Metacat

/**

 *  '$RCSfile$'

 *    Purpose: Implements a service for managing a Hazelcast cluster member

 *  Copyright: 2011 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Christopher Jones

 * 

 *   '$Author$'

 *     '$Date$'

 * '$Revision$'

 *

 * 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

 */

package edu.ucsb.nceas.metacat.dataone.hazelcast;

import org.apache.log4j.Logger;

import org.dataone.service.types.v1.Identifier;

import org.dataone.service.types.v1.SystemMetadata;

import com.hazelcast.core.Hazelcast;

import com.hazelcast.core.IMap;

import com.hazelcast.core.InstanceEvent;

import com.hazelcast.core.InstanceListener;

import edu.ucsb.nceas.metacat.shared.BaseService;

import edu.ucsb.nceas.metacat.shared.ServiceException;

/**

 * The Hazelcast service enables Metacat as a Hazelcast cluster member

 */

public class HazelcastService extends BaseService

  implements InstanceListener {

  /* The instance of the logging class */

  private static Logger logMetacat = Logger.getLogger(HazelcastService.class);

  /* The singleton instance of the hazelcast service */

  private static HazelcastService hazelcastService = null;

  /*The distributed DataONE system metadata map*/

  private IMap<Identifier, SystemMetadata> systemMetadata;

  /* the name of the system metadata map in hazelcast */

  private String systemMetadataMap = "hzSystemMetadata";

  /*

   * Constructor: Creates an instance of the hazelcast service. Since

   * this uses a singleton pattern, use getInstance() to gain the instance.

   */

  private HazelcastService() {

    super();

    _serviceName="HazelcastService";

    try {

      doRefresh();

    } catch (ServiceException se) {

      logMetacat.debug("There was a problem creating the HazelcastService. " +

                       "The error message was: " + se.getMessage());

    }

  }

  /**

   *  Get the instance of the HazelcastService that has been instantiated,

   *  or instantiate one if it has not been already.

   *

   * @return hazelcastService - The instance of the hazelcast service

   */

  public static HazelcastService getInstance(){

    if ( hazelcastService == null ) {

      hazelcastService = new HazelcastService();

    }

    return hazelcastService;

  }

  /**

   * Refreshes the Hazelcast service

   */

  public void doRefresh() throws ServiceException {

    logMetacat.debug("HazelcastService.doRefresh() called.");

    this.systemMetadata = Hazelcast.getMap(this.systemMetadataMap);

    return;

  }

  /**

   * Indicate whether or not this service is refreshable.

   *

   * @return refreshable - the boolean refreshable status

   */

  public boolean refreshable() {

    return false; //right?

  }

  /**

   * Stop the HazelcastService. When stopped, the service will no longer

   * respond to requests.

   */

  public void stop() throws ServiceException {

    Hazelcast.getLifecycleService().shutdown();

  }

  /**

   * Listen for new Hazelcast member events

   */

	@Override

  public void instanceCreated(InstanceEvent event) {

		logMetacat.info("New Hazelcast instance created: " +

			event.getInstance().getId() + ", " +

			event.getInstance().getInstanceType());

  }

	@Override

  public void instanceDestroyed(InstanceEvent event) {

		logMetacat.info("Hazelcast instance removed: " +

				event.getInstance().getId() + ", " +

				event.getInstance().getInstanceType());

  }

}