1 /* 2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 import java.security.*; 25 import java.lang.instrument.*; 26 import java.lang.reflect.*; 27 import java.lang.management.ManagementFactory; 28 import com.sun.tools.attach.VirtualMachine; 29 30 class A { 31 void m() { 32 } 33 } 34 35 class B extends A { 36 void m() { 37 } 38 } 39 40 class C extends A { 41 void m() { 42 } 43 } 44 45 class Test { 46 47 static public void m() throws Exception { 48 for (int i = 0; i < 20000; i++) { 49 m1(a); 50 } 51 for (int i = 0; i < 4; i++) { 52 m1(b); 53 } 54 } 55 56 static boolean m1(A a) { 57 boolean res = Agent.m2(a); 58 return res; 59 } 60 61 static public A a = new A(); 62 static public B b = new B(); 63 static public C c = new C(); 64 } 65 66 public class Agent implements ClassFileTransformer { 67 68 69 static class MemoryChunk { 70 MemoryChunk other; 71 long[] array; 72 MemoryChunk(MemoryChunk other) { 73 other = other; 74 array = new long[1024 * 1024 * 1024]; 75 } 76 } 77 78 static public boolean m2(A a) { 79 boolean res = false; 80 if (a.getClass() == B.class) { 81 a.m(); 82 } else { 83 res = true; 84 } 85 return res; 86 } 87 88 static public void main(String[] args) throws Exception { 89 // Create speculative trap entries 90 Test.m(); 91 92 String nameOfRunningVM = ManagementFactory.getRuntimeMXBean().getName(); 93 int p = nameOfRunningVM.indexOf('@'); 94 String pid = nameOfRunningVM.substring(0, p); 95 96 // Make the nmethod go away 97 for (int i = 0; i < 10; i++) { 98 System.gc(); 99 } 100 101 // Redefine class 102 try { 103 VirtualMachine vm = VirtualMachine.attach(pid); 104 vm.loadAgent(System.getProperty("test.classes",".") + "/agent.jar", ""); 105 vm.detach(); 106 } catch (Exception e) { 107 throw new RuntimeException(e); 108 } 109 110 Test.m(); 111 // GC will hit dead method pointer 112 for (int i = 0; i < 10; i++) { 113 System.gc(); 114 } 115 } 116 117 public synchronized byte[] transform(final ClassLoader classLoader, 118 final String className, 119 Class<?> classBeingRedefined, 120 ProtectionDomain protectionDomain, 121 byte[] classfileBuffer) { 122 System.out.println("Transforming class " + className); 123 return classfileBuffer; 124 } 125 126 public static void redefine(String agentArgs, Instrumentation instrumentation, Class to_redefine) { 127 128 try { 129 instrumentation.retransformClasses(to_redefine); 130 } catch (Exception e) { 131 e.printStackTrace(); 132 } 133 134 } 135 136 public static void agentmain(String agentArgs, Instrumentation instrumentation) throws Exception { 137 Agent transformer = new Agent(); 138 instrumentation.addTransformer(transformer, true); 139 140 redefine(agentArgs, instrumentation, Test.class); 141 } 142 }