Code cleanup

src/main/java/it/cavallium/dbengine/client/Hits.java

@@ -16,18 +16,26 @@ import reactor.core.publisher.Mono;
 import reactor.util.function.Tuples;
 
 public final class Hits<T> extends SimpleResource {
+
+	private static final Hits<?> EMPTY_HITS = new Hits<>(Flux.empty(), TotalHitsCount.of(0, true), null, false);
 	private Flux<T> results;
 	private TotalHitsCount totalHitsCount;
 	private Runnable onClose;
 
 	public Hits(Flux<T> results, TotalHitsCount totalHitsCount, Runnable onClose) {
+		this(results, totalHitsCount, onClose, true);
+	}
+
+	private Hits(Flux<T> results, TotalHitsCount totalHitsCount, Runnable onClose, boolean canClose) {
+		super(canClose);
 		this.results = results;
 		this.totalHitsCount = totalHitsCount;
 		this.onClose = onClose;
 	}
 
+	@SuppressWarnings("unchecked")
 	public static <T> Hits<T> empty() {
-		return new Hits<>(Flux.empty(), TotalHitsCount.of(0, true), null);
+		return (Hits<T>) EMPTY_HITS;
 	}
 
 	public static <K, V> Hits<LazyHitEntry<K, V>> withValuesLazy(Hits<LazyHitKey<K>> hits,

src/main/java/it/cavallium/dbengine/client/LuceneIndexImpl.java

@@ -124,7 +124,7 @@ public class LuceneIndexImpl<T, U> implements LuceneIndex<T, U> {
 				.collectList()
 				.flatMap(shards -> mergeResults(queryParams, shards))
 				.map(this::mapResults)
-				.single()
+				.defaultIfEmpty(Hits.empty())
 				.doOnDiscard(LLSearchResultShard.class, SimpleResource::close)
 				.doOnDiscard(Hits.class, SimpleResource::close);
 	}
@@ -153,9 +153,7 @@ public class LuceneIndexImpl<T, U> implements LuceneIndex<T, U> {
 				.query(query)
 				.timeout(Duration.ofSeconds(30))
 				.limit(0)
-				.build()), searchResultKeys -> {
-			return Mono.just(searchResultKeys.totalHitsCount());
-		}, LLUtils::finalizeResource);
+				.build()), searchResultKeys -> Mono.just(searchResultKeys.totalHitsCount()), LLUtils::finalizeResource);
 	}
 
 	@Override

src/main/java/it/cavallium/dbengine/utils/SimpleResource.java

@@ -6,20 +6,29 @@ import java.util.concurrent.atomic.AtomicBoolean;
 public abstract class SimpleResource implements SafeCloseable {
 
 	private final AtomicBoolean closed = new AtomicBoolean();
+	private final boolean canClose;
+
+	public SimpleResource() {
+		canClose = true;
+	}
+
+	protected SimpleResource(boolean canClose) {
+		this.canClose = canClose;
+	}
 
 	@Override
 	public final void close() {
-		if (closed.compareAndSet(false, true)) {
+		if (canClose && closed.compareAndSet(false, true)) {
 			onClose();
 		}
 	}
 
 	private boolean isClosed() {
-		return closed.get();
+		return canClose && closed.get();
 	}
 
 	protected void ensureOpen() {
-		if (closed.get()) {
+		if (canClose && closed.get()) {
 			throw new IllegalStateException("Resource is closed");
 		}
 	}