001 /* QueryEval.java -- An evaluation context for a MBean server query.
002 Copyright (C) 2007 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package javax.management;
039
040 import java.io.Serializable;
041
042 /**
043 * Represents the evaluation context of a {@link MBeanServer}
044 * query by retaining the server used on a thread-by-thread
045 * basis.
046 *
047 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
048 * @since 1.5
049 */
050 public class QueryEval
051 implements Serializable
052 {
053
054 /**
055 * Compatible with JDK 1.5
056 */
057 private static final long serialVersionUID = 2675899265640874796L;
058
059 /**
060 * Stores the server used, on a
061 * thread-by-thread basis.
062 */
063 private static InheritableThreadLocal<MBeanServer> server =
064 new InheritableThreadLocal<MBeanServer>();
065
066 /**
067 * Returns the {@link MBeanServer} last supplied to the
068 * {@link #setMBeanServer(MBeanServer)} method. If this method
069 * has not been called for this thread, then the value will be
070 * inherited from any parent thread on which the method has
071 * been called. If the method has never been called, then
072 * <code>null</code> is returned.
073 *
074 * @return the server.
075 * @see #setMBeanServer(MBeanServer)
076 */
077 public static MBeanServer getMBeanServer()
078 {
079 return server.get();
080 }
081
082 /**
083 * Sets the {@link MBeanServer} on which the query will be
084 * performed. This value is inherited automatically by
085 * child threads. This method is only non-static for historical
086 * reasons; it makes no use of instance-related values.
087 *
088 * @param svr the server to use.
089 */
090 public void setMBeanServer(MBeanServer svr)
091 {
092 server.set(svr);
093 }
094
095 }