Basic.java revision 6073:cea72c2bf071 
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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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
30import java.nio.ByteBuffer;
31import java.nio.MappedByteBuffer;
32import java.nio.file.Path;
33import java.nio.file.Files;
34import static java.nio.file.StandardOpenOption.*;
35import java.nio.channels.FileChannel;
36import java.lang.management.BufferPoolMXBean;
37import java.lang.management.ManagementFactory;
38import javax.management.MBeanServer;
39import javax.management.ObjectName;
40import java.lang.ref.WeakReference;
41import java.util.*;
42
43public 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}
118