libjava/classpath/javax/management/QueryEval.java

   1 /* QueryEval.java -- An evaluation context for a MBean server query.
   2    Copyright (C) 2007 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package javax.management;
  39
  40 import java.io.Serializable;
  41
  42 /**
  43  * Represents the evaluation context of a {@link MBeanServer}
  44  * query by retaining the server used on a thread-by-thread
  45  * basis.
  46  *
  47  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  48  * @since 1.5
  49  */
  50 public class QueryEval
  51   implements Serializable
  52 {
  53
  54   /**
  55    * Compatible with JDK 1.5
  56    */
  57   private static final long serialVersionUID = 2675899265640874796L;
  58
  59   /**
  60    * Stores the server used, on a
  61    * thread-by-thread basis.
  62    */
  63   private static InheritableThreadLocal<MBeanServer> server =
  64     new InheritableThreadLocal<MBeanServer>();
  65
  66   /**
  67    * Returns the {@link MBeanServer} last supplied to the
  68    * {@link #setMBeanServer(MBeanServer)} method.  If this method
  69    * has not been called for this thread, then the value will be
  70    * inherited from any parent thread on which the method has
  71    * been called.  If the method has never been called, then
  72    * <code>null</code> is returned.
  73    *
  74    * @return the server.
  75    * @see #setMBeanServer(MBeanServer)
  76    */
  77   public static MBeanServer getMBeanServer()
  78   {
  79     return server.get();
  80   }
  81
  82   /**
  83    * Sets the {@link MBeanServer} on which the query will be
  84    * performed.  This value is inherited automatically by
  85    * child threads.  This method is only non-static for historical
  86    * reasons; it makes no use of instance-related values.
  87    *
  88    * @param svr the server to use.
  89    */
  90   public void setMBeanServer(MBeanServer svr)
  91   {
  92     server.set(svr);
  93   }
  94
  95 }