LUCENE-7749: Made LRUQueryCache delegate the scoreSupplier method.

lucene/CHANGES.txt

@@ -106,6 +106,9 @@ Bug Fixes
 * LUCENE-7755: Fixed join queries to not reference IndexReaders, as it could
   cause leaks if they are cached. (Adrien Grand)
 
+* LUCENE-7749: Made LRUQueryCache delegate the scoreSupplier method.
+  (Martin Amirault via Adrien Grand)
+
 Other
 
 * LUCENE-7763: Remove outdated comment in IndexWriterConfig.setIndexSort javadocs.

lucene/core/src/java/org/apache/lucene/search/LRUQueryCache.java

@@ -717,7 +717,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
     }
 
     @Override
-    public Scorer scorer(LeafReaderContext context) throws IOException {
+    public ScorerSupplier scorerSupplier(LeafReaderContext context) throws IOException {
       if (used.compareAndSet(false, true)) {
         policy.onUse(getQuery());
       }
@@ -726,18 +726,18 @@ public class LRUQueryCache implements QueryCache, Accountable {
       final IndexReader.CacheHelper cacheHelper = context.reader().getCoreCacheHelper();
       if (cacheHelper == null) {
         // this segment is not suitable for caching
-        return in.scorer(context);
+        return in.scorerSupplier(context);
       }
 
       // Short-circuit: Check whether this segment is eligible for caching
       // before we take a lock because of #get
       if (shouldCache(context) == false) {
-        return in.scorer(context);
+        return in.scorerSupplier(context);
       }
 
       // If the lock is already busy, prefer using the uncached version than waiting
       if (lock.tryLock() == false) {
-        return in.scorer(context);
+        return in.scorerSupplier(context);
       }
 
       DocIdSet docIdSet;
@@ -752,7 +752,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
           docIdSet = cache(context);
           putIfAbsent(in.getQuery(), context, docIdSet, cacheHelper);
         } else {
-          return in.scorer(context);
+          return in.scorerSupplier(context);
         }
       }
 
@@ -765,7 +765,27 @@ public class LRUQueryCache implements QueryCache, Accountable {
         return null;
       }
 
-      return new ConstantScoreScorer(this, 0f, disi);
+      return new ScorerSupplier() {
+        @Override
+        public Scorer get(boolean randomAccess) throws IOException {
+          return new ConstantScoreScorer(CachingWrapperWeight.this, 0f, disi);
+        }
+        
+        @Override
+        public long cost() {
+          return disi.cost();
+        }
+      };
+
+    }
+
+    @Override
+    public Scorer scorer(LeafReaderContext context) throws IOException {
+      ScorerSupplier scorerSupplier = scorerSupplier(context);
+      if (scorerSupplier == null) {
+        return null;
+      }
+      return scorerSupplier.get(false);
     }
 
     @Override

lucene/core/src/test/org/apache/lucene/search/TestLRUQueryCache.java

@@ -1273,4 +1273,80 @@ public class TestLRUQueryCache extends LuceneTestCase {
     w.close();
     dir.close();
   }
+
+  private static class DummyQuery2 extends Query {
+
+    private final AtomicBoolean scorerCreated;
+
+    DummyQuery2(AtomicBoolean scorerCreated) {
+      this.scorerCreated = scorerCreated;
+    }
+
+    @Override
+    public Weight createWeight(IndexSearcher searcher, boolean needsScores, float boost) throws IOException {
+      return new ConstantScoreWeight(this, boost) {
+        @Override
+        public Scorer scorer(LeafReaderContext context) throws IOException {
+          return scorerSupplier(context).get(false);
+        }
+        @Override
+        public ScorerSupplier scorerSupplier(LeafReaderContext context) throws IOException {
+          final Weight weight = this;
+          return new ScorerSupplier() {
+            @Override
+            public Scorer get(boolean randomAccess) throws IOException {
+              scorerCreated.set(true);
+              return new ConstantScoreScorer(weight, boost, DocIdSetIterator.all(1));
+            }
+
+            @Override
+            public long cost() {
+              return 1;
+            }
+          };
+        }
+      };
+    }
+
+    @Override
+    public boolean equals(Object other) {
+      return sameClassAs(other);
+    }
+
+    @Override
+    public int hashCode() {
+      return 0;
+    }
+
+    @Override
+    public String toString(String field) {
+      return "DummyQuery2";
+    }
+
+  }
+
+  public void testPropagatesScorerSupplier() throws IOException {
+    Directory dir = newDirectory();
+    IndexWriterConfig iwc = newIndexWriterConfig().setMergePolicy(NoMergePolicy.INSTANCE);
+    RandomIndexWriter w = new RandomIndexWriter(random(), dir, iwc);
+    w.addDocument(new Document());
+    DirectoryReader reader = w.getReader();
+    IndexSearcher searcher = newSearcher(reader);
+    searcher.setQueryCachingPolicy(NEVER_CACHE);
+
+    LRUQueryCache cache = new LRUQueryCache(1, 1000);
+    searcher.setQueryCache(cache);
+
+    AtomicBoolean scorerCreated = new AtomicBoolean(false);
+    Query query = new DummyQuery2(scorerCreated);
+    Weight weight = searcher.createNormalizedWeight(query, false);
+    ScorerSupplier supplier = weight.scorerSupplier(searcher.getIndexReader().leaves().get(0));
+    assertFalse(scorerCreated.get());
+    supplier.get(random().nextBoolean());
+    assertTrue(scorerCreated.get());
+
+    reader.close();
+    w.close();
+    dir.close();
+  }
 }