source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/service/GS2LuceneSearch.java@ 32619

/*
 *    GS2LuceneSearch.java
 *    Copyright (C) 2006 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *   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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

package org.greenstone.gsdl3.service;

// Greenstone classes
import java.io.File;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Vector;

// For maintaining Lucene IndexReader objects at collection level
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;

import org.apache.log4j.Logger;
import org.greenstone.LuceneWrapper4.GS2LuceneQuery;
import org.greenstone.LuceneWrapper4.LuceneQueryResult;
import org.greenstone.gsdl3.util.FacetWrapper;
import org.greenstone.gsdl3.util.GSFile;
import org.greenstone.gsdl3.util.GSXML;
import org.greenstone.gsdl3.util.XMLConverter;
import org.w3c.dom.Document;
import org.w3c.dom.Element;


public class GS2LuceneSearch extends SharedSoleneGS2FieldSearch
{

  protected static final String SORT_ORDER_PARAM = "reverseSort";
  protected static final String SORT_ORDER_REVERSE = "1";
  protected static final String SORT_ORDER_NORMAL = "0";

    // IndexReader objects are to be opened for each index level (e.g. one for didx, one for sidx) of a 
    // collection and will live for the duration of that collection, which is from collection activation
    // until deactivation.
    // So we want singletons of each index level's IndexReader, since IndexReaders are "multi-threaded
    // re-entrant", so there's support for just one reader per index with concurrent access by multiple users'
    // search queries.
    // When a collection is deactivated, we need to close the reader objects to prevent handles to the 
    // index lingering and causing file locking issues on windows.
    // Since GS2LuceneQuery now becomes a local member variable instantiated per query, we have to maintain
    // IndexReader objects in GS2LuceneSearch instead, as GS2LuceneSearch is a collection's service, and
    // therefore activated and deactivated along with the collection.
    // The uniqueness of an IndexReader is indicated in the filepath to its index folder (collection path + sidx/didx).
    // It doesn't have to be a static map of index_dir to IndexReader, and can be a member variable, since
    // no other collection will refer to the same didx and sidx index folders: each collection has unique filepaths
    // to its collection folder's index subdirs, not shared with other collections so the Readers don't have to be
    // shared between collections either.

    // We now store IndexReaders in a map of singleton index_dir -> IndexReaders opened for this collection:
    // one Reader singleton for each index_dir
    private Map<String, IndexReader> index_to_reader_map = new HashMap<String, IndexReader>();
  
    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.service.GS2LuceneSearch.class.getName());

    public GS2LuceneSearch()
    {
      does_paging = true;
        paramDefaults.put(SORT_ORDER_PARAM, SORT_ORDER_NORMAL);
    }

    public void cleanUp()
    {
        super.cleanUp();
        
        // Prevent file locking issues: close all IndexReader objects maintained for this collection
        synchronized(index_to_reader_map) { // Regular Map implementations are not synchronized, so adding/removing requires synchronizing on the map object.
                                        // see https://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html
                                        // And ConcurrentHashMap seems complicated, https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentHashMap.html
                                        
                                        // Synchronizing *outside* the loop because cleanUp() clears the entire HashMap.
                                        // Don't let any other threads access the map, hence synchronizing.
                                        // Not sure if there may be other threads accessing the map when deactivating a collection which calls cleanUp().
                                        // However, when multiple users' search queries lead to adding to the hashmap, definitely need to
                                        // synchronize as there's a greater possibility of concurrent access then.                                      
                                            
            Iterator<Map.Entry<String,IndexReader>> map_iterator = index_to_reader_map.entrySet().iterator(); 
                        // Can use the Map.Entry Set view iterator to remove (key, value) entry from underlying Map!
                        // See https://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html#keySet()
                        // Same thread creates the iterator as synchronizes on the map, so we should be allowed to remove() from the map
                        // but only through iterator!
            while(map_iterator.hasNext()) {             
                Map.Entry<String,IndexReader> entry = map_iterator.next();
                //index_to_reader_map.remove(...); // concurrentmodexception! Only allowed to remove through iterator. Will remove recent object returned by next()
                IndexReader reader = entry.getValue(); //keys are index dir paths, e.g. path to current collection's didx folder, values are IndexReader objects
                map_iterator.remove();  // removes current key's (key,value) entry from underlying map! (Remember, we're iterating on the keyset)
                                        // We're first removing the reader singleton from map because reader.close() will only close the reader
                                        //if it's the final reference to it in case that has a bearing here
                
                if(reader != null) { // if there was a reader singleton instantiated for this index directory, e.g. coll-didx, close it                     
                    try {
                        // We're opening an IndexReader per indexdir once and closing it once: at start and end of collection.
                        // If Reader was a member var of GS2LuceneQuery and if multiple GS2LuceneQuery Objects were to call close() on the
                        // same reader object (on the singleton instance of reader for an index dir), so close is called multiple times,
                        // then would use incRef and decRef, see http://lucene.472066.n3.nabble.com/IndexReader-close-behavior-td2865515.html
                        // But then when concurrent queries are done, the final one would have closed the IndexReader and it would have to
                        // be reopened for the next query. We'd rather keep an opened IndexReader around until the collection's deactivated.
                        reader.close();
                        // Closes files associated with this index. Also saves any new deletions to disk. 
                        // No other methods should be called after this has been called.
                    } catch (IOException exception) {
                        exception.printStackTrace();
                    }           
                }               
            } // end loop
        } // end synchronising on index_to_reader_map

        // Now we've closed all the Readers maintained for this collection and cleared the map.
    }
    
  public boolean configure(Element info, Element extra_info)
  {
    if (!super.configure(info, extra_info))
      {
    return false;
      }
    logger.info("Configuring GS2LuceneSearch...");

    // add our reverseSort param to be saved to the session
    this.save_params.add(SORT_ORDER_PARAM);
    return true;
  }
    /** add in the Lucene specific params to TextQuery */
    protected void addCustomQueryParams(Element param_list, String lang)
    {
        super.addCustomQueryParams(param_list, lang);
        /** Add in the reverse sort on/off param */
        createParameter(SORT_ORDER_PARAM, param_list, lang);
    }
  /** add in Lucene specific params for AdvancedFieldQuery */
  protected void addCustomQueryParamsAdvField(Element param_list, String lang)
    {
        super.addCustomQueryParamsAdvField(param_list, lang);
        createParameter(SORT_ORDER_PARAM, param_list, lang);
        
    }
    /** create a param and add to the list */
  protected void createParameter(String name, Element param_list, String lang)
  {
    Document doc = param_list.getOwnerDocument();
    Element param = null;
    String param_default = paramDefaults.get(name);
    if (name.equals(SORT_ORDER_PARAM)) {
        String[] vals = { SORT_ORDER_REVERSE, SORT_ORDER_NORMAL };
        String[] vals_texts = { getTextString("param." + SORT_ORDER_PARAM + "." + SORT_ORDER_REVERSE, lang), getTextString("param." + SORT_ORDER_PARAM + "." + SORT_ORDER_NORMAL, lang) };

        param = GSXML.createParameterDescription(doc, SORT_ORDER_PARAM, getTextString("param." + SORT_ORDER_PARAM, lang), GSXML.PARAM_TYPE_ENUM_SINGLE, param_default, vals, vals_texts);
    }

    if (param != null)
      {
    param_list.appendChild(param);
      }
    else
      {
    super.createParameter(name, param_list, lang);
      }
    
  }
   
    /** methods to handle actually doing the query */

    /** do any initialisation of the query object */
    protected Object setUpQueryer(HashMap params)
    {
        // local Query object
        GS2LuceneQuery lucene_src = new GS2LuceneQuery();
        
        String indexdir = GSFile.collectionBaseDir(this.site_home, this.cluster_name) + File.separatorChar + "index" + File.separatorChar;

        String index = "didx";
        if (this.default_level.toUpperCase().equals("SEC")) {
          index = "sidx";
        }
        String physical_index_language_name = null;
        String physical_sub_index_name = null;
        int hits_per_page = Integer.parseInt(paramDefaults.get(HITS_PER_PAGE_PARAM));
        int start_page = Integer.parseInt(paramDefaults.get(START_PAGE_PARAM));
        String sort_field = getLuceneSort(default_sort);
        String sort_order = paramDefaults.get(SORT_ORDER_PARAM);
           
        // set up the query params
        Set entries = params.entrySet();
        Iterator i = entries.iterator();
        while (i.hasNext())
        {
            Map.Entry m = (Map.Entry) i.next();
            String name = (String) m.getKey();
            String value = (String) m.getValue();

            if (name.equals(HITS_PER_PAGE_PARAM))
            {
              if (value.equals("all")) {
                hits_per_page = -1;
              } else {
                hits_per_page = Integer.parseInt(value);
              }
            }
            else if (name.equals(START_PAGE_PARAM))
            {
                start_page = Integer.parseInt(value);

            }
            else if (name.equals(MATCH_PARAM))
            {
                if (value.equals(MATCH_PARAM_ALL))
                {
                    lucene_src.setDefaultConjunctionOperator("AND");
                }
                else
                {
                    lucene_src.setDefaultConjunctionOperator("OR");
                }
            }
            else if (name.equals(RANK_PARAM))
            {
              sort_field = getLuceneSort(value);
              lucene_src.setSortField(sort_field);

            }
            else if (name.equals(SORT_ORDER_PARAM)) {
              sort_order = value;
            }
            else if (name.equals(LEVEL_PARAM))
            {
                if (value.toUpperCase().equals("SEC"))
                {
                    index = "sidx";
                }
                else
                {
                    index = "didx";
                }
            }
            else if (name.equals(INDEX_SUBCOLLECTION_PARAM))
            {
                physical_sub_index_name = value;
            }
            else if (name.equals(INDEX_LANGUAGE_PARAM))
            {
                physical_index_language_name = value;
            } // ignore any others
        }
        // set up start and end results if necessary
        // start results always start at 0
        int start_results = 0; 
        if (start_page > 1 && hits_per_page > 0)
        {
          start_results = ((start_page - 1) * hits_per_page) ; 
        }
        int end_results = Integer.MAX_VALUE;
        if (hits_per_page > 0) {
          end_results = hits_per_page * start_page;
        }
        lucene_src.setStartResults(start_results);
        lucene_src.setEndResults(end_results);

        if (index.equals("sidx") || index.equals("didx"))
        {
            if (physical_sub_index_name != null)
            {
                index += physical_sub_index_name;
            }
            if (physical_index_language_name != null)
            {
                index += physical_index_language_name;
            }
        }

        if (sort_order.equals(SORT_ORDER_REVERSE)) {
          lucene_src.setReverseSort(true);
        } else {
          lucene_src.setReverseSort(false);
        }
        
        String full_index_dir_str = indexdir + index;
        lucene_src.setIndexDir(full_index_dir_str);     
        
        // Ensure we have an IndexReader for this full_index_dir_str:
        // check the hashmap first, in case we already opened a reader and searcher for this index dir, e.g. didx
        // if there was a reader singleton instantiated for this index directory, e.g. <coll>didx, use that.
        // Else open a new reader for this index_dir and store it in the map.
        IndexReader reader = index_to_reader_map.get(full_index_dir_str);       
        if(reader == null) { 
            try {           
                Directory full_indexdir_dir = FSDirectory.open(new File(full_index_dir_str));
                reader = DirectoryReader.open(full_indexdir_dir); // Returns an IndexReader reading the index in the given Directory. now readOnly=true by default, and therefore also for searcher
                synchronized(index_to_reader_map) {
                    // If storing searcher along with reader, mimic Pairs with: https://stackoverflow.com/questions/2670982/using-pairs-or-2-tuples-in-java
                    index_to_reader_map.put(full_index_dir_str, reader);
                }
            }
            catch (IOException exception) {
                exception.printStackTrace();                
            }           
        }
        
        lucene_src.initialise(reader); // sets IndexReader and IndexSearcher
        
        return lucene_src; // return the queryobject
    }

    /** do the query */
    protected Object runQuery(Object queryObject, String query)
    {
        GS2LuceneQuery lucene_src = (GS2LuceneQuery) queryObject;
        try
        {
            LuceneQueryResult lqr = lucene_src.runQuery(query);
            return lqr;
        }
        catch (Exception e)
        {
            logger.error("Exception happened in runQuery(): ", e);
        }

        return null;
    }

    /** get the total number of docs that match */
    protected long numDocsMatched(Object query_result)
    {
        return ((LuceneQueryResult) query_result).getTotalDocs();
    }

    /** get the list of doc ids */
    protected String[] getDocIDs(Object query_result)
    {
        Vector docs = ((LuceneQueryResult) query_result).getDocs();
        String[] doc_nums = new String[docs.size()];
        for (int d = 0; d < docs.size(); d++)
        {
            String doc_num = ((LuceneQueryResult.DocInfo) docs.elementAt(d)).id_;
            doc_nums[d] = doc_num;
        }
        return doc_nums;
    }

    /** get the list of doc ranks */
    protected String[] getDocRanks(Object query_result)
    {
        Vector docs = ((LuceneQueryResult) query_result).getDocs();
        String[] doc_ranks = new String[docs.size()];
        for (int d = 0; d < docs.size(); d++)
        {
            doc_ranks[d] = Float.toString(((LuceneQueryResult.DocInfo) docs.elementAt(d)).rank_);
        }
        return doc_ranks;
    }

    /** add in term info if available */
    protected boolean addTermInfo(Element term_list, HashMap params, Object query_result)
    {
      Document doc = term_list.getOwnerDocument();
        String query_level = (String) params.get(LEVEL_PARAM); // the current query level

        Vector terms = ((LuceneQueryResult) query_result).getTerms();
        for (int t = 0; t < terms.size(); t++)
        {
            LuceneQueryResult.TermInfo term_info = (LuceneQueryResult.TermInfo) terms.get(t);

            Element term_elem = doc.createElement(GSXML.TERM_ELEM);
            term_elem.setAttribute(GSXML.NAME_ATT, term_info.term_);
            term_elem.setAttribute(FREQ_ATT, "" + term_info.term_freq_);
            term_elem.setAttribute(NUM_DOCS_MATCH_ATT, "" + term_info.match_docs_);
            term_elem.setAttribute(FIELD_ATT, term_info.field_);
            term_list.appendChild(term_elem);
        }

        Vector stopwords = ((LuceneQueryResult) query_result).getStopWords();
        for (int t = 0; t < stopwords.size(); t++)
        {
            String stopword = (String) stopwords.get(t);

            Element stopword_elem = doc.createElement(GSXML.STOPWORD_ELEM);
            stopword_elem.setAttribute(GSXML.NAME_ATT, stopword);
            term_list.appendChild(stopword_elem);
        }

        return true;
    }
    
  protected ArrayList<FacetWrapper> getFacets(Object query_result, String lang)
    {
        return null;
    }

  protected String getLuceneSort(String gs3_sort) {

    if (gs3_sort.equals(RANK_PARAM_RANK)) {
      return GS2LuceneQuery.SORT_RANK;
    }
    if (gs3_sort.equals(RANK_PARAM_NONE)) {
      return GS2LuceneQuery.SORT_NATURAL;
    }
    return gs3_sort;
  }

@Override
protected Map<String, Map<String, List<String>>> getHighlightSnippets(
        Object query_result) {
    // TODO Auto-generated method stub
    return null;
}

}