eclipse plugin does not work after update to juno (eclipse 4)

Question

I created an eclipse plugin that will hook into the save action to create a minified javascript file with the goolge closure compiler. See files below. That worked until eclipse 3.7.2. Unfortunately now in eclipse 4.2.1 it seems that this creates an endless loop sometimes. The job "compile .min.js" (line 64 in ResourceChangedListener.java) seems the be the cause. It results in the case that the workspaced starts to build over and over. I guess this is because that job creates or changes a file triggering the workspace build again, which again triggers the job which triggers the build and so on. But I can not figure out how to prevent this.

// Activator.java

package closure_compiler_save;

import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.ui.plugin.AbstractUIPlugin;
import org.osgi.framework.BundleContext;

/**
 * The activator class controls the plug-in life cycle
 */
public class Activator extends AbstractUIPlugin  {

    // The plug-in ID
    public static final String PLUGIN_ID = "closure-compiler-save"; //$NON-NLS-1$

    // The shared instance
    private static Activator plugin;

    /**
     * The constructor
     */
    public Activator() {
    }

    @Override
      public void start(BundleContext context) throws Exception {
        super.start(context);
        Activator.plugin = this;

        ResourceChangedListener listener = new ResourceChangedListener();
          ResourcesPlugin.getWorkspace().addResourceChangeListener(listener);
    }

    @Override
      public void stop(BundleContext context) throws Exception {
        Activator.plugin = null;
        super.stop(context);
    }

    /**
     * Returns the shared instance
     *
     * @return the shared instance
     */
    public static Activator getDefault() {
        return plugin;
    }
}

// ResourceChangedListener.java

package closure_compiler_save;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;

public class ResourceChangedListener implements IResourceChangeListener {

    public void resourceChanged(IResourceChangeEvent event) {
        if (event.getType() != IResourceChangeEvent.POST_CHANGE)
            return;

        IResourceDelta delta = event.getDelta();
        try {
            processDelta(delta);
        } catch (CoreException e) {
            e.printStackTrace();
        }
    }

    // find out which class files were just built
    private void processDelta(IResourceDelta delta) throws CoreException {

        IResourceDelta[] kids = delta.getAffectedChildren();
        for (IResourceDelta delta2 : kids) {
            if (delta2.getAffectedChildren().length == 0) {
                if (delta.getKind() != IResourceDelta.CHANGED)
                    return;

                IResource res = delta2.getResource();
                if (res.getType() == IResource.FILE && "js".equalsIgnoreCase(res.getFileExtension())) {
                    if (res.getName().contains("min"))
                        return;
                    compile(res);
                }
            }
            processDelta(delta2);
        }
    }

    private void compile(final IResource res) throws CoreException {

        final IPath fullPath = res.getFullPath();
        final IPath fullLocation = res.getLocation();
        final String fileName = fullPath.lastSegment().toString();
        final String outputFilename = fileName.substring(0, fileName.lastIndexOf(".")).concat(".min.js");
        final String outputPath = fullPath.removeFirstSegments(1).removeLastSegments(1).toString();

        final IProject project = res.getProject();
        final IFile newFile = project.getFile(outputPath.concat("/".concat(outputFilename)));
        Job compileJob = new Job("Compile .min.js") {
            public IStatus run(IProgressMonitor monitor) {
                byte[] bytes = null;
                try {
                    bytes = CallCompiler.compile(fullLocation.toString(), CallCompiler.SIMPLE_OPTIMIZATION).getBytes();

                    InputStream source = new ByteArrayInputStream(bytes);
                    if (!newFile.exists()) {
                        newFile.create(source, IResource.NONE, null);
                    } else {
                        newFile.setContents(source, IResource.NONE, null);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (CoreException e) {
                    e.printStackTrace();
                }
                return Status.OK_STATUS;
            }
        };
        compileJob.setRule(newFile.getProject()); // this will ensure that no two jobs are writing simultaneously on the same file
        compileJob.schedule();
    }

}

Answer 1

After I setup a blank eclipse classic environment, started a new eclipse plugin project there and recreated all files it works again partly. In this environment starting a debug session I can save .js files and .min.js files are created automatically. So far so good! But when I install the plugin to my real developing eclipse environment automatic saving does not work.

At least one step further!

Step 2: There were some files not included in the build obviously needed, like manifest. No idea why they were deselected. Anyway it seems just setting up a blank eclipse 4 classic and going through the eclipse plugin wizard fixed my original problem. I still would love to know what was the actual problem...