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190 lines
8.3 KiB
190 lines
8.3 KiB
// AbstractIndex.java
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// -----------------------------
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// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 15.3.2009 on http://yacy.net
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//
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// This is a part of YaCy, a peer-to-peer based web search engine
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//
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// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
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// $LastChangedRevision: 1986 $
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// $LastChangedBy: orbiter $
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//
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// LICENSE
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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 net.yacy.kelondro.rwi;
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import java.io.IOException;
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import java.util.Iterator;
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import java.util.TreeMap;
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import java.util.TreeSet;
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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.Order;
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public abstract class AbstractIndex <ReferenceType extends Reference> implements Index<ReferenceType> {
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final protected ReferenceFactory<ReferenceType> factory;
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public AbstractIndex(final ReferenceFactory<ReferenceType> factory) {
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this.factory = factory;
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}
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public void removeDelayed(final HandleSet termHashes, final byte[] urlHashBytes) throws IOException {
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// remove the same url hashes for multiple words
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// this is mainly used when correcting a index after a search
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final Iterator<byte[]> i = termHashes.iterator();
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while (i.hasNext()) {
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removeDelayed(i.next(), urlHashBytes);
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}
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}
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public int remove(final HandleSet termHashes, final byte[] urlHashBytes) throws IOException {
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// remove the same url hashes for multiple words
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// this is mainly used when correcting a index after a search
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final Iterator<byte[]> i = termHashes.iterator();
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int c = 0;
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while (i.hasNext()) {
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if (remove(i.next(), urlHashBytes)) c++;
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}
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return c;
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}
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public synchronized TreeSet<ReferenceContainer<ReferenceType>> references(final byte[] startHash, final boolean rot, int count) throws IOException {
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// creates a set of indexContainers
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// this does not use the cache
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final Order<ReferenceContainer<ReferenceType>> containerOrder = new ReferenceContainerOrder<ReferenceType>(factory, this.ordering().clone());
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final ReferenceContainer<ReferenceType> emptyContainer = ReferenceContainer.emptyContainer(factory, startHash);
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containerOrder.rotate(emptyContainer);
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final TreeSet<ReferenceContainer<ReferenceType>> containers = new TreeSet<ReferenceContainer<ReferenceType>>(containerOrder);
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final Iterator<ReferenceContainer<ReferenceType>> i = references(startHash, rot);
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//if (ram) count = Math.min(size(), count);
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ReferenceContainer<ReferenceType> container;
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// this loop does not terminate using the i.hasNex() predicate when rot == true
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// because then the underlying iterator is a rotating iterator without termination
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// in this case a termination must be ensured with a counter
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// It must also be ensured that the counter is in/decreased every loop
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while ((count > 0) && (i.hasNext())) {
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container = i.next();
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if (container != null && !container.isEmpty()) {
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containers.add(container);
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}
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count--; // decrease counter even if the container was null or empty to ensure termination
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}
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return containers; // this may return less containers as demanded
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}
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// methods to search in the index
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/**
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* collect containers for given word hashes.
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* This collection stops if a single container does not contain any references.
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* In that case only a empty result is returned.
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* @param wordHashes
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* @param urlselection
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* @return map of wordhash:indexContainer
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*/
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public TreeMap<byte[], ReferenceContainer<ReferenceType>> searchConjunction(final HandleSet wordHashes, final HandleSet urlselection) {
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// first check if there is any entry that has no match; this uses only operations in ram
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/*
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Iterator<byte[]> i = wordHashes.iterator();
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while (i.hasNext()) {
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if (!this.has(i.next())); return new TreeMap<byte[], ReferenceContainer<ReferenceType>>(0);
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}
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*/
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// retrieve entities that belong to the hashes
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final TreeMap<byte[], ReferenceContainer<ReferenceType>> containers = new TreeMap<byte[], ReferenceContainer<ReferenceType>>(Base64Order.enhancedCoder);
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byte[] singleHash;
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ReferenceContainer<ReferenceType> singleContainer;
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final Iterator<byte[]> i = wordHashes.iterator();
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while (i.hasNext()) {
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// get next word hash:
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singleHash = i.next();
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// retrieve index
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try {
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singleContainer = this.get(singleHash, urlselection);
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} catch (IOException e) {
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Log.logException(e);
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continue;
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}
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// check result
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if ((singleContainer == null || singleContainer.isEmpty())) return new TreeMap<byte[], ReferenceContainer<ReferenceType>>(Base64Order.enhancedCoder);
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containers.put(singleHash, singleContainer);
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}
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return containers;
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}
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/**
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* collect containers for given word hashes and join them as they are retrieved.
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* This collection stops if a single container does not contain any references
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* or the current result of the container join results in an empty container.
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* In any fail case only a empty result container is returned.
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* @param wordHashes
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* @param urlselection
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* @param maxDistance the maximum distance that the words in the result may have
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* @return ReferenceContainer the join result
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* @throws RowSpaceExceededException
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*/
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public ReferenceContainer<ReferenceType> searchJoin(final HandleSet wordHashes, final HandleSet urlselection, final int maxDistance) throws RowSpaceExceededException {
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// first check if there is any entry that has no match;
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// this uses only operations in ram
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for (byte[] wordHash: wordHashes) {
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if (!this.has(wordHash)) return ReferenceContainer.emptyContainer(factory, null, 0);
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}
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// retrieve entities that belong to the hashes
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ReferenceContainer<ReferenceType> resultContainer = null;
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ReferenceContainer<ReferenceType> singleContainer;
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for (byte[] wordHash: wordHashes) {
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// retrieve index
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try {
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singleContainer = this.get(wordHash, urlselection);
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} catch (IOException e) {
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Log.logException(e);
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continue;
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}
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// check result
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if ((singleContainer == null || singleContainer.isEmpty())) return ReferenceContainer.emptyContainer(factory, null, 0);
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if (resultContainer == null) resultContainer = singleContainer; else {
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resultContainer = ReferenceContainer.joinConstructive(factory, resultContainer, singleContainer, maxDistance);
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}
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// finish if the result is empty
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if (resultContainer.isEmpty()) return resultContainer;
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}
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return resultContainer;
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}
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public TermSearch<ReferenceType> query(
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final HandleSet queryHashes,
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final HandleSet excludeHashes,
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final HandleSet urlselection,
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final ReferenceFactory<ReferenceType> termFactory,
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final int maxDistance) throws RowSpaceExceededException {
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return new TermSearch<ReferenceType>(this, queryHashes, excludeHashes, urlselection, termFactory, maxDistance);
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}
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}
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