1 /*
   2  * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 import java.util.Arrays;
  25 import java.util.concurrent.*;
  26 
  27 public class TestPinnedGarbage {
  28     static {
  29         System.loadLibrary("TestPinnedGarbage");
  30     }
  31 
  32     private static final int NUM_RUNS      = 1_000;
  33     private static final int OBJS_COUNT    = 1 << 10;
  34     private static final int GARBAGE_COUNT = 1 << 18;
  35 
  36     private static native void pin(int[] a);
  37     private static native void unpin(int[] a);
  38 
  39     public static void main(String[] args) {
  40         ThreadLocalRandom rng = ThreadLocalRandom.current();
  41         for (int i = 0; i < NUM_RUNS; i++) {
  42             test(rng);
  43         }
  44     }
  45 
  46     private static void test(ThreadLocalRandom rng) {
  47         Object[] objs = new Object[OBJS_COUNT];
  48         for (int i = 0; i < OBJS_COUNT; i++) {
  49             objs[i] = new MyClass();
  50         }
  51 
  52         int[] cog = new int[10];
  53         int cogIdx = rng.nextInt(OBJS_COUNT);
  54         objs[cogIdx] = cog;
  55         pin(cog);
  56 
  57         for (int i = 0; i < GARBAGE_COUNT; i++) {
  58             int rIdx = rng.nextInt(OBJS_COUNT);
  59             if (rIdx != cogIdx) {
  60                 objs[rIdx] = new MyClass();
  61             }
  62         }
  63 
  64         unpin(cog);
  65     }
  66 
  67     public static class MyClass {
  68         public Object ref = new Object();
  69     }
  70 
  71 }