Github user hanm commented on a diff in the pull request: https://github.com/apache/zookeeper/pull/590#discussion_r219912709 --- Diff: src/java/main/org/apache/zookeeper/server/watch/WatchManagerOptimized.java --- @@ -0,0 +1,355 @@ +/** + * 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.zookeeper.server.watch; + +import java.io.PrintWriter; +import java.util.HashMap; +import java.util.BitSet; +import java.util.HashSet; +import java.util.ArrayList; +import java.util.LinkedHashMap; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Random; +import java.util.Set; +import java.util.Iterator; +import java.lang.Iterable; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.locks.ReadWriteLock; +import java.util.concurrent.locks.ReentrantReadWriteLock; + +import org.apache.zookeeper.WatchedEvent; +import org.apache.zookeeper.Watcher; +import org.apache.zookeeper.Watcher.Event.EventType; +import org.apache.zookeeper.Watcher.Event.KeeperState; +import org.apache.zookeeper.server.ServerCnxn; +import org.apache.zookeeper.server.util.BitMap; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Optimized in memory and time complexity, compared to WatchManager, both the + * memory consumption and time complexity improved a lot, but it cannot + * efficiently remove the watcher when the session or socket is closed, for + * majority usecase this is not a problem. --- End diff -- nit: use case
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