When cancelling the bluetooth server socket before accepting, the whole process dies. Why?

Question

I am compiling for SDK 10 (2.3.3):

android:minSdkVersion="10"
android:targetSdkVersion="16"

I am testing on two Sony Ericsson smartphones. One has Android 2.3.7 on it and the other 4.0.1.

I am using listenUsingInsecureRfcommWithServiceRecord to open a new server socket on bluetooth and listen to connections.

If the connection is accepted successfully then everything works fine. I can even try to cancel the server socket but that does not seem to bother the connection socket just created.

BUT when I want to cancel the server socket before having accepted any connections as soon as the line bluetoothServerSocket.close(); gets executed the entire activity closes and the process dies. And furthermore this is not a regular exception which I could handle.

Actually even logcat itself quits!! and I have to quickly execute it again in order to grab the errors you can see below:

Zygote  D  Process 25471 terminated by signal (11)
  295         InputDispatcher  W  channel '2c2e20a8 com.pligor.test/activities.MainActivity (server)' ~ Consumer closed input channel or an error occurred.  events=0x8
  295         InputDispatcher  E  channel '2c2e20a8 com.pligor.test/activities.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
  295                dalvikvm  D  GC_FOR_ALLOC freed 1299K, 21% free 13252K/16583K, paused 93ms
  295         InputDispatcher  W  Attempted to unregister already unregistered input channel '2c2e20a8 com.pligor.test/activities.MainActivity (server)'
  295        BluetoothService  D  Tracked app 25471 diedType:10
  295        BluetoothService  D  Removing service record 10009 for pid 25471
  132          SurfaceFlinger  D  Release buffer at 0x61c08
  295           WindowManager  I  WINDOW DIED Window{2c2e20a8 com.pligor.test/activities.MainActivity paused=false}
  295         ActivityManager  I  Process com.pligor.test (pid 25471) has died.
  295         ActivityManager  W  Force removing ActivityRecord{2c021800 com.pligor.test/activities.MainActivity}: app died, no saved state
  295           WindowManager  W  Failed looking up window
  295           WindowManager  W  java.lang.IllegalArgumentException: Requested window android.os.BinderProxy@2bf3e798 does not exist
  295           WindowManager  W    at com.android.server.wm.WindowManagerService.windowForClientLocked(WindowManagerService.java:7165)
  295           WindowManager  W    at com.android.server.wm.WindowManagerService.windowForClientLocked(WindowManagerService.java:7156)
  295           WindowManager  W    at com.android.server.wm.WindowState$DeathRecipient.binderDied(WindowState.java:1545)
  295           WindowManager  W    at android.os.BinderProxy.sendDeathNotice(Binder.java:417)
  295           WindowManager  W    at dalvik.system.NativeStart.run(Native Method)
  295           WindowManager  I  WIN DEATH: null
  295      BluetoothEventLoop  D  Property Changed: UUIDs : 11
  295    hAdapterStateMachine  D  BluetoothOn process message: 51
  295     InputManagerService  W  Got RemoteException sending setActive(false) notification to pid 25471 uid 10040

Note: Process terminated by signal (11) means Segmentation fault (http://en.wikipedia.org/wiki/SIGSEGV).

EDIT

I create the Bluetooth server socket using the following code (Scala):

private val bluetoothServerSocket: BluetoothServerSocket = try {
    bluetoothAdapter.listenUsingInsecureRfcommWithServiceRecord(MY_SERVICE_NAME_INSE‌​CURE, MY_UUID_INSECURE); 
} 
catch { 
    case e: IOException => throw new ServerSocketException; 
} 

I use this code to close the Bluetooth socket:

try { 
    isCancelled = true; 
    bluetoothServerSocket.close(); 
} catch { 
    case e: IOException => throw new NotClosedException; 
}

Answer 1

I think I have found a workaround for this issue. The "I think" is because this has not been tested on many devices yet.

code below is Scala

For the workaround I take advantage of the overloaded method accept(int) which has a timeout

So we have a variable for the state of the infinite loop you are seeing below

private var toContinue = true;

We just repeat accepting in a while loop

while (toContinue) {
  try {
    //this is a blocking call and will only return on a successful connection or an exception, or on timeout
    val socket = bluetoothServerSocket.accept(10000); //msec

    connectionAccepted(socket);
  } catch {
    case e: IOException => {
      Logger("accepting timed out");
    }
  }
}

So now instead of calling the bluetoothServerSocket.close() we are just setting variable to false

def cancel() {
    toContinue = false;
}

Actual code is a little bit more complex since you need a callback function to do something upon the exit of the while loop but the main issue is resolved as shown above