| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.openjpa.enhance; |
| |
| import java.io.*; |
| import java.lang.instrument.*; |
| import java.lang.management.*; |
| import java.lang.reflect.InvocationTargetException; |
| import java.util.zip.*; |
| import org.apache.openjpa.lib.util.*; |
| |
| |
| /** |
| * Factory for obtaining an {@link Instrumentation} instance. |
| * |
| * @author Marc Prud'hommeaux |
| * @since 1.0.0 |
| */ |
| public class InstrumentationFactory { |
| private static Instrumentation _inst; |
| private static boolean _dynamicallyInstall = true; |
| |
| public static void setInstrumentation(Instrumentation inst) { |
| _inst = inst; |
| } |
| |
| /** |
| * Configures whether or not this instance should attempt to dynamically |
| * install an agent in the VM. Defaults to <code>true</code>. |
| */ |
| public static synchronized void setDynamicallyInstallAgent(boolean val) { |
| _dynamicallyInstall = val; |
| } |
| |
| public static synchronized Instrumentation getInstrumentation() |
| throws IOException, NoSuchMethodException, IllegalAccessException, |
| InvocationTargetException, ClassNotFoundException { |
| if (_inst != null || !_dynamicallyInstall) |
| return _inst; |
| |
| // dynamic loading of the agent is only available in JDK 1.6+ |
| if (JavaVersions.VERSION < 6) |
| return null; |
| |
| String agentPath = getAgentJar(); |
| |
| // first obtain the PID of the currently-running process |
| // ### this relies on the undocumented convention of the RuntimeMXBean's |
| // ### name starting with the PID, but there appears to be no other |
| // ### way to obtain the current process' id, which we need for |
| // ### the attach process |
| RuntimeMXBean runtime = ManagementFactory.getRuntimeMXBean(); |
| String pid = runtime.getName(); |
| if (pid.indexOf("@") != -1) |
| pid = pid.substring(0, pid.indexOf("@")); |
| |
| // JDK1.6: now attach to the current VM so we can deploy a new agent |
| // ### this is a Sun JVM specific feature; other JVMs may offer |
| // ### this feature, but in an implementation-dependent way |
| Class vmClass = Class.forName("com.sun.tools.attach.VirtualMachine"); |
| Object vm = vmClass.getMethod("attach", new Class[] { String.class }). |
| invoke(null, new String[] { pid }); |
| |
| // now deploy the actual agent, which will wind up calling agentmain() |
| vm.getClass().getMethod("loadAgent", new Class[] { String.class }). |
| invoke(vm, new Object[] { agentPath }); |
| |
| if (_inst != null) |
| return _inst; |
| |
| return null; |
| } |
| |
| /** |
| * Create a new jar file for the sole purpose of specifying an |
| * Agent-Class to load into the JVM. |
| */ |
| private static String getAgentJar() throws IOException { |
| File file = File.createTempFile( |
| InstrumentationFactory.class.getName(), ".jar"); |
| file.deleteOnExit(); |
| |
| ZipOutputStream zout = new ZipOutputStream(new FileOutputStream(file)); |
| zout.putNextEntry(new ZipEntry("META-INF/MANIFEST.MF")); |
| |
| PrintWriter writer = new PrintWriter |
| (new OutputStreamWriter(zout)); |
| |
| writer.println("Agent-Class: " |
| + InstrumentationFactory.class.getName()); |
| writer.println("Can-Redefine-Classes: true"); |
| writer.println("Can-Retransform-Classes: true"); |
| |
| writer.close(); |
| |
| return file.getAbsolutePath(); |
| } |
| |
| /** |
| * The method that is called when a jar is added as an agent at runtime. |
| * All this method does is store the {@link Instrumentation} for |
| * later use. |
| */ |
| public static void agentmain(String agentArgs, Instrumentation inst) { |
| InstrumentationFactory.setInstrumentation(inst); |
| } |
| } |