Fix Bug 527: Creating a context w/ shared context, while the latter is in use (threading)

Bug 527 describes the situation where wglShareLists() fails (throws exception)
while the shared context is in use by another thread (some Animator).

It was reported by Jerome Jouvie.

The exception happens not everytime, but at least around 20% on manual tests
I have performed on the Windows platform.

The context in question are all JOGL's GL2, which natively where bound to an OpenGL 3.0 profile.
The WGL_ARB_create_context spec says http://www.opengl.org/registry/specs/ARB/wgl_create_context.txt:
+++
    Future versions of OpenGL may only support being added to a share
    group at context creation time. Specifying such a version of a
    context as either the <hglrc1> or <hglrc2> arguments to
    wglShareLists will fail. wglShareLists will return FALSE, and
    GetLastError will return ERROR_INCOMPATIBLE_DEVICE_CONTEXTS_ARB.
+++
Hence the 1st patch was to remove 'wglShareLists()' usage in case
we use the new WGL_ARB_create_context context creation method.
Even though this is a desired change, and works in general, it didn't fix the issue.

It seems that the shared context, which is passed @ new context creation,
cannot be used while it is in use itself in another thread.

This conclusion leads to the actual fix, ie. locking the shared context
while creating the new context which shares it.
Manual tests using this patch could not reproduce this issue (40 attempts).

Test: TestSharedContextListNEWT2

1 files changed, 12 insertions, 12 deletions

diff --git a/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java b/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java
index 90b7fa949..300b5c5c7 100644
--- a/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java
+++ b/src/jogl/classes/jogamp/opengl/windows/wgl/WindowsWGLContext.java
@@ -55,7 +55,6 @@ import com.jogamp.gluegen.runtime.ProcAddressTable;
 import com.jogamp.gluegen.runtime.opengl.GLProcAddressResolver;
 import jogamp.nativewindow.windows.GDI;
 import jogamp.opengl.GLContextImpl;
-import jogamp.opengl.GLContextShareSet;
 import jogamp.opengl.GLDrawableImpl;
 
 public class WindowsWGLContext extends GLContextImpl {
@@ -257,20 +256,19 @@ public class WindowsWGLContext extends GLContextImpl {
    * Creates and initializes an appropriate OpenGL context. Should only be
    * called by {@link #makeCurrentImpl()}.
    */
-  protected boolean createImpl() {
-    WindowsWGLDrawableFactory factory = (WindowsWGLDrawableFactory)drawable.getFactoryImpl();
+  protected boolean createImpl(GLContextImpl shareWith) {
     AbstractGraphicsConfiguration config = drawable.getNativeSurface().getGraphicsConfiguration();
     AbstractGraphicsDevice device = config.getScreen().getDevice();
+    WindowsWGLDrawableFactory factory = (WindowsWGLDrawableFactory)drawable.getFactoryImpl();
     WindowsWGLContext sharedContext = (WindowsWGLContext) factory.getOrCreateSharedContextImpl(device);
     GLCapabilitiesImmutable glCaps = drawable.getChosenGLCapabilities();
 
     isGLReadDrawableAvailable(); // trigger setup wglGLReadDrawableAvailable
 
     // Windows can set up sharing of display lists after creation time
-    WindowsWGLContext other = (WindowsWGLContext) GLContextShareSet.getShareContext(this);
     long share = 0;
-    if (other != null) {
-      share = other.getHandle();
+    if (null != shareWith) {
+      share = shareWith.getHandle();
       if (share == 0) {
         throw new GLException("GLContextShareSet returned an invalid OpenGL context");
       }
@@ -347,17 +345,19 @@ public class WindowsWGLContext extends GLContextImpl {
             WGL.wglDeleteContext(contextHandle);
             throw new GLException("Error making old context current: 0x" + toHexString(contextHandle) + ", werr: " + GDI.GetLastError());
         }
+        if(0!=share) {
+            // Only utilize the classic GDI 'wglShareLists' shared context method 
+            // for traditional non ARB context.
+            if (!WGL.wglShareLists(share, contextHandle)) {
+                throw new GLException("wglShareLists(" + toHexString(share) +
+                                      ", " + toHexString(contextHandle) + ") failed: werr " + GDI.GetLastError());
+            }
+        }
         if (DEBUG) {
             System.err.println(getThreadName() + ": createImpl: OK (old) share "+share);
         }
     }
 
-    if(0!=share) {
-        if (!WGL.wglShareLists(share, contextHandle)) {
-            throw new GLException("wglShareLists(" + toHexString(share) +
-                                  ", " + toHexString(contextHandle) + ") failed: werr " + GDI.GetLastError());
-        }
-    }
     return true;
   }