Clean/Fix: Threading Code

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

4 files changed, 40 insertions, 21 deletions

diff --git a/src/nativewindow/classes/com/jogamp/nativewindow/NativeWindowVersion.java b/src/nativewindow/classes/com/jogamp/nativewindow/NativeWindowVersion.java
index ccb2176fc..38bd70a90 100644
--- a/src/nativewindow/classes/com/jogamp/nativewindow/NativeWindowVersion.java
+++ b/src/nativewindow/classes/com/jogamp/nativewindow/NativeWindowVersion.java
@@ -42,7 +42,7 @@ public class NativeWindowVersion extends JogampVersion {
     }
 
     public static NativeWindowVersion getInstance() {
-        if(null == jogampCommonVersionInfo) {
+        if(null == jogampCommonVersionInfo) { // volatile: ok
             synchronized(NativeWindowVersion.class) {
                 if( null == jogampCommonVersionInfo ) {
                     final String packageName = "javax.media.nativewindow";
diff --git a/src/nativewindow/classes/javax/media/nativewindow/awt/AWTWindowClosingProtocol.java b/src/nativewindow/classes/javax/media/nativewindow/awt/AWTWindowClosingProtocol.java
index 7112f944d..e7db942e4 100644
--- a/src/nativewindow/classes/javax/media/nativewindow/awt/AWTWindowClosingProtocol.java
+++ b/src/nativewindow/classes/javax/media/nativewindow/awt/AWTWindowClosingProtocol.java
@@ -51,6 +51,7 @@ public class AWTWindowClosingProtocol implements WindowClosingProtocol {
   }
 
   class WindowClosingAdapter extends WindowAdapter {
+    @Override
     public void windowClosing(WindowEvent e) {
       int op = AWTWindowClosingProtocol.this.getDefaultCloseOperation();
 
@@ -80,7 +81,7 @@ public class AWTWindowClosingProtocol implements WindowClosingProtocol {
    * @return
    */
   public final boolean addClosingListenerOneShot() {
-    if(!closingListenerSet) {
+    if(!closingListenerSet) { // volatile: ok
       synchronized(closingListenerLock) {
         if(!closingListenerSet) {
             closingListenerSet=addClosingListenerImpl();
@@ -92,7 +93,7 @@ public class AWTWindowClosingProtocol implements WindowClosingProtocol {
   }
 
   public final boolean removeClosingListener() {
-    if(closingListenerSet) {
+    if(closingListenerSet) { // volatile: ok
       synchronized(closingListenerLock) {
         if(closingListenerSet) {
             Window w = AWTMisc.getWindow(comp);
diff --git a/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java b/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java
index d5811d9c5..80dd5c402 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/jawt/JAWTUtil.java
@@ -60,13 +60,23 @@ public class JAWTUtil {
   private static final Method isQueueFlusherThread;
   private static final boolean j2dExist;
 
-  private static Class   sunToolkitClass;
-  private static Method  sunToolkitAWTLockMethod;
-  private static Method  sunToolkitAWTUnlockMethod;
-  private static boolean hasSunToolkitAWTLock;
+  private static final Class   sunToolkitClass;
+  private static final Method  sunToolkitAWTLockMethod;
+  private static final Method  sunToolkitAWTUnlockMethod;
+  private static final boolean hasSunToolkitAWTLock;
 
   private static final JAWTToolkitLock jawtToolkitLock;
 
+  private static class PrivilegedDataBlob1 {
+    PrivilegedDataBlob1() {
+        ok = false;
+    }  
+    Class   sunToolkitClass;
+    Method  sunToolkitAWTLockMethod;
+    Method  sunToolkitAWTUnlockMethod;
+    boolean ok;
+  }
+  
   static {
     JAWTJNILibLoader.loadAWTImpl();
     JAWTJNILibLoader.loadNativeWindow("awt");
@@ -87,22 +97,28 @@ public class JAWTUtil {
     isQueueFlusherThread = m;
     j2dExist = ok;
 
-    AccessController.doPrivileged(new PrivilegedAction() {
+    PrivilegedDataBlob1 pdb1 = (PrivilegedDataBlob1) AccessController.doPrivileged(new PrivilegedAction() {        
         public Object run() {
-            try {
-                sunToolkitClass = Class.forName("sun.awt.SunToolkit");
-                sunToolkitAWTLockMethod = sunToolkitClass.getDeclaredMethod("awtLock", new Class[]{});
-                sunToolkitAWTLockMethod.setAccessible(true);
-                sunToolkitAWTUnlockMethod = sunToolkitClass.getDeclaredMethod("awtUnlock", new Class[]{});
-                sunToolkitAWTUnlockMethod.setAccessible(true);
+            PrivilegedDataBlob1 d = new PrivilegedDataBlob1();
+            try {                
+                d.sunToolkitClass = Class.forName("sun.awt.SunToolkit");
+                d.sunToolkitAWTLockMethod = sunToolkitClass.getDeclaredMethod("awtLock", new Class[]{});
+                d.sunToolkitAWTLockMethod.setAccessible(true);
+                d.sunToolkitAWTUnlockMethod = sunToolkitClass.getDeclaredMethod("awtUnlock", new Class[]{});
+                d.sunToolkitAWTUnlockMethod.setAccessible(true);
+                d.ok=true;
             } catch (Exception e) {
                 // Either not a Sun JDK or the interfaces have changed since 1.4.2 / 1.5
             }
-            return null;
+            return d;
         }
     });
+    sunToolkitClass = pdb1.sunToolkitClass;
+    sunToolkitAWTLockMethod = pdb1.sunToolkitAWTLockMethod;
+    sunToolkitAWTUnlockMethod = pdb1.sunToolkitAWTUnlockMethod;
+    
     boolean _hasSunToolkitAWTLock = false;
-    if (null != sunToolkitAWTLockMethod && null != sunToolkitAWTUnlockMethod) {
+    if ( pdb1.ok ) {
         try {
             sunToolkitAWTLockMethod.invoke(null, (Object[])null);
             sunToolkitAWTUnlockMethod.invoke(null, (Object[])null);
@@ -152,11 +168,11 @@ public class JAWTUtil {
   }
 
 
-  public static final boolean hasJava2D() {
+  public static boolean hasJava2D() {
     return j2dExist;
   }
 
-  public static final boolean isJava2DQueueFlusherThread() {
+  public static boolean isJava2DQueueFlusherThread() {
     boolean b = false;
     if(j2dExist) {
         try {
diff --git a/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java b/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java
index 4098e101b..052a9934e 100644
--- a/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java
+++ b/src/nativewindow/classes/jogamp/nativewindow/x11/X11Util.java
@@ -54,7 +54,7 @@ public class X11Util {
     private static final boolean DEBUG = Debug.debug("X11Util");
     private static final boolean TRACE_DISPLAY_LIFECYCLE = Debug.getBooleanProperty("nativewindow.debug.X11Util.TraceDisplayLifecycle", true, AccessController.getContext());
 
-    private static String nullDisplayName = null;
+    private static volatile String nullDisplayName = null;
     private static boolean isFirstX11ActionOnProcess = false;
     private static boolean isInit = false;
 
@@ -117,7 +117,7 @@ public class X11Util {
     }
 
     public static String getNullDisplayName() {
-        if(null==nullDisplayName) {
+        if(null==nullDisplayName) { // volatile: ok
             synchronized(X11Util.class) {
                 if(null==nullDisplayName) {
                     NativeWindowFactory.getDefaultToolkitLock().lock();
@@ -174,17 +174,19 @@ public class X11Util {
 
         public final Throwable getCreationStack() { return creationStack; }
 
+        @Override
         public Object clone() throws CloneNotSupportedException {
           return super.clone();
         }
 
+        @Override
         public String toString() {
             return "NamedX11Display["+name+", 0x"+Long.toHexString(handle)+", refCount "+refCount+", unCloseable "+unCloseable+"]";
         }
     }
 
     /** Returns the number of unclosed X11 Displays.
-      * @param realXCloseAndPendingDisplays if true, {@link #closePendingDisplayConnections()} is called.
+     * @param realXCloseOpenAndPendingDisplays if true, {@link #closePendingDisplayConnections()} is called.
       */
     public static int shutdown(boolean realXCloseOpenAndPendingDisplays, boolean verbose) {
         int num=0;