clientIf field in Android BluetoothGatt class

Question

Android BluetoothGatt.class has mClientIf private field. Most of the log messages related to BLE events contain this value. For example:

onClientRegistered() - status=0 clientIf=17

What does the mClientIf field represent? What does the integer value of this field tell?

Answer 1

mClientf is a scannerId from Bluetooth scanner,

If you dig through the source of BluetoothGatt and BluetoothLeScanner you can find the following:

mBluetoothGatt.unregisterClient(scannerId); method is implemented in

GattService.java unregisterClient(int clientIf)

---

BluetoothLeScanner.java

...
/**
 * Application interface registered - app is ready to go
 */
@Override
public void onScannerRegistered(int status, int scannerId) {
    Log.d(TAG, "onScannerRegistered() - status=" + status +
            " scannerId=" + scannerId + " mScannerId=" + mScannerId);
    synchronized (this) {
        if (status == BluetoothGatt.GATT_SUCCESS) {
            try {
                if (mScannerId == -1) {
                    // Registration succeeds after timeout, unregister client.
                    mBluetoothGatt.unregisterClient(scannerId);
                } else {
                    mScannerId = scannerId;
                    mBluetoothGatt.startScan(mScannerId, mSettings, mFilters,
                            mResultStorages,
                            ActivityThread.currentOpPackageName());
                }
            } catch (RemoteException e) {
                Log.e(TAG, "fail to start le scan: " + e);
                mScannerId = -1;
            }
        } else {
            // registration failed
            mScannerId = -1;
        }
        notifyAll();
    }
}
...

---

GattService.java

...
/**
 * Unregister the current application and callbacks.
 */
private IBluetoothGatt mService;
.
.   
public void unregisterClient(int clientIf) {
    GattService service = getService();
    if (service == null) return;
    service.unregisterClient(clientIf);
}
...