epotyom commented on code in PR #13568: URL: https://github.com/apache/lucene/pull/13568#discussion_r1709975382
########## lucene/core/src/java/org/apache/lucene/search/CollectorOwner.java: ########## @@ -0,0 +1,74 @@ +/* + * 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.lucene.search; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.List; + +/** + * This class wraps {@link CollectorManager} and owns the collectors the manager creates. It is + * convenient that clients of the class don't have to worry about keeping the list of collectors, as + * well as about making the collector's type (C) compatible when reduce is called. Instances of this + * class cache results of {@link CollectorManager#reduce(Collection)}. + * + * <p>Note that instance of this class ignores any {@link Collector} created by {@link + * CollectorManager#newCollector()} directly, not through {@link #newCollector()} + * + * @lucene.experimental + */ +public final class CollectorOwner<C extends Collector, T> { + + private final CollectorManager<C, T> manager; + + private T result; + private boolean reduced; + + // TODO: For IndexSearcher, the list doesn't have to be synchronized + // because we create new collectors sequentially. Drill sideways creates new collectors in + // DrillSidewaysQuery#Weight#bulkScorer which is already called concurrently. + // I think making the list synchronized here is not a huge concern, at the same time, do we want + // to do something about it? + // e.g. have boolean property in constructor that makes it threads friendly when set? + private final List<C> collectors = Collections.synchronizedList(new ArrayList<>()); + + public CollectorOwner(CollectorManager<C, T> manager) { + this.manager = manager; + } + + /** Return a new {@link Collector}. This must return a different instance on each call. */ + public C newCollector() throws IOException { + C collector = manager.newCollector(); + collectors.add(collector); + return collector; + } + + public C getCollector(int i) { + return collectors.get(i); + } + + /** Returns result of {@link CollectorManager#reduce(Collection)}. The result is cached. */ + public T getResult() throws IOException { Review Comment: It is not called concurrently today. I'll add a comment - thanks! -- 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: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
