Github user meiercaleb commented on a diff in the pull request:
https://github.com/apache/incubator-rya/pull/206#discussion_r133450932
--- Diff:
common/rya.api/src/main/java/org/apache/rya/api/persist/utils/RyaDaoQueryWrapper.java
---
@@ -0,0 +1,179 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.rya.api.persist.utils;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import org.apache.rya.api.RdfCloudTripleStoreConfiguration;
+import org.apache.rya.api.domain.RyaStatement;
+import org.apache.rya.api.persist.RyaDAO;
+import org.apache.rya.api.resolver.RyaToRdfConversions;
+import org.openrdf.model.Resource;
+import org.openrdf.model.Statement;
+import org.openrdf.model.URI;
+import org.openrdf.model.Value;
+import org.openrdf.query.QueryEvaluationException;
+
+import info.aduna.iteration.CloseableIteration;
+
+/**
+ * Wraps Rya DAO queries into a simpler interface that just passes in the
+ * statement to query for and a handler for dealing with each statement in
the
+ * query result. This handles iterating over the query, throwing any
exceptions,
+ * and closing the query iterator when done. The same wrapper can be
re-used
+ * for multiple queries.
+ */
+public class RyaDaoQueryWrapper {
+ private final RyaDAO<?> ryaDao;
+ private final RdfCloudTripleStoreConfiguration conf;
+
+ /**
+ * Creates a new instance of {@link RyaDaoQueryWrapper}.
+ * @param ryaDao the {@link RyaDAO}. (not {@code null})
+ * @param conf the {@link RdfCloudTripleStoreConfiguration}.
+ * (not {@code null})
+ */
+ public RyaDaoQueryWrapper(final RyaDAO<?> ryaDao, final
RdfCloudTripleStoreConfiguration conf) {
+ this.ryaDao = checkNotNull(ryaDao);
+ this.conf = checkNotNull(conf);
+ }
+
+ /**
+ * Creates a new instance of {@link RyaDaoQueryWrapper}.
+ * @param ryaDao the {@link RyaDAO}. (not {@code null})
+ */
+ public RyaDaoQueryWrapper(final RyaDAO<?> ryaDao) {
+ this(checkNotNull(ryaDao), ryaDao.getConf());
+ }
+
+ /**
+ * Handles all results of a query. Closes the query iterator when done.
+ * @param subject the subject {@link Resource} to query for.
+ * @param predicate the predicate {@link URI} to query for.
+ * @param object the object {@link Value} to query for.
+ * @param ryaDaoStatementIterHandler the {@link
RyaDaoStatementIterHandler}
+ * to use for handling each statement returned. (not {@code null})
+ * @param contexts the context {@link Resource}s to query for.
+ * @throws QueryEvaluationException
+ */
+ public void queryAll(final Resource subject, final URI predicate,
final Value object, final RyaDaoStatementIterHandler
ryaDaoStatementIterHandler, final Resource... contexts) throws
QueryEvaluationException {
+ checkNotNull(ryaDaoStatementIterHandler);
+ final CloseableIteration<Statement, QueryEvaluationException> iter
= RyaDAOHelper.query(ryaDao, subject, predicate, object, conf, contexts);
+ try {
+ while (iter.hasNext()) {
+ final Statement statement = iter.next();
+ try {
+
ryaDaoStatementIterHandler.handleStatementIter(statement);
+ } catch (final Exception e) {
+ throw new QueryEvaluationException("Error handling
statement.", e);
+ }
+ }
+ } finally {
+ if (iter != null) {
+ iter.close();
+ }
+ }
+ }
+
+ /**
+ * Handles all results of a query. Closes the query iterator when done.
+ * @param statement the {@link Statement} to query for.
+ * @param ryaDaoStatementIterHandler the {@link
RyaDaoStatementIterHandler}
+ * to use for handling each statement returned. (not {@code null})
+ * @throws QueryEvaluationException
+ */
+ public void queryAll(final Statement statement, final
RyaDaoStatementIterHandler ryaDaoStatementIterHandler) throws
QueryEvaluationException {
+ final Resource subject = statement != null ?
statement.getSubject() : null;
+ final URI predicate = statement != null ? statement.getPredicate()
: null;
+ final Value object = statement != null ? statement.getObject() :
null;
+ final Resource context = statement != null ?
statement.getContext() : null;
+ queryAll(subject, predicate, object, ryaDaoStatementIterHandler,
context);
--- End diff --
It seems like you want to allow for the possibility of a null statement
here (which would result in scanning the entire Rya instance). Given that we
don't support such look ups, wouldn't it be cleaner to just require the
Statement to be non-null here?
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