timoninmaxim commented on a change in pull request #9081: URL: https://github.com/apache/ignite/pull/9081#discussion_r725850692
########## File path: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/query/reducer/NodePageStream.java ########## @@ -0,0 +1,144 @@ +/* + * 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.reducer; + +import java.util.Collection; +import java.util.Collections; +import java.util.UUID; +import java.util.concurrent.CompletableFuture; + +/** + * This class provides an interface {@link #nextPage()} that returns a {@link NodePage} of cache query result from + * single node. A new page requests when previous page was fetched by class consumer. + */ +public class NodePageStream<R> { + /** Node ID to stream pages */ + private final UUID nodeId; + + /** Flags shows whether there are no available pages on a query node. */ + private boolean noRemotePages; + + /** Last delivered page from the stream. */ + private NodePage<R> head; + + /** Promise to notify the stream consumer about delivering new page. */ + private CompletableFuture<UUID> pageReady = new CompletableFuture<>(); + + /** This lock syncs {@link #head} and {@link #noRemotePages}. */ + private final Object pagesLock = new Object(); + + /** Request pages action. */ + private final Runnable reqPages; + + /** */ + public NodePageStream(UUID nodeId, Runnable reqPages) { + this.nodeId = nodeId; + this.reqPages = reqPages; + } + + /** */ + public UUID nodeId() { + return nodeId; + } + + /** + * @return Future that will be completed when a new page delivered. + */ + public CompletableFuture<UUID> pageReady() { + return pageReady; + } + + /** + * Returns a last delivered page from this stream. Note, that this method has to be invoked after getting + * the future provided with {@link #pageReady()}. + * + * @return Query result page. + */ + public NodePage<R> nextPage() { + boolean loadPage = false; + + NodePage<R> page; + + synchronized (pagesLock) { + assert head != null; + + page = head; + + head = null; + + if (!noRemotePages) + loadPage = true; + } + + if (loadPage) { + pageReady = new CompletableFuture<>(); + + reqPages.run(); + } + + return page; + } + + /** + * Add new query result page of data. + * + * @param data Collection of query result items. + * @param last Whether it is the last page from this node. + */ + public void addPage(Collection<R> data, boolean last) { + synchronized (pagesLock) { + head = new NodePage<>(nodeId, data); + + if (last) + noRemotePages = true; + } + + pageReady.complete(nodeId); + } + + /** + * Cancel query on all nodes. + */ + public void cancel() { + synchronized (pagesLock) { + head = new NodePage<>(nodeId, Collections.emptyList()); Review comment: Future already completed there. This is a callback for clearing owned resources. -- 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]
