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307 lines
12 KiB
307 lines
12 KiB
// yacyDHTAction.java
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// -------------------------------------
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// (C) by Michael Peter Christen; mc@anomic.de
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2005
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//
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// $LastChangedDate$
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// $LastChangedRevision$
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// $LastChangedBy$
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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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//
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// Using this software in any meaning (reading, learning, copying, compiling,
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// running) means that you agree that the Author(s) is (are) not responsible
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// for cost, loss of data or any harm that may be caused directly or indirectly
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// by usage of this softare or this documentation. The usage of this software
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// is on your own risk. The installation and usage (starting/running) of this
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// software may allow other people or application to access your computer and
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// any attached devices and is highly dependent on the configuration of the
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// software which must be done by the user of the software; the author(s) is
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// (are) also not responsible for proper configuration and usage of the
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// software, even if provoked by documentation provided together with
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// the software.
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//
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// Any changes to this file according to the GPL as documented in the file
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// gpl.txt aside this file in the shipment you received can be done to the
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// lines that follows this copyright notice here, but changes must not be
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// done inside the copyright notive above. A re-distribution must contain
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// the intact and unchanged copyright notice.
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// Contributions and changes to the program code must be marked as such.
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package de.anomic.yacy;
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import java.util.Enumeration;
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import de.anomic.kelondro.kelondroException;
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import de.anomic.kelondro.kelondroMScoreCluster;
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import de.anomic.server.logging.serverLog;
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public class yacyDHTAction implements yacyPeerAction {
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protected yacySeedDB seedDB;
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protected kelondroMScoreCluster seedCrawlReady;
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public yacyDHTAction(yacySeedDB seedDB) {
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this.seedDB = seedDB;
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this.seedCrawlReady = new kelondroMScoreCluster();
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// init crawl-ready table
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try {
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Enumeration en = seedDB.seedsConnected(true, false, null, (float) 0.0);
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yacySeed ys;
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while (en.hasMoreElements()) {
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ys = (yacySeed) en.nextElement();
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if ((ys != null) && (ys.getVersion() >= ((float) 0.3))) seedCrawlReady.setScore(ys.hash, yacyCore.yacyTime());
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}
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} catch (IllegalArgumentException e) {
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}
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}
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public Enumeration getDHTSeeds(boolean up, String firstHash, 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(up, firstHash, minVersion);
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}
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class seedDHTEnum implements Enumeration {
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Enumeration e1, e2;
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boolean up;
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int steps;
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float minVersion;
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public seedDHTEnum(boolean up, String firstHash, float minVersion) {
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this.steps = seedDB.sizeConnected();
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this.up = up;
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this.minVersion = minVersion;
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this.e1 = seedDB.seedsConnected(up, false, firstHash, minVersion);
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this.e2 = null;
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}
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public boolean hasMoreElements() {
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return (steps > 0) && ((e2 == null) || (e2.hasMoreElements()));
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}
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public Object nextElement() {
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if (steps == 0) return null;
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steps--;
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if ((e1 != null) && (e1.hasMoreElements())) {
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Object n = e1.nextElement();
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if (!(e1.hasMoreElements())) {
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e1 = null;
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e2 = seedDB.seedsConnected(up, false, null, minVersion);
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}
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return n;
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} else {
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if (e2 == null) {
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e1 = null;
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e2 = seedDB.seedsConnected(up, false, null, minVersion);
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}
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return e2.nextElement();
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}
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}
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}
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public Enumeration getAcceptRemoteIndexSeeds(String starthash) {
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// returns an enumeration of yacySeed-Objects
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// that have the AcceptRemoteIndex-Flag set
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// the seeds are enumerated in the right order according DHT
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return new acceptRemoteIndexSeedEnum(starthash);
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}
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class acceptRemoteIndexSeedEnum implements Enumeration {
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Enumeration se;
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yacySeed nextSeed;
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public acceptRemoteIndexSeedEnum(String starthash) {
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se = getDHTSeeds(true, starthash, yacyVersion.YACY_HANDLES_COLLECTION_INDEX);
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nextSeed = nextInternal();
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}
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public boolean hasMoreElements() {
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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.hasMoreElements()) {
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s = (yacySeed) se.nextElement();
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if (s == null) return null;
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if (s.getFlagAcceptRemoteIndex()) return s;
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}
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} catch (kelondroException e) {
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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 Object nextElement() {
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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 Enumeration getAcceptRemoteCrawlSeeds(String starthash, boolean available) {
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return new acceptRemoteCrawlSeedEnum(starthash, available);
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}
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class acceptRemoteCrawlSeedEnum implements Enumeration {
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Enumeration se;
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yacySeed nextSeed;
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boolean available;
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public acceptRemoteCrawlSeedEnum(String starthash, boolean available) {
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this.se = getDHTSeeds(true, starthash, (float) 0.0);
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this.available = available;
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nextSeed = nextInternal();
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}
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public boolean hasMoreElements() {
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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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while (se.hasMoreElements()) {
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s = (yacySeed) se.nextElement();
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if (s == null) return null;
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s.available = seedCrawlReady.getScore(s.hash);
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if (available) {
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if (seedCrawlReady.getScore(s.hash) < yacyCore.yacyTime()) return s;
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} else {
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if (seedCrawlReady.getScore(s.hash) > yacyCore.yacyTime()) return s;
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}
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}
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return null;
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}
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public Object nextElement() {
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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 synchronized yacySeed getCrawlSeed(String urlHash) {
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Enumeration e = getAcceptRemoteCrawlSeeds(urlHash, true);
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yacySeed seed;
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if (e.hasMoreElements()) seed = (yacySeed) e.nextElement(); else seed = null;
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e = null;
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return seed;
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}
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public void setCrawlTime(String seedHash, int newYacyTime) {
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if (newYacyTime < yacyCore.yacyTime()) newYacyTime = yacyCore.yacyTime();
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seedCrawlReady.setScore(seedHash, newYacyTime);
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}
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public void setCrawlDelay(String seedHash, int newDelay) {
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seedCrawlReady.setScore(seedHash, yacyCore.yacyTime() + newDelay);
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}
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public void processPeerArrival(yacySeed peer, boolean direct) {
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if (peer.getVersion() >= ((float) 0.3)) {
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if (!(seedCrawlReady.existsScore(peer.hash))) seedCrawlReady.setScore(peer.hash, yacyCore.yacyTime());
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} else {
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seedCrawlReady.deleteScore(peer.hash);
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}
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}
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public void processPeerDeparture(yacySeed peer) {
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seedCrawlReady.deleteScore(peer.hash);
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}
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public void processPeerPing(yacySeed peer) {
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}
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public static boolean shallBeOwnWord(String wordhash) {
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if (yacyCore.seedDB == null) return false;
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if (yacyCore.seedDB.mySeed.isPotential()) return false;
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final double distance = dhtDistance(yacyCore.seedDB.mySeed.hash, wordhash);
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final double max = 1.2 / yacyCore.seedDB.sizeConnected();
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//System.out.println("Distance for " + wordhash + ": " + distance + "; max is " + max);
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return (distance > 0) && (distance <= max);
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}
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public static double dhtDistance(String peer, String word) {
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// the dht distance is a positive value between 0 and 1
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// if the distance is small, the word more probably belongs to the peer
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double d = hashDistance(peer, word);
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if (d > 0) {
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return d; // case where the word is 'before' the peer
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} else {
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return 1 + d; // wrap-around case
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}
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}
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private static double hashDistance(String from, String to) {
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// computes the distance between two hashes.
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// the maximum distance between two hashes is 1, the minimum -1
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// this can be used like "from - to"
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// the result is positive if from > to
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if ((from == null) || (to == null) ||
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(from.length() == 0) || (to.length() == 0) ||
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(from.length() != to.length())) return (double) 0.0;
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return hashDistance(from.charAt(0), to.charAt(0)) + hashDistance(from.substring(1), to.substring(1)) / maxAtomarDistance;
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}
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private static final double maxAtomarDistance = (double) (1+ ((byte) 'z') - ((byte) '-'));
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private static double hashDistance(char from, char to) {
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// the distance is a little bit fuzzy, since not all characters are used in a hash.
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if (from < to)
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return -hashDistance(to, from);
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else
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return ((double) (((byte) from) - ((byte) to))) / maxAtomarDistance;
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}
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public synchronized yacySeed[] getDHTTargets(serverLog log, int primaryPeerCount, int reservePeerCount, String firstKey, String lastKey, double maxDist) {
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// find a list of DHT-peers
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yacySeed[] seeds = new yacySeed[primaryPeerCount + reservePeerCount];
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int hc0 = 0;
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double ownDistance = Math.min(yacyDHTAction.dhtDistance(yacyCore.seedDB.mySeed.hash, firstKey), yacyDHTAction.dhtDistance(yacyCore.seedDB.mySeed.hash, lastKey));
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double maxDistance = Math.min(ownDistance, maxDist);
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double avdist;
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Enumeration e = this.getAcceptRemoteIndexSeeds(lastKey);
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while ((e.hasMoreElements()) && (hc0 < seeds.length)) {
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seeds[hc0] = (yacySeed) e.nextElement();
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if (seeds[hc0] != null) {
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avdist = Math.max(yacyDHTAction.dhtDistance(seeds[hc0].hash, firstKey), yacyDHTAction.dhtDistance(seeds[hc0].hash, lastKey));
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if (avdist < maxDistance) {
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if (log != null) log.logInfo("Selected " + ((hc0 < primaryPeerCount) ? "primary" : "reserve") + " DHT target peer " + seeds[hc0].getName() + ":" + seeds[hc0].hash + ", distance = " + avdist);
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hc0++;
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}
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}
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}
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e = null; // finish enumeration
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if (hc0 == seeds.length) {
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return seeds;
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} else {
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yacySeed[] s = new yacySeed[hc0];
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System.arraycopy(seeds, 0, s, 0, hc0);
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return s;
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}
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}
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}
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