JDIRedefiner.java

/*
 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */
package org.hotswap.agent.plugin.proxy;

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.sun.jdi.Bootstrap;
import com.sun.jdi.ReferenceType;
import com.sun.jdi.VirtualMachine;
import com.sun.jdi.VirtualMachineManager;
import com.sun.jdi.connect.AttachingConnector;
import com.sun.jdi.connect.Connector.Argument;
import com.sun.jdi.connect.IllegalConnectorArgumentsException;

/**
 * Utility class for performing class redefinition using JDI. </li> </ul>
 * 
 * @author Thomas Wuerthinger
 * @author Kerstin Breiteneder
 * @author Christoph Wimberger
 * 
 */
public class JDIRedefiner implements Redefiner {
	
	private static final String PORT_ARGUMENT_NAME = "port";
	private static final String TRANSPORT_NAME = "dt_socket";
	
	private VirtualMachine vm;
	
	/** Port at which to connect to the agent of the VM. **/
	public static final int PORT = 4000;
	
	public JDIRedefiner(int port) throws IOException {
		vm = connect(port);
	}
	
	@Override
	public void close() throws IOException {
		disconnect();
	}
	
	private VirtualMachine connect(int port) throws IOException {
		VirtualMachineManager manager = Bootstrap.virtualMachineManager();
		
		// Find appropiate connector
		List<AttachingConnector> connectors = manager.attachingConnectors();
		AttachingConnector chosenConnector = null;
		for (AttachingConnector c : connectors) {
			if (c.transport().name().equals(TRANSPORT_NAME)) {
				chosenConnector = c;
				break;
			}
		}
		if (chosenConnector == null) {
			throw new IllegalStateException("Could not find socket connector");
		}
		
		// Set port argument
		AttachingConnector connector = chosenConnector;
		Map<String, Argument> defaults = connector.defaultArguments();
		Argument arg = defaults.get(PORT_ARGUMENT_NAME);
		if (arg == null) {
			throw new IllegalStateException("Could not find port argument");
		}
		arg.setValue(Integer.toString(port));
		
		// Attach
		try {
			System.out.println("Connector arguments: " + defaults);
			return connector.attach(defaults);
		} catch (IllegalConnectorArgumentsException e) {
			throw new IllegalArgumentException("Illegal connector arguments", e);
		}
	}
	
	public void disconnect() {
		if (vm != null) {
			vm.dispose();
			vm = null;
		}
	}
	
	public void redefineClasses(Map<Class<?>, byte[]> classes) {
		refreshAllClasses();
		List<ReferenceType> references = vm.allClasses();
		
		Map<ReferenceType, byte[]> map = new HashMap<ReferenceType, byte[]>(classes.size());
		for (Map.Entry<Class<?>, byte[]> entry : classes.entrySet()) {
			map.put(findReference(references, entry.getKey().getName()), entry.getValue());
		}
		vm.redefineClasses(map);
	}
	
	/**
	 * Call this method before calling allClasses() in order to refresh the JDI state of loaded classes. This is
	 * necessary because the JDI map of all loaded classes is only updated based on events received over JDWP (network
	 * connection) and therefore it is not necessarily up-to-date with the real state within the VM.
	 */
	private void refreshAllClasses() {
		try {
			Field f = vm.getClass().getDeclaredField("retrievedAllTypes");
			f.setAccessible(true);
			f.set(vm, false);
		} catch (IllegalArgumentException ex) {
			Logger.getLogger(HotSwapTool.class.getName()).log(Level.SEVERE, null, ex);
		} catch (IllegalAccessException ex) {
			Logger.getLogger(HotSwapTool.class.getName()).log(Level.SEVERE, null, ex);
		} catch (NoSuchFieldException ex) {
			Logger.getLogger(HotSwapTool.class.getName()).log(Level.SEVERE, null, ex);
		} catch (SecurityException ex) {
			Logger.getLogger(HotSwapTool.class.getName()).log(Level.SEVERE, null, ex);
		}
	}
	
	private static ReferenceType findReference(List<ReferenceType> list, String name) {
		for (ReferenceType ref : list) {
			if (ref.name().equals(name)) {
				return ref;
			}
		}
		throw new IllegalArgumentException("Cannot find corresponding reference for class name '" + name + "'");
	}
}