Fix NEWT EDTUtil Deadlock on EDTUtil.start()

DisplayImpl.runOnEDTIfAvail(..) issues EDTUtil.start()
while holding it's object-lock - if the EDT is not running,
then invokes the given task.

EDTUtil.start() impl. holds it's own edt-lock
while starting, then releases it's edt-lock while issuing a null-task.

If another thread injects a blocking task right in-between
which also acquires the display's object-lock it deadlocks.

Simply remove issuing the null-task, so EDTUtil.start()
can return immediatly (releasing edt-lock)
and allowing DisplayImpl.runOnEDTIfAvail(..)
also to release it's object-lock.

The other threads task then can be executed,
where the 'starting task' would come second - which is OK,
even though a rare occasion.

Above situation was triggered via AWT/NEWT reparenting w/ forced recreation
via TestParenting01dAWT.

+++

The null-task at EDTUtil.start() was remaining code to ensure
that the EDT completed starting, which is redundant.

5 files changed, 21 insertions, 24 deletions

diff --git a/src/newt/classes/com/jogamp/newt/util/EDTUtil.java b/src/newt/classes/com/jogamp/newt/util/EDTUtil.java
index 582dc3e1f..58aa67105 100644
--- a/src/newt/classes/com/jogamp/newt/util/EDTUtil.java
+++ b/src/newt/classes/com/jogamp/newt/util/EDTUtil.java
@@ -71,13 +71,13 @@ public interface EDTUtil {
      * and the caller should wait {@link #waitUntilStopped() until it's stopped}.
      * </p>
      *
-     * @return true if EDT has been successfully restarted, otherwise false
      * @throws IllegalStateException if EDT is running and not subject to be stopped, i.e. {@link #isRunning()} returns true
+     * @throws RuntimeException if EDT could not be started
      *
      * @see #invokeStop(boolean, java.lang.Runnable)
      * @see #waitUntilStopped()
      */
-    public boolean start() throws IllegalStateException;
+    public void start() throws IllegalStateException;
 
     /**
      * Returns true if the current thread is the event dispatch thread (EDT).
diff --git a/src/newt/classes/jogamp/newt/DefaultEDTUtil.java b/src/newt/classes/jogamp/newt/DefaultEDTUtil.java
index d481ce8f9..7afa8d746 100644
--- a/src/newt/classes/jogamp/newt/DefaultEDTUtil.java
+++ b/src/newt/classes/jogamp/newt/DefaultEDTUtil.java
@@ -82,7 +82,7 @@ public class DefaultEDTUtil implements EDTUtil {
     }
 
     @Override
-    public final boolean start() throws IllegalStateException {
+    public final void start() throws IllegalStateException {
         synchronized(edtLock) {
             if( edt.isRunning() ) {
                 throw new IllegalStateException("EDT still running and not subject to stop. Curr "+Thread.currentThread().getName()+", EDT "+edt.getName()+", isRunning "+edt.isRunning+", shouldStop "+edt.shouldStop);
@@ -103,7 +103,9 @@ public class DefaultEDTUtil implements EDTUtil {
             }
             startImpl();
         }
-        return invoke(true, nullTask);
+        if( !edt.isRunning() ) {
+            throw new RuntimeException("EDT could not be started: "+edt);
+        }
     }
 
     private final void startImpl() {
diff --git a/src/newt/classes/jogamp/newt/driver/awt/AWTEDTUtil.java b/src/newt/classes/jogamp/newt/driver/awt/AWTEDTUtil.java
index 4a7193306..407d3abf9 100644
--- a/src/newt/classes/jogamp/newt/driver/awt/AWTEDTUtil.java
+++ b/src/newt/classes/jogamp/newt/driver/awt/AWTEDTUtil.java
@@ -68,7 +68,7 @@ public class AWTEDTUtil implements EDTUtil {
     }
 
     @Override
-    public final boolean start() throws IllegalStateException {
+    public final void start() throws IllegalStateException {
         synchronized(edtLock) {
             if( nedt.isRunning() ) {
                 throw new IllegalStateException("EDT still running and not subject to stop. Curr "+Thread.currentThread().getName()+", NEDT "+nedt.getName()+", isRunning "+nedt.isRunning+", shouldStop "+nedt.shouldStop+", on AWT-EDT "+EventQueue.isDispatchThread());
@@ -82,7 +82,9 @@ public class AWTEDTUtil implements EDTUtil {
             }
             startImpl();
         }
-        return invoke(true, nullTask);
+        if( !nedt.isRunning() ) {
+            throw new RuntimeException("EDT could not be started: "+nedt);
+        }
     }
 
     private final void startImpl() {
@@ -128,11 +130,6 @@ public class AWTEDTUtil implements EDTUtil {
         return invokeImpl(wait, task, false);
     }
 
-    private static Runnable nullTask = new Runnable() {
-        @Override
-        public void run() { }
-    };
-
     private final boolean invokeImpl(boolean wait, Runnable task, boolean stop) {
         Throwable throwable = null;
         RunnableTask rTask = null;
diff --git a/src/newt/classes/jogamp/newt/swt/SWTEDTUtil.java b/src/newt/classes/jogamp/newt/swt/SWTEDTUtil.java
index db89690f4..91c18f023 100644
--- a/src/newt/classes/jogamp/newt/swt/SWTEDTUtil.java
+++ b/src/newt/classes/jogamp/newt/swt/SWTEDTUtil.java
@@ -78,7 +78,7 @@ public class SWTEDTUtil implements EDTUtil {
     }
 
     @Override
-    public final boolean start() throws IllegalStateException {
+    public final void start() throws IllegalStateException {
         final boolean swtDisposed = swtDisplay.isDisposed();
         synchronized(edtLock) {
             if( nedt.isRunning() ) {
@@ -99,9 +99,11 @@ public class SWTEDTUtil implements EDTUtil {
             }
         }
         if( !swtDisposed ) {
-            return invoke(true, nullTask);
+            if( !nedt.isRunning() ) {
+                throw new RuntimeException("EDT could not be started: "+nedt);
+            }
         } else {
-            return false;
+            // FIXME: Throw exception ?
         }
     }
 
@@ -149,11 +151,6 @@ public class SWTEDTUtil implements EDTUtil {
         return invokeImpl(wait, task, false);
     }
 
-    private static Runnable nullTask = new Runnable() {
-        @Override
-        public void run() { }
-    };
-
     private final boolean invokeImpl(boolean wait, Runnable task, boolean stop) {
         Throwable throwable = null;
         RunnableTask rTask = null;
diff --git a/src/test/com/jogamp/opengl/test/junit/newt/TestDisplayLifecycle01NEWT.java b/src/test/com/jogamp/opengl/test/junit/newt/TestDisplayLifecycle01NEWT.java
index b007f57f3..8989f3a89 100644
--- a/src/test/com/jogamp/opengl/test/junit/newt/TestDisplayLifecycle01NEWT.java
+++ b/src/test/com/jogamp/opengl/test/junit/newt/TestDisplayLifecycle01NEWT.java
@@ -3,14 +3,14 @@
  *
  * Redistribution and use in source and binary forms, with or without modification, are
  * permitted provided that the following conditions are met:
- * 
+ *
  *    1. Redistributions of source code must retain the above copyright notice, this list of
  *       conditions and the following disclaimer.
- * 
+ *
  *    2. Redistributions in binary form must reproduce the above copyright notice, this list
  *       of conditions and the following disclaimer in the documentation and/or other materials
  *       provided with the distribution.
- * 
+ *
  * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
@@ -20,7 +20,7 @@
  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- * 
+ *
  * The views and conclusions contained in the software and documentation are those of the
  * authors and should not be interpreted as representing official policies, either expressed
  * or implied, of JogAmp Community.
@@ -69,7 +69,7 @@ public class TestDisplayLifecycle01NEWT extends UITestCase {
 
         //
         // Create native windowing resources .. X11/Win/OSX
-        // 
+        //
         GLWindow glWindow;
         if(null!=screen) {
             Window window = NewtFactory.createWindow(screen, caps);
@@ -209,6 +209,7 @@ public class TestDisplayLifecycle01NEWT extends UITestCase {
             Assert.assertNotNull(edtUtil);
             Assert.assertEquals(false,edtUtil.isRunning());
             edtUtil.start();
+            Assert.assertEquals(true,edtUtil.isRunning());
             edtUtil.invoke(true, null);
             Assert.assertEquals(true,edtUtil.isRunning());
             edtUtil.invokeStop(true, null);