Ebean shutdown hack, for shutting down an individual ebeanserver before the Ebean shutdown hook runs

EbeanShutdownHack.java

package com.avaje.ebeaninternal.server.lib;

import java.lang.reflect.Field;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Exists to work around this issue:
 *
 * https://github.com/rbygrave/avaje-ebeanorm-server/issues/4
 *
 * As luck would have it, Ebean tends to use package private fields, which allows us to do hacks like this without
 * using reflection.
 *
 * @author jroper
 */
public class EbeanShutdownHack {
    private static final Logger logger = Logger.getLogger(EbeanShutdownHack.class.getName());

    public static void shutdownAllActiveEbeanServers() {
        // First remove all the background thread runnables.  To do this, we need to synchronize on its monitor field,
        // which is private
        Object monitor = getPrivateField(BackgroundThread.class, "monitor",
                getPrivateField(BackgroundThread.class, "me", null));
        synchronized (monitor) {
            Iterator<BackgroundRunnable> runnables = BackgroundThread.runnables();
            while (runnables.hasNext()) {
                runnables.next();
                runnables.remove();
            }
        }
        // Now shut down the ebean servers
        synchronized (ShutdownManager.runnables) {
            for (Runnable runnable: ShutdownManager.runnables) {
                try {
                    runnable.run();
                } catch (Exception ex) {
                    logger.log(Level.SEVERE, null, ex);
                    ex.printStackTrace();
                }

            }
            ShutdownManager.runnables.clear();
        }
    }

    private static Object getPrivateField(Class clazz, String name, Object object) {
        try {
            Field field = clazz.getDeclaredField(name);
            field.setAccessible(true);
            return field.get(object);
        } catch (Exception e) {
            throw new RuntimeException("Error getting private filed " + name + " on class " + clazz + " from object " + object, e);
        }
    }
}