Fix: Ensure initial TransferState is reported on setting TransferListener (#2930)

* fix: ensure initial status is reported on setting transfer listener

* accidental comment out

Author: tylerjroach

aws-android-sdk-s3/src/main/java/com/amazonaws/mobileconnectors/s3/transferutility/TransferObserver.java

@@ -154,18 +154,22 @@ protected void updateFromDB(Cursor c) {
      * @param listener A TransferListener used to receive notification.
      */
     public void setTransferListener(TransferListener listener) {
-        if (listener != null) {
             synchronized (this) {
                 // Remove previous listener.
                 cleanTransferListener();
 
                 // One additional listener is attached so that the basic transfer
                 // info gets updated along side.
-                statusListener = new TransferStatusListener();
-                TransferStatusUpdater.registerListener(id, statusListener);
-                transferListener = listener;
-                TransferStatusUpdater.registerListener(id, transferListener);
-            }
+                if (statusListener == null) {
+                    statusListener = new TransferStatusListener();
+                    TransferStatusUpdater.registerListener(id, statusListener);
+                }
+
+                if (listener != null) {
+                    transferListener = listener;
+                    transferListener.onStateChanged(id, transferState);
+                    TransferStatusUpdater.registerListener(id, transferListener);
+                }
         }
     }
 
@@ -251,7 +255,7 @@ public void cleanTransferListener() {
     /**
      * A listener that can update the {@link TransferObserver}.
      */
-    private class TransferStatusListener implements TransferListener {
+    protected class TransferStatusListener implements TransferListener {
 
         @Override
         @SuppressWarnings("checkstyle:hiddenfield")

aws-android-sdk-s3/src/main/java/com/amazonaws/mobileconnectors/s3/transferutility/TransferStatusUpdater.java

@@ -218,12 +218,18 @@ synchronized void updateState(final int id, final TransferState newState) {
 
             // invoke TransferListener callback on main thread
             for (final TransferListener l : list) {
-                mainHandler.post(new Runnable() {
-                    @Override
-                    public void run() {
-                        l.onStateChanged(id, newState);
-                    }
-                });
+                // If instance is TransferStatusListener, post immediately.
+                // Posting to main thread can cause a missed status.
+                if (l instanceof TransferObserver.TransferStatusListener) {
+                    l.onStateChanged(id, newState);
+                } else {
+                    mainHandler.post(new Runnable() {
+                        @Override
+                        public void run() {
+                            l.onStateChanged(id, newState);
+                        }
+                    });
+                }
             }
 
             // remove all LISTENERS when the transfer is in a final state so