Apache ZooKeeper Server Source Code

Apache ZooKeeper is an open-source server which enables highly reliable distributed coordination.

Apache ZooKeeper Server Source Code files are provided in the source packge (apache-zookeeper-3.7.0.tar.gz). You can download it at Apache ZooKeeper Website.

You can also browse Apache ZooKeeper Server Source Code below:

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 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.zookeeper.server.watch;

import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.zookeeper.Watcher;

class WatcherModeManager {
    private final Map<Key, WatcherMode> watcherModes = new ConcurrentHashMap<>();
    private final AtomicInteger recursiveQty = new AtomicInteger(0);

    private static class Key {
        private final Watcher watcher;
        private final String path;

        Key(Watcher watcher, String path) {
            this.watcher = watcher;
            this.path = path;

        public boolean equals(Object o) {
            if (this == o) {
                return true;
            if (o == null || getClass() != o.getClass()) {
                return false;
            Key key = (Key) o;
            return watcher.equals(key.watcher) && path.equals(key.path);

        public int hashCode() {
            return Objects.hash(watcher, path);

    // VisibleForTesting
    Map<Key, WatcherMode> getWatcherModes() {
        return watcherModes;

    void setWatcherMode(Watcher watcher, String path, WatcherMode mode) {
        if (mode == WatcherMode.DEFAULT_WATCHER_MODE) {
            removeWatcher(watcher, path);
        } else {
            adjustRecursiveQty(watcherModes.put(new Key(watcher, path), mode), mode);

    WatcherMode getWatcherMode(Watcher watcher, String path) {
        return watcherModes.getOrDefault(new Key(watcher, path), WatcherMode.DEFAULT_WATCHER_MODE);

    void removeWatcher(Watcher watcher, String path) {
        adjustRecursiveQty(watcherModes.remove(new Key(watcher, path)), WatcherMode.DEFAULT_WATCHER_MODE);

    int getRecursiveQty() {
        return recursiveQty.get();

    // recursiveQty is an optimization to avoid having to walk the map every time this value is needed
    private void adjustRecursiveQty(WatcherMode oldMode, WatcherMode newMode) {
        if (oldMode == null) {
            oldMode = WatcherMode.DEFAULT_WATCHER_MODE;
        if (oldMode.isRecursive() != newMode.isRecursive()) {
            if (newMode.isRecursive()) {
            } else {



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2018-10-18, 28999👍, 1💬