| /* |
| * 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.lang.instrument.ClassFileTransformer; |
| import java.lang.instrument.Instrumentation; |
| import java.security.ProtectionDomain; |
| import java.util.Map; |
| |
| import org.apache.openjpa.conf.OpenJPAConfiguration; |
| import org.apache.openjpa.lib.log.Log; |
| import org.apache.openjpa.lib.util.JavaVersions; |
| import org.apache.openjpa.lib.util.Localizer; |
| import org.apache.openjpa.util.InternalException; |
| |
| /** |
| * Redefines the method bodies of existing classes. Supports Java 5 VMs that |
| * have a java agent installed on the command line as well as newer VMs without |
| * any <code>-javaagent</code> flag. |
| * |
| * @since 1.0.0 |
| */ |
| public class ClassRedefiner { |
| |
| private static final Localizer _loc = Localizer.forPackage(ClassRedefiner.class); |
| |
| private static Boolean _canRedefine = null; |
| |
| /** |
| * For each element in <code>classes</code>, this method will redefine |
| * all the element's methods such that field accesses are intercepted |
| * in-line. If {@link #canRedefineClasses(Log)} returns <code>false</code>, |
| * this method is a no-op. |
| */ |
| public static void redefineClasses(OpenJPAConfiguration conf, |
| final Map<Class<?>,byte[]> classes) { |
| Log log = conf.getLog(OpenJPAConfiguration.LOG_ENHANCE); |
| if (classes == null || classes.size() == 0 || !canRedefineClasses(log)) |
| return; |
| |
| Instrumentation inst = null; |
| ClassFileTransformer t = null; |
| try { |
| inst = InstrumentationFactory.getInstrumentation(log); |
| |
| Class<?>[] array = classes.keySet().toArray(new Class[classes.size()]); |
| log.trace(_loc.get("retransform-types", classes.keySet())); |
| |
| t = new ClassFileTransformer() { |
| @Override |
| public byte[] transform(ClassLoader loader, String clsName, |
| Class<?> classBeingRedefined, ProtectionDomain pd, |
| byte[] classfileBuffer) { |
| return classes.get(classBeingRedefined); |
| } |
| }; |
| |
| inst.addTransformer(t, true); |
| inst.retransformClasses(array); |
| } catch (Exception e) { |
| throw new InternalException(e); |
| } finally { |
| if (inst != null && t != null) |
| inst.removeTransformer(t); |
| } |
| } |
| |
| /** |
| * @return whether or not this VM has an instrumentation installed that |
| * permits redefinition of classes. This assumes that all the arguments |
| * will be modifiable classes according to |
| * {@link java.lang.instrument.Instrumentation#isModifiableClass}, and |
| * only checks whether or not an instrumentation is available and |
| * if retransformation is possible. |
| */ |
| public static boolean canRedefineClasses(Log log) { |
| if (_canRedefine == null) { |
| try { |
| Instrumentation inst = InstrumentationFactory.getInstrumentation(log); |
| if (inst == null) { |
| _canRedefine = Boolean.FALSE; |
| } else if (JavaVersions.VERSION == 5) { |
| // if instrumentation is non-null and we're using Java 5, |
| // isRetransformClassesSupported isn't available, |
| // so we use the more basic class redefinition instead. |
| _canRedefine = Boolean.TRUE; |
| } else { |
| _canRedefine = (Boolean) Instrumentation.class.getMethod( |
| "isRetransformClassesSupported").invoke(inst); |
| } |
| } catch (Exception e) { |
| _canRedefine = Boolean.FALSE; |
| } |
| } |
| return _canRedefine; |
| } |
| } |