[glib] Menu model exporter: clean up the API

[Ryan Lortie <ryanl src gnome org>]

commit cfbc1b5a4b0bdf6de856fc054149e8f558970dff
Author: Ryan Lortie <desrt desrt ca>
Date:   Fri Dec 2 15:36:15 2011 -0500

    Menu model exporter: clean up the API
    
    Give it the same treatment as the exporter for GActionGroup just got.
    
    There is a wart here: the exporter attempt to re-enter GDBusConnection
    when it is freed in order to cancel outstanding name watches.
    GDBusConnection holds its own lock while calling the destroy notify, so
    the attempt at reentrancy results in a deadlock.
    
    We have a workaround to deal with that for now...

 gio/gmenuexporter.c    |  176 +++++++++++++-----------------------------------
 gio/gmenuexporter.h    |   15 ++---
 gio/tests/gmenumodel.c |   12 ++--
 3 files changed, 58 insertions(+), 145 deletions(-)
---
diff --git a/gio/gmenuexporter.c b/gio/gmenuexporter.c
index ba938d9..3934f20 100644
--- a/gio/gmenuexporter.c
+++ b/gio/gmenuexporter.c
@@ -770,10 +770,12 @@ g_menu_exporter_create_group (GMenuExporter *exporter)
   return group;
 }
 
+
+static GMenuExporter *g_menu_exporter_to_free;
+
 static void
-g_menu_exporter_free (GMenuExporter *exporter)
+g_menu_exporter_actually_free (GMenuExporter *exporter)
 {
-  g_dbus_connection_unregister_object (exporter->connection, exporter->registration_id);
   g_menu_exporter_menu_free (exporter->root);
   g_hash_table_unref (exporter->remotes);
   g_hash_table_unref (exporter->groups);
@@ -784,6 +786,20 @@ g_menu_exporter_free (GMenuExporter *exporter)
 }
 
 static void
+g_menu_exporter_free (gpointer user_data)
+{
+  /* XXX: hack
+   *
+   * GDBusConnection calls the destroy notify while holding its own lock
+   * which means that we get a deadlock on re-entering it.
+   *
+   * Work around this for now...
+   */
+  g_assert (g_menu_exporter_to_free == NULL);
+  g_menu_exporter_to_free = user_data;
+}
+
+static void
 g_menu_exporter_method_call (GDBusConnection       *connection,
                              const gchar           *sender,
                              const gchar           *object_path,
@@ -813,55 +829,8 @@ g_menu_exporter_method_call (GDBusConnection       *connection,
   g_variant_unref (group_ids);
 }
 
-static GDBusConnection *
-g_menu_exporter_get_connection (GMenuExporter *exporter)
-{
-  return exporter->connection;
-}
-
-static const gchar *
-g_menu_exporter_get_object_path (GMenuExporter *exporter)
-{
-  return exporter->object_path;
-}
-
-static GMenuExporter *
-g_menu_exporter_new (GDBusConnection  *connection,
-                     const gchar      *object_path,
-                     GMenuModel       *model,
-                     GError          **error)
-{
-  const GDBusInterfaceVTable vtable = {
-    g_menu_exporter_method_call,
-  };
-  GMenuExporter *exporter;
-  guint id;
-
-  exporter = g_slice_new0 (GMenuExporter);
-
-  id = g_dbus_connection_register_object (connection, object_path, org_gtk_Menus_get_interface (),
-                                          &vtable, exporter, NULL, error);
-
-  if (id == 0)
-    {
-      g_slice_free (GMenuExporter, exporter);
-      return NULL;
-    }
-
-  exporter->connection = g_object_ref (connection);
-  exporter->object_path = g_strdup (object_path);
-  exporter->registration_id = id;
-  exporter->groups = g_hash_table_new (NULL, NULL);
-  exporter->remotes = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_menu_exporter_remote_free);
-  exporter->root = g_menu_exporter_group_add_menu (g_menu_exporter_create_group (exporter), model);
-
-  return exporter;
-}
-
 /* {{{1 Public API */
 
-static GHashTable *exported_menus;
-
 /**
  * g_menu_model_dbus_export_start:
  * @connection: a #GDBusConnection
@@ -886,101 +855,48 @@ static GHashTable *exported_menus;
  * Returns: %TRUE if the export is successful, or %FALSE (with
  *     @error set) in the event of a failure.
  */
-gboolean
-g_menu_model_dbus_export_start (GDBusConnection  *connection,
-                                const gchar      *object_path,
-                                GMenuModel       *menu,
-                                GError          **error)
+guint
+g_dbus_connection_export_menu_model (GDBusConnection  *connection,
+                                     const gchar      *object_path,
+                                     GMenuModel       *menu,
+                                     GError          **error)
 {
+  const GDBusInterfaceVTable vtable = {
+    g_menu_exporter_method_call,
+  };
   GMenuExporter *exporter;
+  guint id;
 
-  if G_UNLIKELY (exported_menus == NULL)
-    exported_menus = g_hash_table_new (NULL, NULL);
+  exporter = g_slice_new0 (GMenuExporter);
 
-  if G_UNLIKELY (g_hash_table_lookup (exported_menus, menu))
+  id = g_dbus_connection_register_object (connection, object_path, org_gtk_Menus_get_interface (),
+                                          &vtable, exporter, g_menu_exporter_free, error);
+
+  if (id == 0)
     {
-      g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_FILE_EXISTS,
-                   "The given GMenuModel has already been exported");
-      return FALSE;
+      g_slice_free (GMenuExporter, exporter);
+      return 0;
     }
 
-  exporter = g_menu_exporter_new (connection, object_path, menu, error);
-
-  if (exporter == NULL)
-    return FALSE;
-
-  g_hash_table_insert (exported_menus, menu, exporter);
-
-  return TRUE;
-}
-
-/**
- * g_menu_model_dbus_export_stop:
- * @menu: a #GMenuModel
- *
- * Stops the export of @menu.
- *
- * This reverses the effect of a previous call to
- * g_menu_model_dbus_export_start() for @menu.
- *
- * Returns: %TRUE if an export was stopped or %FALSE
- *     if @menu was not exported in the first place
- */
-gboolean
-g_menu_model_dbus_export_stop (GMenuModel *menu)
-{
-  GMenuExporter *exporter;
-
-  if G_UNLIKELY (exported_menus == NULL)
-    return FALSE;
-
-  exporter = g_hash_table_lookup (exported_menus, menu);
-  if G_UNLIKELY (exporter == NULL)
-    return FALSE;
-
-  g_hash_table_remove (exported_menus, menu);
-  g_menu_exporter_free (exporter);
+  exporter->connection = g_object_ref (connection);
+  exporter->object_path = g_strdup (object_path);
+  exporter->groups = g_hash_table_new (NULL, NULL);
+  exporter->remotes = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_menu_exporter_remote_free);
+  exporter->root = g_menu_exporter_group_add_menu (g_menu_exporter_create_group (exporter), menu);
 
-  return TRUE;
+  return id;
 }
 
-/**
- * g_menu_model_dbus_export_query:
- * @menu: a #GMenuModel
- * @connection: (out): the #GDBusConnection used for exporting
- * @object_path: (out): the object path used for exporting
- *
- * Queries if and where @menu is exported.
- *
- * If @menu is exported, %TRUE is returned. If @connection is
- * non-%NULL then it is set to the #GDBusConnection used for
- * the export. If @object_path is non-%NULL then it is set to
- * the object path.
- *
- * If the @menu is not exported, %FALSE is returned and
- * @connection and @object_path remain unmodified.
- *
- * Returns: %TRUE if @menu was exported, else %FALSE
- */
 gboolean
-g_menu_model_dbus_export_query (GMenuModel       *menu,
-                                GDBusConnection **connection,
-                                const gchar     **object_path)
+g_dbus_connection_unexport_menu_model (GDBusConnection *connection,
+                                       guint            export_id)
 {
-  GMenuExporter *exporter;
-
-  if (exported_menus == NULL)
+  if (!g_dbus_connection_unregister_object (connection, export_id))
     return FALSE;
 
-  exporter = g_hash_table_lookup (exported_menus, menu);
-  if (exporter == NULL)
-    return FALSE;
-
-  if (connection)
-    *connection = g_menu_exporter_get_connection (exporter);
-
-  if (object_path)
-    *object_path = g_menu_exporter_get_object_path (exporter);
+  g_assert (g_menu_exporter_to_free != NULL);
+  g_menu_exporter_actually_free (g_menu_exporter_to_free);
+  g_menu_exporter_to_free = NULL;
 
   return TRUE;
 }
diff --git a/gio/gmenuexporter.h b/gio/gmenuexporter.h
index 5d07185..f9eb513 100644
--- a/gio/gmenuexporter.h
+++ b/gio/gmenuexporter.h
@@ -27,16 +27,13 @@
 
 G_BEGIN_DECLS
 
-gboolean g_menu_model_dbus_export_start (GDBusConnection  *connection,
-                                         const gchar      *object_path,
-                                         GMenuModel       *menu,
-                                         GError          **error);
+guint                   g_dbus_connection_export_menu_model             (GDBusConnection  *connection,
+                                                                         const gchar      *object_path,
+                                                                         GMenuModel       *menu,
+                                                                         GError          **error);
 
-gboolean g_menu_model_dbus_export_stop  (GMenuModel       *menu);
-
-gboolean g_menu_model_dbus_export_query (GMenuModel       *menu,
-                                         GDBusConnection **connection,
-                                         const gchar     **object_path);
+gboolean                g_dbus_connection_unexport_menu_model           (GDBusConnection  *connection,
+                                                                         guint             export_id);
 
 G_END_DECLS
 
diff --git a/gio/tests/gmenumodel.c b/gio/tests/gmenumodel.c
index 12e6124..59ffaac 100644
--- a/gio/tests/gmenumodel.c
+++ b/gio/tests/gmenumodel.c
@@ -586,6 +586,7 @@ test_dbus_roundtrip (void)
 {
   struct roundtrip_state state;
   GDBusConnection *bus;
+  guint export_id;
   guint id;
 
   bus = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, NULL);
@@ -593,8 +594,7 @@ test_dbus_roundtrip (void)
   state.rand = g_rand_new_with_seed (g_test_rand_int ());
 
   state.random = random_menu_new (state.rand, 2);
-  g_menu_model_dbus_export_start (bus, "/", G_MENU_MODEL (state.random), NULL);
-  g_assert (g_menu_model_dbus_export_query (G_MENU_MODEL (state.random), NULL, NULL));
+  export_id = g_dbus_connection_export_menu_model (bus, "/", G_MENU_MODEL (state.random), NULL);
   state.proxy = g_menu_proxy_get (bus, g_dbus_connection_get_unique_name (bus), "/");
   state.proxy_mirror = mirror_menu_new (G_MENU_MODEL (state.proxy));
   state.count = 0;
@@ -608,8 +608,7 @@ test_dbus_roundtrip (void)
   g_main_loop_unref (state.loop);
   g_source_remove (id);
   g_object_unref (state.proxy);
-  g_menu_model_dbus_export_stop (G_MENU_MODEL (state.random));
-  g_assert (!g_menu_model_dbus_export_query (G_MENU_MODEL (state.random), NULL, NULL));
+  g_dbus_connection_unexport_menu_model (bus, export_id);
   g_object_unref (state.random);
   g_object_unref (state.proxy_mirror);
   g_rand_free (state.rand);
@@ -646,6 +645,7 @@ test_dbus_subscriptions (void)
   GMenuProxy *proxy;
   GMainLoop *loop;
   GError *error = NULL;
+  guint export_id;
 
   loop = g_main_loop_new (NULL, FALSE);
 
@@ -653,7 +653,7 @@ test_dbus_subscriptions (void)
 
   menu = g_menu_new ();
 
-  g_menu_model_dbus_export_start (bus, "/", G_MENU_MODEL (menu), &error);
+  export_id = g_dbus_connection_export_menu_model (bus, "/", G_MENU_MODEL (menu), &error);
   g_assert_no_error (error);
 
   proxy = g_menu_proxy_get (bus, g_dbus_connection_get_unique_name (bus), "/");
@@ -706,7 +706,7 @@ test_dbus_subscriptions (void)
 
   g_assert_cmpint (items_changed_count, ==, 6);
 
-  g_menu_model_dbus_export_stop (G_MENU_MODEL (menu));
+  g_dbus_connection_unexport_menu_model (bus, export_id);
   g_object_unref (menu);
 
   g_main_loop_unref (loop);