1 /*
   2  * Copyright (c) 2018, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.jfr.jvm;
  27 
  28 import java.io.ByteArrayOutputStream;
  29 import java.io.InputStream;
  30 
  31 import jdk.jfr.Event;
  32 import jdk.jfr.FlightRecorder;
  33 import jdk.jfr.internal.JVM;
  34 
  35 /**
  36  * @test
  37  * @key jfr
  38  * @summary Unit test for JVM#getUnloadedEventClassCount
  39  *
  40  *
  41  * @library /lib /
  42  *
  43  *
  44  * @run main/othervm -XX:+PrintGCDetails -XX:+PrintGC  -verbose:class -Xmx16m jdk.jfr.jvm.TestUnloadEventClassCount
  45  */
  46 public class TestUnloadEventClassCount {
  47 
  48     private static final String EVENT_NAME = "jdk.jfr.jvm.TestUnloadEventClassCount$ToBeUnloaded";
  49 
  50     public static class ToBeUnloaded extends Event {
  51     }
  52 
  53     static public class MyClassLoader extends ClassLoader {
  54         public MyClassLoader() {
  55             super(null);
  56         }
  57 
  58         public final Class<?> defineClass(String name, byte[] b) {
  59             return super.defineClass(name, b, 0, b.length);
  60         }
  61     }
  62 
  63     public static MyClassLoader myClassLoader;
  64 
  65     public static void main(String[] args) throws Throwable {
  66         FlightRecorder.getFlightRecorder();
  67         myClassLoader = createClassLoaderWithEventClass();
  68         System.out.println("MyClassLoader instance created");
  69         long initialCount = JVM.getJVM().getUnloadedEventClassCount();
  70         System.out.println("Initiali unloaded count is " + initialCount);
  71         myClassLoader = null;
  72         System.out.println("Reference to class loader cleared");
  73         long count = 0;
  74         do {
  75             System.gc();
  76             System.out.println("GC triggered");
  77             count = JVM.getJVM().getUnloadedEventClassCount();
  78             System.out.println("Unloaded count was " + count);
  79             Thread.sleep(1000); // sleep to reduce log
  80         } while (count != initialCount + 1);
  81     }
  82 
  83     private static MyClassLoader createClassLoaderWithEventClass() throws Exception {
  84         String resourceName = EVENT_NAME.replace('.', '/') + ".class";
  85         try (InputStream is = TestUnloadEventClassCount.class.getClassLoader().getResourceAsStream(resourceName)) {
  86             ByteArrayOutputStream baos = new ByteArrayOutputStream();
  87             byte[] buffer = new byte[4096];
  88             int byteValue = 0;
  89             while ((byteValue = is.read(buffer, 0, buffer.length)) != -1) {
  90                 baos.write(buffer, 0, byteValue);
  91             }
  92             baos.flush();
  93             MyClassLoader myClassLoader = new MyClassLoader();
  94             Class<?> eventClass = myClassLoader.defineClass(EVENT_NAME, baos.toByteArray());
  95             if (eventClass == null) {
  96                 throw new Exception("Could not define test class");
  97             }
  98             if (eventClass.getSuperclass() != Event.class) {
  99                 throw new Exception("Superclass should be jdk.jfr.Event");
 100             }
 101             if (eventClass.getSuperclass().getClassLoader() != null) {
 102                 throw new Exception("Class loader of jdk.jfr.Event should be null");
 103             }
 104             if (eventClass.getClassLoader() != myClassLoader) {
 105                 throw new Exception("Incorrect class loader for event class");
 106             }
 107             eventClass.newInstance(); // force <clinit>
 108             return myClassLoader;
 109         }
 110     }
 111 }