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226 lines
8.2 KiB
226 lines
8.2 KiB
// ReverseIndexCell.java
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// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 1.3.2009 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: 2009-01-02 12:38:20 +0100 (Fr, 02 Jan 2009) $
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// $LastChangedRevision: 5432 $
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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 de.anomic.kelondro.text;
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import java.io.File;
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import java.io.IOException;
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import java.util.HashSet;
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import java.util.Set;
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import de.anomic.kelondro.index.Row;
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import de.anomic.kelondro.order.CloneableIterator;
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import de.anomic.kelondro.order.MergeIterator;
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import de.anomic.kelondro.order.Order;
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/*
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* an index cell is a part of the horizontal index in the new segment-oriented index
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* data structure of YaCy. If there is no filter in front of a cell, it might also be
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* the organization for a complete segment index. Each cell consists of a number of BLOB files, that
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* must be merged to represent a single index. In fact these index files are only merged on demand
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* if there are too many of them. An index merge can be done with a stream read and stream write operation.
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* in normal operation, there are only a number of read-only BLOB files and a single RAM cache that is
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* kept in the RAM as long as a given limit of entries is reached. Then the cache is flushed and becomes
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* another BLOB file in the index array.
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*/
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public final class IndexCell implements Index {
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// class variables
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private ReferenceContainerArray array;
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private ReferenceContainerCache ram;
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private int maxRamEntries;
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public IndexCell(
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final File cellPath,
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final Row payloadrow,
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final int maxRamEntries
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) throws IOException {
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this.array = new ReferenceContainerArray(cellPath, payloadrow);
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this.ram = new ReferenceContainerCache(payloadrow);
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this.maxRamEntries = maxRamEntries;
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}
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private void cacheDump() throws IOException {
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// dump the ram
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File dumpFile = this.array.newContainerBLOBFile();
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this.ram.dump(dumpFile);
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// get a fresh ram cache
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this.ram = new ReferenceContainerCache(this.array.rowdef());
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// add the dumped indexContainerBLOB to the array
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this.array.mountBLOBContainer(dumpFile);
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}
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/**
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* add entries to the cell: this adds the new entries always to the RAM part, never to BLOBs
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* @throws IOException
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*/
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public synchronized void addReferences(ReferenceContainer newEntries) throws IOException {
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this.ram.addReferences(newEntries);
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if (this.ram.size() > this.maxRamEntries) cacheDump();
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}
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/**
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* clear the RAM and BLOB part, deletes everything in the cell
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*/
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public synchronized void clear() throws IOException {
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this.ram.clear();
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this.array.clear();
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}
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/**
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* when a cell is closed, the current RAM is dumped to a file which will be opened as
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* BLOB file the next time a cell is opened. A name for the dump is automatically generated
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* and is composed of the current date and the cell salt
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*/
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public synchronized void close() {
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// dump the ram
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try {
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this.ram.dump(this.array.newContainerBLOBFile());
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} catch (IOException e) {
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e.printStackTrace();
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}
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// close all
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this.ram.close();
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this.array.close();
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}
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/**
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* deleting a container affects the containers in RAM and all the BLOB files
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* the deleted containers are merged and returned as result of the method
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*/
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public ReferenceContainer deleteAllReferences(String wordHash) throws IOException {
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ReferenceContainer c0 = this.ram.deleteAllReferences(wordHash);
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ReferenceContainer c1 = this.array.get(wordHash);
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if (c1 == null) {
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if (c0 == null) return null;
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return c0;
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}
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this.array.delete(wordHash);
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if (c0 == null) return c1;
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return c1.merge(c0);
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}
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/**
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* all containers in the BLOBs and the RAM are merged and returned
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*/
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public ReferenceContainer getReferences(String wordHash, Set<String> urlselection) throws IOException {
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ReferenceContainer c0 = this.ram.getReferences(wordHash, null);
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ReferenceContainer c1 = this.array.get(wordHash);
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if (c1 == null) {
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if (c0 == null) return null;
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return c0;
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}
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if (c0 == null) return c1;
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return c1.merge(c0);
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}
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public int countReferences(String wordHash) {
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ReferenceContainer c0 = this.ram.getReferences(wordHash, null);
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ReferenceContainer c1;
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try {
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c1 = this.array.get(wordHash);
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} catch (IOException e) {
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c1 = null;
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}
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if (c1 == null) {
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if (c0 == null) return 0;
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return c0.size();
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}
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if (c0 == null) return c1.size();
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return c1.size() + c0.size();
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}
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/**
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* checks if there is any container for this wordHash, either in RAM or any BLOB
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*/
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public boolean hasReferences(String wordHash) {
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if (this.ram.hasReferences(wordHash)) return true;
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return this.array.has(wordHash);
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}
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public int minMem() {
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return 10 * 1024 * 1024;
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}
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/**
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* remove url references from a selected word hash. this deletes also in the BLOB
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* files, which means that there exists new gap entries after the deletion
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* The gaps are never merged in place, but can be eliminated when BLOBs are merged into
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* new BLOBs. This returns the sum of all url references that have been removed
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* @throws IOException
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* @throws IOException
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*/
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public int removeReferences(String wordHash, Set<String> urlHashes) throws IOException {
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int reduced = this.array.replace(wordHash, new RemoveRewriter(urlHashes));
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return reduced / this.array.rowdef().objectsize;
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}
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public boolean removeReference(String wordHash, String urlHash) throws IOException {
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int reduced = this.array.replace(wordHash, new RemoveRewriter(urlHash));
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return reduced > 0;
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}
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public int size() {
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return this.ram.size() + this.array.size();
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}
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public CloneableIterator<ReferenceContainer> referenceIterator(String startWordHash, boolean rot, boolean ram) throws IOException {
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final Order<ReferenceContainer> containerOrder = new ReferenceContainerOrder(this.ram.rowdef().getOrdering().clone());
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containerOrder.rotate(new ReferenceContainer(startWordHash, this.ram.rowdef(), 0));
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if (ram) {
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return this.ram.referenceIterator(startWordHash, rot, true);
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}
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return new MergeIterator<ReferenceContainer>(
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this.ram.referenceIterator(startWordHash, false, true),
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this.array.wordContainerIterator(startWordHash, false, false),
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containerOrder,
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ReferenceContainer.containerMergeMethod,
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true);
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}
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private static class RemoveRewriter implements ReferenceContainerArray.ContainerRewriter {
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Set<String> urlHashes;
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public RemoveRewriter(Set<String> urlHashes) {
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this.urlHashes = urlHashes;
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}
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public RemoveRewriter(String urlHash) {
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this.urlHashes = new HashSet<String>();
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this.urlHashes.add(urlHash);
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}
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public ReferenceContainer rewrite(ReferenceContainer container) {
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container.removeEntries(urlHashes);
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return container;
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}
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}
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}
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