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Merged
merged 2 commits into from
Jul 27, 2017
Merged

Caching a MinDocQuery can lead to wrong results. #25909

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Caching a MinDocQuery can lead to wrong results.
jpountz Jul 26, 2017
a4db072
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jpountz Jul 27, 2017
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28 changes: 26 additions & 2 deletions core/src/main/java/org/apache/lucene/queries/MinDocQuery.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@

package org.apache.lucene.queries;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.ConstantScoreScorer;
import org.apache.lucene.search.ConstantScoreWeight;
Expand All @@ -35,16 +36,26 @@
* to a configured doc ID. */
public final class MinDocQuery extends Query {

// Matching documents depend on the sequence of segments that the index reader
// wraps. Yet matches must be cacheable per-segment, so we need to incorporate
// the reader id in the identity of the query so that a cache entry may only
// be reused if this query is run against the same index reader.
private final Object readerId;
private final int minDoc;

/** Sole constructor. */
public MinDocQuery(int minDoc) {
this(minDoc, null);
}

MinDocQuery(int minDoc, Object readerId) {
this.minDoc = minDoc;
this.readerId = readerId;
}

@Override
public int hashCode() {
return Objects.hash(classHash(), minDoc);
return Objects.hash(classHash(), minDoc, readerId);
}

@Override
Expand All @@ -53,11 +64,24 @@ public boolean equals(Object obj) {
return false;
}
MinDocQuery that = (MinDocQuery) obj;
return minDoc == that.minDoc;
return minDoc == that.minDoc && Objects.equals(readerId, that.readerId);
}

@Override
public Query rewrite(IndexReader reader) throws IOException {
if (Objects.equals(reader.getContext().id(), readerId) == false) {
return new MinDocQuery(minDoc, reader.getContext().id());
}
return this;
}

@Override
public Weight createWeight(IndexSearcher searcher, boolean needsScores, float boost) throws IOException {
if (readerId == null) {
throw new IllegalStateException("Rewrite first");
} else if (Objects.equals(searcher.getIndexReader().getContext().id(), readerId) == false) {
throw new IllegalStateException("Executing against a different reader than the query has been rewritten against");
}
return new ConstantScoreWeight(this, boost) {
@Override
public Scorer scorer(LeafReaderContext context) throws IOException {
Expand Down
15 changes: 15 additions & 0 deletions core/src/test/java/org/apache/lucene/queries/MinDocQueryTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,10 @@

import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.MultiReader;
import org.apache.lucene.index.RandomIndexWriter;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.QueryUtils;
import org.apache.lucene.store.Directory;
import org.elasticsearch.test.ESTestCase;
Expand All @@ -38,6 +40,19 @@ public void testBasics() {
QueryUtils.check(query1);
QueryUtils.checkEqual(query1, query2);
QueryUtils.checkUnequal(query1, query3);

MinDocQuery query4 = new MinDocQuery(42, new Object());
MinDocQuery query5 = new MinDocQuery(42, new Object());
QueryUtils.checkUnequal(query4, query5);
}

public void testRewrite() throws Exception {
IndexReader reader = new MultiReader();
MinDocQuery query = new MinDocQuery(42);
Query rewritten = query.rewrite(reader);
QueryUtils.checkUnequal(query, rewritten);
Query rewritten2 = rewritten.rewrite(reader);
assertSame(rewritten, rewritten2);
}

public void testRandom() throws IOException {
Expand Down