Classloader isolation in Kb

gistfile1.java

// Killbill object interface
package com.ning.billing.beatrix.util;

import java.util.List;

public interface MyKBI {

    List getList();
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Killbill object implementation
package com.ning.billing.beatrix.util;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import com.ning.billing.beatrix.util.MyList;

public class MyKBImpl implements MyKBI {
   @Override
    public List<?> getList() {
        return new MyList();
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Killbill specific MyList implementation
package com.ning.billing.beatrix.util;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

public class MyList implements List<Integer> {

        @Override
        public int size() {
            return 1;
        }

        @Override
        public boolean isEmpty() {
            return false;
        }

        @Override
        public boolean contains(final Object o) {
            return false;
        }

        @Override
        public Iterator<Integer> iterator() {
            return null;
        }

        @Override
        public Object[] toArray() {
            return new Object[0];
        }

        @Override
        public <T> T[] toArray(final T[] a) {
            return null;
        }

        @Override
        public boolean add(final Integer integer) {
            return false;
        }

        @Override
        public boolean remove(final Object o) {
            return false;
        }

        @Override
        public boolean containsAll(final Collection<?> c) {
            return false;
        }

        @Override
        public boolean addAll(final Collection<? extends Integer> c) {
            return false;
        }

        @Override
        public boolean addAll(final int index, final Collection<? extends Integer> c) {
            return false;
        }

        @Override
        public boolean removeAll(final Collection<?> c) {
            return false;
        }

        @Override
        public boolean retainAll(final Collection<?> c) {
            return false;
        }

        @Override
        public void clear() {
        }

        @Override
        public Integer get(final int index) {
            return null;
        }

        @Override
        public Integer set(final int index, final Integer element) {
            return null;
        }

        @Override
        public void add(final int index, final Integer element) {
        }

        @Override
        public Integer remove(final int index) {
            return null;
        }

        @Override
        public int indexOf(final Object o) {
            return 0;
        }

        @Override
        public int lastIndexOf(final Object o) {
            return 0;
        }

        @Override
        public ListIterator<Integer> listIterator() {
            return null;
        }

        @Override
        public ListIterator<Integer> listIterator(final int index) {
            return null;
        }

        @Override
        public List<Integer> subList(final int fromIndex, final int toIndex) {
            return null;
        }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Killbill plugin interface
package com.ning.billing.beatrix.util;

public interface MyPluginI {

    public void doSomething(MyKBI kbObject);
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Killbill plugin implementation
package com.ning.billing.beatrix.util;

import java.util.List;
import com.ning.billing.beatrix.util.MyPluginI;
import com.ning.billing.beatrix.util.MyList;

public class MyPlugin implements MyPluginI {

    public void doSomething(MyKBI bleh) {
        System.out.println(this.getClass().getClassLoader().toString());
        System.out.println(bleh.getList().size());
        System.out.println(bleh.getList().getClass().toString());
        System.out.println(bleh.getList().getClass().getClassLoader().toString());
        final List myList = new MyList();
        System.out.println(myList.size());
        System.out.println(myList.getClass().toString());
        System.out.println(myList.getClass().getClassLoader().toString());
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Plugin specific MyList implementation
package com.ning.billing.beatrix.util;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

public class MyList implements List<Integer> {

        @Override
        public int size() {
            return -1;
        }

        @Override
        public boolean isEmpty() {
            return false;
        }

        @Override
        public boolean contains(final Object o) {
            return false;
        }

        @Override
        public Iterator<Integer> iterator() {
            return null;
        }

        @Override
        public Object[] toArray() {
            return new Object[0];
        }

        @Override
        public <T> T[] toArray(final T[] a) {
            return null;
        }

        @Override
        public boolean add(final Integer integer) {
            return false;
        }

        @Override
        public boolean remove(final Object o) {
            return false;
        }

        @Override
        public boolean containsAll(final Collection<?> c) {
            return false;
        }

        @Override
        public boolean addAll(final Collection<? extends Integer> c) {
            return false;
        }

        @Override
        public boolean addAll(final int index, final Collection<? extends Integer> c) {
            return false;
        }

        @Override
        public boolean removeAll(final Collection<?> c) {
            return false;
        }

        @Override
        public boolean retainAll(final Collection<?> c) {
            return false;
        }

        @Override
        public void clear() {
        }

        @Override
        public Integer get(final int index) {
            return null;
        }

        @Override
        public Integer set(final int index, final Integer element) {
            return null;
        }

        @Override
        public void add(final int index, final Integer element) {
        }

        @Override
        public Integer remove(final int index) {
            return null;
        }

        @Override
        public int indexOf(final Object o) {
            return 0;
        }

        @Override
        public int lastIndexOf(final Object o) {
            return 0;
        }

        @Override
        public ListIterator<Integer> listIterator() {
            return null;
        }

        @Override
        public ListIterator<Integer> listIterator(final int index) {
            return null;
        }

        @Override
        public List<Integer> subList(final int fromIndex, final int toIndex) {
            return null;
        }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

public class Kb {

    static class KbCoreClassLoader extends URLClassLoader {

        public KbCoreClassLoader(URL[] urls) {
            super(urls);
        }
    }

    static class PluginClassLoader extends URLClassLoader {

        public PluginClassLoader(URL[] urls) {
            super(urls);
        }
    }

    public static void main(final String[] args) throws Exception {
        // Killbill specific classloader
        final ClassLoader kbCoreClassLoader = new KbCoreClassLoader(new URL[]{new URL("file:///tmp/kb/")});
        final MyKBI kbObject = (MyKBI) kbCoreClassLoader.loadClass("com.ning.billing.beatrix.util.MyKBImpl").newInstance();

        // Plugin specific classloader
        final ClassLoader kbPluginClassLoader = new PluginClassLoader(new URL[]{new URL("file:///tmp/plugin/")});
        final MyPluginI kbPluginInstance = (MyPluginI) kbPluginClassLoader.loadClass("com.ning.billing.beatrix.util.MyPlugin").newInstance();
        kbPluginInstance.doSomething(kbObject);

        // com.ning.billing.beatrix.util.Kb$PluginClassLoader@3dac2f9c
        // 1
        // class com.ning.billing.beatrix.util.MyList
        // com.ning.billing.beatrix.util.Kb$KbCoreClassLoader@457471e0
        // -1
        // class com.ning.billing.beatrix.util.MyList
        // com.ning.billing.beatrix.util.Kb$PluginClassLoader@3dac2f9c
    }

   static class CoreRunnable implements Runnable {

        MyPluginI pluginI;

        CoreRunnable(final MyPluginI pluginI) {
            this.pluginI = pluginI;
        }

        @Override
        public void run() {
            try {
                final MyKBI bleh = (MyKBI) Thread.currentThread().getContextClassLoader().loadClass("com.ning.billing.beatrix.util.MyKBImpl").newInstance();
                System.out.println("Kb calling plugin");
                pluginI.doSomething(bleh);
                while (true) {
                    Thread.sleep(100000);
                }
            } catch (InstantiationException e) {
            } catch (IllegalAccessException e) {
            } catch (ClassNotFoundException e) {
            } catch (InterruptedException e) {
            }
        }
    }

    static class PluginRunnable implements Runnable {

        MyPluginI pluginI;

        @Override
        public void run() {
            try {
                pluginI = (MyPluginI) Thread.currentThread().getContextClassLoader().loadClass("com.ning.billing.beatrix.util.MyPlugin").newInstance();
                System.out.println("Plugin started");
                while (true) {
                    Thread.sleep(100000);
                }
            } catch (InstantiationException e) {
            } catch (IllegalAccessException e) {
            } catch (ClassNotFoundException e) {
            } catch (InterruptedException e) {
            }
        }

        public MyPluginI getPluginI() {
            return pluginI;
        }
    }

    public static void mainWithThreads(String[] args) throws MalformedURLException, ClassNotFoundException, IllegalAccessException, InstantiationException, InterruptedException {
        final PluginRunnable pluginRunnable = new PluginRunnable();
        final Thread pluginThread = new Thread(pluginRunnable);
        pluginThread.setContextClassLoader(new PluginClassLoader(new URL[]{new URL("file:///tmp/plugin/")}));

        pluginThread.start();
        Thread.sleep(1000);

        final Runnable coreRunnable = new CoreRunnable(pluginRunnable.getPluginI());
        final Thread kbCoreThread = new Thread(coreRunnable);
        kbCoreThread.setContextClassLoader(new KbCoreClassLoader(new URL[]{new URL("file:///tmp/kb/")}));

        kbCoreThread.start();
        Thread.currentThread().join();
    }

    public static void mainBroken(String[] args) throws MalformedURLException, ClassNotFoundException, IllegalAccessException, InstantiationException, InterruptedException {
        final ClassLoader commonClassLoader = new KbCoreClassLoader(new URL[]{new URL("file:///tmp/kb/"), new URL("file:///tmp/plugin/")});

        final MyKBI kbObject = (MyKBI) commonClassLoader.loadClass("com.ning.billing.beatrix.util.MyKBImpl").newInstance();
        final MyPluginI kbPluginInstance = (MyPluginI) commonClassLoader.loadClass("com.ning.billing.beatrix.util.MyPlugin").newInstance();
        kbPluginInstance.doSomething(kbObject);

        // Note! Doesn't work here because the parent is searched first
        //
        // com.ning.billing.beatrix.util.Kb$KbCoreClassLoader@721cdeff
        // 1
        // class com.ning.billing.beatrix.util.MyList
        // com.ning.billing.beatrix.util.Kb$KbCoreClassLoader@721cdeff
        // 1
        // class com.ning.billing.beatrix.util.MyList
        // com.ning.billing.beatrix.util.Kb$KbCoreClassLoader@721cdeff
    }
}