Replace volatile cancel flag with coroutine Job cancellation in EspFlasher

android/app/src/main/java/com/eddy/atomrelay/EspFlasher.kt

@@ -24,20 +24,13 @@ class EspFlasher(private val context: Context) {
         fun onProgress(percent: Int, message: String)
     }
 
-    @Volatile
-    private var cancelled = false
-
-    fun cancel() {
-        cancelled = true
-    }
-
     suspend fun flashDevice(usbManager: UsbManager, device: UsbDevice, callback: FlashCallback) {
-        cancelled = false
         try {
             withContext(kotlinx.coroutines.Dispatchers.IO) {
                 doFlash(usbManager, device, callback)
             }
         } catch (e: CancellationException) {
+            Log.i(TAG, "Flash cancelled")
             throw e
         } catch (e: Exception) {
             Log.e(TAG, "Flash failed", e)
@@ -56,7 +49,7 @@ class EspFlasher(private val context: Context) {
 
     private suspend fun doFlash(usbManager: UsbManager, device: UsbDevice, callback: FlashCallback) {
         kotlinx.coroutines.delay(500)
-        checkCancelled()
+        coroutineContext.ensureActive()
 
         val connection = usbManager.openDevice(device)
             ?: throw IOException("Kan USB-apparaat niet openen")
@@ -77,7 +70,7 @@ class EspFlasher(private val context: Context) {
             callback.onProgress(0, "Verbinden met ESP bootloader...")
 
             val transport = UsbSerialTransport(connection, epOut, epIn)
-            checkCancelled()
+            coroutineContext.ensureActive()
 
             val assets = context.assets
             val bootloader = assets.open("firmware/bootloader.bin").readBytes()
@@ -116,7 +109,7 @@ class EspFlasher(private val context: Context) {
             stub.eraseFlash()
 
             for (step in steps) {
-                checkCancelled()
+                coroutineContext.ensureActive()
                 val sizeStr = if (step.data.size > 1024) "${step.data.size / 1024}KB" else "${step.data.size} bytes"
                 callback.onProgress(step.baseProgress, "${step.name} schrijven ($sizeStr)...")
 
@@ -136,9 +129,4 @@ class EspFlasher(private val context: Context) {
         }
     }
 
-    private suspend fun checkCancelled() {
-        if (cancelled) {
-            coroutineContext.ensureActive()
-        }
-    }
 }

android/app/src/main/java/com/eddy/atomrelay/SettingsActivity.kt

@@ -22,9 +22,9 @@ import android.widget.Toast
 import androidx.appcompat.app.AppCompatActivity
 import androidx.lifecycle.lifecycleScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.withContext
 import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 import java.nio.charset.StandardCharsets
 import java.security.SecureRandom
 
@@ -47,7 +47,7 @@ class SettingsActivity : AppCompatActivity() {
     private var currentAction = UsbAction.NONE
     private var progressDialog: AlertDialog? = null
     private var dialog: AlertDialog? = null
-    private var flasher: EspFlasher? = null
+    private var flasherJob: Job? = null
 
     private val usbAttachedReceiver = object : BroadcastReceiver() {
         override fun onReceive(context: Context, intent: Intent) {
@@ -124,8 +124,8 @@ class SettingsActivity : AppCompatActivity() {
     override fun onDestroy() {
         super.onDestroy()
         currentAction = UsbAction.NONE
-        flasher?.cancel()
+        flasherJob?.cancel()
-        flasher = null
+        flasherJob = null
         try { unregisterReceiver(usbAttachedReceiver) } catch (_: Exception) {}
         try { unregisterReceiver(usbPermissionReceiver) } catch (_: Exception) {}
         try { unregisterReceiver(usbDetachedReceiver) } catch (_: Exception) {}
@@ -211,7 +211,7 @@ class SettingsActivity : AppCompatActivity() {
         dialog = null
         showProgressDialog("Firmware Flashen", "Initialiseren...", STYLE_HORIZONTAL)
 
-        flasher = EspFlasher(this)
+        val flasher = EspFlasher(this)
         val progressCallback = object : EspFlasher.FlashCallback {
             override fun onProgress(percent: Int, message: String) {
                 lifecycleScope.launch(Dispatchers.Main) {
@@ -221,9 +221,9 @@ class SettingsActivity : AppCompatActivity() {
                 }
             }
         }
-        lifecycleScope.launch {
+        flasherJob = lifecycleScope.launch {
             try {
-                flasher?.flashDevice(usbManager, device, progressCallback)
+                flasher.flashDevice(usbManager, device, progressCallback)
                 if (isFinishing || isDestroyed) return@launch
                 currentAction = UsbAction.NONE
                 progressDialog?.dismiss()
@@ -240,6 +240,7 @@ class SettingsActivity : AppCompatActivity() {
                     .show()
             } catch (e: kotlinx.coroutines.CancellationException) {
                 cleanupAction()
+                throw e
             } catch (e: Exception) {
                 progressDialog?.dismiss()
                 progressDialog = null
@@ -290,7 +291,7 @@ class SettingsActivity : AppCompatActivity() {
             .setTitle(title)
             .setView(view)
             .setNegativeButton("Annuleren") { _, _ ->
-                flasher?.cancel()
+                flasherJob?.cancel()
                 cleanupAction()
             }
             .setCancelable(false)