yacy_search_server/source/de/anomic/yacy/dht/PeerSelection.java
orbiter 5892fff51f introduction of dht-burst modes: this can expand the number of target peers in some cases where a better heuristic is needed. The problematic cases are either when a muti-word search is made (still a hard case for our term-oriented DHT) or when a network operator wants that all robinson peers are asked. We therefore introduced two new network steering values that switch on more peers during the peer selection. Because the number of peers can now be very large, the number of maximum httpc connections was also increased.
Please see new coments in yacy.network.freeworld.unit for details of the new DHT selection methods.
The number of maximum peers is now not fixed to a specific number but may increase with
- the partition exponent
- the number of redundant peers
- the robinson burst percentage
- the multiword burst percentage
The maximum can then be the number of senior peers (all visible peers).

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@7479 6c8d7289-2bf4-0310-a012-ef5d649a1542
2011-02-13 17:37:28 +00:00

438 lines
18 KiB
Java
Executable File

// PeerSelection.java
// -------------------------------------
// (C) by Michael Peter Christen; mc@yacy.net
// first published 05.11.2008 on http://yacy.net
// Frankfurt, Germany, 2008
//
// $LastChangedDate: 2008-09-03 02:30:21 +0200 (Mi, 03 Sep 2008) $
// $LastChangedRevision: 5102 $
// $LastChangedBy: orbiter $
//
// 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.yacy.dht;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import net.yacy.cora.date.AbstractFormatter;
import net.yacy.cora.storage.DynamicScore;
import net.yacy.cora.storage.ScoreCluster;
import net.yacy.kelondro.data.word.Word;
import net.yacy.kelondro.index.HandleSet;
import net.yacy.kelondro.index.RowSpaceExceededException;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.order.Base64Order;
import net.yacy.kelondro.order.Digest;
import net.yacy.kelondro.util.kelondroException;
import de.anomic.yacy.yacyCore;
import de.anomic.yacy.yacySeed;
import de.anomic.yacy.yacySeedDB;
import de.anomic.yacy.yacyVersion;
/*
* this package is a collection of peer selection iterations that had been
* part of yacyPeerActions, yacyDHTActions and yacySeedDB
*/
public class PeerSelection {
public static yacySeed[] selectClusterPeers(final yacySeedDB seedDB, final SortedMap<byte[], String> peerhashes) {
final Iterator<Map.Entry<byte[], String>> i = peerhashes.entrySet().iterator();
final List<yacySeed> l = new ArrayList<yacySeed>();
Map.Entry<byte[], String> entry;
yacySeed s;
while (i.hasNext()) {
entry = i.next();
s = seedDB.get(new String(entry.getKey())); // should be getConnected; get only during testing time
if (s != null) {
s.setAlternativeAddress(entry.getValue());
l.add(s);
}
}
return l.toArray(new yacySeed[l.size()]);
}
public static yacySeed[] selectSearchTargets(
final yacySeedDB seedDB,
final HandleSet wordhashes,
int redundancy,
int burstRobinsonPercent,
int burstMultiwordPercent) {
// find out a specific number of seeds, that would be relevant for the given word hash(es)
// the result is ordered by relevance: [0] is most relevant
// the seedcount is the maximum number of wanted results
if (seedDB == null) { return null; }
// put in seeds according to dht
final Map<String, yacySeed> regularSeeds = new HashMap<String, yacySeed>(); // dht position seeds
yacySeed seed;
Iterator<yacySeed> dhtEnum;
Iterator<byte[]> iter = wordhashes.iterator();
while (iter.hasNext()) {
selectDHTPositions(seedDB, iter.next(), redundancy, regularSeeds);
}
//int minimumseeds = Math.min(seedDB.scheme.verticalPartitions(), regularSeeds.size()); // that should be the minimum number of seeds that are returned
//int maximumseeds = seedDB.scheme.verticalPartitions() * redundancy; // this is the maximum number of seeds according to dht and heuristics. It can be more using burst mode.
// put in some seeds according to size of peer.
// But not all, that would produce too much load on the largest peers
dhtEnum = seedDB.seedsSortedConnected(false, yacySeed.ICOUNT);
int c = Math.max(Math.min(5, seedDB.sizeConnected()), wordhashes.size() > 1 ? seedDB.sizeConnected() * burstMultiwordPercent / 100 : 0);
while (dhtEnum.hasNext() && c-- > 0) {
seed = dhtEnum.next();
if (seed == null) continue;
if (seed.getAge() < 1) { // the 'workshop feature'
Log.logInfo("DHT", "selectPeers/Age: " + seed.hash + ":" + seed.getName() + ", is newbie, age = " + seed.getAge());
regularSeeds.put(seed.hash, seed);
continue;
}
if (Math.random() * 100 + (wordhashes.size() > 1 ? burstMultiwordPercent : 25) >= 50) {
if (Log.isFine("DHT")) Log.logFine("DHT", "selectPeers/CountBurst: " + seed.hash + ":" + seed.getName() + ", RWIcount=" + seed.getWordCount());
regularSeeds.put(seed.hash, seed);
continue;
}
}
// create a set that contains only robinson peers because these get a special handling
dhtEnum = seedDB.seedsConnected(true, false, null, 0.50f);
Set<yacySeed> robinson = new HashSet<yacySeed>();
while (dhtEnum.hasNext()) {
seed = dhtEnum.next();
if (seed == null) continue;
if (!seed.getFlagAcceptRemoteIndex()) robinson.add(seed);
}
// add robinson peers according to robinson burst rate
dhtEnum = robinson.iterator();
c = robinson.size() * burstRobinsonPercent / 100;
while (dhtEnum.hasNext() && c-- > 0) {
seed = dhtEnum.next();
if (Math.random() * 100 + burstRobinsonPercent >= 100) {
if (Log.isFine("DHT")) Log.logFine("DHT", "selectPeers/RobinsonBurst: " + seed.hash + ":" + seed.getName());
regularSeeds.put(seed.hash, seed);
continue;
}
}
// put in seeds that are public robinson peers and where the peer tags match with query
// or seeds that are newbies to ensure that private demonstrations always work
dhtEnum = robinson.iterator();
while (dhtEnum.hasNext()) {
seed = dhtEnum.next();
if (seed.matchPeerTags(wordhashes)) {
// peer tags match
String specialized = seed.getPeerTags().toString();
if (!specialized.equals("[*]")) Log.logInfo("DHT", "selectPeers/PeerTags: " + seed.hash + ":" + seed.getName() + ", is specialized peer for " + specialized);
regularSeeds.put(seed.hash, seed);
}
}
// produce return set
yacySeed[] result = new yacySeed[regularSeeds.size()];
result = regularSeeds.values().toArray(result);
return result;
}
private static void selectDHTPositions(
final yacySeedDB seedDB,
byte[] wordhash,
int redundancy,
Map<String, yacySeed> regularSeeds) {
// this method is called from the search target computation
final long[] dhtVerticalTargets = seedDB.scheme.dhtPositions(wordhash);
yacySeed seed;
for (long dhtVerticalTarget : dhtVerticalTargets) {
wordhash = FlatWordPartitionScheme.positionToHash(dhtVerticalTarget);
Iterator<yacySeed> dhtEnum = getAcceptRemoteIndexSeeds(seedDB, wordhash, redundancy, false);
int c = Math.min(seedDB.sizeConnected(), redundancy);
int cc = 3; // select a maximum of 3, this is enough redundancy
while (dhtEnum.hasNext() && c > 0 && cc-- > 0) {
seed = dhtEnum.next();
if (seed == null || seed.hash == null) continue;
if (!seed.getFlagAcceptRemoteIndex()) continue; // probably a robinson peer
if (Log.isFine("DHT")) Log.logFine("DHT", "selectPeers/DHTorder: " + seed.hash + ":" + seed.getName() + "/ score " + c);
regularSeeds.put(seed.hash, seed);
c--;
}
}
}
public static byte[] selectTransferStart() {
return Base64Order.enhancedCoder.encode(Digest.encodeMD5Raw(Long.toString(System.currentTimeMillis()))).substring(2, 2 + Word.commonHashLength).getBytes();
}
public static byte[] limitOver(final yacySeedDB seedDB, final byte[] startHash) {
final Iterator<yacySeed> seeds = getAcceptRemoteIndexSeeds(seedDB, startHash, 1, false);
if (seeds.hasNext()) return seeds.next().hash.getBytes();
return null;
}
protected static List<yacySeed> getAcceptRemoteIndexSeedsList(
yacySeedDB seedDB,
final byte[] starthash,
int max,
boolean alsoMyOwn) {
final Iterator<yacySeed> seedIter = getAcceptRemoteIndexSeeds(seedDB, starthash, max, alsoMyOwn);
final ArrayList<yacySeed> targets = new ArrayList<yacySeed>();
while (seedIter.hasNext() && max-- > 0) targets.add(seedIter.next());
return targets;
}
/**
* returns an enumeration of yacySeed-Objects that have the AcceptRemoteIndex-Flag set
* the seeds are enumerated in the right order according to the DHT
* @param seedDB
* @param starthash
* @param max
* @param alsoMyOwn
* @return
*/
public static Iterator<yacySeed> getAcceptRemoteIndexSeeds(final yacySeedDB seedDB, final byte[] starthash, final int max, final boolean alsoMyOwn) {
return new acceptRemoteIndexSeedEnum(seedDB, starthash, Math.min(max, seedDB.sizeConnected()), alsoMyOwn);
}
private static class acceptRemoteIndexSeedEnum implements Iterator<yacySeed> {
private final Iterator<yacySeed> se;
private yacySeed nextSeed;
private final yacySeedDB seedDB;
private final HandleSet doublecheck;
private int remaining;
private boolean alsoMyOwn;
private acceptRemoteIndexSeedEnum(yacySeedDB seedDB, final byte[] starthash, int max, boolean alsoMyOwn) {
this.seedDB = seedDB;
this.se = getDHTSeeds(seedDB, starthash, yacyVersion.YACY_HANDLES_COLLECTION_INDEX);
this.remaining = max;
this.doublecheck = new HandleSet(12, Base64Order.enhancedCoder, 0);
this.nextSeed = nextInternal();
this.alsoMyOwn = alsoMyOwn && nextSeed != null && (Base64Order.enhancedCoder.compare(seedDB.mySeed().hash.getBytes(), nextSeed.hash.getBytes()) > 0);
}
public boolean hasNext() {
return nextSeed != null;
}
private yacySeed nextInternal() {
if (this.remaining <= 0) return null;
yacySeed s;
try {
while (se.hasNext()) {
s = se.next();
if (s == null) return null;
byte[] hashb = s.hash.getBytes();
if (doublecheck.has(hashb)) return null;
try {
this.doublecheck.put(hashb);
} catch (RowSpaceExceededException e) {
Log.logException(e);
break;
}
if (s.getFlagAcceptRemoteIndex()) {
this.remaining--;
return s;
}
}
} catch (final kelondroException e) {
System.out.println("DEBUG acceptRemoteIndexSeedEnum:" + e.getMessage());
yacyCore.log.logSevere("database inconsistency (" + e.getMessage() + "), re-set of db.");
seedDB.resetActiveTable();
return null;
}
return null;
}
public yacySeed next() {
if (alsoMyOwn && Base64Order.enhancedCoder.compare(seedDB.mySeed().hash.getBytes(), nextSeed.hash.getBytes()) < 0) {
// take my own seed hash instead the enumeration result
alsoMyOwn = false;
return seedDB.mySeed();
} else {
final yacySeed next = nextSeed;
nextSeed = nextInternal();
return next;
}
}
public void remove() {
throw new UnsupportedOperationException();
}
}
/**
* enumerate seeds for DHT target positions
* @param seedDB
* @param firstHash
* @param minVersion
* @return
*/
protected static Iterator<yacySeed> getDHTSeeds(final yacySeedDB seedDB, final byte[] firstHash, final float minVersion) {
// enumerates seed-type objects: all seeds with starting point in the middle, rotating at the end/beginning
return new seedDHTEnum(seedDB, firstHash, minVersion);
}
private static class seedDHTEnum implements Iterator<yacySeed> {
private Iterator<yacySeed> e1, e2;
private int steps;
private float minVersion;
private yacySeedDB seedDB;
private seedDHTEnum(final yacySeedDB seedDB, final byte[] firstHash, final float minVersion) {
this.seedDB = seedDB;
this.steps = seedDB.sizeConnected();
this.minVersion = minVersion;
this.e1 = seedDB.seedsConnected(true, false, firstHash, minVersion);
this.e2 = null;
}
public boolean hasNext() {
return (steps > 0) && ((e2 == null) || (e2.hasNext()));
}
public yacySeed next() {
if (steps == 0) return null;
steps--;
if (e1 == null || !e1.hasNext()) {
if (e2 == null) {
e1 = null;
e2 = seedDB.seedsConnected(true, false, null, minVersion);
}
return e2.next();
}
final yacySeed n = e1.next();
if (!(e1.hasNext())) {
e1 = null;
e2 = seedDB.seedsConnected(true, false, null, minVersion);
}
return n;
}
public void remove() {
throw new UnsupportedOperationException();
}
}
/**
* enumerate peers that provide remote crawl urls
* @param seedDB
* @return an iterator of seed objects
*/
public static Iterator<yacySeed> getProvidesRemoteCrawlURLs(final yacySeedDB seedDB) {
return new providesRemoteCrawlURLsEnum(seedDB);
}
private static class providesRemoteCrawlURLsEnum implements Iterator<yacySeed> {
private Iterator<yacySeed> se;
private yacySeed nextSeed;
private yacySeedDB seedDB;
private providesRemoteCrawlURLsEnum(final yacySeedDB seedDB) {
this.seedDB = seedDB;
se = getDHTSeeds(seedDB, null, yacyVersion.YACY_POVIDES_REMOTECRAWL_LISTS);
nextSeed = nextInternal();
}
public boolean hasNext() {
return nextSeed != null;
}
private yacySeed nextInternal() {
yacySeed s;
try {
while (se.hasNext()) {
s = se.next();
if (s == null) return null;
if (s.getLong(yacySeed.RCOUNT, 0) > 0) return s;
}
} catch (final kelondroException e) {
System.out.println("DEBUG providesRemoteCrawlURLsEnum:" + e.getMessage());
yacyCore.log.logSevere("database inconsistency (" + e.getMessage() + "), re-set of db.");
seedDB.resetActiveTable();
return null;
}
return null;
}
public yacySeed next() {
final yacySeed next = nextSeed;
nextSeed = nextInternal();
return next;
}
public void remove() {
throw new UnsupportedOperationException();
}
}
/**
* get either the youngest or oldest peers from the seed db. Count as many as requested
* @param seedDB
* @param up if up = true then get the most recent peers, if up = false then get oldest
* @param count number of wanted peers
* @return a hash map of peer hashes to seed object
*/
public static Map<String, yacySeed> seedsByAge(final yacySeedDB seedDB, final boolean up, int count) {
if (count > seedDB.sizeConnected()) count = seedDB.sizeConnected();
// fill a score object
final DynamicScore<String> seedScore = new ScoreCluster<String>();
yacySeed ys;
long absage;
final Iterator<yacySeed> s = seedDB.seedsConnected(true, false, null, (float) 0.0);
int searchcount = 1000;
if (searchcount > seedDB.sizeConnected()) searchcount = seedDB.sizeConnected();
try {
while ((s.hasNext()) && (searchcount-- > 0)) {
ys = s.next();
if ((ys != null) && (ys.get(yacySeed.LASTSEEN, "").length() > 10)) try {
absage = Math.abs(System.currentTimeMillis() + AbstractFormatter.dayMillis - ys.getLastSeenUTC()) / 1000 / 60;
if (absage > Integer.MAX_VALUE) absage = Integer.MAX_VALUE;
seedScore.inc(ys.hash, (int) absage); // the higher absage, the older is the peer
} catch (final Exception e) {}
}
// result is now in the score object; create a result vector
final Map<String, yacySeed> result = new HashMap<String, yacySeed>();
final Iterator<String> it = seedScore.keys(up);
int c = 0;
while ((c < count) && (it.hasNext())) {
c++;
ys = seedDB.getConnected(it.next());
if ((ys != null) && (ys.hash != null)) result.put(ys.hash, ys);
}
return result;
} catch (final kelondroException e) {
yacyCore.log.logSevere("Internal Error at yacySeedDB.seedsByAge: " + e.getMessage(), e);
return null;
}
}
}