AMashenkov commented on a change in pull request #592: URL: https://github.com/apache/ignite-3/pull/592#discussion_r796402774
########## File path: modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/sql/JdbcQueryCursor.java ########## @@ -0,0 +1,109 @@ +/* + * 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.ignite.client.handler.requests.sql; + +import java.util.Iterator; +import java.util.NoSuchElementException; +import org.apache.ignite.internal.sql.engine.ResultSetMetadata; +import org.apache.ignite.internal.sql.engine.SqlCursor; +import org.apache.ignite.internal.sql.engine.SqlQueryType; + +/** + * Sql query cursor with the ability to limit the maximum number of rows returned. + * The maxRows parameter is responsible for the number of rows returned. + * It can either be equal to zero or have a positive value. + * Zero means that there are no additional restrictions other than the hasNext function, + * and the cursor behaves like a normal iterator. + * A positive value means that the cursor will return values either until the hasNext function + * returns false, or until the number of records already returned equals maxRows. + */ +public class JdbcQueryCursor<T> implements SqlCursor<T> { + /** Max rows. */ + private final long maxRows; + + /** Query result rows. */ + private final SqlCursor<T> cur; + + /** Number of fetched rows. */ + private long fetched; + + /** + * Constructor. + * + * @param maxRows Max rows. + * @param cur Query cursor. + */ + public JdbcQueryCursor(int maxRows, SqlCursor<T> cur) { + this.maxRows = maxRows; + this.cur = cur; + + this.fetched = 0; + } + + /** + * Returns true if the iteration has more elements and the limit of maxRows has not been reached. + * + * @return {@code true} if the cursor has more rows and the limit of the maximum rows hasn't been reached. + */ + @Override + public boolean hasNext() { + return cur.hasNext() && !(maxRows > 0 && fetched >= maxRows); + } + + /** + * Returns the next element in the iteration if the iteration has more elements + * and the limit of maxRows has not been reached. + * + * @return the next element if the cursor has more rows and the limit of the maximum rows hasn't been reached. + */ + @Override + public T next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } + + T res = cur.next(); + + fetched++; + + return res; + } + + /** {@inheritDoc} */ + @Override public void close() throws Exception { Review comment: ```suggestion @Override public void close() throws Exception { ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
