/*

 * Copyright (c) 2003, 2006, 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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package sun.management.snmp.util;

import com.sun.jmx.mbeanserver.Util;

import com.sun.jmx.snmp.agent.SnmpUserDataFactory;

import com.sun.jmx.snmp.SnmpPdu;

import com.sun.jmx.snmp.SnmpStatusException;

import java.util.Collections;

import java.util.HashMap;

import java.util.Map;

public class JvmContextFactory implements SnmpUserDataFactory {

    /**

     * Called by the <CODE>SnmpAdaptorServer</CODE> adaptor.

     * Allocate a contextual object containing some user data. This method

     * is called once for each incoming SNMP request. The scope

     * of this object will be the whole request. Since the request can be

     * handled in several threads, the user should make sure that this

     * object can be accessed in a thread-safe manner. The SNMP framework

     * will never access this object directly - it will simply pass

     * it to the <code>SnmpMibAgent</code> within

     * <code>SnmpMibRequest</code> objects - from where it can be retrieved

     * through the {@link com.sun.jmx.snmp.agent.SnmpMibRequest#getUserData() getUserData()} accessor.

     * <code>null</code> is considered to be a valid return value.

     *

     * This method is called just after the SnmpPduPacket has been

     * decoded.

     *

     * @param requestPdu The SnmpPduPacket received from the SNMP manager.

     *        <b>This parameter is owned by the SNMP framework and must be

     *        considered as transient.</b> If you wish to keep some of its

     *        content after this method returns (by storing it in the

     *        returned object for instance) you should clone that

     *        information.

     *

     * @return A newly allocated user-data contextual object, or

     *         <code>null</code>

     * @exception SnmpStatusException If an SnmpStatusException is thrown,

     *            the request will be aborted.

     *

     * @since Java DMK 5.0

     **/

    public Object allocateUserData(SnmpPdu requestPdu)

        throws SnmpStatusException {

        return Collections.synchronizedMap(new HashMap<Object, Object>());

    }

    /**

     * Called by the <CODE>SnmpAdaptorServer</CODE> adaptor.

     * Release a previously allocated contextual object containing user-data.

     * This method is called just before the responsePdu is sent back to the

     * manager. It gives the user a chance to alter the responsePdu packet

     * before it is encoded, and to free any resources that might have

     * been allocated when creating the contextual object.

     *

     * @param userData The contextual object being released.

     * @param responsePdu The SnmpPduPacket that will be sent back to the

     *        SNMP manager.

     *        <b>This parameter is owned by the SNMP framework and must be

     *        considered as transient.</b> If you wish to keep some of its

     *        content after this method returns you should clone that

     *        information.

     *

     * @exception SnmpStatusException If an SnmpStatusException is thrown,

     *            the responsePdu is dropped and nothing is returned to

     *            to the manager.

     *

     * @since Java DMK 5.0

     **/

    public void releaseUserData(Object userData, SnmpPdu responsePdu)

        throws SnmpStatusException {

        ((Map<?, ?>)userData).clear();

    }

    public static Map<Object, Object> getUserData() {

        final Object userData =

            com.sun.jmx.snmp.ThreadContext.get("SnmpUserData");

        if (userData instanceof Map<?, ?>) return Util.cast(userData);

        else return null;

    }

}