Bluez MediaEndpoint1 Timeout Issue When Replying To Dbus Call From Node Addon - node.js

Question

Bluez Version: 5.43
Let me get straight to the point:
I have following error inside the Bluez log file:
Calling SetConfiguration: name = :1.3 path = /MediaEndpoint/A2DPSink
...
Endpoint replied with an error: org.freedesktop.DBus.Error.NoReply
If I change this line of code
#define REQUEST_TIMEOUT (3 * 1000) /* 3 seconds */
inside the ~/bluez-5.43/profiles/audio/media.c file,
to be a value greater, like 5 or so... The bug goes away.
So what is this bug?
basically, I have nodejs addon code that does the following:
Intialize endpoint
void endpoint_init(DBusConnection *connection, const char *endpoint) {
DBusObjectPathVTable vtable_endpoint;
vtable_endpoint.message_function = endpoint_handler;
dbus_connection_register_object_path(connection, endpoint, &vtable_endpoint, NULL);
}
Inside the Bluez log you will see bluetoothd[25176]: Endpoint registered: sender=:1.130 path=/MediaEndpoint/A2DPSink
The endpoint_handler function will be notified of a call to set_configuration or select_configuration function...
When a call is received, it will be be replied to like so...
sender = dbus_message_get_sender(m);
r = dbus_message_new_method_return(m);
printf("!! ----- endpoint_set_configuration, time_right_before_reply_sent: ");
print_time();
assert( dbus_connection_send(conn, r, NULL) );
dbus_connection_flush(conn);
printf("!! ----- endpoint_set_configuration, time_right_after_reply_sent: ");
print_time();
As you can see I am logging some time information.
Now, I also logged time information inside Bluez and recompiled it.
Here is log from Bluez:
bluetoothd[789]: profiles/audio/media.c:media_endpoint_async_call() Calling SetConfiguration: name = :1.3 path = /MediaEndpoint/A2DPSink
bluetoothd[789]: profiles/audio/media.c:endpoint_reply() [GOT HERE -- endpoint_reply -- original_msg --] SetConfiguration: name = :1.3 path = /MediaEndpoint/A2DPSink
bluetoothd[789]: profiles/audio/media.c:print_time() TIME BEFORE -- dbus_pending_call_steal_reply --: 2017-01-25 04:54:01
bluetoothd[789]: profiles/audio/media.c:print_time() TIME AFTER -- dbus_pending_call_steal_reply --: 2017-01-25 04:54:01
bluetoothd[789]: profiles/audio/media.c:endpoint_reply() [GOT HERE -- endpoint_reply -- reply_msg] (null): name = (null) path = (null)
bluetoothd[789]: Endpoint replied with an error: org.freedesktop.DBus.Error.NoReply
Here is log from my node addon:
endpoint_handler: path=/MediaEndpoint/A2DPSink, interface=org.bluez.MediaEndpoint1, member=SetConfiguration
!! ----- endpoint_set_configuration, endpoint_path: /MediaEndpoint/A2DPSink
!! ----- endpoint_set_configuration, time_right_before_reply_sent:
2017-01-25 04:54:03
!! ----- endpoint_set_configuration, time_right_after_reply_sent:
2017-01-25 04:54:03
You can CLEARLY see with the Bluez default timeout of 3 seconds is too short... the reply is still on its way...
But pulseaudio's implementation does not have this problem... why?
Is it because there are two different event loops, ie the node addon uses lib-uv event loop and Bluez and pulse use the glib event loop...
What is going on here, can anyone please explain.
I would prefer to either identify it as Bluez bug or understand how to fix it on my node addon end...
Thank You Stackoverflowers :)
P.S.
Bluez ~/bluez-5.43/profiles/audio/media.c has code that advises to keep the REQUEST_TIMEOUT at 3, this worries me...
/* Timeout should be less than avdtp request timeout (4 seconds) */
if (g_dbus_send_message_with_reply(btd_get_dbus_connection(),
msg, &request->call,
REQUEST_TIMEOUT) == FALSE) {
error("D-Bus send failed");
g_free(request);
return FALSE;
}

Answer 1

I found that there is some conflict with the glib and libuv running together under the same process..
the node-dbus addon i am using is a c level binding and it instantiates a glib event loop...
nodejs has a libuv event loop
they dont work well together...
this is what i can assume the problem is..
my solution was to rip the c code from bluez media enpoint and i created my own nodejs NAN bindings to it...without using any glib event loop.
this is the node-dbus library i am using:
https://github.com/Shouqun/node-dbus