core/calendar: Ensure notify happens in main thread

The notify signals of ESourceSelectable seem to come from the
ESourceRegistry thread, and this has the potential to derail
the execution of Calendar. This might be true for all signals
we connect to.

Make sure to always emit notify signals on the main thread.

src/core/gcal-calendar.c

@@ -21,6 +21,7 @@
 #define G_LOG_DOMAIN "GcalCalendar"
 
 #include "gcal-calendar.h"
+#include "gcal-core-macros.h"
 #include "gcal-debug.h"
 #include "gcal-utils.h"
 
@@ -38,10 +39,21 @@ typedef struct
   gulong              readonly_changed_handler_id;
   gulong              visible_changed_handler_id;
   gboolean            initialized;
+
+  struct {
+    GMutex            mutex;
+    guint             update_idle_id;
+    gboolean          color_changed;
+    gboolean          name_changed;
+    gboolean          readonly_changed;
+    gboolean          visibility_changed;
+  } shared;
 } GcalCalendarPrivate;
 
 static void          g_initable_iface_init                       (GInitableIface     *iface);
 
+static gboolean      update_idle_cb                              (gpointer            data);
+
 G_DEFINE_TYPE_WITH_CODE (GcalCalendar, gcal_calendar, G_TYPE_OBJECT,
                          G_ADD_PRIVATE (GcalCalendar)
                          G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE, g_initable_iface_init)
@@ -84,6 +96,18 @@ save_calendar (GcalCalendar *self)
   e_source_write (priv->source, NULL, NULL, NULL);
 }
 
+static void
+schedule_idle_update_unlocked (GcalCalendar *self)
+{
+  GcalCalendarPrivate *priv = gcal_calendar_get_instance_private (self);
+
+  if (priv->shared.update_idle_id == 0)
+    priv->shared.update_idle_id = g_idle_add_full (G_PRIORITY_DEFAULT_IDLE,
+                                                   update_idle_cb,
+                                                   g_object_ref (self),
+                                                   g_object_unref);
+}
+
 static void
 update_color (GcalCalendar *self)
 {
@@ -103,13 +127,76 @@ update_color (GcalCalendar *self)
  * Callbacks
  */
 
+static gboolean
+update_idle_cb (gpointer data)
+{
+  g_autoptr (GMutexLocker) locker = NULL;
+  GcalCalendarPrivate *priv;
+  GcalCalendar *self;
+
+  GCAL_ENTRY;
+
+  g_assert (GCAL_IS_MAIN_THREAD ());
+
+  self = GCAL_CALENDAR (data);
+  priv = gcal_calendar_get_instance_private (self);
+
+  locker = g_mutex_locker_new (&priv->shared.mutex);
+
+  if (priv->shared.name_changed)
+    {
+      g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_NAME]);
+      priv->shared.name_changed = FALSE;
+    }
+
+  if (priv->shared.color_changed)
+    {
+      update_color (self);
+      g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_COLOR]);
+      priv->shared.color_changed = FALSE;
+    }
+
+  if (priv->shared.readonly_changed)
+    {
+      g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_READ_ONLY]);
+      priv->shared.readonly_changed = FALSE;
+    }
+
+  if (priv->shared.visibility_changed)
+    {
+      ESourceSelectable *selectable_extension;
+      gboolean visible;
+
+      selectable_extension = e_source_get_extension (priv->source, E_SOURCE_EXTENSION_CALENDAR);
+      visible = e_source_selectable_get_selected (selectable_extension);
+
+      if (visible != priv->visible)
+        {
+          priv->visible = visible;
+          g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_VISIBLE]);
+        }
+
+      priv->shared.visibility_changed = FALSE;
+    }
+
+  priv->shared.update_idle_id = 0;
+
+  GCAL_RETURN (G_SOURCE_REMOVE);
+}
+
 static void
 on_source_color_changed_cb (ESourceSelectable *source,
                             GParamSpec        *pspec,
                             GcalCalendar      *self)
 {
-  update_color (self);
-  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_COLOR]);
+  g_autoptr (GMutexLocker) locker = NULL;
+  GcalCalendarPrivate *priv;
+
+  priv = gcal_calendar_get_instance_private (self);
+  locker = g_mutex_locker_new (&priv->shared.mutex);
+
+  priv->shared.color_changed = TRUE;
+  schedule_idle_update_unlocked (self);
 }
 
 static void
@@ -117,7 +204,14 @@ on_source_name_changed_cb (ESource      *source,
                            GParamSpec   *pspec,
                            GcalCalendar *self)
 {
-  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_NAME]);
+  g_autoptr (GMutexLocker) locker = NULL;
+  GcalCalendarPrivate *priv;
+
+  priv = gcal_calendar_get_instance_private (self);
+  locker = g_mutex_locker_new (&priv->shared.mutex);
+
+  priv->shared.name_changed = TRUE;
+  schedule_idle_update_unlocked (self);
 }
 
 static void
@@ -125,7 +219,14 @@ on_client_readonly_changed_cb (EClient      *client,
                                GParamSpec   *pspec,
                                GcalCalendar *self)
 {
-  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_READ_ONLY]);
+  g_autoptr (GMutexLocker) locker = NULL;
+  GcalCalendarPrivate *priv;
+
+  priv = gcal_calendar_get_instance_private (self);
+  locker = g_mutex_locker_new (&priv->shared.mutex);
+
+  priv->shared.readonly_changed = TRUE;
+  schedule_idle_update_unlocked (self);
 }
 
 static void
@@ -133,17 +234,14 @@ on_source_visible_changed_cb (ESourceSelectable *source,
                               GParamSpec        *pspec,
                               GcalCalendar      *self)
 {
+  g_autoptr (GMutexLocker) locker = NULL;
   GcalCalendarPrivate *priv;
-  gboolean visible;
 
   priv = gcal_calendar_get_instance_private (self);
-  visible = e_source_selectable_get_selected (source);
+  locker = g_mutex_locker_new (&priv->shared.mutex);
 
-  if (visible == priv->visible)
-    return;
-
-  priv->visible = visible;
-  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_VISIBLE]);
+  priv->shared.visibility_changed = TRUE;
+  schedule_idle_update_unlocked (self);
 }
 
 
@@ -246,6 +344,10 @@ gcal_calendar_finalize (GObject *object)
   gcal_clear_signal_handler (&priv->readonly_changed_handler_id, priv->client);
   gcal_clear_signal_handler (&priv->visible_changed_handler_id, selectable_extension);
 
+  g_mutex_lock (&priv->shared.mutex);
+  g_clear_handle_id (&priv->shared.update_idle_id, g_source_remove);
+  g_mutex_unlock (&priv->shared.mutex);
+
   g_clear_object (&priv->client);
   g_clear_object (&priv->source);