1 /*

     2  * Copyright (c) 2013, 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 package com.oracle.java.testlibrary;

    25 

    26 import sun.jvmstat.monitor.Monitor;

    27 

    28 /**

    29  * Represents a performance counter in the JVM.

    30  *

    31  * See http://openjdk.java.net/groups/hotspot/docs/Serviceability.html#bjvmstat

    32  * for more details about performance counters.

    33  */

    34 public class PerfCounter {

    35     private final Monitor monitor;

    36     private final String name;

    37 

    38     PerfCounter(Monitor monitor, String name) {

    39         this.monitor = monitor;

    40         this.name = name;

    41     }

    42 

    43     /**

    44      * Returns the value of this performance counter as a long.

    45      *

    46      * @return The long value of this performance counter

    47      * @throws RuntimeException If the value of the performance counter isn't a long

    48      */

    49     public long longValue() {

    50         Object value = monitor.getValue();

    51         if (value instanceof Long) {

    52             return ((Long) value).longValue();

    53         }

    54         throw new RuntimeException("Expected " + monitor.getName() + " to have a long value");

    55     }

    56 

    57     /**

    58      * Returns the name of the performance counter.

    59      *

    60      * @return The name of the performance counter.

    61      */

    62     public String getName() {

    63         return name;

    64     }

    65 

    66     @Override

    67     public String toString() {

    68         return name;

    69     }

    70 }