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.rmi;
27
28import sun.jvmstat.monitor.*;
29import sun.jvmstat.monitor.remote.*;
30import sun.jvmstat.perfdata.monitor.*;
31import java.io.*;
32import java.rmi.RemoteException;
33import java.nio.ByteBuffer;
34
35/**
36 * The concrete PerfDataBuffer implementation for the <em>rmi:</em>
37 * protocol for the HotSpot PerfData monitoring implementation.
38 * <p>
39 * This class is responsible for acquiring the instrumentation buffer
40 * data for a remote target HotSpot Java Virtual Machine.
41 *
42 * @author Brian Doherty
43 * @since 1.5
44 */
45public class PerfDataBuffer extends AbstractPerfDataBuffer {
46
47    private RemoteVm rvm;
48
49    /**
50     * Create a PerfDataBuffer instance for accessing the specified
51     * instrumentation buffer.
52     *
53     * @param rvm the proxy to the remote MonitredVm object
54     * @param lvmid the local Java Virtual Machine Identifier of the
55     *              remote target.
56     *
57     * @throws MonitorException
58     */
59    public PerfDataBuffer(RemoteVm rvm, int lvmid) throws MonitorException {
60
61        this.rvm = rvm;
62        try {
63            ByteBuffer buffer = ByteBuffer.allocate(rvm.getCapacity());
64            sample(buffer);
65            createPerfDataBuffer(buffer, lvmid);
66
67        } catch (RemoteException e) {
68            throw new MonitorException("Could not read data for remote JVM "
69                                       + lvmid, e);
70        }
71    }
72
73    /**
74     * Get a copy of the remote instrumentation buffer.
75     *<p>
76     * The data in the remote instrumentation buffer is copied into
77     * the local byte buffer.
78     *
79     * @param buffer the buffer to receive the copy of the remote
80     *               instrumentation buffer.
81     * @throws RemoteException Thrown on any communications errors with
82     *                         the remote system.
83     */
84    public void sample(ByteBuffer buffer) throws RemoteException {
85        assert buffer != null;
86        assert rvm != null;
87        synchronized(buffer) {
88            buffer.clear();
89            buffer.put(rvm.getBytes());
90        }
91    }
92}
93