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From Randgalt <...@git.apache.org>
Subject [GitHub] curator pull request: CURATOR-33 recursive TreeCache recipe
Date Fri, 01 Aug 2014 00:08:21 GMT
Github user Randgalt commented on a diff in the pull request:

    https://github.com/apache/curator/pull/17#discussion_r15677537
  
    --- Diff: curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/TreeCache.java
---
    @@ -0,0 +1,605 @@
    +/**
    + * 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.curator.framework.recipes.cache;
    +
    +import com.google.common.base.Function;
    +import com.google.common.collect.ImmutableSortedSet;
    +import com.google.common.collect.Maps;
    +import org.apache.curator.framework.CuratorFramework;
    +import org.apache.curator.framework.api.BackgroundCallback;
    +import org.apache.curator.framework.api.CuratorEvent;
    +import org.apache.curator.framework.listen.ListenerContainer;
    +import org.apache.curator.framework.state.ConnectionState;
    +import org.apache.curator.framework.state.ConnectionStateListener;
    +import org.apache.curator.utils.CloseableExecutorService;
    +import org.apache.curator.utils.ThreadUtils;
    +import org.apache.curator.utils.ZKPaths;
    +import org.apache.zookeeper.KeeperException;
    +import org.apache.zookeeper.WatchedEvent;
    +import org.apache.zookeeper.Watcher;
    +import org.apache.zookeeper.data.Stat;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +import java.io.Closeable;
    +import java.io.IOException;
    +import java.util.ArrayList;
    +import java.util.Collections;
    +import java.util.List;
    +import java.util.SortedSet;
    +import java.util.concurrent.ConcurrentMap;
    +import java.util.concurrent.ExecutorService;
    +import java.util.concurrent.Executors;
    +import java.util.concurrent.ThreadFactory;
    +import java.util.concurrent.atomic.AtomicLong;
    +import java.util.concurrent.atomic.AtomicReference;
    +
    +/**
    + * <p>A utility that attempts to keep all data from all children of a ZK path locally
cached. This class
    + * will watch the ZK path, respond to update/create/delete events, pull down the data,
etc. You can
    + * register a listener that will get notified when changes occur.</p>
    + * <p></p>
    + * <p><b>IMPORTANT</b> - it's not possible to stay transactionally
in sync. Users of this class must
    + * be prepared for false-positives and false-negatives. Additionally, always use the
version number
    + * when updating data to avoid overwriting another process' change.</p>
    + */
    +public class TreeCache implements Closeable
    +{
    +    private static final Logger LOG = LoggerFactory.getLogger(TreeCache.class);
    +
    +    private enum NodeState
    +    {
    +        PENDING, LIVE, DEAD
    +    }
    +
    +    final class TreeNode implements Watcher, BackgroundCallback
    +    {
    +        private final AtomicReference<NodeState> nodeState = new AtomicReference<NodeState>(NodeState.PENDING);
    +        private final String path;
    +        private final TreeNode parent;
    +        private final AtomicReference<Stat> stat = new AtomicReference<Stat>();
    +        private final AtomicReference<byte[]> data = new AtomicReference<byte[]>();
    +        private final AtomicReference<ConcurrentMap<String, TreeNode>> children
= new AtomicReference<ConcurrentMap<String, TreeNode>>();
    +
    +        TreeNode(String path, TreeNode parent)
    +        {
    +            this.path = path;
    +            this.parent = parent;
    +        }
    +
    +        private void refreshChildren() throws Exception
    +        {
    +            outstandingOps.incrementAndGet();
    +            client.getChildren().usingWatcher(this).inBackground(this).forPath(path);
    +        }
    +
    +        private void refreshData() throws Exception
    +        {
    +            outstandingOps.incrementAndGet();
    +            if ( dataIsCompressed )
    +            {
    +                client.getData().decompressed().usingWatcher(this).inBackground(this).forPath(path);
    +            }
    +            else
    +            {
    +                client.getData().usingWatcher(this).inBackground(this).forPath(path);
    +            }
    +        }
    +
    +        private void wasReconnected() throws Exception
    +        {
    +            refreshData();
    +            refreshChildren();
    +            ConcurrentMap<String, TreeNode> childMap = children.get();
    +            if ( childMap != null )
    +            {
    +                for ( TreeNode child : childMap.values() )
    +                {
    +                    child.wasReconnected();
    +                }
    +            }
    +        }
    +
    +        private void wasCreated() throws Exception
    --- End diff --
    
    Maybe move the common two method calls into a private method. I'm just concerned about
maintenance of two methods that do mostly the same thing.


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