LUCENE-9988: Fix DrillSideways bug discovered in randomized testing (#167)

lucene/CHANGES.txt

@@ -293,6 +293,8 @@ Bug fixes
 * LUCENE-9823: Prevent unsafe rewrites for SynonymQuery and CombinedFieldQuery. Before, rewriting
   could slightly change the scoring when weights were specified. (Naoto Minami via Julie Tibshirani)
 
+* LUCENE-9988: Fix DrillSideways correctness bug introduced in LUCENE-9944 (Greg Miller)
+
 Changes in Backwards Compatibility Policy
 
 * LUCENE-9904: regenerated UAX29URLEmailTokenizer and the corresponding analyzer with up-to-date top

lucene/facet/src/java/org/apache/lucene/facet/DrillSidewaysQuery.java

@@ -65,11 +65,34 @@ class DrillSidewaysQuery extends Query {
       FacetsCollectorManager[] drillSidewaysCollectorManagers,
       Query[] drillDownQueries,
       boolean scoreSubDocsAtOnce) {
+    this(
+        baseQuery,
+        drillDownCollectorManager,
+        drillSidewaysCollectorManagers,
+        new ArrayList<>(),
+        new ArrayList<>(),
+        drillDownQueries,
+        scoreSubDocsAtOnce);
+  }
+
+  /**
+   * Needed for {@link #rewrite(IndexReader)}. Ensures the same "managed" lists get used since
+   * {@link DrillSideways} accesses references to these through the original {@code
+   * DrillSidewaysQuery}.
+   */
+  private DrillSidewaysQuery(
+      Query baseQuery,
+      FacetsCollectorManager drillDownCollectorManager,
+      FacetsCollectorManager[] drillSidewaysCollectorManagers,
+      List<FacetsCollector> managedDrillDownCollectors,
+      List<FacetsCollector[]> managedDrillSidewaysCollectors,
+      Query[] drillDownQueries,
+      boolean scoreSubDocsAtOnce) {
     this.baseQuery = Objects.requireNonNull(baseQuery);
     this.drillDownCollectorManager = drillDownCollectorManager;
     this.drillSidewaysCollectorManagers = drillSidewaysCollectorManagers;
-    this.managedDrillDownCollectors = new ArrayList<>();
+    this.managedDrillDownCollectors = managedDrillDownCollectors;
-    this.managedDrillSidewaysCollectors = new ArrayList<>();
+    this.managedDrillSidewaysCollectors = managedDrillSidewaysCollectors;
     this.drillDownQueries = drillDownQueries;
     this.scoreSubDocsAtOnce = scoreSubDocsAtOnce;
   }
@@ -96,6 +119,8 @@ class DrillSidewaysQuery extends Query {
           newQuery,
           drillDownCollectorManager,
           drillSidewaysCollectorManagers,
+          managedDrillDownCollectors,
+          managedDrillSidewaysCollectors,
           drillDownQueries,
           scoreSubDocsAtOnce);
     }

lucene/facet/src/test/org/apache/lucene/facet/TestDrillSideways.java

@@ -358,26 +358,31 @@ public class TestDrillSideways extends FacetTestCase {
     RandomIndexWriter writer = new RandomIndexWriter(random(), dir);
 
     Document doc = new Document();
+    doc.add(newStringField("content", "foo", Field.Store.NO));
     doc.add(new FacetField("Author", "Bob"));
     doc.add(new FacetField("Publish Date", "2010", "10", "15"));
     writer.addDocument(config.build(taxoWriter, doc));
 
     doc = new Document();
+    doc.add(newStringField("content", "foo", Field.Store.NO));
     doc.add(new FacetField("Author", "Lisa"));
     doc.add(new FacetField("Publish Date", "2010", "10", "20"));
     writer.addDocument(config.build(taxoWriter, doc));
 
     doc = new Document();
+    doc.add(newStringField("content", "foo", Field.Store.NO));
     doc.add(new FacetField("Author", "Lisa"));
     doc.add(new FacetField("Publish Date", "2012", "1", "1"));
     writer.addDocument(config.build(taxoWriter, doc));
 
     doc = new Document();
+    doc.add(newStringField("content", "bar", Field.Store.NO));
     doc.add(new FacetField("Author", "Susan"));
     doc.add(new FacetField("Publish Date", "2012", "1", "7"));
     writer.addDocument(config.build(taxoWriter, doc));
 
     doc = new Document();
+    doc.add(newStringField("content", "bar", Field.Store.NO));
     doc.add(new FacetField("Author", "Frank"));
     doc.add(new FacetField("Publish Date", "1999", "5", "5"));
     writer.addDocument(config.build(taxoWriter, doc));
@@ -581,6 +586,27 @@ public class TestDrillSideways extends FacetTestCase {
     // Expect null facets since we provided a null FacetsCollectorManager
     assertNull(r.facets);
 
+    // Test the case where the base query rewrites itself. See LUCENE-9988:
+    Query baseQuery =
+        new TermQuery(new Term("content", "foo")) {
+          @Override
+          public Query rewrite(IndexReader reader) {
+            // return a new instance, forcing the DrillDownQuery to also rewrite itself, exposing
+            // the bug in LUCENE-9988:
+            return new TermQuery(getTerm());
+          }
+        };
+    ddq = new DrillDownQuery(config, baseQuery);
+    ddq.add("Author", "Lisa");
+    r = ds.search(ddq, manager);
+    assertEquals(2, r.collectorResult.size());
+    assertEquals(
+        "dim=Publish Date path=[] value=2 childCount=2\n  2010 (1)\n  2012 (1)\n",
+        r.facets.getTopChildren(10, "Publish Date").toString());
+    assertEquals(
+        "dim=Author path=[] value=3 childCount=2\n  Lisa (2)\n  Bob (1)\n",
+        r.facets.getTopChildren(10, "Author").toString());
+
     writer.close();
     IOUtils.close(searcher.getIndexReader(), taxoReader, taxoWriter, dir, taxoDir);
   }