org.wikidata.wdtk.dumpfiles.MwRevisionProcessorBroker Maven / Gradle / Ivy
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package org.wikidata.wdtk.dumpfiles;
/*
* #%L
* Wikidata Toolkit Dump File Handling
* %%
* Copyright (C) 2014 Wikidata Toolkit Developers
* %%
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* #L%
*/
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.wikidata.wdtk.storage.datastructures.BitVector;
import org.wikidata.wdtk.storage.datastructures.BitVectorImpl;
/**
* This MwRevisionPRocessor distributes revisions to subscribers that register
* their interest in some type of message (revision). Duplicate revisions are
* filtered.
*
* The broker also allows subscribers to receive only the most current revision
* of a page rather than all revisions. To compute this efficiently, the broker
* assumes that blocks of revisions are processed in inverse chronological
* order, as it is the case when processing MediaWiki dump files in inverse
* chronological order. Revisions within a single block of revisions for one
* page do not need to be ordered in any specific way.
*
* @author Markus Kroetzsch
*
*/
public class MwRevisionProcessorBroker implements MwRevisionProcessor {
/**
* Simple data container to store information about the registered
* subscribers.
*
* @author Markus Kroetzsch
*
*/
class RevisionSubscription {
MwRevisionProcessor mwRevisionProcessor;
String model;
boolean onlyCurrentRevisions;
@Override
public String toString() {
return "Subscription of "
+ this.mwRevisionProcessor.getClass().toString()
+ " to model " + this.model + " (current: "
+ this.onlyCurrentRevisions + ")";
}
}
final List revisionSubscriptions;
/**
* Holds the most current revision found in the block of revisions that is
* currently being processed. If the current page block is not the first for
* that page, this will not be stored and the value is null.
*/
MwRevisionImpl mostCurrentRevision;
/**
* Page id of the currently processed block of page revisions. Used to
* detect when the block changes.
*/
int currentPageId;
final BitVector encounteredPages;
final BitVector encounteredRevisions;
public MwRevisionProcessorBroker() {
this.revisionSubscriptions = new ArrayList();
this.mostCurrentRevision = null;
this.currentPageId = -1;
// TODO these initial sizes need to be configurable
encounteredPages = new BitVectorImpl(20000000);
encounteredRevisions = new BitVectorImpl(200000000);
}
/**
* Registers an MwRevisionProcessor, which will henceforth be notified of
* all revisions that are encountered in the dump.
*
* Importantly, the {@link MwRevision} that the registered processors will
* receive is owned by this {@link MwRevisionProcessorBroker}. Its data is
* valid only during the execution of
* {@link MwRevisionProcessor#processRevision(MwRevision)}, but it
* will not be permanent. If the data is to be retained permanently, the
* revision processor needs to make its own copy.
*
* @param mwRevisionProcessor
* the revision processor to register
* @param model
* the content model that the processor is registered for; it
* will only be notified of revisions in that model; if null is
* given, all revisions will be processed whatever their model
* @param onlyCurrentRevisions
* if true, then the subscriber is only notified of the most
* current revisions; if false, then it will receive all
* revisions, current or not
*/
public void registerMwRevisionProcessor(
MwRevisionProcessor mwRevisionProcessor, String model,
boolean onlyCurrentRevisions) {
MwRevisionProcessorBroker.RevisionSubscription rs = new MwRevisionProcessorBroker.RevisionSubscription();
rs.mwRevisionProcessor = mwRevisionProcessor;
rs.model = model;
rs.onlyCurrentRevisions = onlyCurrentRevisions;
this.revisionSubscriptions.add(rs);
}
@Override
public void startRevisionProcessing(String siteName, String baseUrl,
Map namespaces) {
for (MwRevisionProcessorBroker.RevisionSubscription rs : this.revisionSubscriptions) {
rs.mwRevisionProcessor.startRevisionProcessing(siteName, baseUrl,
namespaces);
}
}
@Override
public void processRevision(MwRevision mwRevision) {
boolean revisionIsNew = !this.encounteredRevisions.getBit(mwRevision
.getRevisionId());
if (revisionIsNew) {
this.encounteredRevisions.setBit(mwRevision.getRevisionId(), true);
} else {
return;
}
if (mwRevision.getPageId() != this.currentPageId) {
notifyMwRevisionProcessors(this.mostCurrentRevision, true);
this.currentPageId = mwRevision.getPageId();
boolean currentPageIsNew = !this.encounteredPages
.getBit(this.currentPageId);
if (currentPageIsNew) {
this.encounteredPages.setBit(this.currentPageId, true);
this.mostCurrentRevision = new MwRevisionImpl(mwRevision);
} else {
this.mostCurrentRevision = null;
}
} else if (this.mostCurrentRevision != null
&& mwRevision.getRevisionId() > this.mostCurrentRevision
.getRevisionId()) {
this.mostCurrentRevision = new MwRevisionImpl(mwRevision);
}
notifyMwRevisionProcessors(mwRevision, false);
}
/**
* Notifies all interested subscribers of the given revision.
*
* @param mwRevision
* the given revision
* @param isCurrent
* true if this is guaranteed to be the most current revision
*/
void notifyMwRevisionProcessors(MwRevision mwRevision, boolean isCurrent) {
if (mwRevision == null || mwRevision.getPageId() <= 0) {
return;
}
for (MwRevisionProcessorBroker.RevisionSubscription rs : this.revisionSubscriptions) {
if (rs.onlyCurrentRevisions == isCurrent
&& (rs.model == null || mwRevision.getModel().equals(
rs.model))) {
rs.mwRevisionProcessor.processRevision(mwRevision);
}
}
}
/**
* Finalises the processing of one dump file (and hence of the current block
* of pages). In particular, this means that the most current revision found
* up to this point is really the most current one, so that subscribers
* should be notified.
*/
@Override
public void finishRevisionProcessing() {
notifyMwRevisionProcessors(this.mostCurrentRevision, true);
this.mostCurrentRevision = null;
for (MwRevisionProcessorBroker.RevisionSubscription rs : this.revisionSubscriptions) {
rs.mwRevisionProcessor.finishRevisionProcessing();
}
}
}