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: cjones $'

 *     '$Date: 2011-09-11 18:12:50 -0700 (Sun, 11 Sep 2011) $'

 * '$Revision: 6407 $'

 *

 * 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 java.io.File;

import org.apache.log4j.Logger;

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

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

import com.hazelcast.config.Config;

import com.hazelcast.core.Hazelcast;

import com.hazelcast.core.HazelcastInstance;

import com.hazelcast.core.IMap;

import com.hazelcast.core.IdGenerator;

import com.hazelcast.core.InstanceEvent;

import com.hazelcast.core.InstanceListener;

import edu.ucsb.nceas.metacat.properties.PropertyService;

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

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

import edu.ucsb.nceas.utilities.PropertyNotFoundException;

/**

 * 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 hzService = null;

  /* The Hazelcast instance that is a cluster member */

  private HazelcastInstance hzMember;

  /* The Hazelcast configuration */

  private Config hzConfig;

  /* The task id namespace (for generating cluster-wide unqique task ids */

  private String taskIds;

  /* The Hazelcast Id Genrator used to generate unique task ids */

  IdGenerator idGenerator;

  /*

   * 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 {

      init();

    } 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 ( hzService == null ) {

      hzService = new HazelcastService();

    }

    return hzService;

  }

  /**

   * Initializes the Hazelcast service

   */

  public void init() throws ServiceException {

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

    try {

      File hzConfigFile =

        new File(PropertyService.getProperty("dataone.hazelcast.configFilePath"));

      hzConfig = new Config();

      hzConfig.setConfigurationFile(hzConfigFile);

      hzMember = Hazelcast.init(hzConfig);

      taskIds = 

        PropertyService.getProperty("dataone.hazelcast.storageCluster.tasksIdNamespace");

      idGenerator = hzMember.getIdGenerator(taskIds);

    } catch (PropertyNotFoundException e) {

      String msg = "Couldn't find the Hazelcast configuration file.";

      logMetacat.error(msg);

      throw new ServiceException(msg);

    } catch (IllegalStateException e) {

      String msg = "This instance of Hazelcast has already been created.";

      logMetacat.error(msg);

      throw new ServiceException(msg);

    }

    return;

  }

  /**

   * Indicate whether or not this service is refreshable.

   *

   * @return refreshable - the boolean refreshable status

   */

  public boolean refreshable() {

    // TODO: Determine the consequences of restarting the Hazelcast instance

    // Set this to true if it's okay to drop from the cluster, lose the maps,

    // and start back up again

    return false;

  }

  /**

   * 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());

  }

  /**

   * Refresh the Hazelcast service by restarting it

   */

  @Override

  protected void doRefresh() throws ServiceException {

    // TODO: verify that the correct config file is still used

    Hazelcast.getLifecycleService().restart();

  }

}