1 /*
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   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  *
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  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
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  22  */
  23 
  24 /* @test
  25  * @bug 6606598 7024172
  26  * @summary Unit test for java.lang.management.BufferPoolMXBean
  27  * @run main/othervm Basic

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