/*

 * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 * questions.

 */

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();

    }

}