trapdipmgr.java

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//
// This file is part of the OpenNMS(R) Application.
//
// OpenNMS(R) is Copyright (C) 2002-2003 The OpenNMS Group, Inc.  All rights reserved.
// OpenNMS(R) is a derivative work, containing both original code, included code and modified
// code that was published under the GNU General Public License. Copyrights for modified 
// and included code are below.
//
// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
//
// Modifications:
//
// 2003 Jan 31: Cleaned up some unused imports.
//
// Original code base Copyright (C) 1999-2001 Oculan Corp.  All rights reserved.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 for more details.                                                            
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//       
// For more information contact: 
//      OpenNMS Licensing       <[e-mail]>
//      http://www.opennms.org/
//      http://www.opennms.com/
//
// Tab Size = 8
//

package org.opennms.netmgt.trapd;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Map;

import org.opennms.netmgt.config.DatabaseConnectionFactory;

/**
 * This class represents a singular instance that is used to map trap IP
 * addresses to known nodes.
 * 
 * @author <a href="mailto:[e-mail]">Brian Weaver </a>
 * @author <a href="mailto:[e-mail]">Tarus Balog </a>
 * @author <a href="http://www.opennms.org/">OpenNMS </a>
 * 
 */
final class TrapdIPMgr {
    /**
     * The SQL statement used to extract the list of currently known IP
     * addresses and their node IDs from the IP Interface table.
     */
    private final static String IP_LOAD_SQL = "SELECT ipAddr, nodeid FROM ipInterface";

    /**
     * A Map of IP addresses and node IDs
     */
    private static Map m_knownips = new HashMap();

    /**
     * Default construct for the instance. This constructor always throws an
     * exception to the caller.
     * 
     * @throws java.lang.UnsupportedOperationException
     *             Always thrown.
     * 
     */
    private TrapdIPMgr() {
        throw new UnsupportedOperationException("Construction is not supported");
    }

    /**
     * Clears and synchronizes the internal known IP address cache with the
     * current information contained in the database. To synchronize the cache
     * the method opens a new connection to the database, loads the address, and
     * then closes it's connection.
     * 
     * @throws java.sql.SQLException
     *             Thrown if the connection cannot be created or a database
     *             error occurs.
     * 
     */
    static synchronized void dataSourceSync() throws SQLException {
        java.sql.Connection c = null;
        try {
            // Get database connection
            c = DatabaseConnectionFactory.getInstance().getConnection();

            // Run with it
            //
            // c.setReadOnly(true);

            Statement s = c.createStatement();
            ResultSet rs = s.executeQuery(IP_LOAD_SQL);

            if (rs != null) {
                m_knownips.clear();
                while (rs.next()) {
                    String ipstr = rs.getString(1);
                    String ipnodeid = rs.getString(2);
                    m_knownips.put(ipstr, ipnodeid);
                }
                rs.close();
            }

            s.close();
        } finally {
            try {
                if (c != null)
                    c.close();
            } catch (SQLException sqlE) {
            }
        }
    }

    /**
     * Returns the nodeid for the IP Address
     * 
     * @param addr
     *            The IP Address to query.
     * 
     * @return The node ID of the IP Address if known.
     * 
     */
    static synchronized String getNodeId(String addr) {
        if (addr == null)
            return null;
        return (String) m_knownips.get(addr);
    }

    /**
     * Sets the IP Address and Node ID in the Map.
     * 
     * @param addr
     *            The IP Address to add.
     * @param nodeid
     *            The Node ID to add.
     * 
     * @return The nodeid if it existed in the map.
     * 
     */
    static synchronized String setNodeId(String addr, String nodeid) {
        if (addr == null || nodeid == null)
            return null;
        else
            return (String) m_knownips.put(addr, nodeid);
    }

    /**
     * Removes an address from the node ID map.
     * 
     * @param addr
     *            The address to remove from the node ID map.
     * 
     * @return The nodeid that was in the map.
     * 
     */
    static String removeNodeId(String addr) {
        if (addr == null)
            return null;
        return (String) m_knownips.remove(addr);
    }

} // end TrapdIPMgr