timoninmaxim commented on a change in pull request #9081: URL: https://github.com/apache/ignite/pull/9081#discussion_r695554903
########## File path: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/query/CacheQueryReducer.java ########## @@ -0,0 +1,65 @@ +/* + * 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.internal.processors.cache.query; + +import java.util.Collection; +import java.util.UUID; +import org.apache.ignite.IgniteCheckedException; + +/** + * This class is responsible for reducing results of cache query. Query results are delivered via callback + * {@link #onPage(UUID, Collection, boolean)}. + * + * <T> is a type of cache query result item. + */ +public interface CacheQueryReducer<T> { + /** + * @return Next item. + */ + public T next() throws IgniteCheckedException; + + /** + * @return {@code true} if there is a next item, otherwise {@code false}. + */ + public boolean hasNext() throws IgniteCheckedException; + + /** + * Callback that invoked on receiving a new page. + * + * @param nodeId Node ID that sent this page. + * @param data Page data rows. + * @param last Whether this page is last for specified {@code nodeId}. + * @return {@code true} if this page is final page for query and no more pages are waited, otherwise {@code false}. + */ + public boolean onPage(UUID nodeId, Collection<T> data, boolean last); + + /** + * Callback in case of page with error. + */ + public void onError(); + + /** + * Callback that invokes after a query future is done. + */ + public void onFinish(); Review comment: It's not possible, as it's required to release latch after `onDone()`. Actually there is a tough coupling of future and reducer. Don't think this is a problem -- 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]
