[evolution-data-server] ECalBackend: Follow up on a timezone-related FIXME comment.

[Matthew Barnes <mbarnes src gnome org>]

commit 1aff5e7648e66dbd33cd304bdb8894f3107729e1
Author: Matthew Barnes <mbarnes redhat com>
Date:   Fri Feb 22 09:45:35 2013 -0500

    ECalBackend: Follow up on a timezone-related FIXME comment.
    
    Emit the "timezone-added" signal from an idle callback on ECalBackend's
    GMainContext, instead of from whichever thread the timezone was added.
    This makes life easier for any handlers of that signal.

 calendar/libedata-cal/e-cal-backend.c |   61 ++++++++++++++++++++++++++++-----
 1 files changed, 52 insertions(+), 9 deletions(-)
---
diff --git a/calendar/libedata-cal/e-cal-backend.c b/calendar/libedata-cal/e-cal-backend.c
index dba3098..e2a31e1 100644
--- a/calendar/libedata-cal/e-cal-backend.c
+++ b/calendar/libedata-cal/e-cal-backend.c
@@ -35,6 +35,8 @@
 #define EDC_ERROR(_code)       e_data_cal_create_error (_code, NULL)
 #define EDC_NOT_OPENED_ERROR   e_data_cal_create_error (NotOpened, NULL)
 
+typedef struct _SignalClosure SignalClosure;
+
 /* Private part of the CalBackend structure */
 struct _ECalBackendPrivate {
        ESourceRegistry *registry;
@@ -59,7 +61,11 @@ struct _ECalBackendPrivate {
 
        /* ECalBackend to pass notifications on to */
        ECalBackend *notification_proxy;
+};
 
+struct _SignalClosure {
+       ECalBackend *backend;
+       icaltimezone *cached_zone;
 };
 
 /* Property IDs */
@@ -88,6 +94,17 @@ G_DEFINE_TYPE_WITH_CODE (
                e_cal_backend_timezone_cache_init))
 
 static void
+signal_closure_free (SignalClosure *signal_closure)
+{
+       g_object_unref (signal_closure->backend);
+
+       /* The icaltimezone is cached in ECalBackend's internal
+        * "zone_cache" hash table and must not be freed here. */
+
+       g_slice_free (SignalClosure, signal_closure);
+}
+
+static void
 cal_backend_free_zone (icaltimezone *zone)
 {
        icaltimezone_free (zone, 1);
@@ -160,6 +177,19 @@ cal_backend_get_backend_property (ECalBackend *backend,
        }
 }
 
+static gboolean
+cal_backend_emit_timezone_added_idle_cb (gpointer user_data)
+{
+       SignalClosure *signal_closure = user_data;
+
+       g_signal_emit_by_name (
+               signal_closure->backend,
+               "timezone-added",
+               signal_closure->cached_zone);
+
+       return FALSE;
+}
+
 static void
 cal_backend_set_backend_property (ECalBackend *backend,
                                   EDataCal *cal,
@@ -333,7 +363,6 @@ cal_backend_add_cached_timezone (ETimezoneCache *cache,
 {
        ECalBackendPrivate *priv;
        const gchar *tzid;
-       gboolean timezone_added = FALSE;
 
        priv = E_CAL_BACKEND_GET_PRIVATE (cache);
 
@@ -345,6 +374,9 @@ cal_backend_add_cached_timezone (ETimezoneCache *cache,
         * invalidate any icaltimezone pointers that may have already
         * been returned through e_timezone_cache_get_timezone(). */
        if (!g_hash_table_contains (priv->zone_cache, tzid)) {
+               GSource *idle_source;
+               GMainContext *main_context;
+               SignalClosure *signal_closure;
                icalcomponent *icalcomp;
                icaltimezone *cached_zone;
 
@@ -357,17 +389,28 @@ cal_backend_add_cached_timezone (ETimezoneCache *cache,
                        priv->zone_cache,
                        g_strdup (tzid), cached_zone);
 
-               timezone_added = TRUE;
+               /* The closure's backend reference will keep the
+                * internally cached icaltimezone alive for the
+                * duration of the idle callback. */
+               signal_closure = g_slice_new0 (SignalClosure);
+               signal_closure->backend = g_object_ref (cache);
+               signal_closure->cached_zone = cached_zone;
+
+               main_context = e_backend_ref_main_context (E_BACKEND (cache));
+
+               idle_source = g_idle_source_new ();
+               g_source_set_callback (
+                       idle_source,
+                       cal_backend_emit_timezone_added_idle_cb,
+                       signal_closure,
+                       (GDestroyNotify) signal_closure_free);
+               g_source_attach (idle_source, main_context);
+               g_source_unref (idle_source);
+
+               g_main_context_unref (main_context);
        }
 
        g_mutex_unlock (&priv->zone_cache_lock);
-
-       /* FIXME Should emit this from an idle GSource on
-        *       a stored GMainContext, but we don't have
-        *       a stored GMainContext.  Check back after
-        *       the D-Bus API rewrite. */
-       if (timezone_added)
-               g_signal_emit_by_name (cache, "timezone-added", zone);
 }
 
 static icaltimezone *