Add two test cases which covers disconnection scenario in another thread

1) Check that schedule_call_in_idle code branch of gdbusnamewatching.c
   is working to call vanished handler in the thread which had watched the name
2) Check cancellation of vanished handler if the name is unwatched before
   vanished callback is dispatched.

Closes #2011

Signed-off-by: Frederic Martinsons <frederic.martinsons@sigfox.com>

gio/tests/gdbus-names.c

@@ -1,6 +1,7 @@
 /* GLib testing framework examples and tests
  *
  * Copyright (C) 2008-2010 Red Hat, Inc.
+ * Copyright (C) 2021 Frederic Martinsons
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -16,6 +17,7 @@
  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  *
  * Author: David Zeuthen <davidz@redhat.com>
+ * Author: Frederic Martinsons <frederic.martinsons@gmail.com>
  */
 
 #include <gio/gio.h>
@@ -495,6 +497,20 @@ typedef struct
   guint num_free_func;
 } WatchNameData;
 
+typedef struct
+{
+  WatchNameData data;
+  GDBusConnection *connection;
+  GMutex cond_mutex;
+  GCond cond;
+  gboolean started;
+  gboolean name_acquired;
+  gboolean ended;
+  gboolean unwatch_early;
+  GMutex mutex;
+  guint watch_id;
+} WatchNameThreadData;
+
 static void
 watch_name_data_free_func (WatchNameData *data)
 {
@@ -862,6 +878,248 @@ test_bus_watch_name (gconstpointer d)
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+/* Called in the same thread as watcher_thread() */
+static void
+t_watch_name_data_free_func (WatchNameThreadData *thread_data)
+{
+  thread_data->data.num_free_func++;
+}
+
+/* Called in the same thread as watcher_thread() */
+static void
+t_name_appeared_handler (GDBusConnection *connection,
+                         const gchar     *name,
+                         const gchar     *name_owner,
+                         gpointer         user_data)
+{
+  WatchNameThreadData *thread_data = user_data;
+  thread_data->data.num_appeared += 1;
+}
+
+/* Called in the same thread as watcher_thread() */
+static void
+t_name_vanished_handler (GDBusConnection *connection,
+                         const gchar     *name,
+                         gpointer         user_data)
+{
+  WatchNameThreadData *thread_data = user_data;
+  thread_data->data.num_vanished += 1;
+}
+
+/* Called in the thread which constructed the GDBusConnection */
+static void
+connection_closed_cb (GDBusConnection *connection,
+                      gboolean         remote_peer_vanished,
+                      GError          *error,
+                      gpointer         user_data)
+{
+  WatchNameThreadData *thread_data = (WatchNameThreadData *) user_data;
+  if (thread_data->unwatch_early)
+    {
+      g_mutex_lock (&thread_data->mutex);
+      g_bus_unwatch_name (g_atomic_int_get (&thread_data->watch_id));
+      g_atomic_int_set (&thread_data->watch_id, 0);
+      g_cond_signal (&thread_data->cond);
+      g_mutex_unlock (&thread_data->mutex);
+    }
+}
+
+static gpointer
+watcher_thread (gpointer user_data)
+{
+  WatchNameThreadData *thread_data = user_data;
+  GMainContext *thread_context;
+
+  thread_context = g_main_context_new ();
+  g_main_context_push_thread_default (thread_context);
+
+  // Notify that the thread has started
+  g_mutex_lock (&thread_data->cond_mutex);
+  g_atomic_int_set (&thread_data->started, TRUE);
+  g_cond_signal (&thread_data->cond);
+  g_mutex_unlock (&thread_data->cond_mutex);
+
+  // Wait for the main thread to own the name before watching it
+  g_mutex_lock (&thread_data->cond_mutex);
+  while (!g_atomic_int_get (&thread_data->name_acquired))
+    g_cond_wait (&thread_data->cond, &thread_data->cond_mutex);
+  g_mutex_unlock (&thread_data->cond_mutex);
+
+  thread_data->data.num_appeared = 0;
+  thread_data->data.num_vanished = 0;
+  thread_data->data.num_free_func = 0;
+  // g_signal_connect_after is important to have default handler be called before our code
+  g_signal_connect_after (thread_data->connection, "closed", G_CALLBACK (connection_closed_cb), thread_data);
+
+  g_mutex_lock (&thread_data->mutex);
+  thread_data->watch_id = g_bus_watch_name_on_connection (thread_data->connection,
+                                                          "org.gtk.GDBus.Name1",
+                                                          G_BUS_NAME_WATCHER_FLAGS_NONE,
+                                                          t_name_appeared_handler,
+                                                          t_name_vanished_handler,
+                                                          thread_data,
+                                                          (GDestroyNotify) t_watch_name_data_free_func);
+  g_mutex_unlock (&thread_data->mutex);
+
+  g_assert_cmpint (thread_data->data.num_appeared, ==, 0);
+  g_assert_cmpint (thread_data->data.num_vanished, ==, 0);
+  while (thread_data->data.num_appeared == 0)
+    g_main_context_iteration (thread_context, TRUE);
+  g_assert_cmpint (thread_data->data.num_appeared, ==, 1);
+  g_assert_cmpint (thread_data->data.num_vanished, ==, 0);
+  thread_data->data.num_appeared = 0;
+
+  /* Close the connection and:
+   *  - check that we had received a vanished event even begin in different thread
+   *  - or check that unwatching the bus when a vanished had been scheduled
+   *    make it correctly unscheduled (unwatch_early condition)
+   */
+  g_dbus_connection_close_sync (thread_data->connection, NULL, NULL);
+  if (thread_data->unwatch_early)
+    {
+      // Wait for the main thread to iterate in order to have close connection handled
+      g_mutex_lock (&thread_data->mutex);
+      while (g_atomic_int_get (&thread_data->watch_id) != 0)
+        g_cond_wait (&thread_data->cond, &thread_data->mutex);
+      g_mutex_unlock (&thread_data->mutex);
+
+      while (thread_data->data.num_free_func == 0)
+        g_main_context_iteration (thread_context, TRUE);
+      g_assert_cmpint (thread_data->data.num_vanished, ==, 0);
+      g_assert_cmpint (thread_data->data.num_appeared, ==, 0);
+      g_assert_cmpint (thread_data->data.num_free_func, ==, 1);
+    }
+  else
+    {
+      while (thread_data->data.num_vanished == 0)
+        {
+          /*
+           * Close of connection is treated in the context of the thread which
+           * creates the connection. We must run iteration on it (to have the 'closed'
+           * signal handled) and also run current thread loop to have name_vanished
+           * callback handled.
+           */
+          g_main_context_iteration (thread_context, TRUE);
+        }
+      g_assert_cmpint (thread_data->data.num_vanished, ==, 1);
+      g_assert_cmpint (thread_data->data.num_appeared, ==, 0);
+      g_mutex_lock (&thread_data->mutex);
+      g_bus_unwatch_name (g_atomic_int_get (&thread_data->watch_id));
+      g_atomic_int_set (&thread_data->watch_id, 0);
+      g_mutex_unlock (&thread_data->mutex);
+      while (thread_data->data.num_free_func == 0)
+        g_main_context_iteration (thread_context, TRUE);
+      g_assert_cmpint (thread_data->data.num_free_func, ==, 1);
+    }
+
+  g_mutex_lock (&thread_data->cond_mutex);
+  thread_data->ended = TRUE;
+  g_main_context_wakeup (NULL);
+  g_cond_signal (&thread_data->cond);
+  g_mutex_unlock (&thread_data->cond_mutex);
+
+  g_signal_handlers_disconnect_by_func (thread_data->connection, connection_closed_cb, thread_data);
+  g_object_unref (thread_data->connection);
+  g_main_context_pop_thread_default (thread_context);
+  g_main_context_unref (thread_context);
+
+  g_mutex_lock (&thread_data->mutex);
+  g_assert_cmpint (thread_data->watch_id, ==, 0);
+  g_mutex_unlock (&thread_data->mutex);
+  return NULL;
+}
+
+static void
+watch_with_different_context (gboolean unwatch_early)
+{
+  OwnNameData own_data;
+  WatchNameThreadData thread_data;
+  GDBusConnection *connection;
+  GThread *watcher;
+  guint id;
+
+  session_bus_up ();
+
+  connection = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, NULL);
+  g_assert (connection != NULL);
+
+  g_mutex_init (&thread_data.mutex);
+  g_mutex_init (&thread_data.cond_mutex);
+  g_cond_init (&thread_data.cond);
+  thread_data.started = FALSE;
+  thread_data.name_acquired = FALSE;
+  thread_data.ended = FALSE;
+  thread_data.connection = g_object_ref (connection);
+  thread_data.unwatch_early = unwatch_early;
+
+  // Create a thread which will watch a name and wait for it to be ready
+  g_mutex_lock (&thread_data.cond_mutex);
+  watcher = g_thread_new ("watcher", watcher_thread, &thread_data);
+  while (!g_atomic_int_get (&thread_data.started))
+    g_cond_wait (&thread_data.cond, &thread_data.cond_mutex);
+  g_mutex_unlock (&thread_data.cond_mutex);
+
+  own_data.num_acquired = 0;
+  own_data.num_lost = 0;
+  own_data.num_free_func = 0;
+  own_data.expect_null_connection = FALSE;
+  // Own the name to avoid direct name vanished in watcher thread
+  id = g_bus_own_name_on_connection (connection,
+                                     "org.gtk.GDBus.Name1",
+                                     G_BUS_NAME_OWNER_FLAGS_REPLACE,
+                                     w_name_acquired_handler,
+                                     w_name_lost_handler,
+                                     &own_data,
+                                     (GDestroyNotify) own_name_data_free_func);
+  while (own_data.num_acquired == 0)
+    g_main_context_iteration (NULL, TRUE);
+  g_assert_cmpint (own_data.num_acquired, ==, 1);
+  g_assert_cmpint (own_data.num_lost, ==, 0);
+
+  // Wake the thread for it to begin watch
+  g_mutex_lock (&thread_data.cond_mutex);
+  g_atomic_int_set (&thread_data.name_acquired, TRUE);
+  g_cond_signal (&thread_data.cond);
+  g_mutex_unlock (&thread_data.cond_mutex);
+
+  // Iterate the loop until thread is waking us up
+  while (!thread_data.ended)
+    g_main_context_iteration (NULL, TRUE);
+
+  g_thread_join (watcher);
+
+  g_bus_unown_name (id);
+  while (own_data.num_free_func == 0)
+    g_main_context_iteration (NULL, TRUE);
+  g_assert_cmpint (own_data.num_free_func, ==, 1);
+
+  g_mutex_clear (&thread_data.mutex);
+  g_mutex_clear (&thread_data.cond_mutex);
+  g_cond_clear (&thread_data.cond);
+
+  session_bus_stop ();
+  g_assert_true (g_dbus_connection_is_closed (connection));
+  g_object_unref (connection);
+  session_bus_down ();
+}
+
+static void
+test_bus_watch_different_context (void)
+{
+  watch_with_different_context (FALSE);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
+static void
+test_bus_unwatch_early (void)
+{
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/604");
+  watch_with_different_context (TRUE);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
 static void
 test_validate_names (void)
 {
@@ -984,6 +1242,8 @@ main (int   argc,
   g_test_add_data_func ("/gdbus/bus-watch-name-closures-auto-start",
                         &watch_closures_flags_auto_start,
                         test_bus_watch_name);
+  g_test_add_func ("/gdbus/bus-watch-different-context", test_bus_watch_different_context);
+  g_test_add_func ("/gdbus/bus-unwatch-early", test_bus_unwatch_early);
   g_test_add_func ("/gdbus/escape-object-path", test_escape_object_path);
   ret = g_test_run();