1/*
2 * Copyright (c) 2004, 2010, 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;
27
28import sun.jvmstat.monitor.*;
29import java.nio.ByteBuffer;
30
31/**
32 * Class for monitoring a PerfData Byte Array instrumentation object.
33 *
34 * This class is provided to support the PerfStringMonitor classes.
35 * Instrumentation objects of this direct type currently cannot be
36 * created or monitored.
37 *
38 * @author Brian Doherty
39 * @since 1.5
40 * @see sun.jvmstat.instrument.ByteArrayInstrument
41 */
42public class PerfByteArrayMonitor extends AbstractMonitor
43       implements ByteArrayMonitor {
44
45    /**
46     * The buffer containing the data for the byte array instrument.
47     */
48    ByteBuffer bb;
49
50    /**
51     * Constructor to create a ByteArrayMonitor for the byte array instrument
52     * represented by the data in the given buffer.
53     *
54     * @param name the name of the instrumentation object
55     * @param u the units of measure attribute
56     * @param v the variability attribute
57     * @param supported support level indicator
58     * @param bb the buffer containing the byte array instrument data
59     * @param vectorLength the length of the vector.
60     */
61    public PerfByteArrayMonitor(String name, Units u, Variability v,
62                                boolean supported, ByteBuffer bb,
63                                int vectorLength) {
64        super(name, u, v, supported, vectorLength);
65        this.bb = bb;
66    }
67
68    /**
69     * {@inheritDoc}
70     * The object returned contains a byte[] with a copy of the current
71     * elements of the ByteArrayInstrument.
72     *
73     * @return Object - a copy of the current value of the elements of the
74     *                  byte array instrument. The return type is guaranteed
75     *                  to be of type byte[].
76     */
77    public Object getValue() {
78        return byteArrayValue();
79    }
80
81    /**
82     * Get a copy of the elements of the byte array instrument.
83     *
84     * @return byte[] - a copy of the current value of the elements of the
85     *                  byte array instrument.
86     */
87    public byte[] byteArrayValue() {
88        bb.position(0);
89        byte[] b = new byte[bb.limit()];
90
91        // copy the bytes
92        bb.get(b);
93
94        return b;
95    }
96
97    /**
98     * Get the current value of an element of the byte array instrument.
99     *
100     * @return byte - a copy of the current value of the element at index
101     *                {@code index} of the byte array instrument.
102     */
103    public byte byteAt(int index) {
104        bb.position(index);
105        return bb.get();
106    }
107
108    /**
109     * Get the maximum length of the byte array for this byte array instrument.
110     *
111     * @return int - the maximum length of the byte array.
112     */
113    public int getMaximumLength() {
114        return bb.limit();
115    }
116}
117