ProxyClassLoadingDelegate.java

package org.hotswap.agent.plugin.owb.command;

import java.util.HashMap;
import java.util.Map;

import org.apache.webbeans.proxy.AbstractProxyFactory;
import org.hotswap.agent.config.PluginManager;
import org.hotswap.agent.logging.AgentLogger;
import org.hotswap.agent.util.ReflectionHelper;

/**
 * The OWB proxyFactory has its class loading tasks delegated to this class, which can then have some magic applied
 * to make OWB think that the class has not been loaded yet.
 *
 * @author Vladimir Dvorak
 */
public class ProxyClassLoadingDelegate {

    private static AgentLogger LOGGER = AgentLogger.getLogger(ProxyClassLoadingDelegate.class);

    private static final ThreadLocal<Boolean> MAGIC_IN_PROGRESS = new ThreadLocal<Boolean>() {
        @Override
        protected Boolean initialValue() {
            return false;
        }
    };

    public static final void beginProxyRegeneration() {
        MAGIC_IN_PROGRESS.set(true);
    }

    public static final void endProxyRegeneration() {
        MAGIC_IN_PROGRESS.remove();
    }

    public static Class<?> forName(String name, boolean initialize, ClassLoader loader) throws ClassNotFoundException {
        if (MAGIC_IN_PROGRESS.get()) {
            throw new ClassNotFoundException("HotswapAgent");
        }
        return Class.forName(name, initialize, loader);
    }

    public static Class defineAndLoadClass(AbstractProxyFactory proxyFactory, ClassLoader classLoader, String proxyName, byte[] proxyBytes) {
        if (MAGIC_IN_PROGRESS.get()) {
            try {
                final Class<?> originalProxyClass = classLoader.loadClass(proxyName);
                try {
                    Map<Class<?>, byte[]> reloadMap = new HashMap<Class<?>, byte[]>();
                    reloadMap.put(originalProxyClass, proxyBytes);
                    // TODO : is this standard way how to reload class?
                    PluginManager.getInstance().hotswap(reloadMap);
                    return originalProxyClass;
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            } catch (ClassNotFoundException e) {
                //it has not actually been loaded yet
            }
        }
        try {
            return (Class<?>) ReflectionHelper.invoke(proxyFactory, AbstractProxyFactory.class, "defineAndLoadClass",
                    new Class[]{ClassLoader.class, String.class, byte[].class},
                    classLoader, proxyName, proxyBytes);
        } catch (Exception e) {
            LOGGER.error("defineAndLoadClass() exception {}", e.getMessage());
        }
        return null;
    }

}