yacy_search_server/source/de/anomic/plasma/plasmaSearchEvent.java

// plasmaSearchEvent.java
// (C) 2005 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 10.10.2005 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
// $LastChangedRevision: 1986 $
// $LastChangedBy: orbiter $
//
// LICENSE
// 
// 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 de.anomic.plasma;

import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

import de.anomic.index.indexContainer;
import de.anomic.index.indexRWIEntry;
import de.anomic.index.indexURLEntry;
import de.anomic.kelondro.kelondroBitfield;
import de.anomic.kelondro.kelondroMSetTools;
import de.anomic.kelondro.kelondroRow;
import de.anomic.server.logging.serverLog;
import de.anomic.yacy.yacyCore;
import de.anomic.yacy.yacyDHTAction;
import de.anomic.yacy.yacySearch;
import de.anomic.yacy.yacySeed;
import de.anomic.yacy.yacyURL;

public final class plasmaSearchEvent {
    
    public static int workerThreadCount = 10;
    public static String lastEventID = "";
    private static HashMap lastEvents = new HashMap(); // a cache for objects from this class: re-use old search requests
    public static final long eventLifetime = 600000; // the time an event will stay in the cache, 10 Minutes
    
    private long eventTime;
    private plasmaSearchQuery query;
    private plasmaSearchRankingProfile ranking;
    private plasmaWordIndex wordIndex;
    private plasmaSearchContainer rankedCache; // ordered search results, grows dynamically as all the query threads enrich this container
    private Map rcAbstracts; // cache for index abstracts; word:TreeMap mapping where the embedded TreeMap is a urlhash:peerlist relation
    private plasmaSearchProcessing process;
    private yacySearch[] primarySearchThreads, secondarySearchThreads;
    private Thread localSearchThread;
    private TreeMap preselectedPeerHashes;
    //private Object[] references;
    public  TreeMap IAResults, IACount;
    public  String IAmaxcounthash, IAneardhthash;
    private int localcount;
    private resultWorker[] workerThreads;
    private ArrayList resultList; // list of this.Entry objects
    //private int resultListLock; // a pointer that shows that all elements below this pointer are fixed and may not be changed again
    private HashMap failedURLs; // a mapping from a urlhash to a fail reason string
    TreeSet snippetFetchWordHashes; // a set of word hashes that are used to match with the snippets
    private long urlRetrievalAllTime;
    private long snippetComputationAllTime;
    
    private plasmaSearchEvent(plasmaSearchQuery query,
                             plasmaSearchRankingProfile ranking,
                             plasmaSearchProcessing localTiming,
                             plasmaWordIndex wordIndex,
                             TreeMap preselectedPeerHashes,
                             boolean generateAbstracts,
                             TreeSet abstractSet) {
        this.eventTime = System.currentTimeMillis(); // for lifetime check
        this.wordIndex = wordIndex;
        this.query = query;
        this.ranking = ranking;
        this.rcAbstracts = (query.queryHashes.size() > 1) ? new TreeMap() : null; // generate abstracts only for combined searches
        this.process = localTiming;
        this.primarySearchThreads = null;
        this.secondarySearchThreads = null;
        this.preselectedPeerHashes = preselectedPeerHashes;
        this.IAResults = new TreeMap();
        this.IACount = new TreeMap();
        this.IAmaxcounthash = null;
        this.IAneardhthash = null;
        this.localcount = 0;
        this.urlRetrievalAllTime = 0;
        this.snippetComputationAllTime = 0;
        this.workerThreads = null;
        this.resultList = new ArrayList(10); // this is the result set which is filled up with search results, enriched with snippets
        //this.resultListLock = 0; // no locked elements until now
        this.failedURLs = new HashMap(); // a map of urls to reason strings where a worker thread tried to work on, but failed.
        
        // snippets do not need to match with the complete query hashes,
        // only with the query minus the stopwords which had not been used for the search
        final TreeSet filtered = kelondroMSetTools.joinConstructive(query.queryHashes, plasmaSwitchboard.stopwords);
        this.snippetFetchWordHashes = (TreeSet) query.queryHashes.clone();
        if ((filtered != null) && (filtered.size() > 0)) {
            kelondroMSetTools.excludeDestructive(this.snippetFetchWordHashes, plasmaSwitchboard.stopwords);
        }
        
        long start = System.currentTimeMillis();
        if ((query.domType == plasmaSearchQuery.SEARCHDOM_GLOBALDHT) ||
            (query.domType == plasmaSearchQuery.SEARCHDOM_CLUSTERALL)) {
            this.rankedCache = new plasmaSearchContainer(query, ranking, plasmaSearchQuery.cleanQuery(query.queryString)[0]);
            
            int fetchpeers = (int) (query.maximumTime / 500L); // number of target peers; means 10 peers in 10 seconds
            if (fetchpeers > 50) fetchpeers = 50;
            if (fetchpeers < 30) fetchpeers = 30;

            // do a global search
            // the result of the fetch is then in the rcGlobal
            process.startTimer();
            serverLog.logFine("SEARCH_EVENT", "STARTING " + fetchpeers + " THREADS TO CATCH EACH " + query.displayResults() + " URLs");
            this.primarySearchThreads = yacySearch.primaryRemoteSearches(
                    plasmaSearchQuery.hashSet2hashString(query.queryHashes),
                    plasmaSearchQuery.hashSet2hashString(query.excludeHashes),
                    "",
                    query.prefer,
                    query.urlMask,
                    query.displayResults(),
                    query.maxDistance,
                    wordIndex,
                    rankedCache, 
                    rcAbstracts,
                    fetchpeers,
                    plasmaSwitchboard.urlBlacklist,
                    ranking,
                    query.constraint,
                    (query.domType == plasmaSearchQuery.SEARCHDOM_GLOBALDHT) ? null : preselectedPeerHashes);
            process.yield("remote search thread start", this.primarySearchThreads.length);
            
            // meanwhile do a local search
            localSearchThread = new localSearchProcess();
            localSearchThread.start();
           
            // finished searching
            serverLog.logFine("SEARCH_EVENT", "SEARCH TIME AFTER GLOBAL-TRIGGER TO " + primarySearchThreads.length + " PEERS: " + ((System.currentTimeMillis() - start) / 1000) + " seconds");
        } else {
            Map[] searchContainerMaps = process.localSearchContainers(query, wordIndex, null);
            
            if (generateAbstracts) {
                // compute index abstracts
                process.startTimer();
                Iterator ci = searchContainerMaps[0].entrySet().iterator();
                Map.Entry entry;
                int maxcount = -1;
                double mindhtdistance = 1.1, d;
                String wordhash;
                while (ci.hasNext()) {
                    entry = (Map.Entry) ci.next();
                    wordhash = (String) entry.getKey();
                    indexContainer container = (indexContainer) entry.getValue();
                    assert (container.getWordHash().equals(wordhash));
                    if (container.size() > maxcount) {
                        IAmaxcounthash = wordhash;
                        maxcount = container.size();
                    }
                    d = yacyDHTAction.dhtDistance(yacyCore.seedDB.mySeed().hash, wordhash);
                    if (d < mindhtdistance) {
                        // calculate the word hash that is closest to our dht position
                        mindhtdistance = d;
                        IAneardhthash = wordhash;
                    }
                    IACount.put(wordhash, new Integer(container.size()));
                    IAResults.put(wordhash, plasmaSearchProcessing.compressIndex(container, null, 1000).toString());
                }
                process.yield("abstract generation", searchContainerMaps[0].size());
            }
            
            indexContainer rcLocal =
                (searchContainerMaps == null) ?
                  plasmaWordIndex.emptyContainer(null, 0) :
                      process.localSearchJoinExclude(
                          searchContainerMaps[0].values(),
                          searchContainerMaps[1].values(),
                          query.maxDistance);
            this.localcount = rcLocal.size();
            plasmaSearchPreOrder sort = new plasmaSearchPreOrder(query, process, ranking, rcLocal);
            
            process.startTimer();
            rcLocal = sort.strippedContainer(200);
            process.yield("result strip", rcLocal.size());
            
            this.rankedCache = new plasmaSearchContainer(query, ranking, plasmaSearchQuery.cleanQuery(query.queryString)[0], rcLocal);
        }
        
        if (query.onlineSnippetFetch) {
            // start worker threads to fetch urls and snippets
            this.workerThreads = new resultWorker[workerThreadCount];
            for (int i = 0; i < workerThreadCount; i++) {
                this.workerThreads[i] = new resultWorker(i, process.getTargetTime() * 3);
                this.workerThreads[i].start();
            }
        } else {
            // prepare result vector directly without worker threads
            int rankedIndex = 0;
            process.startTimer();
            
            while ((rankedIndex < rankedCache.container().size()) && (resultList.size() < (query.neededResults()))) {
                // fetch next entry to work on
                indexContainer c = rankedCache.container();
                indexRWIEntry entry = new indexRWIEntry(c.get(rankedIndex++));
                indexURLEntry page = wordIndex.loadedURL.load(entry.urlHash(), entry);
                
                if (page == null) {
                    registerFailure(entry.urlHash(), "url does not exist in lurl-db");
                    continue;
                }
                
                ResultEntry resultEntry = obtainResultEntry(page, false);
                if (resultEntry == null) continue; // the entry had some problems, cannot be used
                urlRetrievalAllTime += resultEntry.dbRetrievalTime;
                snippetComputationAllTime += resultEntry.snippetComputationTime;
                
                // place the result to the result vector
                synchronized (resultList) {
                    resultList.add(resultEntry);
                }

                // add references
                synchronized (rankedCache) {
                    rankedCache.addReferences(resultEntry);
                }
            }
            process.yield("offline snippet fetch", resultList.size());
        }
        
        // clean up events
        cleanupEvents();
        
        // store this search to a cache so it can be re-used
        lastEvents.put(query.id(), this);
        lastEventID = query.id();
    }
    

    private class localSearchProcess extends Thread {
        
        public localSearchProcess() {
        }
        
        public void run() {
            // do a local search
            Map[] searchContainerMaps = process.localSearchContainers(query, wordIndex, null);
            
            // use the search containers to fill up rcAbstracts locally
            /*
            if ((rcAbstracts != null) && (searchContainerMap != null)) {
                Iterator i, ci = searchContainerMap.entrySet().iterator();
                Map.Entry entry;
                String wordhash;
                indexContainer container;
                TreeMap singleAbstract;
                String mypeerhash = yacyCore.seedDB.mySeed.hash;
                while (ci.hasNext()) {
                    entry = (Map.Entry) ci.next();
                    wordhash = (String) entry.getKey();
                    container = (indexContainer) entry.getValue();
                    // collect all urlhashes from the container
                    synchronized (rcAbstracts) {
                        singleAbstract = (TreeMap) rcAbstracts.get(wordhash); // a mapping from url-hashes to a string of peer-hashes
                        if (singleAbstract == null) singleAbstract = new TreeMap();
                        i = container.entries();
                        while (i.hasNext()) singleAbstract.put(((indexEntry) i.next()).urlHash(), mypeerhash);
                        rcAbstracts.put(wordhash, singleAbstract);
                    }
                }
            }
            */
            
            // join and exlcude the local result
            indexContainer rcLocal =
                (searchContainerMaps == null) ?
                  plasmaWordIndex.emptyContainer(null, 0) :
                      process.localSearchJoinExclude(
                          searchContainerMaps[0].values(),
                          searchContainerMaps[1].values(),
                          query.maxDistance);
            localcount = rcLocal.size();
            
            // sort the local containers and truncate it to a limited count,
            // so following sortings together with the global results will be fast
            plasmaSearchPreOrder firstsort = new plasmaSearchPreOrder(query, process, ranking, rcLocal);
            rcLocal = firstsort.strippedContainer(200);
            synchronized (rankedCache) {
                rankedCache.insert(rcLocal, true, true);
            }
        }
    }

    private static void cleanupEvents() {
        // remove old events in the event cache
        Iterator i = lastEvents.entrySet().iterator();
        plasmaSearchEvent cleanEvent;
        while (i.hasNext()) {
            cleanEvent = (plasmaSearchEvent) ((Map.Entry) i.next()).getValue();
            if (cleanEvent.eventTime + eventLifetime < System.currentTimeMillis()) {
                // execute deletion of failed words
                Set removeWords = cleanEvent.query.queryHashes;
                removeWords.addAll(cleanEvent.query.excludeHashes);
                cleanEvent.wordIndex.removeEntriesMultiple(removeWords, cleanEvent.failedURLs.keySet());
                serverLog.logInfo("SearchEvents", "cleaning up event " + cleanEvent.query.id() + ", removed " + cleanEvent.failedURLs.size() + " URL references on " + removeWords.size() + " words");
                
                // remove the event
                i.remove();
            }
        }
    }
    
    private ResultEntry obtainResultEntry(indexURLEntry page, boolean fetchSnippetOnline) {

        // a search result entry needs some work to produce a result Entry:
        // - check if url entry exists in LURL-db
        // - check exclusions, constraints, masks, media-domains
        // - load snippet (see if page exists) and check if snippet contains searched word
        
        // load only urls if there was not yet a root url of that hash
        // find the url entry
        
        long startTime = System.currentTimeMillis();
        indexURLEntry.Components comp = page.comp();
        String pagetitle = comp.title().toLowerCase();
        if (comp.url() == null) {
            registerFailure(page.hash(), "url corrupted (null)");
            return null; // rare case where the url is corrupted
        }
        String pageurl = comp.url().toString().toLowerCase();
        String pageauthor = comp.author().toLowerCase();
        long dbRetrievalTime = System.currentTimeMillis() - startTime;
        
        // check exclusion
        if ((plasmaSearchQuery.matches(pagetitle, query.excludeHashes)) ||
            (plasmaSearchQuery.matches(pageurl, query.excludeHashes)) ||
            (plasmaSearchQuery.matches(pageauthor, query.excludeHashes))) {
            return null;
        }
            
        // check url mask
        if (!(pageurl.matches(query.urlMask))) {
            return null;
        }
            
        // check constraints
        if ((!(query.constraint.equals(plasmaSearchQuery.catchall_constraint))) &&
            (query.constraint.get(plasmaCondenser.flag_cat_indexof)) &&
            (!(comp.title().startsWith("Index of")))) {
            final Iterator wi = query.queryHashes.iterator();
            while (wi.hasNext()) wordIndex.removeEntry((String) wi.next(), page.hash());
            registerFailure(page.hash(), "index-of constrained not fullfilled");
            return null;
        }
        
        if ((query.contentdom == plasmaSearchQuery.CONTENTDOM_AUDIO) && (page.laudio() == 0)) {
            registerFailure(page.hash(), "contentdom-audio constrained not fullfilled");
            return null;
        }
        if ((query.contentdom == plasmaSearchQuery.CONTENTDOM_VIDEO) && (page.lvideo() == 0)) {
            registerFailure(page.hash(), "contentdom-video constrained not fullfilled");
            return null;
        }
        if ((query.contentdom == plasmaSearchQuery.CONTENTDOM_IMAGE) && (page.limage() == 0)) {
            registerFailure(page.hash(), "contentdom-image constrained not fullfilled");
            return null;
        }
        if ((query.contentdom == plasmaSearchQuery.CONTENTDOM_APP) && (page.lapp() == 0)) {
            registerFailure(page.hash(), "contentdom-app constrained not fullfilled");
            return null;
        }
            
        // load snippet
        if (query.contentdom == plasmaSearchQuery.CONTENTDOM_TEXT) {
            // attach text snippet
            startTime = System.currentTimeMillis();
            plasmaSnippetCache.TextSnippet snippet = plasmaSnippetCache.retrieveTextSnippet(comp.url(), snippetFetchWordHashes, fetchSnippetOnline, query.constraint.get(plasmaCondenser.flag_cat_indexof), 180, 3000, (fetchSnippetOnline) ? Integer.MAX_VALUE : 100000);
            long snippetComputationTime = System.currentTimeMillis() - startTime;
            
            if (snippet.getErrorCode() < 11) {
                // we loaded the file and found the snippet
                return new ResultEntry(page, wordIndex, snippet, null, dbRetrievalTime, snippetComputationTime); // result with snippet attached
            } else if (!fetchSnippetOnline) {
                // we did not demand online loading, therefore a failure does not mean that the missing snippet causes a rejection of this result
                // this may happen during a remote search, because snippet loading is omitted to retrieve results faster
                return new ResultEntry(page, wordIndex, null, null, dbRetrievalTime, snippetComputationTime); // result without snippet
            } else {
                // problems with snippet fetch
                registerFailure(page.hash(), "no text snippet for URL " + comp.url());
                plasmaSnippetCache.failConsequences(snippet, query.id());
                return null;
            }
        } else {
            // attach media information
            startTime = System.currentTimeMillis();
            ArrayList mediaSnippets = plasmaSnippetCache.retrieveMediaSnippets(comp.url(), snippetFetchWordHashes, query.contentdom, fetchSnippetOnline, 6000);
            long snippetComputationTime = System.currentTimeMillis() - startTime;
            
            if ((mediaSnippets != null) && (mediaSnippets.size() > 0)) {
                // found media snippets, return entry
                return new ResultEntry(page, wordIndex, null, mediaSnippets, dbRetrievalTime, snippetComputationTime);
            } else if (!fetchSnippetOnline) {
                return new ResultEntry(page, wordIndex, null, null, dbRetrievalTime, snippetComputationTime);
            } else {
                // problems with snippet fetch
                registerFailure(page.hash(), "no media snippet for URL " + comp.url());
                return null;
            }
        }
        // finished, no more actions possible here
    }
    
    private boolean anyWorkerAlive() {
        if (this.workerThreads == null) return false;
        for (int i = 0; i < workerThreadCount; i++) {
           if ((this.workerThreads[i] != null) && (this.workerThreads[i].isAlive())) return true;
        }
        return false;
    }
    
    private boolean anyRemoteSearchAlive() {
        // check primary search threads
        if ((this.primarySearchThreads != null) && (this.primarySearchThreads.length != 0)) {
            for (int i = 0; i < this.primarySearchThreads.length; i++) {
                if ((this.primarySearchThreads[i] != null) && (this.primarySearchThreads[i].isAlive())) return true;
            }
        }
        // maybe a secondary search thread is alivem check this
        if ((this.secondarySearchThreads != null) && (this.secondarySearchThreads.length != 0)) {
            for (int i = 0; i < this.primarySearchThreads.length; i++) {
                if ((this.secondarySearchThreads[i] != null) && (this.secondarySearchThreads[i].isAlive())) return true;
            }
        }
        return false;
    }
    
    public plasmaSearchQuery getQuery() {
        return query;
    }
    
    public plasmaSearchRankingProfile getRanking() {
        return ranking;
    }
    
    public plasmaSearchProcessing getProcess() {
        return process;
    }
    
    public yacySearch[] getPrimarySearchThreads() {
        return primarySearchThreads;
    }
    public yacySearch[] getSecondarySearchThreads() {
        return secondarySearchThreads;
    }
    
    public int getLocalCount() {
        return this.localcount;
    }
    
    public int getGlobalCount() {
        return this.rankedCache.getGlobalCount();
    }
    
    public long getURLRetrievalTime() {
        return this.urlRetrievalAllTime;
    }
    
    public long getSnippetComputationTime() {
        return this.snippetComputationAllTime;
    }

    public static plasmaSearchEvent getEvent(String eventID) {
        synchronized (lastEvents) {
            return (plasmaSearchEvent) lastEvents.get(eventID);
        }
    }
    
    public static plasmaSearchEvent getEvent(plasmaSearchQuery query,
            plasmaSearchRankingProfile ranking,
            plasmaSearchProcessing localTiming,
            plasmaWordIndex wordIndex,
            TreeMap preselectedPeerHashes,
            boolean generateAbstracts,
            TreeSet abstractSet) {
        synchronized (lastEvents) {
            plasmaSearchEvent event = (plasmaSearchEvent) lastEvents.get(query.id());
            if (event == null) {
                event = new plasmaSearchEvent(query, ranking, localTiming, wordIndex, preselectedPeerHashes, generateAbstracts, abstractSet);
            } else {
                //re-new the event time for this event, so it is not deleted next time too early
                event.eventTime = System.currentTimeMillis();
                // replace the query, because this contains the current result offset
                event.query = query;
            }
        
            // if worker threads had been alive, but did not succeed, start them again to fetch missing links
            if ((query.onlineSnippetFetch) &&
                (!event.anyWorkerAlive()) &&
                (event.resultList.size() < query.neededResults() + 10) &&
                ((event.getLocalCount() + event.getGlobalCount()) > event.resultList.size())) {
                // set new timeout
                event.eventTime = System.currentTimeMillis();
                // start worker threads to fetch urls and snippets
                event.workerThreads = new resultWorker[workerThreadCount];
                for (int i = 0; i < workerThreadCount; i++) {
                    event.workerThreads[i] = event.deployWorker(i, 3 * event.process.getTargetTime());
                }
            }
        
            return event;
        }
        
    }
    
    private resultWorker deployWorker(int id, long lifetime) {
        resultWorker worker = new resultWorker(id, lifetime);
        worker.start();
        return worker;
    }

    private class resultWorker extends Thread {
        
        private indexRWIEntry entry;   // entry this thread is working on
        private long timeout; // the date until this thread should try to work
        private long sleeptime; // the sleeptime of this thread at the beginning of its life
        private int id;
        
        public resultWorker(int id, long lifetime) {
            this.id = id;
            this.timeout = System.currentTimeMillis() + lifetime;
            this.sleeptime = lifetime / 10 * id;
            this.entry = null;
        }

        public void run() {

            // sleep first to give remote loading threads a chance to fetch entries
            if (anyRemoteSearchAlive()) try {Thread.sleep(this.sleeptime);} catch (InterruptedException e1) {}
            
            // start fetching urls and snippets
            while (true) {
                
                if (resultList.size() > query.neededResults() + query.displayResults()) break; // computed enough

                if (System.currentTimeMillis() > this.timeout) break; // time is over
                
                // try secondary search
                prepareSecondarySearch(); // will be executed only once
                
                // fetch next entry to work on
                this.entry = null;
                entry = nextOrder();
                if (entry == null) {
                    if (anyRemoteSearchAlive()) {
                        // wait and try again
                        try {Thread.sleep(100);} catch (InterruptedException e) {}
                        continue;
                    } else {
                        // we will not see that there core more results in
                        break;
                    }
                }
                
                indexURLEntry page = wordIndex.loadedURL.load(entry.urlHash(), entry);
                if (page == null) {
                    registerFailure(entry.urlHash(), "url does not exist in lurl-db");
                    continue;
                }
                
                ResultEntry resultEntry = obtainResultEntry(page, true);
                if (resultEntry == null) continue; // the entry had some problems, cannot be used
                urlRetrievalAllTime += resultEntry.dbRetrievalTime;
                snippetComputationAllTime += resultEntry.snippetComputationTime;
                
                // place the result to the result vector
                synchronized (resultList) {
                    resultList.add(resultEntry);
                }

                // add references
                synchronized (rankedCache) {
                    rankedCache.addReferences(resultEntry);
                }
                
                System.out.println("DEBUG SNIPPET_LOADING: thread " + id + " got " + resultEntry.url());
            }
            serverLog.logInfo("SEARCH", "resultWorker thread " + id + " terminated");
        }
        
        private indexRWIEntry nextOrder() {
            synchronized (rankedCache) {
                indexContainer c = rankedCache.container();
                kelondroRow.Entry entry;
                String urlhash;
                for (int i = 0; i < c.size(); i++) {
                    entry = c.get(i);
                    urlhash = new String(entry.getColBytes(0));
                    if ((anyFailureWith(urlhash)) || (anyWorkerWith(urlhash)) || (anyResultWith(urlhash))) continue;
                    return new indexRWIEntry(entry);
                }
            }
            return null; // no more entries available
        }
        
        private boolean anyWorkerWith(String urlhash) {
            for (int i = 0; i < workerThreadCount; i++) {
                if ((workerThreads[i] == null) || (workerThreads[i] == this)) continue;
                if ((workerThreads[i].entry != null) && (workerThreads[i].entry.urlHash().equals(urlhash))) return true;
            }
            return false;
        }
        
        private boolean anyResultWith(String urlhash) {
            for (int i = 0; i < resultList.size(); i++) {
                if (((ResultEntry) resultList.get(i)).urlentry.hash().equals(urlhash)) return true;
            }
            return false;
        }
        
        private boolean anyFailureWith(String urlhash) {
            return (failedURLs.get(urlhash) != null);
        }
    }
    
    private void registerFailure(String urlhash, String reason) {
        this.failedURLs.put(urlhash, reason);
        serverLog.logInfo("search", "sorted out hash " + urlhash + " during search: " + reason);
    }
    
    public ResultEntry oneResult(int item) {
        // first sleep a while to give accumulation threads a chance to work
        long sleeptime = this.eventTime + (this.query.maximumTime / this.query.displayResults() * ((item % this.query.displayResults()) + 1)) - System.currentTimeMillis();
        if ((anyWorkerAlive()) && (sleeptime > 0)) {
            try {Thread.sleep(sleeptime);} catch (InterruptedException e) {}
        }
        
        // if there are less than 10 more results available, sleep some extra time to get a chance that the "common sense" ranking algorithm can work
        if ((this.resultList.size() <= item + 10) && (anyWorkerAlive())) {
            try {Thread.sleep(300);} catch (InterruptedException e) {}
        }
        // then sleep until any result is available (that should not happen)
        while ((this.resultList.size() <= item) && (anyWorkerAlive())) {
            try {Thread.sleep(100);} catch (InterruptedException e) {}
        }
        
        // finally, if there is something, return the result
        synchronized (this.resultList) {
            // check if we have enough entries
            if (this.resultList.size() <= item) return null;
            
            // fetch the best entry from the resultList, not the entry from item position
            // whenever a specific entry was switched in its position and was returned here
            // a moving pointer is set to assign that item position as not changeable
            int bestpick = postRankingFavourite(item);
            if (bestpick != item) {
                // switch the elements
                ResultEntry buf = (ResultEntry) this.resultList.get(bestpick);
                serverLog.logInfo("SEARCH_POSTRANKING", "prefering [" + bestpick + "] " + buf.urlstring() + " over [" + item + "] " + ((ResultEntry) this.resultList.get(item)).urlstring());
                this.resultList.set(bestpick, (ResultEntry) this.resultList.get(item));
                this.resultList.set(item, buf);
            }
            
            //this.resultListLock = item; // lock the element; be prepared to return it
            return (ResultEntry) this.resultList.get(item);
        }
    }
    
    private int postRankingFavourite(int item) {
        // do a post-ranking on resultList, which should be locked upon time of this call
        long rank, bestrank = 0;
        int bestitem = item;
        ResultEntry entry;
        for (int i = item; i < this.resultList.size(); i++) {
            entry = (ResultEntry) this.resultList.get(i);
            rank = this.ranking.postRanking(this.query, this.references(10), entry, item);
            if (rank > bestrank) {
                bestrank = rank;
                bestitem = i;
            }
        }
        return bestitem;
    }
    
    /*
    public void removeRedundant() {
        // remove all urls from the pageAcc structure that occur double by specific redundancy rules
        // a link is redundant, if a sub-path of the url is cited before. redundant urls are removed
        // we find redundant urls by iteration over all elements in pageAcc
        Iterator i = pageAcc.entrySet().iterator();
        HashMap paths = new HashMap(); // a url-subpath to pageAcc-key relation
        Map.Entry entry;

        // first scan all entries and find all urls that are referenced
        while (i.hasNext()) {
            entry = (Map.Entry) i.next();
            paths.put(((indexURLEntry) entry.getValue()).comp().url().toNormalform(true, true), entry.getKey());
            //if (path != null) path = shortenPath(path);
            //if (path != null) paths.put(path, entry.getKey());
        }

        // now scan the pageAcc again and remove all redundant urls
        i = pageAcc.entrySet().iterator();
        String shorten;
        while (i.hasNext()) {
            entry = (Map.Entry) i.next();
            shorten = shortenPath(((indexURLEntry) entry.getValue()).comp().url().toNormalform(true, true));
            // scan all subpaths of the url
            while (shorten != null) {
                if (pageAcc.size() <= query.wantedResults) break;
                if (paths.containsKey(shorten)) {
                    //System.out.println("deleting path from search result: " + path + " is redundant to " + shorten);
                    try {
                        i.remove();
                    } catch (IllegalStateException e) {

                    }
                }
                shorten = shortenPath(shorten);
            }
        }
    }

    private static String shortenPath(String path) {
        int pos = path.lastIndexOf('/');
        if (pos < 0) return null;
        return path.substring(0, pos);
    }
    */
    
    public ArrayList completeResults(long waitingtime) {
        long timeout = System.currentTimeMillis() + waitingtime;
        while ((this.resultList.size() < query.neededResults()) && (anyWorkerAlive()) && (System.currentTimeMillis() < timeout)) {
            try {Thread.sleep(200);} catch (InterruptedException e) {}
        }
        return this.resultList;
    }
    
    /*
        // generate Result.Entry objects and optionally fetch snippets
        int i = 0;
        Entry entry;
        final boolean includeSnippets = false;
        while ((acc.hasMoreElements()) && (i < query.wantedResults)) {
            try {
                entry = new Entry(acc.nextElement(), wordIndex);
            } catch (final RuntimeException e) {
                continue;
            }
            // check bluelist again: filter out all links where any
            // bluelisted word
            // appear either in url, url's description or search word
            // the search word was sorted out earlier
            
            if (includeSnippets) {
                entry.setSnippet(plasmaSnippetCache.retrieveTextSnippet(
                        entry.url(), query.queryHashes, false,
                        entry.flags().get(plasmaCondenser.flag_cat_indexof), 260,
                        1000));
                // snippet =
                // snippetCache.retrieveTextSnippet(comp.url(),
                // query.queryHashes, false,
                // urlentry.flags().get(plasmaCondenser.flag_cat_indexof),
                // 260, 1000);
            } else {
                // snippet = null;
                entry.setSnippet(null);
            }
            i++;
            hits.add(entry);
        }
    */
    
    boolean secondarySearchStartet = false;
    
    private void prepareSecondarySearch() {
        if (secondarySearchStartet) return; // dont do this twice
        
        if ((rcAbstracts == null) || (rcAbstracts.size() != query.queryHashes.size())) return; // secondary search not possible (yet)
        this.secondarySearchStartet = true;
        
        // catch up index abstracts and join them; then call peers again to submit their urls
        System.out.println("DEBUG-INDEXABSTRACT: " + rcAbstracts.size() + " word references catched, " + query.queryHashes.size() + " needed");

        Iterator i = rcAbstracts.entrySet().iterator();
        Map.Entry entry;
        while (i.hasNext()) {
            entry = (Map.Entry) i.next();
            System.out.println("DEBUG-INDEXABSTRACT: hash " + (String) entry.getKey() + ": " + ((query.queryHashes.contains((String) entry.getKey())) ? "NEEDED" : "NOT NEEDED") + "; " + ((TreeMap) entry.getValue()).size() + " entries");
        }
        
        TreeMap abstractJoin = (rcAbstracts.size() == query.queryHashes.size()) ? kelondroMSetTools.joinConstructive(rcAbstracts.values(), true) : new TreeMap();
        if (abstractJoin.size() == 0) {
            System.out.println("DEBUG-INDEXABSTRACT: no success using index abstracts from remote peers");
        } else {
            System.out.println("DEBUG-INDEXABSTRACT: index abstracts delivered " + abstractJoin.size() + " additional results for secondary search");
            // generate query for secondary search
            TreeMap secondarySearchURLs = new TreeMap(); // a (peerhash:urlhash-liststring) mapping
            Iterator i1 = abstractJoin.entrySet().iterator();
            Map.Entry entry1;
            String url, urls, peer, peers;
            String mypeerhash = yacyCore.seedDB.mySeed().hash;
            boolean mypeerinvolved = false;
            int mypeercount;
            while (i1.hasNext()) {
                entry1 = (Map.Entry) i1.next();
                url = (String) entry1.getKey();
                peers = (String) entry1.getValue();
                System.out.println("DEBUG-INDEXABSTRACT: url " + url + ": from peers " + peers);
                mypeercount = 0;
                for (int j = 0; j < peers.length(); j = j + 12) {
                    peer = peers.substring(j, j + 12);
                    if ((peer.equals(mypeerhash)) && (mypeercount++ > 1)) continue;
                    //if (peers.indexOf(peer) < j) continue; // avoid doubles that may appear in the abstractJoin
                    urls = (String) secondarySearchURLs.get(peer);
                    urls = (urls == null) ? url : urls + url;
                    secondarySearchURLs.put(peer, urls);
                }
                if (mypeercount == 1) mypeerinvolved = true;
            }
            
            // compute words for secondary search and start the secondary searches
            i1 = secondarySearchURLs.entrySet().iterator();
            String words;
            secondarySearchThreads = new yacySearch[(mypeerinvolved) ? secondarySearchURLs.size() - 1 : secondarySearchURLs.size()];
            int c = 0;
            while (i1.hasNext()) {
                entry1 = (Map.Entry) i1.next();
                peer = (String) entry1.getKey();
                if (peer.equals(mypeerhash)) continue; // we dont need to ask ourself
                urls = (String) entry1.getValue();
                words = wordsFromPeer(peer, urls);
                System.out.println("DEBUG-INDEXABSTRACT ***: peer " + peer + "   has urls: " + urls);
                System.out.println("DEBUG-INDEXABSTRACT ***: peer " + peer + " from words: " + words);
                secondarySearchThreads[c++] = yacySearch.secondaryRemoteSearch(
                        words, "", urls, wordIndex, this.rankedCache, peer, plasmaSwitchboard.urlBlacklist,
                        ranking, query.constraint, preselectedPeerHashes);

            }
        }
    }
    
    private String wordsFromPeer(String peerhash, String urls) {
        Map.Entry entry;
        String word, peerlist, url, wordlist = "";
        TreeMap urlPeerlist;
        int p;
        boolean hasURL;
        synchronized (rcAbstracts) {
            Iterator i = rcAbstracts.entrySet().iterator();
            while (i.hasNext()) {
                entry = (Map.Entry) i.next();
                word = (String) entry.getKey();
                urlPeerlist = (TreeMap) entry.getValue();
                hasURL = true;
                for (int j = 0; j < urls.length(); j = j + 12) {
                    url = urls.substring(j, j + 12);
                    peerlist = (String) urlPeerlist.get(url);
                    p = (peerlist == null) ? -1 : peerlist.indexOf(peerhash);
                    if ((p < 0) || (p % 12 != 0)) {
                        hasURL = false;
                        break;
                    }
                }
                if (hasURL) wordlist += word;
            }
        }
        return wordlist;
    }
 
    public void remove(String urlhash) {
        // removes the url hash reference from last search result
        /*indexRWIEntry e =*/ this.rankedCache.remove(urlhash);
        //assert e != null;
    }
    
    public Set references(int count) {
        // returns a set of words that are computed as toplist
        return this.rankedCache.getReferences(count);
    }
    
    public static class ResultEntry {
        // payload objects
        private indexURLEntry urlentry;
        private indexURLEntry.Components urlcomps; // buffer for components
        private String alternative_urlstring;
        private String alternative_urlname;
        private plasmaSnippetCache.TextSnippet textSnippet;
        private ArrayList /* of plasmaSnippetCache.MediaSnippet */ mediaSnippets;
        
        // statistic objects
        public long dbRetrievalTime, snippetComputationTime;
        
        public ResultEntry(indexURLEntry urlentry, plasmaWordIndex wordIndex, plasmaSnippetCache.TextSnippet textSnippet, ArrayList mediaSnippets,
                           long dbRetrievalTime, long snippetComputationTime) {
            this.urlentry = urlentry;
            this.urlcomps = urlentry.comp();
            this.alternative_urlstring = null;
            this.alternative_urlname = null;
            this.textSnippet = textSnippet;
            this.mediaSnippets = mediaSnippets;
            this.dbRetrievalTime = dbRetrievalTime;
            this.snippetComputationTime = snippetComputationTime;
            String host = urlcomps.url().getHost();
            if (host.endsWith(".yacyh")) {
                // translate host into current IP
                int p = host.indexOf(".");
                String hash = yacySeed.hexHash2b64Hash(host.substring(p + 1, host.length() - 6));
                yacySeed seed = yacyCore.seedDB.getConnected(hash);
                String filename = urlcomps.url().getFile();
                String address = null;
                if ((seed == null) || ((address = seed.getPublicAddress()) == null)) {
                    // seed is not known from here
                    try {
                        wordIndex.removeWordReferences(
                            plasmaCondenser.getWords(
                                ("yacyshare " +
                                 filename.replace('?', ' ') +
                                 " " +
                                 urlcomps.title()).getBytes(), "UTF-8").keySet(),
                                 urlentry.hash());
                        wordIndex.loadedURL.remove(urlentry.hash()); // clean up
                        throw new RuntimeException("index void");
                    } catch (UnsupportedEncodingException e) {
                        throw new RuntimeException("parser failed: " + e.getMessage());
                    }
                }
                alternative_urlstring = "http://" + address + "/" + host.substring(0, p) + filename;
                alternative_urlname = "http://share." + seed.getName() + ".yacy" + filename;
                if ((p = alternative_urlname.indexOf("?")) > 0) alternative_urlname = alternative_urlname.substring(0, p);
            }
        }
        
        public String hash() {
            return urlentry.hash();
        }
        public yacyURL url() {
            return urlcomps.url();
        }
        public kelondroBitfield flags() {
            return urlentry.flags();
        }
        public String urlstring() {
            return (alternative_urlstring == null) ? urlcomps.url().toNormalform(false, true) : alternative_urlstring;
        }
        public String urlname() {
            return (alternative_urlname == null) ? urlcomps.url().toNormalform(false, true) : alternative_urlname;
        }
        public String title() {
            return urlcomps.title();
        }
        public plasmaSnippetCache.TextSnippet textSnippet() {
            return this.textSnippet;
        }
        public ArrayList /* of plasmaSnippetCache.MediaSnippet */ mediaSnippets() {
            return this.mediaSnippets;
        }
        public Date modified() {
            return urlentry.moddate();
        }
        public int filesize() {
            return urlentry.size();
        }
        public int limage() {
            return urlentry.limage();
        }
        public int laudio() {
            return urlentry.laudio();
        }
        public int lvideo() {
            return urlentry.lvideo();
        }
        public int lapp() {
            return urlentry.lapp();
        }
        public indexRWIEntry word() {
            return urlentry.word();
        }
        public boolean hasTextSnippet() {
            return (this.textSnippet != null) && (this.textSnippet.getErrorCode() < 11);
        }
        public boolean hasMediaSnippets() {
            return (this.mediaSnippets != null) && (this.mediaSnippets.size() > 0);
        }
        public String resource() {
            // generate transport resource
            if ((textSnippet != null) && (textSnippet.exists())) {
                return urlentry.toString(textSnippet.getLineRaw());
            } else {
                return urlentry.toString();
            }
        }
    }
}