Metacat

/**

 *  '$RCSfile$'

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *

 * Author: Matthew Perry 

 * '$Date: 2011-12-07 12:18:24 -0800 (Wed, 07 Dec 2011) $'

 * '$Revision: 6744 $'

 *

 * 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.spatial;

import java.io.IOException;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.Vector;

import org.apache.log4j.Logger;

import org.opengis.feature.simple.SimpleFeature;

import edu.ucsb.nceas.metacat.database.DBConnection;

/** 

 * Harvests spatial data from metacat database

 * and saves to persistent cache

 */

public class SpatialHarvester {

  private static Logger log = Logger.getLogger(SpatialHarvester.class.getName());

  private DBConnection dbconn;

  /** 

   * constructor to initialize db connection 

   */

  public SpatialHarvester() {

      try {

          dbconn = new DBConnection();

      } catch( Exception e ) {

          log.error("Error getting docids from queryAllDocids");

          e.printStackTrace();

      }

  }

  /**

   * Closes the database connection. 

   * Should be called after you're done with the SpatialHarvester

   */

  public void destroy() {

      try {

          dbconn.close();

      } catch( SQLException e ) {

          log.error("Error closing out dbconn in spatial harvester");

          e.printStackTrace();

      }

  }

  /**

   * Returns a Vector of all the current versions of public docids

   */

  protected Vector<String> queryAllDocids() {

    Vector<String> _docs = new Vector<String>();

    PreparedStatement pstmt = null;

    ResultSet rs = null;

    /*

     * For now, only allow publically readable docids

     * to be considered for the spatial cache

     */

    //String query = "select distinct docid from xml_path_index";

    String query = "select distinct id.docid " +

    		"from xml_access xa, identifier id, xml_documents xd " +

    		"where xa.guid = id.guid " +

    		"and id.docid = xd.docid " +

    		"and id.rev = xd.rev " +

    		"and xa.principal_name = 'public' " +

    		"and xa.perm_type = 'allow'";

    try {

      pstmt = dbconn.prepareStatement(query);

      pstmt.execute();

      rs = pstmt.getResultSet();

      while (rs.next()) {

        String docid = rs.getString(1);

        if (docid != null) {

	        //log.fatal("adding docid: " + docid);

	        _docs.add(docid);

        }

    }

      rs.close();

      pstmt.close();

    }

    catch(Exception e) {

      log.error("Error getting docids from queryAllDocids");

      e.printStackTrace();

    }

    return _docs;

  }

  /**

   * Currently just a wrapper around the harvestDocument method.

   * Eventually we can use this method as a

   * timed que like the indexing process.

   *

   * @param docid The docid to be added to the spatial cache.

   */                   

  public void addToUpdateQue( String docid ) {

      harvestDocument(docid);

  }

  /**

   * Delete a given document from spatial cache.

   * Just a wrapper around deleteDocument method for now.

   *

   * @param docid The docid to be deleted from the spatial cache.

   */

  public void addToDeleteQue( String docid ) {

      deleteDocument(docid);

  }

  /**

   * Given a docid, will attempt to delete it from spatial cache

   *

   * @param docid The docid to be deleted from the spatial cache.

   */

  public void deleteDocument( String docid ) {

     try {

//    	 Read the existing spatial dataset cache

         SpatialDataset sds = new SpatialDataset();

         // Delete both the polygon(s) and point(s)

         sds.delete( "polygon" , docid ); 

         sds.delete( "point" , docid ); 

     } catch (IOException e) {

         log.error("IOException while deleting from spatial cache");

     }

     log.info(" --------- Spatial Harvester - Deleted from spatial cache : " + docid );

  }      

  /**

   * Given a new or updated docid, 

   * will update the spatial cache accordingly.

   *

   * @param docid The docid to be updated or inserted into the spatial cache.

   */

  public void harvestDocument( String docid ) {

     long before = System.currentTimeMillis();

     try {

         //Read the existing spatial dataset cache

         SpatialDataset sds = new SpatialDataset();

         // insert OR update the spatial cache

         // SpatialDataset.insertOrUpdate takes care of the difference 

         SpatialDocument sdoc = new SpatialDocument( docid, dbconn );

         SimpleFeature polygonFeature = sdoc.getPolygonFeature();

         sds.insertOrUpdate("polygon", polygonFeature, docid );

         SimpleFeature pointFeature = sdoc.getPointFeature();

         sds.insertOrUpdate("point", pointFeature, docid );

         long after = System.currentTimeMillis();

         log.info(" ------- Spatial Harvester - spatial cache updated for : " + docid + ".... Time  " + (after - before) + "ms");

     } catch (IOException e) {

         log.error("IOException while performing spatial harvest ");

     }

  }

  /**

   * Completely regenerates the spatial cache. 

   * This can take a long time, especially with lots of documents.

   */

  public void regenerate() throws IOException{

      // Create new Spatial Dataset

      SpatialDataset sds = new SpatialDataset();

      // Get list of all docids in the database

      Vector<String> docids = queryAllDocids(); 

      for (int i = 0; i < docids.size(); i++) {

          SpatialDocument sdoc = new SpatialDocument( (String)docids.elementAt(i), dbconn );

          // Get the polygon representation of SpatialDocument

          // and add it to the spatial dataset

         SimpleFeature polygonFeature = sdoc.getPolygonFeature();

          sds.add("polygon", polygonFeature );

          // Get the point representation of SpatialDocument

          // and add it to the spatial dataset

          SimpleFeature pointFeature = sdoc.getPointFeature();

          sds.add("point", pointFeature );

          log.info(" ****** Spatial harvest of docid " + docids.elementAt(i) );

      }

      // save SpatialDataset

      sds.save();

  }

}