1 /*
   2  * Copyright (c) 2017, Google 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 package MyPackage;
  25 
  26 /**
  27  * @test
  28  * @summary Verifies the JVMTI Heap Monitor Statistics
  29  * @compile HeapMonitorStatSimpleTest.java
  30  * @run main/othervm/native -agentlib:HeapMonitor MyPackage.HeapMonitorStatSimpleTest
  31  */
  32 
  33 public class HeapMonitorStatSimpleTest {
  34 
  35   static {
  36     try {
  37       System.loadLibrary("HeapMonitor");
  38     } catch (UnsatisfiedLinkError ule) {
  39       System.err.println("Could not load HeapMonitor library");
  40       System.err.println("java.library.path: "
  41           + System.getProperty("java.library.path"));
  42       throw ule;
  43     }
  44   }
  45 
  46   private static int g_tmp[];
  47 
  48   private native static int statsNull();
  49   private native static int enableSampling();
  50 
  51   private static int helper() {
  52     int sum = 0;
  53     // Let us assume that the array is 24 bytes of memory.
  54     for (int i = 0; i < 127000 / 6; i++) {
  55       int tmp[] = new int[1];
  56       // Force it to be kept.
  57       g_tmp = tmp;
  58       sum += g_tmp[0];
  59     }
  60     return sum;
  61   }
  62 
  63   private static void wrapper() {
  64     int sum = 0;
  65     for (int j = 0; j < 1000; j++) {
  66       sum += helper();
  67     }
  68     System.out.println(sum);
  69   }
  70 
  71   public static void main(String[] args) {
  72     if (statsNull() == 0) {
  73       throw new RuntimeException("Statistics should be null to begin with.");
  74     }
  75 
  76     enableSampling();
  77     wrapper();
  78 
  79     if (statsNull() != 0) {
  80       throw new RuntimeException("Statistics should not be null now.");
  81     }
  82   }
  83 }