GH-5149 numdocs (#5202)

core/model-api/src/main/java/org/eclipse/rdf4j/model/Model.java

@@ -45,7 +45,7 @@ public interface Model extends Set<Statement>, Serializable, NamespaceAware {
 	 */
 	default Namespace setNamespace(String prefix, String name) {
 		Optional<? extends Namespace> result = getNamespace(prefix);
-		if (!result.isPresent() || !result.get().getName().equals(name)) {
+		if (result.isEmpty() || !result.get().getName().equals(name)) {
 			result = Optional.of(new ModelNamespace(prefix, name));
 			setNamespace(result.get());
 		}

core/model/src/main/java/org/eclipse/rdf4j/model/util/Configurations.java

@@ -240,7 +240,7 @@ public static Optional<Resource> getSubjectByType(Model model, IRI type, IRI leg
 
 	private static void logDiscrepancyWarning(Optional<? extends Value> preferred,
 			Optional<? extends Value> fallback) {
-		if (!fallback.isEmpty() && !preferred.equals(fallback)) {
+		if (fallback.isPresent() && !preferred.equals(fallback)) {
 			var msg = "Discrepancy between use of the old and new config vocabulary.";
 			// depending on whether preferred is set, we log on warn or debug
 			if (preferred.isEmpty()) {

core/model/src/main/java/org/eclipse/rdf4j/model/util/GraphComparisons.java

@@ -169,7 +169,7 @@ private static boolean isomorphicSingleContext(Model model1, Model model2) {
 
 		// Because we have previously already checked that the models are the same size, we don't have to check both
 		// ways to establish model equality.
-		return !missingInModel2.isPresent();
+		return missingInModel2.isEmpty();
 	}
 
 	private static boolean mappingsIncompatible(Map<BNode, HashCode> mapping1, Map<BNode, HashCode> mapping2) {

core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/function/string/Contains.java

@@ -45,7 +45,7 @@ public Literal evaluate(ValueFactory valueFactory, Value... args) throws ValueEx
 			Literal rightLit = (Literal) rightVal;
 
 			if (leftLit.getLanguage().isPresent()) {
-				if (!rightLit.getLanguage().isPresent() || rightLit.getLanguage().equals(leftLit.getLanguage())) {
+				if (rightLit.getLanguage().isEmpty() || rightLit.getLanguage().equals(leftLit.getLanguage())) {
 
 					String leftLexVal = leftLit.getLabel();
 					String rightLexVal = rightLit.getLabel();

core/rio/api/src/main/java/org/eclipse/rdf4j/rio/helpers/RDFParserHelper.java

@@ -190,7 +190,7 @@ public static Literal createLiteral(String label, String lang, IRI datatype, Par
 			try {
 				// Removes datatype for langString datatype with no language tag when VERIFY_DATATYPE_VALUES is False.
 				if ((workingDatatype == null || RDF.LANGSTRING.equals(workingDatatype))
-						&& (!workingLang.isPresent() || workingLang.get().isEmpty())
+						&& (workingLang.isEmpty() || workingLang.get().isEmpty())
 						&& !parserConfig.get(BasicParserSettings.VERIFY_DATATYPE_VALUES)) {
 					workingLang = Optional.ofNullable(null);
 					workingDatatype = null;

core/rio/jsonld-legacy/src/main/java/org/eclipse/rdf4j/rio/jsonld/legacy/JSONLDInternalRDFParser.java

@@ -64,7 +64,7 @@ public void handleStatement(RDFDataset result, Statement nextStatement) {
 
 			// In RDF-1.1, RDF-1.0 Plain Literals are now Typed Literals with
 			// type xsd:String
-			if (!literal.getLanguage().isPresent() && datatype == null) {
+			if (literal.getLanguage().isEmpty() && datatype == null) {
 				datatype = XSD.STRING.stringValue();
 			}
 

core/sail/elasticsearch/src/main/java/org/eclipse/rdf4j/sail/elasticsearch/ElasticsearchIndex.java

@@ -87,14 +87,13 @@
 
 /**
  * Requires an Elasticsearch cluster with the DeleteByQuery plugin.
- *
+ * <p>
  * Note that, while RDF4J is licensed under the EDL, several ElasticSearch dependencies are licensed under the Elastic
  * license or the SSPL, which may have implications for some projects.
- *
+ * <p>
  * Please consult the ElasticSearch website and license FAQ for more information.
  *
  * @see <a href="https://www.elastic.co/licensing/elastic-license/faq">Elastic License FAQ</a>
- *
  * @see LuceneSail
  */
 public class ElasticsearchIndex extends AbstractSearchIndex {
@@ -409,13 +408,8 @@ protected SearchDocument getDocument(String id) throws IOException {
 	@Override
 	protected Iterable<? extends SearchDocument> getDocuments(String resourceId) throws IOException {
 		SearchHits hits = getDocuments(QueryBuilders.termQuery(SearchFields.URI_FIELD_NAME, resourceId));
-		return Iterables.transform(hits, new Function<>() {
-
-			@Override
-			public SearchDocument apply(SearchHit hit) {
-				return new ElasticsearchDocument(hit, geoContextMapper);
-			}
-		});
+		return Iterables.transform(hits,
+				(Function<SearchHit, SearchDocument>) hit -> new ElasticsearchDocument(hit, geoContextMapper));
 	}
 
 	@Override
@@ -577,18 +571,26 @@ protected Iterable<? extends DocumentScore> query(Resource subject, QuerySpec sp
 		}
 
 		SearchHits hits;
-		if (subject != null) {
-			hits = search(subject, request, qb);
+
+		int numDocs;
+
+		Integer specNumDocs = spec.getNumDocs();
+		if (specNumDocs != null) {
+			if (specNumDocs < 0) {
+				throw new IllegalArgumentException("numDocs must be >= 0");
+			}
+			numDocs = specNumDocs;
 		} else {
-			hits = search(request, qb);
+			numDocs = -1;
 		}
-		return Iterables.transform(hits, new Function<>() {
 
-			@Override
-			public DocumentScore apply(SearchHit hit) {
-				return new ElasticsearchDocumentScore(hit, geoContextMapper);
-			}
-		});
+		if (subject != null) {
+			hits = search(subject, request, qb, numDocs);
+		} else {
+			hits = search(request, qb, numDocs);
+		}
+		return Iterables.transform(hits,
+				(Function<SearchHit, DocumentScore>) hit -> new ElasticsearchDocumentScore(hit, geoContextMapper));
 	}
 
 	/**
@@ -600,11 +602,24 @@ public DocumentScore apply(SearchHit hit) {
 	 * @return search hits
 	 */
 	public SearchHits search(Resource resource, SearchRequestBuilder request, QueryBuilder query) {
+		return search(resource, request, query, -1);
+	}
+
+	/**
+	 * Evaluates the given query only for the given resource.
+	 *
+	 * @param resource
+	 * @param request
+	 * @param query
+	 * @param numDocs
+	 * @return search hits
+	 */
+	public SearchHits search(Resource resource, SearchRequestBuilder request, QueryBuilder query, int numDocs) {
 		// rewrite the query
 		QueryBuilder idQuery = QueryBuilders.termQuery(SearchFields.URI_FIELD_NAME,
 				SearchFields.getResourceID(resource));
 		QueryBuilder combinedQuery = QueryBuilders.boolQuery().must(idQuery).must(query);
-		return search(request, combinedQuery);
+		return search(request, combinedQuery, numDocs);
 	}
 
 	@Override
@@ -686,13 +701,8 @@ protected Iterable<? extends DocumentResult> geoRelationQuery(String relation, I
 
 		SearchRequestBuilder request = client.prepareSearch();
 		SearchHits hits = search(request, QueryBuilders.boolQuery().must(qb).filter(fb));
-		return Iterables.transform(hits, new Function<>() {
-
-			@Override
-			public DocumentResult apply(SearchHit hit) {
-				return new ElasticsearchDocumentResult(hit, geoContextMapper);
-			}
-		});
+		return Iterables.transform(hits,
+				(Function<SearchHit, DocumentResult>) hit -> new ElasticsearchDocumentResult(hit, geoContextMapper));
 	}
 
 	private ShapeRelation toSpatialOp(String relation) {
@@ -712,25 +722,43 @@ private ShapeRelation toSpatialOp(String relation) {
 	 * Evaluates the given query and returns the results as a TopDocs instance.
 	 */
 	public SearchHits search(SearchRequestBuilder request, QueryBuilder query) {
+		return search(request, query, -1);
+	}
+
+	/**
+	 * Evaluates the given query and returns the results as a TopDocs instance.
+	 */
+	public SearchHits search(SearchRequestBuilder request, QueryBuilder query, int numDocs) {
 		String[] types = getTypes();
-		int nDocs;
-		if (maxDocs > 0) {
-			nDocs = maxDocs;
-		} else {
+
+		if (numDocs < -1) {
+			throw new IllegalArgumentException("numDocs should be 0 or greater if defined by the user");
+		}
+
+		int size = defaultNumDocs;
+		if (numDocs >= 0) {
+			// If the user has set numDocs we will use that. If it is 0 then the implementation may end up throwing an
+			// exception.
+			size = Math.min(maxDocs, numDocs);
+		}
+
+		if (size < 0) {
+			// defaultNumDocs is not set
 			long docCount = client.prepareSearch(indexName)
 					.setTypes(types)
 					.setSource(new SearchSourceBuilder().size(0).query(query))
 					.get()
 					.getHits()
 					.getTotalHits().value;
-			nDocs = Math.max((int) Math.min(docCount, Integer.MAX_VALUE), 1);
+			size = Math.max((int) Math.min(docCount, maxDocs), 1);
 		}
+
 		SearchResponse response = request.setIndices(indexName)
 				.setTypes(types)
 				.setVersion(false)
 				.seqNoAndPrimaryTerm(true)
 				.setQuery(query)
-				.setSize(nDocs)
+				.setSize(size)
 				.execute()
 				.actionGet();
 		return response.getHits();

core/sail/lucene-api/src/main/java/org/eclipse/rdf4j/sail/lucene/AbstractSearchIndex.java

@@ -41,6 +41,7 @@
 import org.eclipse.rdf4j.query.MalformedQueryException;
 import org.eclipse.rdf4j.query.algebra.Var;
 import org.eclipse.rdf4j.query.algebra.evaluation.QueryBindingSet;
+import org.eclipse.rdf4j.sail.Sail;
 import org.eclipse.rdf4j.sail.SailException;
 import org.eclipse.rdf4j.sail.lucene.util.MapOfListMaps;
 import org.locationtech.spatial4j.context.SpatialContext;
@@ -65,7 +66,8 @@ public abstract class AbstractSearchIndex implements SearchIndex {
 		REJECTED_DATATYPES.add("http://www.w3.org/2001/XMLSchema#float");
 	}
 
-	protected int maxDocs;
+	protected int defaultNumDocs = -1;
+	protected int maxDocs = Integer.MAX_VALUE;
 
 	protected Set<String> wktFields = Collections.singleton(SearchFields.getPropertyField(GEO.AS_WKT));
 
@@ -75,8 +77,29 @@ public abstract class AbstractSearchIndex implements SearchIndex {
 
 	@Override
 	public void initialize(Properties parameters) throws Exception {
-		String maxDocParam = parameters.getProperty(LuceneSail.MAX_DOCUMENTS_KEY);
-		maxDocs = (maxDocParam != null) ? Integer.parseInt(maxDocParam) : -1;
+		String maxDocumentsParam = parameters.getProperty(LuceneSail.MAX_DOCUMENTS_KEY);
+		String defaultNumDocsParam = parameters.getProperty(LuceneSail.DEFAULT_NUM_DOCS_KEY);
+
+		if ((maxDocumentsParam != null)) {
+			maxDocs = Integer.parseInt(maxDocumentsParam);
+
+			// if maxDocs is set then defaultNumDocs is set to maxDocs if it is not set, because we now have a known
+			// upper limit
+			defaultNumDocs = (defaultNumDocsParam != null) ? Math.min(maxDocs, Integer.parseInt(defaultNumDocsParam))
+					: maxDocs;
+		} else {
+			// we can never return more than Integer.MAX_VALUE documents
+			maxDocs = Integer.MAX_VALUE;
+
+			// legacy behaviour is to return the number of documents that the query would return if there was no limit,
+			// so if the defaultNumDocs is not set, we set it to -1 to signal that there is no limit
+			defaultNumDocs = (defaultNumDocsParam != null) ? Integer.parseInt(defaultNumDocsParam) : -1;
+		}
+
+		if (defaultNumDocs > maxDocs) {
+			throw new IllegalArgumentException(LuceneSail.DEFAULT_NUM_DOCS_KEY + " must be less than or equal to "
+					+ LuceneSail.MAX_DOCUMENTS_KEY + " (" + defaultNumDocs + " > " + maxDocs + ")");
+		}
 
 		String wktFieldParam = parameters.getProperty(LuceneSail.WKT_FIELDS);
 		if (wktFieldParam != null) {
@@ -146,7 +169,7 @@ public boolean accept(Literal literal) {
 
 		// we reject literals that aren't in the list of the indexed lang
 		if (indexedLangs != null
-				&& (!literal.getLanguage().isPresent()
+				&& (literal.getLanguage().isEmpty()
 						|| !indexedLangs.contains(literal.getLanguage().get().toLowerCase()
 						))) {
 			return false;
@@ -353,11 +376,8 @@ public final synchronized void addRemoveStatements(Collection<Statement> added,
 									// remove value from both property field and the
 									// corresponding text field
 									String field = SearchFields.getPropertyField(r.getPredicate());
-									Set<String> removedValues = removedOfResource.get(field);
-									if (removedValues == null) {
-										removedValues = new HashSet<>();
-										removedOfResource.put(field, removedValues);
-									}
+									Set<String> removedValues = removedOfResource.computeIfAbsent(field,
+											k -> new HashSet<>());
 									removedValues.add(val);
 								}
 							}
@@ -545,7 +565,8 @@ private Iterable<? extends DocumentScore> evaluateQuery(QuerySpec query) {
 				hits = query(query.getSubject(), query);
 			}
 		} catch (Exception e) {
-			logger.error("There was a problem evaluating query '" + query.getCatQuery() + "'!", e);
+			logger.error("There was a problem evaluating query '{}'!", query.getCatQuery(), e);
+			assert false : "There was a problem evaluating query '" + query.getCatQuery() + "'!";
 		}
 
 		return hits;
@@ -717,6 +738,8 @@ private Iterable<? extends DocumentDistance> evaluateQuery(DistanceQuerySpec que
 		} catch (Exception e) {
 			logger.error("There was a problem evaluating distance query 'within " + distance + getUnitSymbol(units)
 					+ " of " + from.getLabel() + "'!", e);
+			assert false : "There was a problem evaluating distance query 'within " + distance + getUnitSymbol(units)
+					+ " of " + from.getLabel() + "'!";
 		}
 
 		return hits;
@@ -825,6 +848,8 @@ private Iterable<? extends DocumentResult> evaluateQuery(GeoRelationQuerySpec qu
 		} catch (Exception e) {
 			logger.error("There was a problem evaluating spatial relation query '" + query.getRelation() + " "
 					+ qgeom.getLabel() + "'!", e);
+			assert false : "There was a problem evaluating spatial relation query '" + query.getRelation() + " "
+					+ qgeom.getLabel() + "'!";
 		}
 
 		return hits;

core/sail/lucene-api/src/main/java/org/eclipse/rdf4j/sail/lucene/LuceneSail.java

@@ -290,10 +290,17 @@ public class LuceneSail extends NotifyingSailWrapper {
 	public static final String LUCENE_RAMDIR_KEY = "useramdir";
 
 	/**
-	 * Set the key "maxDocuments=<n>" as sail parameter to limit the maximum number of documents to return from a
-	 * search query. The default is to return all documents. NB: this may involve extra cost for some SearchIndex
+	 * Set the key "defaultNumDocs=<n>" as sail parameter to limit the maximum number of documents to return from
+	 * a search query. The default is to return all documents. NB: this may involve extra cost for some SearchIndex
 	 * implementations as they may have to determine this number.
 	 */
+	public static final String DEFAULT_NUM_DOCS_KEY = "defaultNumDocs";
+
+	/**
+	 * Set the key "maxDocuments=<n>" as sail parameter to limit the maximum number of documents the user can
+	 * query at a time to return from a search query. The default is the value of the {@link #DEFAULT_NUM_DOCS_KEY}
+	 * parameter.
+	 */
 	public static final String MAX_DOCUMENTS_KEY = "maxDocuments";
 
 	/**

core/sail/lucene-api/src/main/java/org/eclipse/rdf4j/sail/lucene/LuceneSailSchema.java

@@ -52,6 +52,8 @@ public class LuceneSailSchema {
 
 	public static final IRI CONTEXT;
 
+	public static final IRI NUM_DOCS;
+
 	static {
 		ValueFactory factory = SimpleValueFactory.getInstance(); // compatible with beta4:
 		// creating a new factory
@@ -73,5 +75,6 @@ public class LuceneSailSchema {
 		WITHIN_DISTANCE = factory.createIRI(NAMESPACE + "withinDistance");
 		DISTANCE = factory.createIRI(NAMESPACE + "distance");
 		CONTEXT = factory.createIRI(NAMESPACE + "context");
+		NUM_DOCS = factory.createIRI(NAMESPACE + "numDocs");
 	}
 }