
+#define __G_POWER_PROFILE_MONITOR_H__
+
+#if !defined (__GIO_GIO_H_INSIDE__) && !defined (GIO_COMPILATION)
+#error "Only <gio/gio.h> can be included directly."
+#endif
+
+#include <gio/giotypes.h>
+
+G_BEGIN_DECLS
+
+/**
+ * G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME:
+ *
+ * Extension point for power profile usage monitoring functionality.
+ * See [Extending GIO][extending-gio].
+ *
+ * Since: 2.70
+ */
+#define G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME "gio-power-profile-monitor"
+
+#define G_TYPE_POWER_PROFILE_MONITOR             (g_power_profile_monitor_get_type ())
+GLIB_AVAILABLE_IN_2_70
+G_DECLARE_INTERFACE (GPowerProfileMonitor, g_power_profile_monitor, g, power_profile_monitor, GObject)
+
+#define G_POWER_PROFILE_MONITOR(o)               (G_TYPE_CHECK_INSTANCE_CAST ((o), G_TYPE_POWER_PROFILE_MONITOR, GPowerProfileMonitor))
+#define G_IS_POWER_PROFILE_MONITOR(o)            (G_TYPE_CHECK_INSTANCE_TYPE ((o), G_TYPE_POWER_PROFILE_MONITOR))
+#define G_POWER_PROFILE_MONITOR_GET_INTERFACE(o) (G_TYPE_INSTANCE_GET_INTERFACE ((o), G_TYPE_POWER_PROFILE_MONITOR, GPowerProfileMonitorInterface))
+
+struct _GPowerProfileMonitorInterface
+{
+  /*< private >*/
+  GTypeInterface g_iface;
+};
+
+GLIB_AVAILABLE_IN_2_70
+GPowerProfileMonitor      *g_power_profile_monitor_dup_default              (void);
+
+GLIB_AVAILABLE_IN_2_70
+gboolean                   g_power_profile_monitor_get_power_saver_enabled  (GPowerProfileMonitor *monitor);
+
+G_END_DECLS
+
+#endif /* __G_POWER_PROFILE_MONITOR_H__ */

gio/gpowerprofilemonitordbus.c

@@ -0,0 +1,240 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2019 Red Hat, Inc.
+ * Copyrgith 2021 Igalia S.L.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include "gpowerprofilemonitor.h"
+#include "gpowerprofilemonitordbus.h"
+#include "gioerror.h"
+#include "ginitable.h"
+#include "giomodule-priv.h"
+#include "glibintl.h"
+#include "glib/gstdio.h"
+#include "gcancellable.h"
+#include "gdbusproxy.h"
+#include "gdbusnamewatching.h"
+
+#define G_POWER_PROFILE_MONITOR_DBUS_GET_INITABLE_IFACE(o) (G_TYPE_INSTANCE_GET_INTERFACE ((o), G_TYPE_INITABLE, GInitable))
+
+static void g_power_profile_monitor_dbus_iface_init (GPowerProfileMonitorInterface *iface);
+static void g_power_profile_monitor_dbus_initable_iface_init (GInitableIface *iface);
+
+struct _GPowerProfileMonitorDBus
+{
+  GObject parent_instance;
+
+  guint watch_id;
+  GCancellable *cancellable;
+  GDBusProxy *proxy;
+  gulong signal_id;
+
+  gboolean power_saver_enabled;
+};
+
+typedef enum
+{
+  PROP_POWER_SAVER_ENABLED = 1,
+} GPowerProfileMonitorDBusProperty;
+
+#define POWERPROFILES_DBUS_NAME "net.hadess.PowerProfiles"
+#define POWERPROFILES_DBUS_IFACE "net.hadess.PowerProfiles"
+#define POWERPROFILES_DBUS_PATH "/net/hadess/PowerProfiles"
+
+G_DEFINE_TYPE_WITH_CODE (GPowerProfileMonitorDBus, g_power_profile_monitor_dbus, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
+                                                g_power_profile_monitor_dbus_initable_iface_init)
+                         G_IMPLEMENT_INTERFACE (G_TYPE_POWER_PROFILE_MONITOR,
+                                                g_power_profile_monitor_dbus_iface_init)
+                         _g_io_modules_ensure_extension_points_registered ();
+                         g_io_extension_point_implement (G_POWER_PROFILE_MONITOR_EXTENSION_POINT_NAME,
+                                                         g_define_type_id,
+                                                         "dbus",
+                                                         30))
+
+static void
+g_power_profile_monitor_dbus_init (GPowerProfileMonitorDBus *dbus)
+{
+  dbus->power_saver_enabled = FALSE;
+}
+
+static void
+ppd_properties_changed_cb (GDBusProxy *proxy,
+                           GVariant   *changed_properties,
+                           GStrv      *invalidated_properties,
+                           gpointer    user_data)
+{
+  GPowerProfileMonitorDBus *dbus = user_data;
+  const char *active_profile;
+  gboolean enabled;
+
+  if (!g_variant_lookup (changed_properties, "ActiveProfile", "&s", &active_profile))
+    return;
+
+  enabled = g_strcmp0 (active_profile, "power-saver") == 0;
+  if (enabled == dbus->power_saver_enabled)
+    return;
+
+  dbus->power_saver_enabled = enabled;
+  g_object_notify (G_OBJECT (dbus), "power-saver-enabled");
+}
+
+static void
+ppd_proxy_cb (GObject      *source_object,
+              GAsyncResult *res,
+              gpointer      user_data)
+{
+  GPowerProfileMonitorDBus *dbus = user_data;
+  GVariant *active_profile_variant;
+  GDBusProxy *proxy;
+  GError *error = NULL;
+  const char *active_profile;
+  gboolean power_saver_enabled;
+
+  proxy = g_dbus_proxy_new_finish (res, &error);
+  if (!proxy)
+    {
+      g_debug ("GPowerProfileMonitorDBus: Failed to create PowerProfiles D-Bus proxy: %s",
+               error->message);
+      g_error_free (error);
+      return;
+    }
+
+  active_profile_variant = g_dbus_proxy_get_cached_property (proxy, "ActiveProfile");
+  if (g_variant_is_of_type (active_profile_variant, G_VARIANT_TYPE_STRING))
+    {
+      active_profile = g_variant_get_string (active_profile_variant, NULL);
+      power_saver_enabled = g_strcmp0 (active_profile, "power-saver") == 0;
+      if (power_saver_enabled != dbus->power_saver_enabled)
+        {
+          dbus->power_saver_enabled = power_saver_enabled;
+          g_object_notify (G_OBJECT (dbus), "power-saver-enabled");
+        }
+    }
+
+  dbus->signal_id = g_signal_connect (G_OBJECT (proxy), "g-properties-changed",
+                                      G_CALLBACK (ppd_properties_changed_cb), dbus);
+  dbus->proxy = g_steal_pointer (&proxy);
+}
+
+static void
+ppd_appeared_cb (GDBusConnection *connection,
+                 const gchar     *name,
+                 const gchar     *name_owner,
+                 gpointer         user_data)
+{
+  GPowerProfileMonitorDBus *dbus = user_data;
+
+  g_dbus_proxy_new (connection,
+                    G_DBUS_PROXY_FLAGS_NONE,
+                    NULL,
+                    POWERPROFILES_DBUS_NAME,
+                    POWERPROFILES_DBUS_PATH,
+                    POWERPROFILES_DBUS_IFACE,
+                    dbus->cancellable,
+                    ppd_proxy_cb,
+                    dbus);
+}
+
+static void
+ppd_vanished_cb (GDBusConnection *connection,
+                 const gchar     *name,
+                 gpointer         user_data)
+{
+  GPowerProfileMonitorDBus *dbus = user_data;
+
+  g_clear_signal_handler (&dbus->signal_id, dbus->proxy);
+  g_clear_object (&dbus->proxy);
+
+  dbus->power_saver_enabled = FALSE;
+  g_object_notify (G_OBJECT (dbus), "power-saver-enabled");
+}
+
+static void
+g_power_profile_monitor_dbus_get_property (GObject    *object,
+                                           guint       prop_id,
+                                           GValue     *value,
+                                           GParamSpec *pspec)
+{
+  GPowerProfileMonitorDBus *dbus = G_POWER_PROFILE_MONITOR_DBUS (object);
+
+  switch ((GPowerProfileMonitorDBusProperty) prop_id)
+    {
+    case PROP_POWER_SAVER_ENABLED:
+      g_value_set_boolean (value, dbus->power_saver_enabled);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static gboolean
+g_power_profile_monitor_dbus_initable_init (GInitable     *initable,
+                                            GCancellable  *cancellable,
+                                            GError       **error)
+{
+  GPowerProfileMonitorDBus *dbus = G_POWER_PROFILE_MONITOR_DBUS (initable);
+
+  dbus->cancellable = g_cancellable_new ();
+  dbus->watch_id = g_bus_watch_name (G_BUS_TYPE_SYSTEM,
+                                     POWERPROFILES_DBUS_NAME,
+                                     G_BUS_NAME_WATCHER_FLAGS_AUTO_START,
+                                     ppd_appeared_cb,
+                                     ppd_vanished_cb,
+                                     dbus,
+                                     NULL);
+
+  return TRUE;
+}
+
+static void
+g_power_profile_monitor_dbus_finalize (GObject *object)
+{
+  GPowerProfileMonitorDBus *dbus = G_POWER_PROFILE_MONITOR_DBUS (object);
+
+  g_cancellable_cancel (dbus->cancellable);
+  g_clear_object (&dbus->cancellable);
+  g_clear_signal_handler (&dbus->signal_id, dbus->proxy);
+  g_clear_object (&dbus->proxy);
+  g_clear_handle_id (&dbus->watch_id, g_bus_unwatch_name);
+
+  G_OBJECT_CLASS (g_power_profile_monitor_dbus_parent_class)->finalize (object);
+}
+
+static void
+g_power_profile_monitor_dbus_class_init (GPowerProfileMonitorDBusClass *nl_class)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (nl_class);
+
+  gobject_class->get_property = g_power_profile_monitor_dbus_get_property;
+  gobject_class->finalize = g_power_profile_monitor_dbus_finalize;
+
+  g_object_class_override_property (gobject_class, PROP_POWER_SAVER_ENABLED, "power-saver-enabled");
+}
+
+static void
+g_power_profile_monitor_dbus_iface_init (GPowerProfileMonitorInterface *monitor_iface)
+{
+}
+
+static void
+g_power_profile_monitor_dbus_initable_iface_init (GInitableIface *iface)
+{
+  iface->init = g_power_profile_monitor_dbus_initable_init;
+}

gio/gpowerprofilemonitordbus.h

@@ -0,0 +1,32 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2019 Red Hat, Inc.
+ * Copyright 2021 Igalia S.L.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __G_POWER_PROFILE_MONITOR_DBUS_H__
+#define __G_POWER_PROFILE_MONITOR_DBUS_H__
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+#define G_TYPE_POWER_PROFILE_MONITOR_DBUS         (g_power_profile_monitor_dbus_get_type ())
+G_DECLARE_FINAL_TYPE (GPowerProfileMonitorDBus, g_power_profile_monitor_dbus, G, POWER_PROFILE_MONITOR_DBUS, GObject)
+
+G_END_DECLS
+
+#endif /* __G_POWER_PROFILE_MONITOR_DBUS_H__ */

gio/meson.build

@@ -533,6 +533,8 @@ gio_sources = files(
   'gpollableoutputstream.c',
   'gpollableutils.c',
   'gpollfilemonitor.c',
+  'gpowerprofilemonitor.c',
+  'gpowerprofilemonitordbus.c',
   'gproxy.c',
   'gproxyaddress.c',
   'gproxyaddressenumerator.c',
@@ -673,6 +675,7 @@ gio_headers = files(
   'gpollableinputstream.h',
   'gpollableoutputstream.h',
   'gpollableutils.h',
+  'gpowerprofilemonitor.h',
   'gproxy.h',
   'gproxyaddress.h',
   'gproxyaddressenumerator.h',

gio/tests/meson.build

@@ -75,6 +75,7 @@ gio_tests = {
   'network-monitor-race' : {},
   'permission' : {},
   'pollable' : {'dependencies' : [libdl_dep]},
+  'power-profile-monitor' : {},
   'proxy-test' : {},
   'readwrite' : {},
   'simple-async-result' : {},

gio/tests/power-profile-monitor.c

@@ -0,0 +1,79 @@
+/* GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright 2021 Igalia S.L.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <gio/gio.h>
+
+static void
+test_dup_default (void)
+{
+  GPowerProfileMonitor *monitor;
+
+  monitor = g_power_profile_monitor_dup_default ();
+  g_assert_nonnull (monitor);
+  g_object_unref (monitor);
+}
+
+static void
+power_saver_enabled_cb (GPowerProfileMonitor *monitor,
+                        GParamSpec           *pspec,
+                        gpointer              user_data)
+{
+  gboolean enabled;
+
+  enabled = g_power_profile_monitor_get_power_saver_enabled (monitor);
+  g_debug ("Power Saver %s (%d)", enabled ? "enabled" : "disabled", enabled);
+}
+
+static void
+do_watch_power_profile (void)
+{
+  GPowerProfileMonitor *monitor;
+  GMainLoop *loop;
+  gulong signal_id;
+
+  monitor = g_power_profile_monitor_dup_default ();
+  signal_id = g_signal_connect (G_OBJECT (monitor), "notify::power-saver-enabled",
+		                G_CALLBACK (power_saver_enabled_cb), NULL);
+
+  loop = g_main_loop_new (NULL, TRUE);
+  g_main_loop_run (loop);
+
+  g_signal_handler_disconnect (monitor, signal_id);
+  g_object_unref (monitor);
+  g_main_loop_unref (loop);
+}
+
+int
+main (int argc, char **argv)
+{
+  int ret;
+
+  if (argc == 2 && !strcmp (argv[1], "--watch"))
+    {
+      do_watch_power_profile ();
+      return 0;
+    }
+
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/power-profile-monitor/default", test_dup_default);
+
+  ret = g_test_run ();
+
+  return ret;
+}