org.ow2.cmi.lb.strategy.LocalPreference Maven / Gradle / Ivy

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/**
 * CMI : Cluster Method Invocation
 * Copyright (C) 2007,2008 Bull S.A.S.
 * Contact: [email protected]
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 * --------------------------------------------------------------------------
 * $Id:LocalPreference.java 1124 2007-07-27 16:38:35Z loris $
 * --------------------------------------------------------------------------
 */

package org.ow2.cmi.lb.strategy;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import net.jcip.annotations.Immutable;

import org.ow2.cmi.controller.client.ClientClusterViewManager;
import org.ow2.cmi.controller.common.ClusterViewManager;
import org.ow2.cmi.controller.server.ServerClusterViewManager;
import org.ow2.cmi.lb.LoadBalanceable;
import org.ow2.cmi.reference.ServerRef;
import org.ow2.util.log.Log;
import org.ow2.util.log.LogFactory;

/**
 * Defines a strategy that enable the local preference.
 * @param  The type of objects that are load-balanced
 * @author The new CMI team
 */
@Immutable
public final class LocalPreference implements IStrategy {

    /**
     * Logger.
     */
    private static final Log LOGGER = LogFactory.getLog(LocalPreference.class);

    /**
     * The manager of the cluster view.
     */
    private final ClusterViewManager clusterViewManager;

    /**
     * Constructs a strategy for load-factor.
     * @param clusterViewManager the manager of the cluster view
     */
    public LocalPreference(final ClusterViewManager clusterViewManager) {
        this.clusterViewManager = clusterViewManager;
    }

    /**
     * Returns a list of CMIReference that references the local servers.
     * @param cmiRefs a list of CMIReference
     * @return a list of CMIReference that references the local servers
     */
    public List choose(final Collection cmiRefs) {

        List localServers = new ArrayList();

        for(T cmiRef : cmiRefs) {

            // Gets the reference of server that have deployed the object
            ServerRef serverRef = cmiRef.getServerRef();

            //  Gets its address
            InetAddress inetAddress = serverRef.getInetAddress();

            try {
                // Checks if the addresses match
                if(isLocal(inetAddress)) {
                    // Local address: adds reference in the first position
                    localServers.add(cmiRef);
                }
            } catch (SocketException e) {
                LOGGER.error("Cannot know if is local or not", e);
                throw new RuntimeException("Cannot know if is local or not", e);
            }
        }
        return localServers;
    }

    /**
     * Tests if an address is local.
     * @param inetAddress an address
     * @return true if the given address is local
     * @throws SocketException if an I/O error occurs
     */
    private boolean isLocal(final InetAddress inetAddress) throws SocketException {

        if(clusterViewManager instanceof ClientClusterViewManager) {
            if(NetworkInterface.getByInetAddress(inetAddress)!=null) {
                return true;
            }
        } else if(clusterViewManager instanceof ServerClusterViewManager) {
            if(inetAddress.equals(((ServerClusterViewManager) clusterViewManager).getInetAddress())) {
                return true;
            }
        }
        return false;
    }

    @Override
    public String toString() {
        return "LocalPreference";
    }

}