public AndroidBluetoothDeviceProximityProbe()
{
_bluetoothScannerCallback = new AndroidBluetoothScannerCallback(this);
_bluetoothScannerCallback.DeviceIdEncountered += (sender, bluetoothDeviceProximityDatum) =>
{
lock (EncounteredDeviceData)
{
EncounteredDeviceData.Add(bluetoothDeviceProximityDatum);
}
};
_bluetoothAdvertiserCallback = new AndroidBluetoothAdvertisingCallback(this);
}
protected sealed override IEnumerable <Datum> Poll(System.Threading.CancellationToken cancellationToken)
{
// restart the scan. on android this will cause the thread to sleep while data accumate. we need to sleep in order
// to keep the cpu alive, as we're holding a wakelock for the poll. this is not allowed on ios, where we have a
// limited amount of time to return from the poll. thus, on ios, we just start the scan and return immediately
// without waiting for results to accumulate.
try
{
SensusServiceHelper.Get().Logger.Log("Stopping scan.", LoggingLevel.Normal, GetType());
StopScan();
}
catch (Exception ex)
{
SensusServiceHelper.Get().Logger.Log("Exception while stopping scan: " + ex, LoggingLevel.Normal, GetType());
}
try
{
SensusServiceHelper.Get().Logger.Log("Starting scan.", LoggingLevel.Normal, GetType());
StartScan();
}
catch (Exception ex)
{
SensusServiceHelper.Get().Logger.Log("Exception while starting scan: " + ex, LoggingLevel.Normal, GetType());
}
// create a new list to return any data that have accumulated -- this only plays a role in android, where we
// wait for data to accumulate while holding a wakelock. on ios, data are added directly via Probe.StoreDatumAsync
// because we're not allowed to wait for data to accumulate (background time expiration).
List <BluetoothDeviceProximityDatum> dataToReturn;
lock (EncounteredDeviceData)
{
dataToReturn = EncounteredDeviceData.ToList();
EncounteredDeviceData.Clear();
}
// if we have no new data, return a null datum to signal to the storage system that the poll ran successfully (null won't actually be stored).
if (dataToReturn.Count == 0)
{
dataToReturn.Add(null);
}
return(dataToReturn);
}