synchronized void start() {
if (!serviceMgr.isTowerConnected())
throw new IllegalStateException("Service manager must be connected.");
IDroneApi droneApi = droneApiRef.get();
if (isStarted(droneApi)) return;
try {
droneApi =
serviceMgr
.get3drServices()
.registerDroneApi(this.apiListener, serviceMgr.getApplicationId());
droneApi.asBinder().linkToDeath(binderDeathRecipient, 0);
} catch (RemoteException e) {
throw new IllegalStateException("Unable to retrieve a valid drone handle.");
}
if (asyncScheduler == null || asyncScheduler.isShutdown())
asyncScheduler = Executors.newFixedThreadPool(1);
addAttributesObserver(droneApi, this.droneObserver);
resetFlightTimer();
droneApiRef.set(droneApi);
}
