Fixed race condition between activity start and stop on Android.

When activityStop is called quickly after activityStart, abort the
asynchronous operation for showing the progress if it has not yet
executed.

Author: lorenzodallavecchia

src/android/Notification.java

@@ -51,7 +51,9 @@ public class Notification extends CordovaPlugin {
     public int confirmResult = -1;
     public ProgressDialog spinnerDialog = null;
     public ProgressDialog progressDialog = null;
-
+    
+    private Runnable spinnerDialogUpdate = null;
+    
     /**
      * Constructor.
      */
@@ -366,32 +368,39 @@ public synchronized void activityStart(final String title, final String message,
         }*/
         final Notification notification = this;
         final CordovaInterface cordova = this.cordova;
-        Runnable runnable = new Runnable() {
+        this.spinnerDialogUpdate = new Runnable() {
             public void run() {
-                if (notification.spinnerDialog != null) { //update 
-                    notification.spinnerDialog.setTitle(title);
-                    notification.spinnerDialog.setMessage(message);
-                    notification.spinnerDialog.setCancelable(cancelable);
-                    if (!notification.spinnerDialog.isShowing()) {
+                synchronized (notification) {
+                    if (notification.spinnerDialogUpdate != this) {
+                        return; // operation aborted before run
+                    }
+                    notification.spinnerDialogUpdate = null;
+
+                    if (notification.spinnerDialog != null) { //update 
+                        notification.spinnerDialog.setTitle(title);
+                        notification.spinnerDialog.setMessage(message);
+                        notification.spinnerDialog.setCancelable(cancelable);
+                        if (!notification.spinnerDialog.isShowing()) {
+                            notification.spinnerDialog.show();
+                        }
+                    } else {
+                        notification.spinnerDialog = createProgressDialog(cordova); // new ProgressDialog(cordova.getActivity(), AlertDialog.THEME_DEVICE_DEFAULT_LIGHT);
+                        notification.spinnerDialog.setTitle(title);
+                        notification.spinnerDialog.setMessage(message);
+                        notification.spinnerDialog.setCancelable(cancelable);
+                        notification.spinnerDialog.setIndeterminate(true);
+                        notification.spinnerDialog.setOnCancelListener(
+                                new DialogInterface.OnCancelListener() {
+                                    public void onCancel(DialogInterface dialog) {
+                                        notification.spinnerDialog = null;
+                                    }
+                                });
                         notification.spinnerDialog.show();
                     }
-                } else {
-                    notification.spinnerDialog = createProgressDialog(cordova); // new ProgressDialog(cordova.getActivity(), AlertDialog.THEME_DEVICE_DEFAULT_LIGHT);
-                    notification.spinnerDialog.setTitle(title);
-                    notification.spinnerDialog.setMessage(message);
-                    notification.spinnerDialog.setCancelable(cancelable);
-                    notification.spinnerDialog.setIndeterminate(true);
-                    notification.spinnerDialog.setOnCancelListener(
-                            new DialogInterface.OnCancelListener() {
-                                public void onCancel(DialogInterface dialog) {
-                                    notification.spinnerDialog = null;
-                                }
-                            });
-                    notification.spinnerDialog.show();
-                }                
+                }
             }
         };
-        this.cordova.getActivity().runOnUiThread(runnable);
+        this.cordova.getActivity().runOnUiThread(this.spinnerDialogUpdate);
     }
 
     /**
@@ -402,6 +411,9 @@ public synchronized void activityStop() {
             this.spinnerDialog.dismiss();
             this.spinnerDialog = null;
         }
+        if (this.spinnerDialogUpdate != null) {
+            this.spinnerDialogUpdate = null;
+        }
     }
 
     /**