1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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.
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   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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  23 
  24 /* @test
  25  * @bug 6606598 7024172
  26  * @key randomness
  27  * @summary Unit test for java.lang.management.BufferPoolMXBean
  28  *
  29  * @modules jdk.management
  30  *
  31  * @run main/othervm Basic
  32  */
  33 
  34 import java.nio.ByteBuffer;
  35 import java.nio.MappedByteBuffer;
  36 import java.nio.file.Path;
  37 import java.nio.file.Files;
  38 import static java.nio.file.StandardOpenOption.*;
  39 import java.nio.channels.FileChannel;
  40 import java.lang.management.BufferPoolMXBean;
  41 import java.lang.management.ManagementFactory;
  42 import javax.management.MBeanServer;
  43 import javax.management.ObjectName;
  44 import java.lang.ref.WeakReference;
  45 import java.util.*;
  46 
  47 public class Basic {
  48 
  49     // static fields to ensure buffers aren't GC'ed
  50     static List<ByteBuffer> buffers;
  51     static MappedByteBuffer mbb;
  52 
  53     // check counters
  54     static void check(List<BufferPoolMXBean> pools,
  55                       int minBufferCount,
  56                       long minTotalCapacity)
  57     {
  58         int bufferCount = 0;
  59         long totalCap = 0;
  60         long totalMem = 0;
  61         for (BufferPoolMXBean pool: pools) {
  62             bufferCount += pool.getCount();
  63             totalCap += pool.getTotalCapacity();
  64             totalMem += pool.getMemoryUsed();
  65         }
  66         if (bufferCount < minBufferCount)
  67             throw new RuntimeException("Count less than expected");
  68         if (totalMem < minTotalCapacity)
  69             throw new RuntimeException("Memory usage less than expected");
  70         if (totalCap < minTotalCapacity)
  71             throw new RuntimeException("Total capacity less than expected");
  72     }
  73 
  74     public static void main(String[] args) throws Exception {
  75         Random rand = new Random();
  76 
  77         // allocate a few direct buffers
  78         int bufferCount = 5 + rand.nextInt(20);
  79         buffers = new ArrayList<ByteBuffer>(bufferCount);
  80         long totalCapacity = 0L;
  81         for (int i=0; i<bufferCount; i++) {
  82             int cap = 1024 + rand.nextInt(4096);
  83             buffers.add( ByteBuffer.allocateDirect(cap) );
  84             totalCapacity += cap;
  85         }
  86 
  87         // create a mapped buffer
  88         Path tmpfile = Files.createTempFile("blah", null);
  89         tmpfile.toFile().deleteOnExit();
  90         try (FileChannel fc = FileChannel.open(tmpfile, READ, WRITE)) {
  91             mbb = fc.map(FileChannel.MapMode.READ_WRITE, 10, 100);
  92             bufferCount++;
  93             totalCapacity += mbb.capacity();
  94         }
  95 
  96         // use platform MXBeans directly
  97         List<BufferPoolMXBean> pools =
  98             ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);
  99         check(pools, bufferCount, totalCapacity);
 100 
 101         // use MBeanServer
 102         MBeanServer server = ManagementFactory.getPlatformMBeanServer();
 103         Set<ObjectName> mbeans = server.queryNames(
 104             new ObjectName("java.nio:type=BufferPool,*"), null);
 105         pools = new ArrayList<BufferPoolMXBean>();
 106         for (ObjectName name: mbeans) {
 107             BufferPoolMXBean pool = ManagementFactory
 108                 .newPlatformMXBeanProxy(server, name.toString(), BufferPoolMXBean.class);
 109             pools.add(pool);
 110         }
 111         check(pools, bufferCount, totalCapacity);
 112 
 113         // attempt to unmap mapped buffer
 114         WeakReference<MappedByteBuffer> ref = new WeakReference<>(mbb);
 115         mbb = null;
 116         do {
 117             System.gc();
 118             Thread.sleep(250);
 119         } while (ref.get() != null);
 120     }
 121 }