GH-5149 Add search:numDocs property and maxQueryDocuments param in Lu…

…ceneSail query

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

@@ -577,10 +577,19 @@ protected Iterable<? extends DocumentScore> query(Resource subject, QuerySpec sp
 		}
 
 		SearchHits hits;
+		Integer numDocs = spec.getNumDocs();
 		if (subject != null) {
-			hits = search(subject, request, qb);
+			if (numDocs != null) {
+				hits = search(subject, request, qb, numDocs);
+			} else {
+				hits = search(subject, request, qb);
+			}
 		} else {
-			hits = search(request, qb);
+			if (numDocs != null) {
+				hits = search(request, qb, numDocs);
+			} else {
+				hits = search(request, qb);
+			}
 		}
 		return Iterables.transform(hits, new Function<>() {
 
@@ -600,11 +609,24 @@ 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
@@ -712,9 +734,22 @@ 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) {
+		if (numDocs > 0) {
+			if (maxQueryDocs > 0 && maxQueryDocs < numDocs) {
+				nDocs = maxQueryDocs;
+			} else {
+				nDocs = numDocs;
+			}
+		} else if (maxDocs > 0) {
 			nDocs = maxDocs;
 		} else {
 			long docCount = client.prepareSearch(indexName)

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

@@ -66,6 +66,7 @@ public abstract class AbstractSearchIndex implements SearchIndex {
 	}
 
 	protected int maxDocs;
+	protected int maxQueryDocs;
 
 	protected Set<String> wktFields = Collections.singleton(SearchFields.getPropertyField(GEO.AS_WKT));
 
@@ -77,6 +78,8 @@ public abstract class AbstractSearchIndex implements SearchIndex {
 	public void initialize(Properties parameters) throws Exception {
 		String maxDocParam = parameters.getProperty(LuceneSail.MAX_DOCUMENTS_KEY);
 		maxDocs = (maxDocParam != null) ? Integer.parseInt(maxDocParam) : -1;
+		String maxQueryDocParam = parameters.getProperty(LuceneSail.MAX_QUERY_DOCUMENTS_KEY);
+		maxQueryDocs = (maxQueryDocParam != null) ? Integer.parseInt(maxQueryDocParam) : maxDocs;
 
 		String wktFieldParam = parameters.getProperty(LuceneSail.WKT_FIELDS);
 		if (wktFieldParam != null) {

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

@@ -296,6 +296,13 @@ public class LuceneSail extends NotifyingSailWrapper {
 	 */
 	public static final String MAX_DOCUMENTS_KEY = "maxDocuments";
 
+	/**
+	 * Set the key "maxQueryDocuments=<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 #MAX_DOCUMENTS_KEY}
+	 * parameter.
+	 */
+	public static final String MAX_QUERY_DOCUMENTS_KEY = "maxQueryDocuments";
+
 	/**
 	 * Set this key to configure which fields contain WKT and should be spatially indexed. The value should be a
 	 * space-separated list of URIs. Default is http://www.opengis.net/ont/geosparql#asWKT.

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");
 	}
 }

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

@@ -16,7 +16,9 @@
 import java.util.stream.Collectors;
 
 import org.eclipse.rdf4j.model.IRI;
+import org.eclipse.rdf4j.model.Literal;
 import org.eclipse.rdf4j.model.Resource;
+import org.eclipse.rdf4j.model.Value;
 import org.eclipse.rdf4j.query.algebra.QueryModelNode;
 import org.eclipse.rdf4j.query.algebra.SingletonSet;
 import org.eclipse.rdf4j.query.algebra.StatementPattern;
@@ -67,21 +69,43 @@ private static void append(Var var, StringBuilder buffer) {
 
 	private final StatementPattern idPattern;
 
+	private final StatementPattern numDocsPattern;
+
 	private final Resource subject;
 
 	private final String matchesVarName;
 
 	private final String scoreVarName;
 
+	private final Integer numDocs;
+
 	public QuerySpec(StatementPattern matchesPattern, Collection<QueryParam> queryPatterns,
 			StatementPattern scorePattern, StatementPattern typePattern,
 			StatementPattern idPattern, Resource subject) {
+		this(matchesPattern, queryPatterns, scorePattern, typePattern, idPattern, null, subject);
+	}
+
+	public QuerySpec(StatementPattern matchesPattern, Collection<QueryParam> queryPatterns,
+			StatementPattern scorePattern, StatementPattern typePattern,
+			StatementPattern idPattern, StatementPattern numDocsPattern, Resource subject) {
 		this.matchesPattern = matchesPattern;
 		this.queryPatterns = queryPatterns;
 		this.scorePattern = scorePattern;
 		this.typePattern = typePattern;
 		this.idPattern = idPattern;
+		this.numDocsPattern = numDocsPattern;
 		this.subject = subject;
+		if (numDocsPattern != null) {
+			Value val = numDocsPattern.getObjectVar().getValue();
+			if (val != null && val.isLiteral()) {
+				this.numDocs = ((Literal) val).intValue();
+			} else {
+				throw new IllegalArgumentException("numDocs should be constant literal value");
+			}
+		} else {
+			this.numDocs = null;
+		}
+
 		if (matchesPattern != null) {
 			this.matchesVarName = matchesPattern.getSubjectVar().getName();
 		} else {
@@ -101,9 +125,11 @@ public QuerySpec(String matchesVarName, String propertyVarName, String scoreVarN
 		this.matchesPattern = null;
 		this.scorePattern = null;
 		this.typePattern = null;
+		this.numDocsPattern = null;
 		this.queryPatterns = Set.of();
 		this.idPattern = null;
 		this.subject = subject;
+		this.numDocs = null;
 	}
 
 	@Override
@@ -121,6 +147,7 @@ public QueryModelNode removeQueryPatterns() {
 		replace(getScorePattern(), replacement);
 		replace(getTypePattern(), replacement);
 		replace(getIdPattern(), replacement);
+		replace(getNumDocsPattern(), replacement);
 
 		final QueryModelNode placeholder = new SingletonSet();
 
@@ -154,6 +181,10 @@ public StatementPattern getScorePattern() {
 		return scorePattern;
 	}
 
+	public StatementPattern getNumDocsPattern() {
+		return numDocsPattern;
+	}
+
 	/**
 	 * The variable name associated with the query score
 	 *
@@ -163,6 +194,10 @@ public String getScoreVariableName() {
 		return scoreVarName;
 	}
 
+	public Integer getNumDocs() {
+		return numDocs;
+	}
+
 	public StatementPattern getTypePattern() {
 		return typePattern;
 	}

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

@@ -15,6 +15,7 @@
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.INDEXID;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.LUCENE_QUERY;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.MATCHES;
+import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.NUM_DOCS;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.PROPERTY;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.QUERY;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.SCORE;
@@ -152,7 +153,7 @@ public void process(TupleExpr tupleExpr, BindingSet bindings, Collection<SearchQ
 			}
 
 			// find the relevant outgoing patterns
-			StatementPattern typePattern, propertyPattern, scorePattern, snippetPattern;
+			StatementPattern typePattern, propertyPattern, scorePattern, snippetPattern, numDocsPattern;
 			List<StatementPattern> queryPatterns;
 
 			try {
@@ -161,6 +162,7 @@ public void process(TupleExpr tupleExpr, BindingSet bindings, Collection<SearchQ
 				propertyPattern = getPattern(matchesVar, filter.propertyPatterns);
 				scorePattern = getPattern(matchesVar, filter.scorePatterns);
 				snippetPattern = getPattern(matchesVar, filter.snippetPatterns);
+				numDocsPattern = getPattern(matchesVar, filter.numDocsPatterns);
 			} catch (IllegalArgumentException e) {
 				failOrWarn(e);
 				continue;
@@ -302,7 +304,8 @@ else if (propertyValue != null) {
 						queryString, propertyURI, null));
 			}
 
-			QuerySpec querySpec = new QuerySpec(matchesPattern, queries, scorePattern, typePattern, idPattern, subject);
+			QuerySpec querySpec = new QuerySpec(matchesPattern, queries, scorePattern, typePattern, idPattern,
+					numDocsPattern, subject);
 
 			if (querySpec.isEvaluable()) {
 				// constant optimizer
@@ -341,6 +344,10 @@ else if (propertyValue != null) {
 					funcCall.addArg(new ValueConstant(LuceneSailSchema.SNIPPET));
 					funcCall.addResultVar(snippetVar);
 				}
+				if (numDocsPattern != null) {
+					funcCall.addArg(new ValueConstant(LuceneSailSchema.NUM_DOCS));
+					funcCall.addArg(numDocsPattern.getObjectVar());
+				}
 
 				Join join = new Join();
 				matchesPattern.replaceWith(join);
@@ -465,6 +472,8 @@ private static class PatternFilter extends AbstractQueryModelVisitor<RuntimeExce
 
 		public ArrayList<StatementPattern> boostPatterns = new ArrayList<>();
 
+		public ArrayList<StatementPattern> numDocsPatterns = new ArrayList<>();
+
 		/**
 		 * Method implementing the visitor pattern that gathers all statements using a predicate from the LuceneSail's
 		 * namespace.
@@ -487,6 +496,8 @@ public void meet(StatementPattern node) {
 				idPatterns.add(node);
 			} else if (BOOST.equals(predicate)) {
 				boostPatterns.add(node);
+			} else if (NUM_DOCS.equals(predicate)) {
+				numDocsPatterns.add(node);
 			} else if (TYPE.equals(predicate)) {
 				Value object = node.getObjectVar().getValue();
 				if (LUCENE_QUERY.equals(object)) {

core/sail/lucene-api/src/test/java/org/eclipse/rdf4j/sail/lucene/QuerySpecBuilderTest.java

@@ -14,6 +14,7 @@
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.BOOST;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.LUCENE_QUERY;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.MATCHES;
+import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.NUM_DOCS;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.QUERY;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.SCORE;
 import static org.eclipse.rdf4j.sail.lucene.LuceneSailSchema.SNIPPET;
@@ -55,6 +56,7 @@ public void testQueryInterpretation() {
 				"<" + TYPE + "> <" + LUCENE_QUERY + ">; " +
 				"<" + QUERY + "> \"my Lucene query\"; " +
 				"<" + SCORE + "> ?Score; " +
+				"<" + NUM_DOCS + "> 76; " +
 				"<" + SNIPPET + "> ?Snippet ]. } ";
 		ParsedQuery query = parser.parseQuery(buffer, null);
 		TupleExpr tupleExpr = query.getTupleExpr();
@@ -69,6 +71,8 @@ public void testQueryInterpretation() {
 		assertEquals("Score", querySpec.getScorePattern().getObjectVar().getName());
 		assertEquals("Snippet", param.getSnippetPattern().getObjectVar().getName());
 		assertEquals(LUCENE_QUERY, querySpec.getTypePattern().getObjectVar().getValue());
+		assertEquals(76, querySpec.getNumDocs());
+		assertEquals(76, ((Literal) querySpec.getNumDocsPattern().getObjectVar().getValue()).intValue());
 		assertEquals("my Lucene query", param.getQuery());
 		assertNull(querySpec.getSubject());
 	}
@@ -80,11 +84,13 @@ public void testMultipleQueriesInterpretation() {
 				"<" + TYPE + "> <" + LUCENE_QUERY + ">; " +
 				"<" + QUERY + "> \"my Lucene query\"; " +
 				"<" + SCORE + "> ?score1; " +
+				"<" + NUM_DOCS + "> 86; " +
 				"<" + SNIPPET + "> ?snippet1 ]. " +
 				" ?sub2 <" + MATCHES + "> [ " +
 				"<" + TYPE + "> <" + LUCENE_QUERY + ">; " +
 				"<" + QUERY + "> \"second lucene query\"; " +
 				"<" + SCORE + "> ?score2; " +
+				"<" + NUM_DOCS + "> 13; " +
 				"<" + SNIPPET + "> ?snippet2 ]. " +
 				// and connect them both via any X in between, just as salt to make the
 				// parser do something
@@ -103,6 +109,7 @@ public void testMultipleQueriesInterpretation() {
 				// Matched the first
 				assertEquals("sub1", querySpec.getMatchesPattern().getSubjectVar().getName());
 				assertEquals(1, querySpec.getQueryPatterns().size());
+				assertEquals(86, querySpec.getNumDocs());
 				QuerySpec.QueryParam param = querySpec.getQueryPatterns().iterator().next();
 				assertEquals("my Lucene query",
 						((Literal) param.getQueryPattern().getObjectVar().getValue()).getLabel());
@@ -116,6 +123,7 @@ public void testMultipleQueriesInterpretation() {
 				// and the second
 				assertEquals("sub2", querySpec.getMatchesPattern().getSubjectVar().getName());
 				assertEquals(1, querySpec.getQueryPatterns().size());
+				assertEquals(13, querySpec.getNumDocs());
 				QuerySpec.QueryParam param = querySpec.getQueryPatterns().iterator().next();
 				assertEquals("second lucene query",
 						((Literal) param.getQueryPattern().getObjectVar().getValue()).getLabel());