Add HTA-side implementation of sync-interrupted scenario (HT-508). Also replace deprecated AsyncTask.

app/src/main/java/org/sil/hearthis/AcceptNotificationHandler.java

@@ -32,9 +32,24 @@ public void handle(HttpRequest request, HttpResponse response, HttpContext httpC
 
         // Enhance: allow the notification to contain a message, and pass it on.
         // The copy is made because the onNotification calls may well remove listeners, leading to concurrent modification exceptions.
+
+        // HT-508: to prevent HTA from getting stuck in a bad state when sync is interrupted,
+        // extract and handle sync status that HT inserted into the notification.
+        // The notification received from the HearThis PC is an HttpRequest (RFC 7230), like this:
+        //    POST /notify?message=sync_success HTTP/1.1
+        // Sync status is in the "message" portion. Extract it and send it along.
+        //
+        // NOTE: like several things in HearThisAndroid, HttpRequest is deprecated. It will be
+        // replaced with something more appropriate, hopefully soon.
+
+        String s1 = request.getRequestLine().toString();
+        // We want the part between the two space chars, and after the '='
+        String s2 = s1.substring(s1.indexOf(' ') + 1, s1.lastIndexOf(' '));
+        String status = s2.substring(s2.indexOf('=') + 1);
+
         for (NotificationListener listener: notificationListeners.toArray(new NotificationListener[notificationListeners.size()])) {
-            listener.onNotification("");
+            listener.onNotification(status);
         }
-        response.setEntity(new StringEntity("success"));
+        response.setEntity(new StringEntity(status));
     }
 }

app/src/main/java/org/sil/hearthis/SyncActivity.java

@@ -4,12 +4,13 @@
 import android.annotation.SuppressLint;
 import android.content.Intent;
 import android.content.pm.PackageManager;
-import android.os.AsyncTask;
 import android.os.Bundle;
 
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.app.ActivityCompat;
 
+import android.os.Handler;
+import android.os.Looper;
 import android.util.SparseArray;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -32,6 +33,8 @@
 import java.net.UnknownHostException;
 import java.util.Date;
 import java.util.Enumeration;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
 
 
 public class SyncActivity extends AppCompatActivity implements AcceptNotificationHandler.NotificationListener,
@@ -125,6 +128,8 @@ public void release() {
                         // Toast.makeText(getApplicationContext(), "To prevent memory leaks barcode scanner has been stopped", Toast.LENGTH_SHORT).show();
                     }
 
+                    // Replacing 'AsyncTask' (deprecated) with 'Executors' and 'Handlers' in this method is inspired by:
+                    // https://stackoverflow.com/questions/58767733/the-asynctask-api-is-deprecated-in-android-11-what-are-the-alternatives
                     @Override
                     public void receiveDetections(Detector.Detections<Barcode> detections) {
                         final SparseArray<Barcode> barcodes = detections.getDetectedItems();
@@ -145,15 +150,32 @@ public void run() {
                                                       // provide some users a clue that all is not well.
                                                       ipView.setText(contents);
                                                       preview.setVisibility(View.INVISIBLE);
-                                                      SendMessage sendMessageTask = new SendMessage();
-                                                      sendMessageTask.ourIpAddress = getOurIpAddress();
-                                                      sendMessageTask.execute();
+                                                      ExecutorService executor = Executors.newSingleThreadExecutor();
+                                                      Handler handler = new Handler(Looper.getMainLooper());
+                                                      executor.execute(() -> {
+                                                          // Background work: send UDP packet to IP address given in the QR code.
+                                                          try {
+                                                              String ourIpAddress = getOurIpAddress();
+                                                              String ipAddress = ipView.getText().toString();
+                                                              InetAddress receiverAddress = InetAddress.getByName(ipAddress);
+                                                              DatagramSocket socket = new DatagramSocket();
+                                                              byte[] ipBytes = ourIpAddress.getBytes("UTF-8");
+                                                              DatagramPacket packet = new DatagramPacket(ipBytes, ipBytes.length, receiverAddress, desktopPort);
+                                                              socket.send(packet);
+                                                          } catch (UnknownHostException e) {
+                                                              e.printStackTrace();
+                                                          } catch (IOException e) {
+                                                              e.printStackTrace();
+                                                          }
+                                                          handler.post(() -> {
+                                                              // Background work done, no associated foreground work needed.
+                                                          });
+                                                      });
                                                       cameraSource.stop();
                                                       cameraSource.release();
                                                       cameraSource = null;
                                                   }
                                               });
-
                             }
                         }
                     }
@@ -216,11 +238,8 @@ private String getOurIpAddress() {
                     if (inetAddress.isSiteLocalAddress()) {
                         return inetAddress.getHostAddress();
                     }
-
                 }
-
             }
-
         } catch (SocketException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
@@ -248,7 +267,19 @@ public boolean onOptionsItemSelected(MenuItem item) {
     @Override
     public void onNotification(String message) {
         AcceptNotificationHandler.removeNotificationListener(this);
-        setProgress(getString(R.string.sync_success));
+
+        // HT-508: HearThis PC now includes sync status in its notification to the app.
+        // Possible sync statuses recognized:
+        //   - success
+        //   - interrupted; handling this should prevent the app from getting into a bad state.
+        if (message.equals("sync_success")) {
+            setProgress(getString(R.string.sync_success));
+        } else if (message.equals("sync_interrupted")) {
+            setProgress(getString(R.string.sync_interrupted));
+        } else {
+            // Should never happen. Not sure what to do here, if anything...
+            //Log.d("Sync", "onNotification, illegal message: " + message);
+        }
         runOnUiThread(new Runnable() {
             @Override
             public void run() {
@@ -285,27 +316,4 @@ public void sendingFile(final String name) {
         lastProgress = new Date();
         setProgress("sending " + name);
     }
-
-    // This class is responsible to send one message packet to the IP address we
-    // obtained from the desktop, containing the Android's own IP address.
-    private class SendMessage extends AsyncTask<Void, Void, Void> {
-
-        public String ourIpAddress;
-        @Override
-        protected Void doInBackground(Void... params) {
-            try {
-                String ipAddress = ipView.getText().toString();
-                InetAddress receiverAddress = InetAddress.getByName(ipAddress);
-                DatagramSocket socket = new DatagramSocket();
-                byte[] buffer = ourIpAddress.getBytes("UTF-8");
-                DatagramPacket packet = new DatagramPacket(buffer, buffer.length, receiverAddress, desktopPort);
-                socket.send(packet);
-            } catch (UnknownHostException e) {
-                e.printStackTrace();
-            } catch (IOException e) {
-                e.printStackTrace();
-            }
-            return null;
-        }
-    }
 }

app/src/main/res/values/strings.xml

@@ -17,6 +17,7 @@
     <string name="continue_button_caption">Continue</string>
     <string name="title_activity_choose_book">ChooseBookActivity</string>
     <string name="sync_success">Sync completed successfully!</string>
+    <string name="sync_interrupted">Sync was interrupted or cancelled</string>
     <string name="choose_project">Choose a project</string>
     <string name="choose_book">Choose a book</string>
     <string name="choose_chapter">Choose a chapter</string>