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  * @requires vm.hasJFR
  40  *
  41  * @library /test/lib
  42  * @modules jdk.jfr/jdk.jfr.internal
  43  *          java.base/jdk.internal.misc
  44  *
  45  * @run main/othervm -Xlog:class+unload -Xlog:gc -Xmx16m jdk.jfr.jvm.TestUnloadEventClassCount
  46  */
  47 public class TestUnloadEventClassCount {
  48 
  49     private static final String EVENT_NAME = "jdk.jfr.jvm.TestUnloadEventClassCount$ToBeUnloaded";
  50 
  51     public static class ToBeUnloaded extends Event {
  52     }
  53 
  54     static public class MyClassLoader extends ClassLoader {
  55         public MyClassLoader() {
  56             super("MyClassLoader", null);
  57         }
  58 
  59         public final Class<?> defineClass(String name, byte[] b) {
  60             return super.defineClass(name, b, 0, b.length);
  61         }
  62     }
  63 
  64     public static MyClassLoader myClassLoader;
  65 
  66     public static void main(String[] args) throws Throwable {
  67         FlightRecorder.getFlightRecorder();
  68         myClassLoader = createClassLoaderWithEventClass();
  69         System.out.println("MyClassLoader instance created");
  70         long initialCount = JVM.getJVM().getUnloadedEventClassCount();
  71         System.out.println("Initiali unloaded count is " + initialCount);
  72         myClassLoader = null;
  73         System.out.println("Reference to class loader cleared");
  74         long count = 0;
  75         do {
  76             System.gc();
  77             System.out.println("GC triggered");
  78             count = JVM.getJVM().getUnloadedEventClassCount();
  79             System.out.println("Unloaded count was " + count);
  80             Thread.sleep(1000); // sleep to reduce log
  81         } while (count != initialCount + 1);
  82     }
  83 
  84     private static MyClassLoader createClassLoaderWithEventClass() throws Exception {
  85         String resourceName = EVENT_NAME.replace('.', '/') + ".class";
  86         try (InputStream is = TestUnloadEventClassCount.class.getClassLoader().getResourceAsStream(resourceName)) {
  87             ByteArrayOutputStream baos = new ByteArrayOutputStream();
  88             byte[] buffer = new byte[4096];
  89             int byteValue = 0;
  90             while ((byteValue = is.read(buffer, 0, buffer.length)) != -1) {
  91                 baos.write(buffer, 0, byteValue);
  92             }
  93             baos.flush();
  94             MyClassLoader myClassLoader = new MyClassLoader();
  95             Class<?> eventClass = myClassLoader.defineClass(EVENT_NAME, baos.toByteArray());
  96             if (eventClass == null) {
  97                 throw new Exception("Could not define test class");
  98             }
  99             if (eventClass.getSuperclass() != Event.class) {
 100                 throw new Exception("Superclass should be jdk.jfr.Event");
 101             }
 102             if (eventClass.getSuperclass().getClassLoader() != null) {
 103                 throw new Exception("Class loader of jdk.jfr.Event should be null");
 104             }
 105             if (eventClass.getClassLoader() != myClassLoader) {
 106                 throw new Exception("Incorrect class loader for event class");
 107             }
 108             eventClass.newInstance(); // force <clinit>
 109             return myClassLoader;
 110         }
 111     }
 112 }