1 /*
2  * Copyright (c) 2007, 2016, 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  * @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
check(List<BufferPoolMXBean> pools, int minBufferCount, long minTotalCapacity)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 
main(String[] args)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 }
120