/* QueryEval.java -- An evaluation context for a MBean server query.
   Copyright (C) 2007 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package javax.management;

import java.io.Serializable;

/**
 * Represents the evaluation context of a {@link MBeanServer}
 * query by retaining the server used on a thread-by-thread
 * basis.
 *
 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
 * @since 1.5
 */
public class QueryEval
  implements Serializable
{

  /**
   * Compatible with JDK 1.5
   */
  private static final long serialVersionUID = 2675899265640874796L;

  /**
   * Stores the server used, on a 
   * thread-by-thread basis.
   */
  private static InheritableThreadLocal<MBeanServer> server =
    new InheritableThreadLocal<MBeanServer>();

  /**
   * Returns the {@link MBeanServer} last supplied to the
   * {@link #setMBeanServer(MBeanServer)} method.  If this method
   * has not been called for this thread, then the value will be
   * inherited from any parent thread on which the method has
   * been called.  If the method has never been called, then
   * <code>null</code> is returned.
   *
   * @return the server.
   * @see #setMBeanServer(MBeanServer)
   */
  public static MBeanServer getMBeanServer()
  {
    return server.get();
  }

  /**
   * Sets the {@link MBeanServer} on which the query will be
   * performed.  This value is inherited automatically by
   * child threads.  This method is only non-static for historical
   * reasons; it makes no use of instance-related values. 
   *
   * @param svr the server to use.
   */
  public void setMBeanServer(MBeanServer svr)
  {
    server.set(svr);
  }

}