Clean/Fix: Threading Code

- Remove unsafe double checked locking
- Annotate safe double checked locking (volatile)
- use 'static final' if possible

4 files changed, 7 insertions, 18 deletions

diff --git a/src/jogl/classes/com/jogamp/opengl/JoglVersion.java b/src/jogl/classes/com/jogamp/opengl/JoglVersion.java
index ef1ecd7e7..34108bce6 100644
--- a/src/jogl/classes/com/jogamp/opengl/JoglVersion.java
+++ b/src/jogl/classes/com/jogamp/opengl/JoglVersion.java
@@ -46,7 +46,7 @@ public class JoglVersion extends JogampVersion {
     }
 
     public static JoglVersion getInstance() {
-        if(null == jogampCommonVersionInfo) {
+        if(null == jogampCommonVersionInfo) { // volatile: ok
             synchronized(JoglVersion.class) {
                 if( null == jogampCommonVersionInfo ) {
                     final String packageName = "javax.media.opengl";
diff --git a/src/jogl/classes/jogamp/opengl/GLWorkerThread.java b/src/jogl/classes/jogamp/opengl/GLWorkerThread.java
index e57cbe0bc..ac9655fbb 100644
--- a/src/jogl/classes/jogamp/opengl/GLWorkerThread.java
+++ b/src/jogl/classes/jogamp/opengl/GLWorkerThread.java
@@ -40,7 +40,6 @@
 package jogamp.opengl;
 
 import java.lang.reflect.InvocationTargetException;
-import java.security.*;
 import java.util.*;
 import javax.media.opengl.*;
 
@@ -69,9 +68,11 @@ public class GLWorkerThread {
   
   /** Should only be called by Threading class if creation of the
       GLWorkerThread was requested via the opengl.1thread system
-      property. */
+      property. <br>
+   * Start the GLWorkerThread iff not started yet!
+   */
   public static void start() {
-    if (!started) {
+    if (!started) { // volatile: ok
       synchronized (GLWorkerThread.class) {
         if (!started) {
           lock = new Object();
diff --git a/src/jogl/classes/jogamp/opengl/ThreadingImpl.java b/src/jogl/classes/jogamp/opengl/ThreadingImpl.java
index d63699aad..67a950185 100644
--- a/src/jogl/classes/jogamp/opengl/ThreadingImpl.java
+++ b/src/jogl/classes/jogamp/opengl/ThreadingImpl.java
@@ -203,13 +203,7 @@ public class ThreadingImpl {
                 throw new InternalError();
 
             case WORKER:
-                if (!GLWorkerThread.isStarted()) {
-                    synchronized (GLWorkerThread.class) {
-                        if (!GLWorkerThread.isStarted()) {
-                            GLWorkerThread.start();
-                        }
-                    }
-                }
+                GLWorkerThread.start(); // singleton start via volatile-dbl-checked-locking
                 try {
                     GLWorkerThread.invokeAndWait(r);
                 } catch (InvocationTargetException e) {
diff --git a/src/jogl/classes/jogamp/opengl/awt/AWTThreadingPlugin.java b/src/jogl/classes/jogamp/opengl/awt/AWTThreadingPlugin.java
index a681c5b8f..dd493f5ee 100644
--- a/src/jogl/classes/jogamp/opengl/awt/AWTThreadingPlugin.java
+++ b/src/jogl/classes/jogamp/opengl/awt/AWTThreadingPlugin.java
@@ -103,13 +103,7 @@ public class AWTThreadingPlugin implements ThreadingPlugin {
         break;
 
       case ThreadingImpl.WORKER:
-        if (!GLWorkerThread.isStarted()) {
-          synchronized (GLWorkerThread.class) {
-            if (!GLWorkerThread.isStarted()) {
-              GLWorkerThread.start();
-            }
-          }
-        }
+        GLWorkerThread.start(); // singleton start via volatile-dbl-checked-locking
         try {
           GLWorkerThread.invokeAndWait(r);
         } catch (InvocationTargetException e) {