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