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 

    24 import 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  */

    32 public 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 }