com.browseengine.bobo.query.RecencyBoostScorerBuilder Maven / Gradle / Ivy
/**
* This software is licensed to you under the Apache License, Version 2.0 (the
* "Apache License").
*
* LinkedIn's contributions are made under the Apache License. If you contribute
* to the Software, the contributions will be deemed to have been made under the
* Apache License, unless you expressly indicate otherwise. Please do not make any
* contributions that would be inconsistent with the Apache License.
*
* You may obtain a copy of the Apache License at http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, this software
* distributed under the Apache License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the Apache
* License for the specific language governing permissions and limitations for the
* software governed under the Apache License.
*
* © 2012 LinkedIn Corp. All Rights Reserved.
*/
package com.browseengine.bobo.query;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.Scorer;
import com.browseengine.bobo.api.BoboIndexReader;
import com.browseengine.bobo.facets.data.FacetDataCache;
import com.browseengine.bobo.facets.data.TermLongList;
import com.browseengine.bobo.util.BigSegmentedArray;
public class RecencyBoostScorerBuilder implements ScorerBuilder {
private final float _maxFactor;
private final TimeUnit _timeunit;
private final float _min;
private final float _max;
private final long _cutoffInMillis;
private final float _A;
private final String _timeFacetName;
private final long _now;
public RecencyBoostScorerBuilder(String timeFacetName,float maxFactor,long cutoff,TimeUnit timeunit){
this(timeFacetName,maxFactor,timeunit.convert(System.currentTimeMillis(), TimeUnit.MILLISECONDS),cutoff,timeunit);
}
public RecencyBoostScorerBuilder(String timeFacetName,float maxFactor,long from,long cutoff,TimeUnit timeunit) {
_timeFacetName = timeFacetName;
_maxFactor = maxFactor;
_min = 1.0f;
_max = _maxFactor + _min;
_timeunit = timeunit;
_cutoffInMillis = _timeunit.toMillis(cutoff);
_A = (_min - _max) / (((float)_cutoffInMillis)*((float)_cutoffInMillis));
_now =timeunit.toMillis(from);
}
public Explanation explain(IndexReader reader, int doc,
Explanation innerExplaination) throws IOException {
if (reader instanceof BoboIndexReader){
BoboIndexReader boboReader = (BoboIndexReader)reader;
Object dataObj = boboReader.getFacetData(_timeFacetName);
if (dataObj instanceof FacetDataCache){
FacetDataCache facetDataCache = (FacetDataCache)(boboReader.getFacetData(_timeFacetName));
final BigSegmentedArray orderArray = facetDataCache.orderArray;
final TermLongList termList = (TermLongList)facetDataCache.valArray;
final long now = System.currentTimeMillis();
Explanation finalExpl = new Explanation();
finalExpl.addDetail(innerExplaination);
float rawScore = innerExplaination.getValue();
long timeVal = termList.getPrimitiveValue(orderArray.get(doc));
float timeScore = computeTimeFactor(timeVal);
float finalScore = combineScores(timeScore,rawScore);
finalExpl.setValue(finalScore);
finalExpl.setDescription("final score = (time score: "+timeScore+") * (raw score: "+rawScore+"), timeVal: "+timeVal);
return finalExpl;
}
else{
throw new IllegalStateException("underlying facet data must be of type FacetDataCache");
}
}
else{
throw new IllegalStateException("reader not instance of "+BoboIndexReader.class);
}
}
public Scorer createScorer(final Scorer innerScorer, IndexReader reader,
boolean scoreDocsInOrder, boolean topScorer) throws IOException {
if (reader instanceof BoboIndexReader){
BoboIndexReader boboReader = (BoboIndexReader)reader;
Object dataObj = boboReader.getFacetData(_timeFacetName);
if (dataObj instanceof FacetDataCache){
FacetDataCache facetDataCache = (FacetDataCache)(boboReader.getFacetData(_timeFacetName));
final BigSegmentedArray orderArray = facetDataCache.orderArray;
final TermLongList termList = (TermLongList)facetDataCache.valArray;
return new Scorer(innerScorer.getSimilarity()){
@Override
public float score() throws IOException {
float rawScore = innerScorer.score();
long timeVal = termList.getRawValue(orderArray.get(innerScorer.docID()));
float timeScore = computeTimeFactor(timeVal);
return combineScores(timeScore,rawScore);
}
@Override
public int advance(int target) throws IOException {
return innerScorer.advance(target);
}
@Override
public int docID() {
return innerScorer.docID();
}
@Override
public int nextDoc() throws IOException {
return innerScorer.nextDoc();
}
};
}
else{
throw new IllegalStateException("underlying facet data must be of type FacetDataCache");
}
}
else{
throw new IllegalStateException("reader not instance of "+BoboIndexReader.class);
}
}
protected float computeTimeFactor(long timeVal){
long xVal = _now - timeVal;
if (xVal > _cutoffInMillis){
return _min;
}
else{
float xValFloat = (float)xVal;
return _A*xValFloat*xValFloat+_max;
}
}
private static float combineScores(float timeScore,float rawScore){
return timeScore * rawScore;
}
}