[RFC][plugin]: Class loading problem.

[Denis Lila]

> > + this.uKey = "codebase=" + codebaseAttr +
> > + "cache_archive=" + cache_archiveAttr +
> > + "java_archive=" + java_archiveAttr +
> > + "archive=" + archiveAttr;
> > + // TODO: perhaps add some randomization in the name here?
> > + uKeyToTG.putIfAbsent(this.uKey, new
> > ThreadGroup(Launcher.mainGroup, this.documentURL.toString()));
> 
> The comment below about the constructor parameters for new
> {App,}ThreadGroup() should be moved here.

Will do.

> I am not sure if the name getFutureTG is appropriate, espcially given
> the check currentThreadGroup = getFutureTG() in the next few lines. I
> think getThreadGroup() would be fine.

I agree. That name was getting a bit awkward.

> > @@ -39,14 +40,51 @@
> >    *
> >    * @author Francis Kung<fkung at redhat.com>
> >    */
> > + at SuppressWarnings("serial")
> >   public class NetxPanel extends AppletViewerPanel {
> 
> Is there a particular reason you are suppressing this warning?
> 

It's a pet peeve of mine ;)
Warning marks in eclipse bother me more than they reasonably
should. Should I change it back?

> > - // create the frame.
> > - PluginAppletViewer.framePanel(identifier, handle, panel);
> > + // Framing the panel needs to happen in a thread whose thread
> > group
> > + // is the same as the threadgroup of the applet thread. If this
> > + // isn't the case, the awt eventqueue thread's context classloader
> > + // won't be set to a JNLPClassLoader, and when an applet class
> > needs
> > + // to be loaded from the awt eventqueue, it won't be found.
> > + Thread panelInit = new Thread(panel.getFutureTG(), new Runnable()
> > {
> > + @Override public void run() {
> > + panel.createNewAppContext();
> > + // create the frame.
> > + PluginAppletViewer.framePanel(identifier, handle, panel);
> > + panel.init();
> > + // Start the applet
> > + initEventQueue(panel);
> > + }
> > + }, "NetXPanel initializer");
> >
> > - panel.init();
> > -
> > - // Start the applet
> > - initEventQueue(panel);
> > + panelInit.start();
> > + while(panelInit.isAlive()) {
> > + try {
> > + panelInit.join();
> > + } catch (InterruptedException e) {
> > + }
> > + }
> >
> 
> This part looks fine to me, but I am not too familiar with the
> concurrency requirements and communication between threads that goes
> on in PluginAppletViewer.

This code is meant to be as close to the original as possible, with the
exception that it should happen in the same TG as the one of the thread
that will do the loading in panel.init() (and with a new AppContext so
that we get new eventqueue threads for new applets).

What do you think about the TODO?
I think you suggested something like that to me yesterday. That's why
I put the TODO in there. However, what we have now is what we've always
had (as far as the TG name goes), and I wasn't sure I should change it.

Thank you,
Denis.

----- Original Message -----
> On 04/28/2011 05:24 PM, Denis Lila wrote:
> >>> >  >  The attached patch fixes that. I believe a good enough
> >>> >  >  explanation of what's happening is in the comments (if I'm
> >>> >  >  wrong, don't hesitate to ask).
> >> >
> >> >  Eh, I forgot the attachment again.
> > Hi.
> >
> > Turns out, this patch is incomplete. Better one attached.
> > It also fixes a problem in the pogo.com games where
> > all keystrokes when chatting are ignored.
> >
> 
> Overall, this patch looks fine to me. Some comments inline.
> 
> 
> 


> 
> > @@ -156,9 +182,7 @@
> >
> >           // when this was being done (incorrectly) in Launcher, the
> >           call was
> >           // new AppThreadGroup(mainGroup, file.getTitle());
> > - ThreadGroup tg = new AppThreadGroup(Launcher.mainGroup,
> > - this.documentURL.toString());
> > - handler = new Thread(tg, this);
> > + handler = new Thread(getFutureTG(), this);
> >           handler.start();
> >       }
> >
> > @@ -174,4 +198,19 @@
> >       public boolean isAlive() {
> >           return handler != null&& handler.isAlive()&&
> >           this.appletAlive;
> >       }
> > +
> > + public ThreadGroup getFutureTG() {
> > + return uKeyToTG.get(uKey);
> > + }
> > +
> 

> 
> > + public void createNewAppContext() {
> > + if (Thread.currentThread().getThreadGroup() != getFutureTG()) {
> > + throw new RuntimeException("createNewAppContext called from the
> > wrong thread.");
> > + }
> > + // only create a new one if one hasn't already been created for
> > the
> > + // applets with this unique key.
> > + if (null == appContextCreated.putIfAbsent(uKey, Boolean.TRUE)) {
> > + SunToolkit.createNewAppContext();
> > + }
> > + }
> >   }
> 
> ... snip ...
> 
> > @@ -136,13 +136,29 @@
> >               }
> >           });
> >

> 
> Cheers,
> Omair