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 
  26 package sun.jvmstat.perfdata.monitor;
  27 
  28 import sun.jvmstat.monitor.*;
  29 import java.nio.ByteBuffer;
  30 
  31 /**
  32  * Class for monitoring a constant PerfData String instrument. The
  33  * value associated with a constant string instrument is fixed at
  34  * the string instrument's creation time. Its value and length never
  35  * change.
  36  *
  37  * @author Brian Doherty
  38  * @since 1.5
  39  */
  40 public class PerfStringConstantMonitor extends PerfStringMonitor {
  41 
  42     /**
  43      * The cached value of the string instrument.
  44      */
  45     String data;
  46 
  47     /**
  48      * Constructor to create a StringMonitor object for the constant string
  49      * instrument object represented by the data in the given buffer.
  50      *
  51      * @param name the name of the instrumentation object
  52      * @param supported support level indicator
  53      * @param bb the buffer containing the string instrument data
  54      */
  55     public PerfStringConstantMonitor(String name, boolean supported,
  56                                      ByteBuffer bb) {
  57         super(name, Variability.CONSTANT, supported, bb);
  58         this.data = super.stringValue();
  59     }
  60 
  61     /**
  62      * {@inheritDoc}
  63      */
  64     public Object getValue() {
  65         return data;        // return the cached string
  66     }
  67 
  68     /**
  69      * {@inheritDoc}
  70      */
  71     public String stringValue() {
  72         return data;        // return the cached string
  73     }
  74 }