Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that tracks sessions for MetaCatServlet users.

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

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones

 *    Release: @release@

 *

 *   '$Author: sgarg $'

 *     '$Date: 2005-11-11 10:00:54 -0800 (Fri, 11 Nov 2005) $'

 * '$Revision: 2733 $'

 *

 * 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;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.Vector;

import java.util.HashMap;

import java.lang.Comparable;

import edu.ucsb.nceas.metacat.MetaCatUtil;

import org.apache.log4j.Logger;

public class IndexingQueue {

	private Logger logMetacat = Logger.getLogger(IndexingQueue.class);

	//	 Map used to keep tracks of docids to be indexed

	private HashMap indexingMap = new HashMap();     

	private Vector currentThreads = new Vector();

	public Vector currentDocidsBeingIndexed = new Vector();

	private static IndexingQueue instance = null;

	final static int NUMBEROFINDEXINGTHREADS = 

		Integer.parseInt(MetaCatUtil.getOption("numberOfIndexingThreads"));

	private int sleepTime = 2000; 

    public IndexingQueue() {

	    for (int i = 0; i < NUMBEROFINDEXINGTHREADS; i++) {

	      Thread thread = new IndexingTask();

	      thread.start();

	    }

    }

	public static synchronized IndexingQueue getInstance(){

		if (instance == null) {

			instance = new IndexingQueue();

		}

		return instance;

	}//getInstance

    public void add(String docid, String rev) {

    	add(new IndexingQueueObject(docid, rev, 0));

    }

    protected void add(IndexingQueueObject queueObject) {

	    synchronized (indexingMap) {

	    	if(!indexingMap.containsKey(queueObject.getDocid())){

	    		indexingMap.put(queueObject.getDocid(), queueObject);

	    		indexingMap.notify();

	    	} else {

	    		IndexingQueueObject oldQueueObject = 

	    			(IndexingQueueObject) indexingMap.get(queueObject.getDocid());

	    		if(oldQueueObject.compareTo(queueObject) < 0){

	    	  		indexingMap.put(queueObject.getDocid(), queueObject);

		    		indexingMap.notify();  			

	    		}

	    	}

	    }

	  }

    protected IndexingQueueObject getNext() {

    	IndexingQueueObject returnVal = null;

        synchronized (indexingMap) {

          while (indexingMap.isEmpty()) {

            try {

            	indexingMap.wait();

            } catch (InterruptedException ex) {

              System.err.println("Interrupted");

            }

          }

          String docid = (String) indexingMap.keySet().iterator().next();

          returnVal = (IndexingQueueObject)indexingMap.get(docid);

          indexingMap.remove(docid);

        }

        return returnVal;

      }

}

class IndexingTask extends Thread {

  	  private Logger logMetacat = Logger.getLogger(IndexingTask.class);

      protected final long MAXIMUMINDEXDELAY = Integer.

      	parseInt(MetaCatUtil.getOption("maximumIndexDelay"));;

	  public void run() {

	    while (true) {

	      // blocks until job

	      IndexingQueueObject returnVal = 

	    	  IndexingQueue.getInstance().getNext();

    	  if(!IndexingQueue.getInstance().

	    			currentDocidsBeingIndexed.contains(returnVal.getDocid())){

    		  try {

    			  IndexingQueue.getInstance().

    			  		currentDocidsBeingIndexed.add(returnVal.getDocid());

    		      String docid = returnVal.getDocid() + "." + returnVal.getRev();

    			  checkDocumentTable(docid, "xml_documents");

    			  DocumentImpl doc = new DocumentImpl(docid, false);

    			  logMetacat.warn("Calling buildIndex for " + docid);

    			  doc.buildIndex();

    		  } catch (Exception e) {

    			  logMetacat.warn("Exception: " + e);

    			  e.printStackTrace();

    			  if(returnVal.getCount() < 25){

    				  returnVal.setCount(returnVal.getCount()+1);

    				  // add the docid back to the list

    				  IndexingQueue.getInstance().add(returnVal);

    			  } else {

    				  logMetacat.fatal("Docid " + returnVal.getDocid() 

	        			+ " has been inserted to IndexingQueue "

	        			+ "more than 25 times. Not adding the docid to"

	        			+ " the queue again.");

    			  }

    		  } finally {

    			  IndexingQueue.getInstance().currentDocidsBeingIndexed

	    	  			.remove(returnVal.getDocid());	    	  

    		  }

    	  } else {

				returnVal.setCount(returnVal.getCount()+1);

				IndexingQueue.getInstance().add(returnVal);    		  

    	  }

	    }

	  }

      private void checkDocumentTable(String docid, String tablename) throws Exception{

	        DBConnection dbConn = null;

	        int serialNumber = -1;

	        String revision = docid.substring(docid.lastIndexOf(".")+1,docid.length());

	        docid = docid.substring(0,docid.lastIndexOf("."));

	        logMetacat.warn("docid is " + docid 

	        		+ " and revision is " + revision);

	        try {

	            // Opening separate db connection for writing XML Index

	            dbConn = DBConnectionPool

	                    .getDBConnection("DBSAXHandler.checkDocumentTable");

	            serialNumber = dbConn.getCheckOutSerialNumber();

	            // the following while loop construct checks to make sure that

	            // the docid of the document that we are trying to index is already

	            // in the xml_documents table. if this is not the case, the foreign

	            // key relationship between xml_documents and xml_index is

	            // temporarily broken causing multiple problems.

	            boolean inxmldoc = false;

	            long startTime = System.currentTimeMillis();

	            while (!inxmldoc) {

	                String xmlDocumentsCheck = "select distinct docid from " + tablename

	                        + " where docid ='"

	                        + docid

	                        + "' and "

	                        + " rev ='"

	                        + revision + "'";

	                PreparedStatement xmlDocCheck = dbConn

	                        .prepareStatement(xmlDocumentsCheck);

	                // Increase usage count

	                dbConn.increaseUsageCount(1);

	                xmlDocCheck.execute();

	                ResultSet doccheckRS = xmlDocCheck.getResultSet();

	                boolean tableHasRows = doccheckRS.next();

	                if (tableHasRows) {

	                    inxmldoc = true;

	                }

	                doccheckRS.close();

	                xmlDocCheck.close();

	                // make sure the while loop will be ended in reseaonable time

	                long stopTime = System.currentTimeMillis();

	                if ((stopTime - startTime) > MAXIMUMINDEXDELAY) { 

	                	logMetacat.warn("Couldn't find the docid:" + docid 

	                			+ " for indexing in "

                                + "reseaonable time!");

	                	throw new Exception(

	                        "Couldn't find the docid for index build in "

	                                + "reseaonable time!"); 

	                }

	            }//while

	        } catch (SQLException e) {

	        	   e.printStackTrace();

	        } finally {

	            DBConnectionPool.returnDBConnection(dbConn, serialNumber);

	        }//finally

	    }

	}

class IndexingQueueObject implements Comparable{

	// the docid of the document to be indexed. 

	private String docid;

	// the docid of the document to be indexed. 

	private String rev;

	// the count of number of times the document has been in the queue

	private int count;

	IndexingQueueObject(String docid, String rev, int count){

		this.docid = docid;

		this.rev = rev;

		this.count = count;

	}

	public int getCount(){

		return count;

	}

	public String getDocid(){

		return docid;

	}

	public String getRev(){

		return rev;

	}

	public void setCount(int count){

		this.count = count;

	}

	public void setDocid(String docid){

		this.docid = docid;

	}

	public void setRev(String rev){

		this.rev = rev;

	}

	public int compareTo(Object o){

		if(o instanceof IndexingQueueObject){

			int revision = Integer.parseInt(rev);

			int oRevision = Integer.parseInt(((IndexingQueueObject)o).getRev());

			if(revision == oRevision) {

				return 0;

			} else if (revision > oRevision) {

				return 1;

			} else {

				return -1;

			}

		} else {

			throw new java.lang.ClassCastException();

		}

	}

}