[gnome-settings-daemon/benzea/fix-mpris-disconnect: 7/7] Fix MPRIS issues with disconnecting clients

[Benjamin Berg <bberg src gnome org>]

commit d72de73577dfa8960faf46408e52fb036deb695d
Author: Benjamin Berg <bberg redhat com>
Date:   Mon Dec 10 18:42:38 2018 +0100

    Fix MPRIS issues with disconnecting clients
    
    When clients disconnected and they were not the active client they would
    not be removed from the list. This caused the controller to create a
    proxy for non-existing clients, causing a bad state. The "connecting"
    boolean was also not reset, meaning that a new MPRIS client would never
    be used.
    
    Also, there seems to have been a race caused by the fact that we
    destroyed the DBus proxy from the vanished signal. Change the DBus proxy
    to be removed when its g-name-owner property becomes NULL.
    
    Fixes #45

 plugins/media-keys/mpris-controller.c | 87 +++++++++++++++++++++++++----------
 1 file changed, 62 insertions(+), 25 deletions(-)
---
diff --git a/plugins/media-keys/mpris-controller.c b/plugins/media-keys/mpris-controller.c
index f2baef2d..0a136b17 100644
--- a/plugins/media-keys/mpris-controller.c
+++ b/plugins/media-keys/mpris-controller.c
@@ -39,6 +39,7 @@ struct _MprisControllerPrivate
   gboolean connecting;
 };
 
+static void mpris_player_try_connect (MprisController *self);
 
 static void
 mpris_controller_dispose (GObject *object)
@@ -101,6 +102,24 @@ mpris_controller_key (MprisController *self, const gchar *key)
   return TRUE;
 }
 
+static void
+mpris_client_notify_name_owner_cb (GDBusProxy      *proxy,
+                                   GParamSpec      *pspec,
+                                   MprisController *self)
+{
+  g_autofree gchar *name_owner = NULL;
+
+  /* Owner changed, but the proxy is still valid. */
+  name_owner = g_dbus_proxy_get_name_owner (proxy);
+  if (name_owner)
+    return;
+
+  g_clear_object (&self->priv->mpris_client_proxy);
+  g_object_notify (G_OBJECT (self), "has-active-player");
+
+  mpris_player_try_connect (self);
+}
+
 static void
 mpris_proxy_ready_cb (GObject      *object,
                       GAsyncResult *res,
@@ -115,7 +134,14 @@ mpris_proxy_ready_cb (GObject      *object,
   if (!proxy)
     {
       if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
-        g_warning ("Error connecting to mpris interface %s", error->message);
+        {
+          g_warning ("Error connecting to mpris interface %s", error->message);
+
+          priv = MPRIS_CONTROLLER (user_data)->priv;
+          priv->connecting = FALSE;
+
+          mpris_player_try_connect (MPRIS_CONTROLLER (user_data));
+        }
       g_clear_error (&error);
       return;
     }
@@ -124,6 +150,9 @@ mpris_proxy_ready_cb (GObject      *object,
   priv->mpris_client_proxy = proxy;
   priv->connecting = FALSE;
 
+  g_signal_connect (proxy, "notify::g-name-owner",
+                    G_CALLBACK (mpris_client_notify_name_owner_cb), user_data);
+
   g_object_notify (user_data, "has-active-player");
 }
 
@@ -145,6 +174,30 @@ start_mpris_proxy (MprisController *self, const gchar *name)
   priv->connecting = TRUE;
 }
 
+static void
+mpris_player_try_connect (MprisController *self)
+{
+  MprisControllerPrivate *priv = self->priv;
+
+  GSList *first;
+  gchar *name;
+
+  if (priv->connecting || priv->mpris_client_proxy)
+    return;
+
+  if (!priv->other_players)
+    return;
+
+  first = priv->other_players;
+  name = first->data;
+
+  start_mpris_proxy (self, name);
+
+  priv->other_players = priv->other_players->next;
+  g_free (name);
+  g_slist_free_1 (first);
+}
+
 static void
 mpris_player_appeared (GDBusConnection *connection,
                        const gchar     *name,
@@ -154,10 +207,8 @@ mpris_player_appeared (GDBusConnection *connection,
   MprisController *self = user_data;
   MprisControllerPrivate *priv = MPRIS_CONTROLLER (self)->priv;
 
-  if (priv->mpris_client_proxy == NULL && !priv->connecting)
-    start_mpris_proxy (self, name);
-  else
-    self->priv->other_players = g_slist_prepend (self->priv->other_players, g_strdup (name));
+  priv->other_players = g_slist_prepend (priv->other_players, g_strdup (name));
+  mpris_player_try_connect (self);
 }
 
 static void
@@ -167,28 +218,14 @@ mpris_player_vanished (GDBusConnection *connection,
 {
   MprisController *self = user_data;
   MprisControllerPrivate *priv = MPRIS_CONTROLLER (self)->priv;
+  GSList *elem;
 
-  if (priv->mpris_client_proxy &&
-      g_strcmp0 (name, g_dbus_proxy_get_name (priv->mpris_client_proxy)) == 0)
+  elem = g_slist_find_custom (priv->other_players, name, (GCompareFunc) g_strcmp0);
+  if (elem)
     {
-      g_clear_object (&priv->mpris_client_proxy);
-      g_object_notify (user_data, "has-active-player");
-
-      /* take the next one if there's one */
-      if (self->priv->other_players && !priv->connecting)
-        {
-          GSList *first;
-          gchar *name;
-
-          first = self->priv->other_players;
-          name = first->data;
-
-          start_mpris_proxy (self, name);
-
-          self->priv->other_players = self->priv->other_players->next;
-          g_free (name);
-          g_slist_free_1 (first);
-        }
+      priv->other_players = g_slist_remove_link (priv->other_players, elem);
+      g_free (elem->data);
+      g_slist_free_1 (elem);
     }
 }