Java tutorial
package org.glassfish.pfl.tf.tools.enhancer; /* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 1997-2010,2017 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html * or packager/legal/LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ import org.glassfish.pfl.basic.func.UnaryFunction; import org.glassfish.pfl.tf.spi.EnhancedClassData; import org.glassfish.pfl.tf.spi.EnhancedClassDataASMImpl; import org.glassfish.pfl.tf.spi.TimingPointType; import org.glassfish.pfl.tf.spi.TraceEnhancementException; import org.glassfish.pfl.tf.spi.Util; import org.glassfish.pfl.tf.timer.spi.TimerFactoryBuilder; import org.glassfish.pfl.tf.timer.spi.TimingInfoProcessor; import org.objectweb.asm.ClassAdapter; import org.objectweb.asm.ClassReader; import org.objectweb.asm.ClassVisitor; import org.objectweb.asm.Opcodes; import org.objectweb.asm.tree.ClassNode; import java.util.Iterator; import java.util.Set; /** ClassFile enhancer for the tracing facility. This modifies the bytecode * for an applicable class, then returns the updated bytecode. * Makes extensive use of the ASM library. * * This is split into two parts. The first part modifies the schema * of the class as follows: * <ul> * <li>Adds static fields as required for the SynchronizedHolder<MethodMonitor> * instances. * <li>Modifies the static initializer to set up the new fields, and register * the class with the MethodMonitorRegistry. This also constructs the list * of method names, which is needed by the second part. * <li>Re-writes all @InfoMethod methods to take two extra parameters at the * end of their argument lists. * <li>Re-writes all calls to @InfoMethod methods to supply the two extra * parameters to all calls. * <li>Checks that @InfoMethod methods (which must be private) are only called * from MM annotated methods. * </ul> * <p> * The second part modifies the MM annotated methods as follows: * <li>Adds a preamble to set up some local variables, and to call * the MethodMonitor.enter method when active. * <li>Adds a finally block at the end of the method that handles calling * MethodMonitor.exit whenever an exception is thrown or propagated from the * body of the method. * <li>Modifies all exit point in the method as follows: * <ul> * <li>If the exit point is a return, call MethodMonitor.exit before the return. * <li>If the exit point is a throw, call MethodMonitor.exception before the throw. * </ul> * </ul> * <p> * Note that the second part could be run in a ClassFileTransformer or ClassLoader * if desired, since this design enhances the class files in place for the first * part. * * @author ken */ public class Transformer implements UnaryFunction<byte[], byte[]> { private final Util util; private final EnhanceTool.ProcessingMode mode; private final TimingInfoProcessor tip; private final Set<String> annotationNames; // Initialized in the evaluate method. private EnhancedClassData ecd = null; Transformer(Util util, EnhanceTool.ProcessingMode mode, TimingInfoProcessor tip, Set<String> anames) { this.util = util; this.mode = mode; this.tip = tip; this.annotationNames = anames; } private String getSuffix(String str) { String result = str; final int index = str.lastIndexOf('/'); if (index >= 0) { result = result.substring(index + 1); } return result; } private void processTimers() { final Iterator<String> descriptions = ecd.getDescriptions().iterator(); final Iterator<String> names = ecd.getTimingPointNames().iterator(); final Iterator<TimingPointType> tpts = ecd.getTimingPointTypes().iterator(); final Iterator<String> groups = ecd.getMethodMMAnnotationName().iterator(); final Set<String> classAnnoNames = ecd.getAnnotationToHolderName().keySet(); while (descriptions.hasNext()) { final String desc = descriptions.next(); final String name = names.next(); final TimingPointType tpt = tpts.next(); final String group = groups.next(); if (tpt != TimingPointType.NONE) { final String cname = getSuffix(ecd.getClassName()); final String timerName = TimerFactoryBuilder.getTimerName(cname, name); tip.addTimer(timerName, desc); if (group == null) { for (String str : classAnnoNames) { tip.containedIn(timerName, getSuffix(str)); } } else { tip.containedIn(timerName, getSuffix(group)); } } } } public byte[] evaluate(final byte[] arg) { final ClassNode cn = new ClassNode(); final ClassReader cr = new ClassReader(arg); cr.accept(cn, ClassReader.SKIP_FRAMES); // Ignore annotations and interfaces. if (util.hasAccess(cn.access, Opcodes.ACC_ANNOTATION) || util.hasAccess(cn.access, Opcodes.ACC_INTERFACE)) { return null; } try { ecd = new EnhancedClassDataASMImpl(util, annotationNames, cn); // If this class is not annotated as a traced class, ignore it. if (!ecd.isTracedClass()) { return null; } processTimers(); byte[] phase1 = null; if ((mode == EnhanceTool.ProcessingMode.UpdateSchemas) || (mode == EnhanceTool.ProcessingMode.TraceEnhance)) { phase1 = util.transform(false, arg, new UnaryFunction<ClassVisitor, ClassAdapter>() { public ClassAdapter evaluate(ClassVisitor arg) { return new ClassEnhancer(util, ecd, arg); } }); } // Only communication from part 1 to part2 is a byte[] and // the EnhancedClassData. A runtime version can be regenerated // as above from the byte[] from the class file as it is presented // to a ClassFileTransformer. // Implementation note: runtime would keep byte[] stored of // original version whenever tracing is enabled, so that // disabling tracing simply means using a ClassFileTransformer // to get back to the original code. // // Then add tracing code (part 2). // This is a pure visitor using the AdviceAdapter. // It must NOT modify its input visitor (or you get an // infinite series of calls to onMethodExit...) if (mode == EnhanceTool.ProcessingMode.TraceEnhance) { final byte[] phase2 = util.transform(util.getDebug(), phase1, new UnaryFunction<ClassVisitor, ClassAdapter>() { public ClassAdapter evaluate(ClassVisitor arg) { return new ClassTracer(util, ecd, arg); } }); return phase2; } else { return phase1; } } catch (TraceEnhancementException exc) { if (util.getDebug()) { util.info(1, "Could not enhance file: " + exc); } return null; } } }