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376 lines
15 KiB
376 lines
15 KiB
// PeerSelection.java
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// -------------------------------------
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published 05.11.2008 on http://yacy.net
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// Frankfurt, Germany, 2008
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//
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// $LastChangedDate: 2008-09-03 02:30:21 +0200 (Mi, 03 Sep 2008) $
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// $LastChangedRevision: 5102 $
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// $LastChangedBy: orbiter $
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package de.anomic.yacy.dht;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map;
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import net.yacy.cora.date.AbstractFormatter;
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import net.yacy.cora.storage.DynamicScore;
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import net.yacy.cora.storage.ScoreCluster;
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import net.yacy.kelondro.data.word.Word;
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import net.yacy.kelondro.index.HandleSet;
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import net.yacy.kelondro.index.RowSpaceExceededException;
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import net.yacy.kelondro.logging.Log;
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import net.yacy.kelondro.order.Base64Order;
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import net.yacy.kelondro.order.Digest;
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import net.yacy.kelondro.util.kelondroException;
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import de.anomic.yacy.yacyCore;
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import de.anomic.yacy.yacySeed;
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import de.anomic.yacy.yacySeedDB;
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import de.anomic.yacy.yacyVersion;
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/*
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* this package is a collection of peer selection iterations that had been
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* part of yacyPeerActions, yacyDHTActions and yacySeedDB
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*/
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public class PeerSelection {
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public static void selectDHTPositions(
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final yacySeedDB seedDB,
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byte[] wordhash,
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int redundancy,
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Map<String, yacySeed> regularSeeds,
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DynamicScore<String> ranking) {
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// this method is called from the search target computation
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final long[] dhtVerticalTargets = seedDB.scheme.dhtPositions(wordhash);
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yacySeed seed;
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for (long dhtVerticalTarget : dhtVerticalTargets) {
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wordhash = FlatWordPartitionScheme.positionToHash(dhtVerticalTarget);
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Iterator<yacySeed> dhtEnum = getAcceptRemoteIndexSeeds(seedDB, wordhash, redundancy, false);
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int c = Math.min(seedDB.sizeConnected(), redundancy);
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int cc = 3; // select a maximum of 3, this is enough redundancy
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while (dhtEnum.hasNext() && c > 0 && cc-- > 0) {
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seed = dhtEnum.next();
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if (seed == null || seed.hash == null) continue;
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if (!seed.getFlagAcceptRemoteIndex()) continue; // probably a robinson peer
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if (Log.isFine("PLASMA")) Log.logFine("PLASMA", "selectPeers/DHTorder: " + seed.hash + ":" + seed.getName() + "/ score " + c);
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ranking.inc(seed.hash, 2 * c);
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regularSeeds.put(seed.hash, seed);
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c--;
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}
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}
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}
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private static int guessedOwn = 0;
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public static boolean shallBeOwnWord(final yacySeedDB seedDB, final byte[] wordhash, final String urlhash, final int redundancy) {
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// the guessIfOwnWord is a fast method that should only fail in case that a 'true' may be incorrect, but a 'false' shall always be correct
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if (guessIfOwnWord(seedDB, wordhash, urlhash)) {
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// this case must be verified, because it can be wrong.
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guessedOwn++;
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return verifyIfOwnWord(seedDB, wordhash, urlhash, redundancy);
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} else {
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return false;
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}
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}
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private static boolean guessIfOwnWord(final yacySeedDB seedDB, final byte[] wordhash, final String urlhash) {
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if (seedDB == null) return false;
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int connected = seedDB.sizeConnected();
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if (connected == 0) return true;
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final long target = seedDB.scheme.dhtPosition(wordhash, urlhash);
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final long mypos = seedDB.scheme.dhtPosition(seedDB.mySeed().hash.getBytes(), urlhash);
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long distance = FlatWordPartitionScheme.dhtDistance(target, mypos);
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if (distance <= 0) return false;
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if (distance <= Long.MAX_VALUE / connected * 2) return true;
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return false;
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}
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private static boolean verifyIfOwnWord(final yacySeedDB seedDB, byte[] wordhash, String urlhash, int redundancy) {
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String myHash = seedDB.mySeed().hash;
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wordhash = FlatWordPartitionScheme.positionToHash(seedDB.scheme.dhtPosition(wordhash, urlhash));
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final Iterator<yacySeed> dhtEnum = getAcceptRemoteIndexSeeds(seedDB, wordhash, redundancy, true);
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while (dhtEnum.hasNext()) {
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if (dhtEnum.next().hash.equals(myHash)) return true;
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}
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return false;
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}
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public static byte[] selectTransferStart() {
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return Base64Order.enhancedCoder.encode(Digest.encodeMD5Raw(Long.toString(System.currentTimeMillis()))).substring(2, 2 + Word.commonHashLength).getBytes();
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}
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public static byte[] limitOver(final yacySeedDB seedDB, final byte[] startHash) {
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final Iterator<yacySeed> seeds = getAcceptRemoteIndexSeeds(seedDB, startHash, 1, false);
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if (seeds.hasNext()) return seeds.next().hash.getBytes();
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return null;
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}
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protected static List<yacySeed> getAcceptRemoteIndexSeedsList(
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yacySeedDB seedDB,
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final byte[] starthash,
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int max,
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boolean alsoMyOwn) {
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final Iterator<yacySeed> seedIter = PeerSelection.getAcceptRemoteIndexSeeds(seedDB, starthash, max, alsoMyOwn);
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final ArrayList<yacySeed> targets = new ArrayList<yacySeed>();
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while (seedIter.hasNext() && max-- > 0) targets.add(seedIter.next());
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return targets;
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}
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/**
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* returns an enumeration of yacySeed-Objects that have the AcceptRemoteIndex-Flag set
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* the seeds are enumerated in the right order according to the DHT
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* @param seedDB
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* @param starthash
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* @param max
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* @param alsoMyOwn
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* @return
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*/
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public static Iterator<yacySeed> getAcceptRemoteIndexSeeds(final yacySeedDB seedDB, final byte[] starthash, final int max, final boolean alsoMyOwn) {
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return new acceptRemoteIndexSeedEnum(seedDB, starthash, Math.min(max, seedDB.sizeConnected()), alsoMyOwn);
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}
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private static class acceptRemoteIndexSeedEnum implements Iterator<yacySeed> {
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private final Iterator<yacySeed> se;
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private yacySeed nextSeed;
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private final yacySeedDB seedDB;
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private final HandleSet doublecheck;
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private int remaining;
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private boolean alsoMyOwn;
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public acceptRemoteIndexSeedEnum(yacySeedDB seedDB, final byte[] starthash, int max, boolean alsoMyOwn) {
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this.seedDB = seedDB;
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this.se = getDHTSeeds(seedDB, starthash, yacyVersion.YACY_HANDLES_COLLECTION_INDEX);
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this.remaining = max;
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this.doublecheck = new HandleSet(12, Base64Order.enhancedCoder, 0);
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this.nextSeed = nextInternal();
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this.alsoMyOwn = alsoMyOwn && nextSeed != null && (Base64Order.enhancedCoder.compare(seedDB.mySeed().hash.getBytes(), nextSeed.hash.getBytes()) > 0);
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}
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public boolean hasNext() {
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return nextSeed != null;
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}
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private yacySeed nextInternal() {
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if (this.remaining <= 0) return null;
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yacySeed s;
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try {
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while (se.hasNext()) {
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s = se.next();
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if (s == null) return null;
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byte[] hashb = s.hash.getBytes();
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if (doublecheck.has(hashb)) return null;
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try {
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this.doublecheck.put(hashb);
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} catch (RowSpaceExceededException e) {
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Log.logException(e);
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break;
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}
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if (s.getFlagAcceptRemoteIndex()) {
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this.remaining--;
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return s;
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}
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}
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} catch (final kelondroException e) {
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System.out.println("DEBUG acceptRemoteIndexSeedEnum:" + e.getMessage());
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yacyCore.log.logSevere("database inconsistency (" + e.getMessage() + "), re-set of db.");
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seedDB.resetActiveTable();
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return null;
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}
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return null;
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}
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public yacySeed next() {
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if (alsoMyOwn && Base64Order.enhancedCoder.compare(seedDB.mySeed().hash.getBytes(), nextSeed.hash.getBytes()) < 0) {
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// take my own seed hash instead the enumeration result
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alsoMyOwn = false;
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return seedDB.mySeed();
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} else {
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final yacySeed next = nextSeed;
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nextSeed = nextInternal();
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return next;
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}
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}
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public void remove() {
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throw new UnsupportedOperationException();
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}
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}
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/**
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* enumerate seeds for DHT target positions
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* @param seedDB
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* @param firstHash
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* @param minVersion
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* @return
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*/
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protected static Iterator<yacySeed> getDHTSeeds(final yacySeedDB seedDB, final byte[] firstHash, final float minVersion) {
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// enumerates seed-type objects: all seeds with starting point in the middle, rotating at the end/beginning
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return new seedDHTEnum(seedDB, firstHash, minVersion);
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}
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private static class seedDHTEnum implements Iterator<yacySeed> {
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private Iterator<yacySeed> e1, e2;
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private int steps;
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private float minVersion;
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private yacySeedDB seedDB;
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public seedDHTEnum(final yacySeedDB seedDB, final byte[] firstHash, final float minVersion) {
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this.seedDB = seedDB;
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this.steps = seedDB.sizeConnected();
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this.minVersion = minVersion;
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this.e1 = seedDB.seedsConnected(true, false, firstHash, minVersion);
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this.e2 = null;
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}
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public boolean hasNext() {
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return (steps > 0) && ((e2 == null) || (e2.hasNext()));
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}
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public yacySeed next() {
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if (steps == 0) return null;
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steps--;
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if (e1 == null || !e1.hasNext()) {
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if (e2 == null) {
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e1 = null;
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e2 = seedDB.seedsConnected(true, false, null, minVersion);
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}
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return e2.next();
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}
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final yacySeed n = e1.next();
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if (!(e1.hasNext())) {
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e1 = null;
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e2 = seedDB.seedsConnected(true, false, null, minVersion);
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}
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return n;
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}
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public void remove() {
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throw new UnsupportedOperationException();
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}
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}
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/**
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* enumerate peers that provide remote crawl urls
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* @param seedDB
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* @return an iterator of seed objects
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*/
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public static Iterator<yacySeed> getProvidesRemoteCrawlURLs(final yacySeedDB seedDB) {
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return new providesRemoteCrawlURLsEnum(seedDB);
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}
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private static class providesRemoteCrawlURLsEnum implements Iterator<yacySeed> {
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private Iterator<yacySeed> se;
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private yacySeed nextSeed;
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private yacySeedDB seedDB;
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public providesRemoteCrawlURLsEnum(final yacySeedDB seedDB) {
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this.seedDB = seedDB;
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se = getDHTSeeds(seedDB, null, yacyVersion.YACY_POVIDES_REMOTECRAWL_LISTS);
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nextSeed = nextInternal();
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}
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public boolean hasNext() {
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return nextSeed != null;
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}
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private yacySeed nextInternal() {
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yacySeed s;
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try {
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while (se.hasNext()) {
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s = se.next();
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if (s == null) return null;
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if (s.getLong(yacySeed.RCOUNT, 0) > 0) return s;
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}
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} catch (final kelondroException e) {
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System.out.println("DEBUG providesRemoteCrawlURLsEnum:" + e.getMessage());
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yacyCore.log.logSevere("database inconsistency (" + e.getMessage() + "), re-set of db.");
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seedDB.resetActiveTable();
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return null;
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}
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return null;
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}
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public yacySeed next() {
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final yacySeed next = nextSeed;
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nextSeed = nextInternal();
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return next;
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}
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public void remove() {
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throw new UnsupportedOperationException();
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}
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}
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/**
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* get either the youngest or oldest peers from the seed db. Count as many as requested
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* @param seedDB
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* @param up if up = true then get the most recent peers, if up = false then get oldest
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* @param count number of wanted peers
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* @return a hash map of peer hashes to seed object
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*/
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public static Map<String, yacySeed> seedsByAge(final yacySeedDB seedDB, final boolean up, int count) {
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if (count > seedDB.sizeConnected()) count = seedDB.sizeConnected();
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// fill a score object
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final DynamicScore<String> seedScore = new ScoreCluster<String>();
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yacySeed ys;
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long absage;
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final Iterator<yacySeed> s = seedDB.seedsConnected(true, false, null, (float) 0.0);
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int searchcount = 1000;
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if (searchcount > seedDB.sizeConnected()) searchcount = seedDB.sizeConnected();
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try {
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while ((s.hasNext()) && (searchcount-- > 0)) {
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ys = s.next();
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if ((ys != null) && (ys.get(yacySeed.LASTSEEN, "").length() > 10)) try {
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absage = Math.abs(System.currentTimeMillis() + AbstractFormatter.dayMillis - ys.getLastSeenUTC()) / 1000 / 60;
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if (absage > Integer.MAX_VALUE) absage = Integer.MAX_VALUE;
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seedScore.inc(ys.hash, (int) absage); // the higher absage, the older is the peer
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} catch (final Exception e) {}
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}
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// result is now in the score object; create a result vector
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final Map<String, yacySeed> result = new HashMap<String, yacySeed>();
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final Iterator<String> it = seedScore.keys(up);
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int c = 0;
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while ((c < count) && (it.hasNext())) {
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c++;
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ys = seedDB.getConnected(it.next());
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if ((ys != null) && (ys.hash != null)) result.put(ys.hash, ys);
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}
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return result;
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} catch (final kelondroException e) {
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yacyCore.log.logSevere("Internal Error at yacySeedDB.seedsByAge: " + e.getMessage(), e);
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return null;
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}
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}
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}
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