Gfrktyl

In my app I need to query location and scan wifi periodically. To conserve power I need to change the rate dynamically, depending on the distance to the target. Also I want to wait for both asynchronous calls to complete. Coroutines seemed the obvious choice, but since this is my first take at coroutines I want to have a second opinion.

I came up with the following solution:

@SuppressLint("MissingPermission")

suspend fun getCurrentLocation(context: Context): Location? = suspendCoroutine { cont ->

    val fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(context)

    val locationRequest = LocationRequest()

    locationRequest.priority = LocationRequest.PRIORITY_HIGH_ACCURACY

    locationRequest.numUpdates = 1

    val listener = object : LocationCallback() {

        override fun onLocationResult(locationResult: LocationResult?) {

            cont.resume(locationResult?.lastLocation)

        }

    }

    val task = fusedLocationProviderClient.requestLocationUpdates(locationRequest,

                                                                  listener,

                                                                  null)

    task.addOnFailureListener { cont.resumeWithException(it) }

}

also

class WifiScanner(val context: ContextWrapper) {

    val wifiManager: WifiManager



    init {

        wifiManager = context.baseContext.getSystemService(Context.WIFI_SERVICE) as WifiManager

    }



    suspend fun getCurrentScanResult(): List<ScanResult> =

        suspendCoroutine { cont ->

            val wifiScanReceiver = object : BroadcastReceiver() {

                override fun onReceive(c: Context, intent: Intent) {

                    if (intent.action?.equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION) == true) {

                        val scanResults = wifiManager.scanResults

                        //sort so that strongest signal is on top

                        scanResults.sortByDescending { it.level }

                        Log.i("received wifi", scanResults.toString())

                        context.unregisterReceiver(this)

                        cont.resume(scanResults)

                    }

                }

            }

            context.registerReceiver(wifiScanReceiver,

                                     IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION))

            wifiManager.startScan()

        }

}

Both are executed concurrently like this:

val location = async { getCurrentLocation() }

val wifi = async { wifiScanner.getCurrentScanResult() }

val currentLocation = location.await()

val currentWifiInfo = wifi.await()

In a quick test it works fine, but it feels like abusing the system. Can I use this like that without breaking the common conventions?