Android BLE is NOT connecting again after BLE device timeout [Using RxAndroidBle ]

Question

I am working on Android BLE using RxAndroidBle library. The BLE device has a timeout of 5 min if there is no interaction. i.e. The device will disconnect automatically if there is no read/write operations for 5 minutes. I am getting BleGattException when timeout disconnection happens.

     W/System.err: BleGattException{macAddress=24:71:89:FE:A0:88, status=19 (0x13 -> https://android.googlesource.com/platform/external/bluetooth/bluedroid/+/android-5.1.0_r1/stack/include/gatt_api.h), bleGattOperationType=BleGattOperation{description='CONNECTION_STATE'}}
 W/System.err:     at com.polidea.rxandroidble.internal.connection.RxBleGattCallback.propagateStatusErrorIfGattErrorOccurred(RxBleGattCallback.java:233)
 W/System.err:     at com.polidea.rxandroidble.internal.connection.RxBleGattCallback.access$200(RxBleGattCallback.java:35)
 W/System.err:     at com.polidea.rxandroidble.internal.connection.RxBleGattCallback$3.onConnectionStateChange(RxBleGattCallback.java:86)
 W/System.err:     at android.bluetooth.BluetoothGatt$1.onClientConnectionState(BluetoothGatt.java:228)
 W/System.err:     at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:70)
 W/System.err:     at android.os.Binder.execTransact(Binder.java:453)

 W/BluetoothGatt: Unhandled exception in callback
                                                                  rx.exceptions.OnErrorFailedException: Error occurred when trying to propagate error to Observer.onError
                                                                      at rx.observers.SafeSubscriber._onError(SafeSubscriber.java:194)
                                                                      at rx.observers.SafeSubscriber.onError(SafeSubscriber.java:115)
                                                                      at rx.observers.Subscribers$5.onError(Subscribers.java:230)
                                                                      at rx.observers.Subscribers$5.onError(Subscribers.java:230)
                                                                      at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
                                                                      at rx.observers.Subscribers$5.onError(Subscribers.java:230)
                                                                      at rx.observers.Subscribers$5.onError(Subscribers.java:230)
                                                                      at rx.observers.Subscribers$5.onError(Subscribers.java:230)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.reportError(OperatorMerge.java:266)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.checkTerminate(OperatorMerge.java:818)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.emitLoop(OperatorMerge.java:579)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.emit(OperatorMerge.java:568)
                                                                      at rx.internal.operators.OperatorMerge$InnerSubscriber.onError(OperatorMerge.java:852)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.reportError(OperatorMerge.java:266)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.checkTerminate(OperatorMerge.java:818)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.emitLoop(OperatorMerge.java:579)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.emit(OperatorMerge.java:568)
                                                                      at rx.internal.operators.OperatorMerge$InnerSubscriber.onError(OperatorMerge.java:852)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.reportError(OperatorMerge.java:266)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.checkTerminate(OperatorMerge.java:818)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.emitLoop(OperatorMerge.java:579)
                                                                      at rx.internal.operators.OperatorMerge$MergeSubscriber.emit(OperatorMerge.java:568)
                                                                      at rx.internal.operators.OperatorMerge$InnerSubscriber.onError(OperatorMerge.java:852)
                                                                      at rx.internal.operators.NotificationLite.accept(NotificationLite.java:132)
                                                                      at rx.subjects.SubjectSubscriptionManager$SubjectObserver.emitNext(SubjectSubscriptionManager.java:253)
                                                                      at rx.subjects.BehaviorSubject.onError(BehaviorSubject.java:141)
                                                                      at com.polidea.rxandroidble.internal.connection.RxBleGattCallback.propagateStatusError(RxBleGattCallback.java:241)
                                                                      at com.polidea.rxandroidble.internal.connection.RxBleGattCallback.propagateStatusErrorIfGattErrorOccurred(RxBleGattCallback.java:233)
                                                                      at com.polidea.rxandroidble.internal.connection.RxBleGattCallback.access$200(RxBleGattCallback.java:35)
                                                                      at com.polidea.rxandroidble.internal.connection.RxBleGattCallback$3.onConnectionStateChange(RxBleGattCallback.java:86)
                                                                      at android.bluetooth.BluetoothGatt$1.onClientConnectionState(BluetoothGatt.java:228)
                                                                      at android.bluetooth.IBluetoothGattCallback$Stub.onTransact(IBluetoothGattCallback.java:70)
                                                                      at android.os.Binder.execTransact(Binder.java:453)
                                                                   Caused by: rx.exceptions.OnErrorFailedException: Error occurred when trying to propagate error to Observer.onError
                                                                      at rx.observers.SafeSubscriber._onError(SafeSubscriber.java:187)
                                                                      at rx.observers.SafeSubscriber.onError(SafeSubscriber.java:115)
                                                                      at rx.exceptions.Exceptions.throwOrReport(Exceptions.java:216)
                                                                      at rx.observers.SafeSubscriber.onNext(SafeSubscriber.java:139)
                                                                      at rx.internal.operators.OperatorDistinctUntilChanged$1.onNext(OperatorDistinctUntilChanged.java:96)
                                                                      at rx.internal.operators.NotificationLite.accept(NotificationLite.java:135)
                                                                      at rx.subjects.SubjectSubscriptionManager$SubjectObserver.emitNext(SubjectSubscriptionManager.java:253)
                                                                      at rx.subjects.BehaviorSubject.onNext(BehaviorSubject.java:160)
                                                                      at com.polidea.rxandroidble.internal.RxBleDeviceImpl$1$1.call(RxBleDeviceImpl.java:77)
                                                                      at rx.subscriptions.BooleanSubscription.unsubscribe(BooleanSubscription.java:71)
                                                                      at rx.internal.util.SubscriptionList.unsubscribeFromAll(SubscriptionList.java:136)
                                                                      at rx.internal.util.SubscriptionList.unsubscribe(SubscriptionList.java:125)

Once the device disconnects due to timeout, When I scan again I could find the device in the near by available devices as expected. But when I try to connect to the same device, it throws an exception telling device is already connected

 W/System.err: BleAlreadyConnectedException{macAddress=24:71:89:FE:99:E3}
 W/System.err:     at com.polidea.rxandroidble.internal.RxBleDeviceImpl.lambda$establishConnection$3(RxBleDeviceImpl.java:54)
 W/System.err:     at com.polidea.rxandroidble.internal.RxBleDeviceImpl$$Lambda$1.call(Unknown Source)
 W/System.err:     at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46)
 W/System.err:     at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
 W/System.err:     at rx.Observable.subscribe(Observable.java:10236)
 W/System.err:     at rx.Observable.subscribe(Observable.java:10203)
 W/System.err:     at rx.Observable.subscribe(Observable.java:10043)

But I am able to connect to the device if I turn off and On bluetooth in my mobile or if I kill the app and restart.

And re-connecting is working when I manually disconnect the device and connect again. The issue is only when time-out disconnection happens.

Can any one tell me why is this happening?

Answer 1

Judging from the error and the implementation of the .establishConnection() function you do not unsubscribe from the previous Observable that was returned.

@Override
public Observable<RxBleConnection> establishConnection(final boolean autoConnect) {
    return Observable.defer(new Func0<Observable<RxBleConnection>>() {
        @Override
        public Observable<RxBleConnection> call() {

            if (isConnected.compareAndSet(false, true)) {
                return connector.prepareConnection(autoConnect)
                        .doOnSubscribe(new Action0() {
                            @Override
                            public void call() {
                                connectionStateSubject.onNext(CONNECTING);
                            }
                        })
                        .doOnNext(new Action1<RxBleConnection>() {
                            @Override
                            public void call(RxBleConnection rxBleConnection) {
                                connectionStateSubject.onNext(CONNECTED);
                            }
                        })
                        .doOnUnsubscribe(new Action0() {
                            @Override
                            public void call() {
                                connectionStateSubject.onNext(DISCONNECTED);
                                isConnected.set(false);
                            }
                        });
            } else {
                return Observable.error(new BleAlreadyConnectedException(bluetoothDevice.getAddress()));
            }
        }
    });
}

Once you unsubscribe from the previous one you should be able to establish a new connection.