Eclipse Community Forums: Eclipse Platform » Class loading in SWT Event Thread

Help

Home

Home » Eclipse Projects » Eclipse Platform » Class loading in SWT Event Thread

Show: Today's Messages :: Show Polls :: Message Navigator

Class loading in SWT Event Thread [message #1124378]

Thu, 03 October 2013 13:24

Jan Krakora

Messages: 477
Registered: December 2009
Location: Prague

Senior Member

I'm little confused about class loading in the Eclipse runtime.

I have my own plugin that uses this code:

Display.getDefault().asyncExec(new Runnable() {
    public void run() {
        MyClass class = new MyClass();
        ....
    }
)};

Since the code in run() is executed on the SWT Event thread, I would like to know what class loader will be used for loading the MyClass.class.

Report message to a moderator

Re: Class loading in SWT Event Thread [message #1125078 is a reply to message #1124378]

Fri, 04 October 2013 06:11

Ed Merks

Messages: 33137
Registered: July 2009

Senior Member

Jan,

Set a breakpoint in the debugger an you can see what class loader is
used. In general with OSGi, that's quite a complex question. You
should expect that the class loader of the bundle in which you've
defined the class containing the code you show below to be used. So
that bundle better define MyClass, have a dependency on a bundle that
defines MyClass and exports it, or you might need to deal with things
like buddy class loading (but that doesn't apply for your specific
hard-coded class name below.

Why are you even asking it? You're having some specific problem and you
think the answer to this question will help solve that problem?

On 03/10/2013 3:24 PM, Jan Krakora wrote:
> I'm little confused about class loading in the Eclipse runtime.
> I have my own plugin that uses this code:
>
> Display.getDefault().asyncExec(new Runnable() {
> public void run() {
> MyClass class = new MyClass();
> ....
> }
> )};
>
> Since the code in run() is executed on the SWT Event thread, I would
> like to know what class loader will be used for loading the
> MyClass.class.

Ed Merks
Professional Support: https://www.macromodeling.com/

Report message to a moderator

Re: Class loading in SWT Event Thread [message #1125152 is a reply to message #1125078]

Fri, 04 October 2013 07:55

Jan Krakora

Messages: 477
Registered: December 2009
Location: Prague

Senior Member

Well, my problem is in using lambdaj on the SWT Event thread.

Let's say I have:

plugin A containing MyClass
plugin B containing ByClassB that define the code below
com.google.lambdaj plugin
plugin B has dependency on plugin com.google.lambdaj
plugin B has also dependency on plugin A, so it can use its MyClass

lambdaj internally uses the cglib to create proxy classes. So when I have something like this:

Display.getDefault().asyncExec(new Runnable() {
    public void run() {
        MyClass class = Lambda.selectFirst(collection, having(on(MyClass.class).getId(), Matchers.equalTo(id)));
        ....
    }
)};

I get "java.lang.ClassNotFoundException: net.sf.cglib.proxy.Factory". When I debug it and look at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(...),
I can see the plugin that is looking for the net.sf.cglib.proxy.Factory class is the A plugin.

Since I can't modify the com.google.lambdaj plugin, the only workaround was to put Eclipse-BuddyPolicy: global in my A plugin.
This is AFAIK bad solution because it then looks for the class in all exported packages from the whole RCP application.

The fact that my code runs on the SWT Event thread is maybe irrelevant.

[Updated on: Fri, 04 October 2013 08:06]

Report message to a moderator

Re: Class loading in SWT Event Thread [message #1125320 is a reply to message #1125152]

Fri, 04 October 2013 11:45

Thorsten Schlathölter

Messages: 312
Registered: February 2012
Location: Düsseldorf

Senior Member

Hi,
have you imported the package "net.sf.cglib.proxy" in your A-Bundle? Then it should work. The BuddyPolicy should not be required.

Regards,
Thorsten

Report message to a moderator