1/*
2 * Copyright (c) 2004, 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package sun.jvmstat.perfdata.monitor.protocol.file;
27
28import sun.jvmstat.monitor.*;
29import sun.jvmstat.perfdata.monitor.*;
30import java.io.*;
31import java.net.URI;
32import java.nio.ByteBuffer;
33import java.nio.channels.FileChannel;
34
35/**
36 * The concrete PerfDataBuffer implementation for the <em>file:</em>
37 * protocol for the HotSpot PerfData monitoring implemetation.
38 * <p>
39 * This class is responsible for acquiring access to the instrumentation
40 * buffer stored in a file referenced by a file URI.
41 *
42 * @author Brian Doherty
43 * @since 1.5
44 */
45public class PerfDataBuffer extends AbstractPerfDataBuffer {
46
47    /**
48     * Create a PerfDataBuffer instance for accessing the specified
49     * instrumentation buffer.
50     *
51     * @param vmid the <em>file:</em> URI to the instrumentation buffer file
52     *
53     * @throws MonitorException
54     */
55    public PerfDataBuffer(VmIdentifier vmid) throws MonitorException {
56        File f = new File(vmid.getURI());
57        String mode = vmid.getMode();
58
59        try {
60            FileChannel fc = new RandomAccessFile(f, mode).getChannel();
61            ByteBuffer bb = null;
62
63            if (mode.compareTo("r") == 0) {
64                bb = fc.map(FileChannel.MapMode.READ_ONLY, 0L, (int)fc.size());
65            } else if (mode.compareTo("rw") == 0) {
66                bb = fc.map(FileChannel.MapMode.READ_WRITE, 0L, (int)fc.size());
67            } else {
68                throw new IllegalArgumentException("Invalid mode: " + mode);
69            }
70
71            fc.close();               // doesn't need to remain open
72
73            createPerfDataBuffer(bb, 0);
74        } catch (FileNotFoundException e) {
75            throw new MonitorException("Could not find " + vmid.toString());
76        } catch (IOException e) {
77            throw new MonitorException("Could not read " + vmid.toString());
78        }
79    }
80}
81