org/objectweb/proactive/core/rmi/RegistryHelper.java

/* 
 * ################################################################
 * 
 * ProActive: The Java(TM) library for Parallel, Distributed, 
 *            Concurrent computing with Security and Mobility
 * 
 * Copyright (C) 1997-2007 INRIA/University of Nice-Sophia Antipolis
 * Contact: proactive@objectweb.org
 * 
 * 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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 *  
 *  Initial developer(s):               The ProActive Team
 *                        http://www.inria.fr/oasis/ProActive/contacts.html
 *  Contributor(s): 
 * 
 * ################################################################
 */ 
package org.objectweb.proactive.core.rmi;


import org.apache.log4j.Logger;
import org.objectweb.proactive.core.util.log.Loggers;
import org.objectweb.proactive.core.util.log.ProActiveLogger;


public class RegistryHelper {
    static Logger logger = ProActiveLogger.getLogger(Loggers.RMI);
    protected final static int DEFAULT_REGISTRY_PORT = 1099;

    protected int registryPortNumber = DEFAULT_REGISTRY_PORT;
    protected boolean shouldCreateRegistry = true;
    protected boolean registryChecked;
    protected static java.rmi.registry.Registry registry;

    //following boolean is used to know which runtime has created RMI registry
    protected static boolean registryCreator = false;

    //
    // -- Constructors -----------------------------------------------
    //
    public RegistryHelper() {
        String port = System.getProperty("proactive.rmi.port");
        if (port != null) {
            setRegistryPortNumber(new Integer(port).intValue());
        }
    }

    //
    // -- PUBLIC METHODS -----------------------------------------------
    //
    public int getRegistryPortNumber() {
        return registryPortNumber;
    }

    public void setRegistryPortNumber(int v) {
        registryPortNumber = v;
        registryChecked = false;
    }

    public boolean shouldCreateRegistry() {
        return shouldCreateRegistry;
    }

    public void setShouldCreateRegistry(boolean v) {
        shouldCreateRegistry = v;
    }

    public synchronized void initializeRegistry()
        throws java.rmi.RemoteException {
        try {
            if (!shouldCreateRegistry) {
                return; // don't bother
            }
            if (registryChecked) {
                return; // already done for this VM
            }
            getOrCreateRegistry(registryPortNumber);
            registryChecked = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static java.rmi.registry.Registry getRegistry() {
        return registry;
    }

    public static boolean getRegistryCreator() {
        return registryCreator;
    }

    //
    // -- PRIVATE METHODS -----------------------------------------------
    // 
    private static java.rmi.registry.Registry createRegistry(int port)
        throws java.rmi.RemoteException {
        registry = java.rmi.registry.LocateRegistry.createRegistry(port);
        registryCreator = true;
        return registry;
    }

    private static java.rmi.registry.Registry detectRegistry(int port) {
        // java.rmi.registry.Registry registry = null;
        try {
            // whether an effective registry exists or not we should get a reference
            registry = java.rmi.registry.LocateRegistry.getRegistry(port);
            if (registry == null) {
                return null;
            }

            // doing a lookup should produce ConnectException if registry doesn't exist
            // and no exception or NotBoundException if the registry does exist.
            java.rmi.Remote r = registry.lookup("blah!");
            logger.info("Detected an existing RMI Registry on port " + port);
            return registry;
        } catch (java.rmi.NotBoundException e) {
            logger.info("Detected an existing RMI Registry on port " + port);
            return registry;
        } catch (java.rmi.RemoteException e) {
            return null;
        }
    }

    private static java.rmi.registry.Registry getOrCreateRegistry(int port)
        throws java.rmi.RemoteException {
        registry = detectRegistry(port);
        if (registry != null) {
            return registry;
        }

        // no registry created
        try {
            registry = createRegistry(port);
            logger.info("Created a new registry on port " + port);
            return registry;
        } catch (java.rmi.RemoteException e) {
            // problem to bind the registry : may be somebody created one in the meantime
            // try to find the rmi registry one more time
            registry = detectRegistry(port);
            if (registry != null) {
                return registry;
            }
            logger.error("Cannot detect an existing RMI Registry on port " +
                port + " nor create one e=" + e);
            throw e;
        }
    }
}

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