/*
 * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.management;

// java import
import java.io.Serializable;

/**
 * Allows a query to be performed in the context of a specific MBean server.
 *
 * @since 1.5
 */
public abstract class QueryEval implements Serializable {

 /* Serial version */
 private static final long serialVersionUID = 2675899265640874796L;

 private static ThreadLocal<MBeanServer> server =
 new InheritableThreadLocal<MBeanServer>();

 /**
 * <p>Sets the MBean server on which the query is to be performed.
 * The setting is valid for the thread performing the set.
 * It is copied to any threads created by that thread at the moment
 * of their creation.</p>
 *
 * <p>For historical reasons, this method is not static, but its
 * behavior does not depend on the instance on which it is
 * called.</p>
 *
 * @param s The MBean server on which the query is to be performed.
 *
 * @see #getMBeanServer
 */
 public void setMBeanServer(MBeanServer s) {
 server.set(s);
 }

 /**
 * <p>Return the MBean server that was most recently given to the
 * {@link #setMBeanServer setMBeanServer} method by this thread.
 * If this thread never called that method, the result is the
 * value its parent thread would have obtained from
 * <code>getMBeanServer</code> at the moment of the creation of
 * this thread, or null if there is no parent thread.</p>
 *
 * @return the MBean server.
 *
 * @see #setMBeanServer
 *
 */
 public static MBeanServer getMBeanServer() {
 return server.get();
 }
}