Dbus errors in the console when closing the music-app

[Andrew Hayzen]

Due to bug 1434584 being fixed when you swipe to close an application the following appears in the log, note the dbus errors, and that I am not able to reproduce this on the desktop.

** Application is now inactive
Attempted to deliver an event to a non-existent window, ignoring.
virtual bool QMediaPlaylist::setMediaObject(QMediaObject*)
void QMediaPlaylistPrivate::syncControls(QMediaPlaylistControl*, QMediaPlaylistControl*)
void AalMediaPlayerService::deletePlaylistControl()
virtual AalMediaPlaylistProvider::~AalMediaPlaylistProvider()
void AalMediaPlaylistProvider::disconnect_signals()
virtual AalMediaPlaylistControl::~AalMediaPlaylistControl()
void AalMediaPlayerService::deleteMediaPlayerControl()
void AalMediaPlayerService::destroyPlayerSession()
PlaybackStatusChanged signal arrived via the bus (Status: PlaybackStatus::ready)
PlaybackStatusChanged signal arrived via the bus (Status: PlaybackStatus::stopped)
OnTrackListReset signal arrived via the bus.
Attempted to unregister path (path[0] = com path[1] = canonical) which isn't registered
process 6617: arguments to dbus_connection_close() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2935.
This is normally a bug in some application using the D-Bus library.
process 6617: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2822.
This is normally a bug in some application using the D-Bus library.
process 6617: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2822.
This is normally a bug in some application using the D-Bus library.
process 6617: arguments to dbus_connection_close() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2935.
This is normally a bug in some application using the D-Bus library.
process 6617: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2822.
This is normally a bug in some application using the D-Bus library.
process 6617: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2822.
This is normally a bug in some application using the D-Bus library.
Sdk-Launcher> Stopping Application
Sdk-Launcher> The Application exited, cleaning up
Sdk-Launcher> Finished

[James Henstridge (jamesh)]

This sounds a lot like bug 1422304, by the look of it.

Both QtDBus and dbus-cpp make use of libdbus. Libdbus provides a dbus_shutdown() function that will release various internal global state, which can be used to remove those allocation from the report valgrind produces when analysing your program. Normally applications shouldn't have a need to call it.

Anything allocated (connections, method calls, etc) before the call to shutdown can not be used after the call, which is what the _dbus_current_generation assertions are about.

dbus-cpp makes a call to dbus_shutdown() as an atexit handler. Unfortunately, Qt hasn't cleaned up its connections at this time, leading to errors.

[James Henstridge (jamesh)]

For what it is worth, I managed to catch a segfault on shutdown of music-app (i.e. swiping vertically in the app spread) on the phone. I couldn't get a usable apport crash dump, but managed to catch it in gdb.

This is with libdbus-cpp 4.3.0+15.04.20151126-0ubuntu1 and libmedia-hub-client 4.0.0+15.04.20151209-0ubuntu1 installed.

[Łukasz Zemczak (sil2100)]

This bug was fixed in the package dbus-cpp 4.3.0+15.04.20160112-0ubuntu1 in https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/stable-phone-overlay

---------------

dbus-cpp (4.3.0+15.04.20160112-0ubuntu1) vivid; urgency=medium

  * Only run dbus_shutdown if explicitly requested by env var. (LP:
    #1422304, #1526877)

 -- Thomas Voß <email address hidden> Tue, 12 Jan 2016 16:28:02 +0000