1/*
2 * Copyright (c) 2013, 2015, 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
24import sun.jvmstat.monitor.Monitor;
25
26/**
27 * Represents a performance counter in the JVM.
28 *
29 * See http://openjdk.java.net/groups/hotspot/docs/Serviceability.html#bjvmstat
30 * for more details about performance counters.
31 */
32public class PerfCounter {
33    private final Monitor monitor;
34    private final String name;
35
36    PerfCounter(Monitor monitor, String name) {
37        this.monitor = monitor;
38        this.name = name;
39    }
40
41    /**
42     * Returns the value of this performance counter as a long.
43     *
44     * @return The long value of this performance counter
45     * @throws RuntimeException If the value of the performance counter isn't a long
46     */
47    public long longValue() {
48        Object value = monitor.getValue();
49        if (value instanceof Long) {
50            return ((Long) value).longValue();
51        }
52        throw new RuntimeException("Expected " + monitor.getName() + " to have a long value");
53    }
54
55    /**
56     * Returns the name of the performance counter.
57     *
58     * @return The name of the performance counter.
59     */
60    public String getName() {
61        return name;
62    }
63
64    @Override
65    public String toString() {
66        return name;
67    }
68}
69