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- /*
- * Javassist, a Java-bytecode translator toolkit.
- * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. Alternatively, the contents of this file may be used under
- * the terms of the GNU Lesser General Public License Version 2.1 or later,
- * or the Apache License Version 2.0.
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- */
-
- package javassist.util;
-
- import com.sun.jdi.*;
- import com.sun.jdi.connect.*;
- import com.sun.jdi.event.*;
- import com.sun.jdi.request.*;
- import java.io.*;
- import java.util.*;
-
- class Trigger {
- void doSwap() {}
- }
-
- /**
- * A utility class for dynamically reloading a class by
- * the Java Platform Debugger Architecture (JPDA), or <i>HotSwap</i>.
- * It works only with JDK 1.4 and later.
- *
- * <p><b>Note:</b> The new definition of the reloaded class must declare
- * the same set of methods and fields as the original definition. The
- * schema change between the original and new definitions is not allowed
- * by the JPDA.
- *
- * <p>To use this class, the JVM must be launched with the following
- * command line options:
- *
- * <p>For Java 1.4,<br>
- * <pre>java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000</pre>
- * <p>For Java 5,<br>
- * <pre>java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000</pre>
- *
- * <p>Note that 8000 is the port number used by <code>HotSwapper</code>.
- * Any port number can be specified. Since <code>HotSwapper</code> does not
- * launch another JVM for running a target application, this port number
- * is used only for inter-thread communication.
- *
- * <p>Furthermore, <code>JAVA_HOME/lib/tools.jar</code> must be included
- * in the class path.
- *
- * <p>Using <code>HotSwapper</code> is easy. See the following example:
- *
- * <pre>
- * CtClass clazz = ...
- * byte[] classFile = clazz.toBytecode();
- * HotSwapper hs = new HostSwapper(8000); // 8000 is a port number.
- * hs.reload("Test", classFile);
- * </pre>
- *
- * <p><code>reload()</code>
- * first unload the <code>Test</code> class and load a new version of
- * the <code>Test</code> class.
- * <code>classFile</code> is a byte array containing the new contents of
- * the class file for the <code>Test</code> class. The developers can
- * repatedly call <code>reload()</code> on the same <code>HotSwapper</code>
- * object so that they can reload a number of classes.
- *
- * @since 3.1
- */
- public class HotSwapper {
- private VirtualMachine jvm;
- private MethodEntryRequest request;
- private Map newClassFiles;
-
- private Trigger trigger;
-
- private static final String HOST_NAME = "localhost";
- private static final String TRIGGER_NAME = Trigger.class.getName();
-
- /**
- * Connects to the JVM.
- *
- * @param port the port number used for the connection to the JVM.
- */
- public HotSwapper(int port)
- throws IOException, IllegalConnectorArgumentsException
- {
- this(Integer.toString(port));
- }
-
- /**
- * Connects to the JVM.
- *
- * @param port the port number used for the connection to the JVM.
- */
- public HotSwapper(String port)
- throws IOException, IllegalConnectorArgumentsException
- {
- jvm = null;
- request = null;
- newClassFiles = null;
- trigger = new Trigger();
- AttachingConnector connector
- = (AttachingConnector)findConnector("com.sun.jdi.SocketAttach");
-
- Map arguments = connector.defaultArguments();
- ((Connector.Argument)arguments.get("hostname")).setValue(HOST_NAME);
- ((Connector.Argument)arguments.get("port")).setValue(port);
- jvm = connector.attach(arguments);
- EventRequestManager manager = jvm.eventRequestManager();
- request = methodEntryRequests(manager, TRIGGER_NAME);
- }
-
- private Connector findConnector(String connector) throws IOException {
- List connectors = Bootstrap.virtualMachineManager().allConnectors();
- Iterator iter = connectors.iterator();
- while (iter.hasNext()) {
- Connector con = (Connector)iter.next();
- if (con.name().equals(connector)) {
- return con;
- }
- }
-
- throw new IOException("Not found: " + connector);
- }
-
- private static MethodEntryRequest methodEntryRequests(
- EventRequestManager manager,
- String classpattern) {
- MethodEntryRequest mereq = manager.createMethodEntryRequest();
- mereq.addClassFilter(classpattern);
- mereq.setSuspendPolicy(EventRequest.SUSPEND_EVENT_THREAD);
- return mereq;
- }
-
- /* Stops triggering a hotswapper when reload() is called.
- */
- private void deleteEventRequest(EventRequestManager manager,
- MethodEntryRequest request) {
- manager.deleteEventRequest(request);
- }
-
- /**
- * Reloads a class.
- *
- * @param className the fully-qualified class name.
- * @param classFile the contents of the class file.
- */
- public void reload(String className, byte[] classFile) {
- ReferenceType classtype = toRefType(className);
- Map map = new HashMap();
- map.put(classtype, classFile);
- reload2(map, className);
- }
-
- /**
- * Reloads a class.
- *
- * @param classFiles a map between fully-qualified class names
- * and class files. The type of the class names
- * is <code>String</code> and the type of the
- * class files is <code>byte[]</code>.
- */
- public void reload(Map classFiles) {
- Set set = classFiles.entrySet();
- Iterator it = set.iterator();
- Map map = new HashMap();
- String className = null;
- while (it.hasNext()) {
- Map.Entry e = (Map.Entry)it.next();
- className = (String)e.getKey();
- map.put(toRefType(className), e.getValue());
- }
-
- if (className != null)
- reload2(map, className + " etc.");
- }
-
- private ReferenceType toRefType(String className) {
- List list = jvm.classesByName(className);
- if (list == null || list.isEmpty())
- throw new RuntimeException("no such class: " + className);
- else
- return (ReferenceType)list.get(0);
- }
-
- private void reload2(Map map, String msg) {
- synchronized (trigger) {
- startDaemon();
- newClassFiles = map;
- request.enable();
- trigger.doSwap();
- request.disable();
- Map ncf = newClassFiles;
- if (ncf != null) {
- newClassFiles = null;
- throw new RuntimeException("failed to reload: " + msg);
- }
- }
- }
-
- private void startDaemon() {
- new Thread() {
- private void errorMsg(Throwable e) {
- System.err.print("Exception in thread \"HotSwap\" ");
- e.printStackTrace(System.err);
- }
-
- public void run() {
- EventSet events = null;
- try {
- events = waitEvent();
- EventIterator iter = events.eventIterator();
- while (iter.hasNext()) {
- Event event = iter.nextEvent();
- if (event instanceof MethodEntryEvent) {
- hotswap();
- break;
- }
- }
- }
- catch (Throwable e) {
- errorMsg(e);
- }
- try {
- if (events != null)
- events.resume();
- }
- catch (Throwable e) {
- errorMsg(e);
- }
- }
- }.start();
- }
-
- EventSet waitEvent() throws InterruptedException {
- EventQueue queue = jvm.eventQueue();
- return queue.remove();
- }
-
- void hotswap() {
- Map map = newClassFiles;
- jvm.redefineClasses(map);
- newClassFiles = null;
- }
- }
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