1 /*
   2  * Copyright (c) 2007, 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 /* @test
  25  * @bug 6606598 7024172
  26  * @summary Unit test for java.lang.management.BufferPoolMXBean
  27  * @run main/othervm Basic
  28  * @key randomness
  29  */
  30 
  31 import java.nio.ByteBuffer;
  32 import java.nio.MappedByteBuffer;
  33 import java.nio.file.Path;
  34 import java.nio.file.Files;
  35 import static java.nio.file.StandardOpenOption.*;
  36 import java.nio.channels.FileChannel;
  37 import java.lang.management.BufferPoolMXBean;
  38 import java.lang.management.ManagementFactory;
  39 import javax.management.MBeanServer;
  40 import javax.management.ObjectName;
  41 import java.lang.ref.WeakReference;
  42 import java.util.*;
  43 
  44 public class Basic {
  45 
  46     // static fields to ensure buffers aren't GC'ed
  47     static List<ByteBuffer> buffers;
  48     static MappedByteBuffer mbb;
  49 
  50     // check counters
  51     static void check(List<BufferPoolMXBean> pools,
  52                       int minBufferCount,
  53                       long minTotalCapacity)
  54     {
  55         int bufferCount = 0;
  56         long totalCap = 0;
  57         long totalMem = 0;
  58         for (BufferPoolMXBean pool: pools) {
  59             bufferCount += pool.getCount();
  60             totalCap += pool.getTotalCapacity();
  61             totalMem += pool.getMemoryUsed();
  62         }
  63         if (bufferCount < minBufferCount)
  64             throw new RuntimeException("Count less than expected");
  65         if (totalMem < minTotalCapacity)
  66             throw new RuntimeException("Memory usage less than expected");
  67         if (totalCap < minTotalCapacity)
  68             throw new RuntimeException("Total capacity less than expected");
  69     }
  70 
  71     public static void main(String[] args) throws Exception {
  72         Random rand = new Random();
  73 
  74         // allocate a few direct buffers
  75         int bufferCount = 5 + rand.nextInt(20);
  76         buffers = new ArrayList<ByteBuffer>(bufferCount);
  77         long totalCapacity = 0L;
  78         for (int i=0; i<bufferCount; i++) {
  79             int cap = 1024 + rand.nextInt(4096);
  80             buffers.add( ByteBuffer.allocateDirect(cap) );
  81             totalCapacity += cap;
  82         }
  83 
  84         // create a mapped buffer
  85         Path tmpfile = Files.createTempFile("blah", null);
  86         tmpfile.toFile().deleteOnExit();
  87         try (FileChannel fc = FileChannel.open(tmpfile, READ, WRITE)) {
  88             mbb = fc.map(FileChannel.MapMode.READ_WRITE, 10, 100);
  89             bufferCount++;
  90             totalCapacity += mbb.capacity();
  91         }
  92 
  93         // use platform MXBeans directly
  94         List<BufferPoolMXBean> pools =
  95             ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);
  96         check(pools, bufferCount, totalCapacity);
  97 
  98         // use MBeanServer
  99         MBeanServer server = ManagementFactory.getPlatformMBeanServer();
 100         Set<ObjectName> mbeans = server.queryNames(
 101             new ObjectName("java.nio:type=BufferPool,*"), null);
 102         pools = new ArrayList<BufferPoolMXBean>();
 103         for (ObjectName name: mbeans) {
 104             BufferPoolMXBean pool = ManagementFactory
 105                 .newPlatformMXBeanProxy(server, name.toString(), BufferPoolMXBean.class);
 106             pools.add(pool);
 107         }
 108         check(pools, bufferCount, totalCapacity);
 109 
 110         // attempt to unmap mapped buffer
 111         WeakReference<MappedByteBuffer> ref = new WeakReference<>(mbb);
 112         mbb = null;
 113         do {
 114             System.gc();
 115             Thread.sleep(250);
 116         } while (ref.get() != null);
 117     }
 118 }
--- EOF ---