/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.lucene.search.join;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Locale;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.FilterWeight;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.ScorerSupplier;
import org.apache.lucene.search.TwoPhaseIterator;
import org.apache.lucene.search.Weight;
import org.apache.lucene.util.BitSet;
/**
* This query requires that you index
* children and parent docs as a single block, using the
* {@link IndexWriter#addDocuments IndexWriter.addDocuments()} or {@link
* IndexWriter#updateDocuments IndexWriter.updateDocuments()} API. In each block, the
* child documents must appear first, ending with the parent
* document. At search time you provide a Filter
* identifying the parents, however this Filter must provide
* an {@link BitSet} per sub-reader.
*
* <p>Once the block index is built, use this query to wrap
* any sub-query matching only child docs and join matches in that
* child document space up to the parent document space.
* You can then use this Query as a clause with
* other queries in the parent document space.</p>
*
* <p>See {@link ToChildBlockJoinQuery} if you need to join
* in the reverse order.
*
* <p>The child documents must be orthogonal to the parent
* documents: the wrapped child query must never
* return a parent document.</p>
*
* <p>See {@link org.apache.lucene.search.join} for an
* overview. </p>
*
* @lucene.experimental
*/
public class ToParentBlockJoinQuery extends Query {
private final BitSetProducer parentsFilter;
private final Query childQuery;
private final ScoreMode scoreMode;
/** Create a ToParentBlockJoinQuery.
*
* @param childQuery Query matching child documents.
* @param parentsFilter Filter identifying the parent documents.
* @param scoreMode How to aggregate multiple child scores
* into a single parent score.
**/
public ToParentBlockJoinQuery(Query childQuery, BitSetProducer parentsFilter, ScoreMode scoreMode) {
super();
this.childQuery = childQuery;
this.parentsFilter = parentsFilter;
this.scoreMode = scoreMode;
}
@Override
public Weight createWeight(IndexSearcher searcher, boolean needsScores, float boost) throws IOException {
return new BlockJoinWeight(this, childQuery.createWeight(searcher, needsScores, boost), parentsFilter, needsScores ? scoreMode : ScoreMode.None);
}
/** Return our child query. */
public Query getChildQuery() {
return childQuery;
}
private static class BlockJoinWeight extends FilterWeight {
private final BitSetProducer parentsFilter;
private final ScoreMode scoreMode;
public BlockJoinWeight(Query joinQuery, Weight childWeight, BitSetProducer parentsFilter, ScoreMode scoreMode) {
super(joinQuery, childWeight);
this.parentsFilter = parentsFilter;
this.scoreMode = scoreMode;
}
@Override
public Scorer scorer(LeafReaderContext context) throws IOException {
final ScorerSupplier scorerSupplier = scorerSupplier(context);
if (scorerSupplier == null) {
return null;
}
return scorerSupplier.get(false);
}
// NOTE: acceptDocs applies (and is checked) only in the
// parent document space
@Override
public ScorerSupplier scorerSupplier(LeafReaderContext context) throws IOException {
final ScorerSupplier childScorerSupplier = in.scorerSupplier(context);
if (childScorerSupplier == null) {
return null;
}
// NOTE: this does not take accept docs into account, the responsibility
// to not match deleted docs is on the scorer
final BitSet parents = parentsFilter.getBitSet(context);
if (parents == null) {
// No matches
return null;
}
return new ScorerSupplier() {
@Override
public Scorer get(boolean randomAccess) throws IOException {
return new BlockJoinScorer(BlockJoinWeight.this, childScorerSupplier.get(randomAccess), parents, scoreMode);
}
@Override
public long cost() {
return childScorerSupplier.cost();
}
};
}
@Override
public Explanation explain(LeafReaderContext context, int doc) throws IOException {
BlockJoinScorer scorer = (BlockJoinScorer) scorer(context);
if (scorer != null && scorer.iterator().advance(doc) == doc) {
return scorer.explain(context, in);
}
return Explanation.noMatch("Not a match");
}
}
private static class ParentApproximation extends DocIdSetIterator {
private final DocIdSetIterator childApproximation;
private final BitSet parentBits;
private int doc = -1;
ParentApproximation(DocIdSetIterator childApproximation, BitSet parentBits) {
this.childApproximation = childApproximation;
this.parentBits = parentBits;
}
@Override
public int docID() {
return doc;
}
@Override
public int nextDoc() throws IOException {
return advance(doc + 1);
}
@Override
public int advance(int target) throws IOException {
if (target >= parentBits.length()) {
return doc = NO_MORE_DOCS;
}
final int firstChildTarget = target == 0 ? 0 : parentBits.prevSetBit(target - 1) + 1;
int childDoc = childApproximation.docID();
if (childDoc < firstChildTarget) {
childDoc = childApproximation.advance(firstChildTarget);
}
if (childDoc >= parentBits.length() - 1) {
return doc = NO_MORE_DOCS;
}
return doc = parentBits.nextSetBit(childDoc + 1);
}
@Override
public long cost() {
return childApproximation.cost();
}
}
private static class ParentTwoPhase extends TwoPhaseIterator {
private final ParentApproximation parentApproximation;
private final DocIdSetIterator childApproximation;
private final TwoPhaseIterator childTwoPhase;
ParentTwoPhase(ParentApproximation parentApproximation, TwoPhaseIterator childTwoPhase) {
super(parentApproximation);
this.parentApproximation = parentApproximation;
this.childApproximation = childTwoPhase.approximation();
this.childTwoPhase = childTwoPhase;
}
@Override
public boolean matches() throws IOException {
assert childApproximation.docID() < parentApproximation.docID();
do {
if (childTwoPhase.matches()) {
return true;
}
} while (childApproximation.nextDoc() < parentApproximation.docID());
return false;
}
@Override
public float matchCost() {
// TODO: how could we compute a match cost?
return childTwoPhase.matchCost() + 10;
}
}
static class BlockJoinScorer extends Scorer {
private final Scorer childScorer;
private final BitSet parentBits;
private final ScoreMode scoreMode;
private final DocIdSetIterator childApproximation;
private final TwoPhaseIterator childTwoPhase;
private final ParentApproximation parentApproximation;
private final ParentTwoPhase parentTwoPhase;
private float score;
private int freq;
public BlockJoinScorer(Weight weight, Scorer childScorer, BitSet parentBits, ScoreMode scoreMode) {
super(weight);
//System.out.println("Q.init firstChildDoc=" + firstChildDoc);
this.parentBits = parentBits;
this.childScorer = childScorer;
this.scoreMode = scoreMode;
childTwoPhase = childScorer.twoPhaseIterator();
if (childTwoPhase == null) {
childApproximation = childScorer.iterator();
parentApproximation = new ParentApproximation(childApproximation, parentBits);
parentTwoPhase = null;
} else {
childApproximation = childTwoPhase.approximation();
parentApproximation = new ParentApproximation(childTwoPhase.approximation(), parentBits);
parentTwoPhase = new ParentTwoPhase(parentApproximation, childTwoPhase);
}
}
@Override
public Collection<ChildScorer> getChildren() {
return Collections.singleton(new ChildScorer(childScorer, "BLOCK_JOIN"));
}
@Override
public DocIdSetIterator iterator() {
if (parentTwoPhase == null) {
// the approximation is exact
return parentApproximation;
} else {
return TwoPhaseIterator.asDocIdSetIterator(parentTwoPhase);
}
}
@Override
public TwoPhaseIterator twoPhaseIterator() {
return parentTwoPhase;
}
@Override
public int docID() {
return parentApproximation.docID();
}
@Override
public float score() throws IOException {
setScoreAndFreq();
return score;
}
@Override
public int freq() throws IOException {
setScoreAndFreq();
return freq;
}
private void setScoreAndFreq() throws IOException {
if (childApproximation.docID() >= parentApproximation.docID()) {
return;
}
double score = scoreMode == ScoreMode.None ? 0 : childScorer.score();
int freq = 1;
while (childApproximation.nextDoc() < parentApproximation.docID()) {
if (childTwoPhase == null || childTwoPhase.matches()) {
final float childScore = childScorer.score();
freq += 1;
switch (scoreMode) {
case Total:
case Avg:
score += childScore;
break;
case Min:
score = Math.min(score, childScore);
break;
case Max:
score = Math.max(score, childScore);
break;
case None:
break;
default:
throw new AssertionError();
}
}
}
if (childApproximation.docID() == parentApproximation.docID() && (childTwoPhase == null || childTwoPhase.matches())) {
throw new IllegalStateException("Child query must not match same docs with parent filter. "
+ "Combine them as must clauses (+) to find a problem doc. "
+ "docId=" + parentApproximation.docID() + ", " + childScorer.getClass());
}
if (scoreMode == ScoreMode.Avg) {
score /= freq;
}
this.score = (float) score;
this.freq = freq;
}
public Explanation explain(LeafReaderContext context, Weight childWeight) throws IOException {
int prevParentDoc = parentBits.prevSetBit(parentApproximation.docID() - 1);
int start = context.docBase + prevParentDoc + 1; // +1 b/c prevParentDoc is previous parent doc
int end = context.docBase + parentApproximation.docID() - 1; // -1 b/c parentDoc is parent doc
Explanation bestChild = null;
int matches = 0;
for (int childDoc = start; childDoc <= end; childDoc++) {
Explanation child = childWeight.explain(context, childDoc - context.docBase);
if (child.isMatch()) {
matches++;
if (bestChild == null || child.getValue() > bestChild.getValue()) {
bestChild = child;
}
}
}
assert freq() == matches;
return Explanation.match(score(), String.format(Locale.ROOT,
"Score based on %d child docs in range from %d to %d, best match:", matches, start, end), bestChild
);
}
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
final Query childRewrite = childQuery.rewrite(reader);
if (childRewrite != childQuery) {
return new ToParentBlockJoinQuery(childRewrite,
parentsFilter,
scoreMode);
} else {
return super.rewrite(reader);
}
}
@Override
public String toString(String field) {
return "ToParentBlockJoinQuery ("+childQuery.toString()+")";
}
@Override
public boolean equals(Object other) {
return sameClassAs(other) &&
equalsTo(getClass().cast(other));
}
private boolean equalsTo(ToParentBlockJoinQuery other) {
return childQuery.equals(other.childQuery) &&
parentsFilter.equals(other.parentsFilter) &&
scoreMode == other.scoreMode;
}
@Override
public int hashCode() {
final int prime = 31;
int hash = classHash();
hash = prime * hash + childQuery.hashCode();
hash = prime * hash + scoreMode.hashCode();
hash = prime * hash + parentsFilter.hashCode();
return hash;
}
}