1 /*

     2  * Copyright (c) 2011, 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.lang.instrument.*;

    25 import java.net.*;

    26 import java.util.*;

    27 import java.io.*;

    28 

    29 public class RedefineBigClassAgent {

    30     // N_REDEFINES = 2000 made my Solaris X86 box crawl on its knees

    31     // with the Server VM. The timeout is 600 seconds, but the test

    32     // ran for 675 seconds so it took the harness 75 seconds to kill

    33     // the test.

    34     private static int N_REDEFINES = 1000;

    35     public static Class clz;

    36     public static volatile boolean doneRedefining = false;

    37 

    38     // just read the original class and redefine in a loop via a Timer

    39     public static void premain(String agentArgs, final Instrumentation inst) throws Exception {

    40         String s = agentArgs.substring(0, agentArgs.indexOf(".class"));

    41         clz = Class.forName(s.replace('/', '.'));

    42         ClassLoader loader =

    43             RedefineBigClassAgent.class.getClassLoader();

    44         URL classURL = loader.getResource(agentArgs);

    45         if (classURL == null) {

    46             throw new Exception("Cannot find class: " + agentArgs);

    47         }

    48 

    49         int         redefineLength;

    50         InputStream redefineStream;

    51 

    52         System.out.println("Reading test class from " + classURL);

    53         if (classURL.getProtocol().equals("file")) {

    54             File f = new File(classURL.getFile());

    55             redefineStream = new FileInputStream(f);

    56             redefineLength = (int) f.length();

    57         } else {

    58             URLConnection conn = classURL.openConnection();

    59             redefineStream = conn.getInputStream();

    60             redefineLength = conn.getContentLength();

    61         }

    62 

    63         final byte[] buffer = new byte[redefineLength];

    64         new BufferedInputStream(redefineStream).read(buffer);

    65 

    66         System.gc();  // throw away anything we can before we start testing

    67 

    68         new Timer(true).schedule(new TimerTask() {

    69             public void run() {

    70                 try {

    71                     int i;

    72                     System.out.println("Redefining");

    73                     ClassDefinition cld = new ClassDefinition(clz, buffer);

    74                     for (i = 0; i < N_REDEFINES; i++) {

    75                         inst.redefineClasses(new ClassDefinition[] { cld });

    76                         System.gc();  // throw away anything we can

    77                     }

    78                     System.out.println("Redefined " + i + " times.");

    79                     RedefineBigClassAgent.doneRedefining = true;

    80                 }

    81                 catch (Exception e) { e.printStackTrace(); }

    82             }

    83         }, 500);

    84     }

    85 }