com.bloomreach.zk.replicate.ZookeeperDataTraverser.java Source code

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Here is the source code for com.bloomreach.zk.replicate.ZookeeperDataTraverser.java

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/**
 * Copyright 2014-2015 BloomReach, Inc.
 * Licensed 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 com.bloomreach.zk.replicate;

import org.apache.commons.lang3.exception.ExceptionUtils;
import org.apache.log4j.Logger;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

import java.util.List;

/**
 * Reads and Traverses Zookeeper Data. Fetches the raw bytes for every zk node and stores it inside the
 * {@link com.bloomreach.zk.replicate.ZkDataNode} data structure.
 * </p>
 * <p/>
 * Given a path, it recursively traverses the data and has an in-memory representation of the tree with
 * the path as the root.
 *
 * @author nitin
 * @since 01/06/2015
 */
public class ZookeeperDataTraverser {
    private static final Logger logger = Logger.getLogger(ZookeeperDataTraverser.class);
    /* Represents the zookeper Data Node */
    private final ZkDataNode znode;

    /* Represents the zookeper Handle */
    private ZooKeeper zk;

    /**
     * Constructs a Traverser with a zk Host and Root to traverse
     *
     * @param sourceZk The source Zookeper Host
     * @param path     The root path of the zk to traverse from
     */
    public ZookeeperDataTraverser(String sourceZk, String path) {
        //Initialize ZkData Node based on path.
        ZkDataNode znode = new ZkDataNode(path);
        this.znode = znode;
        //Connects to the zk using the zk connection manager
        this.zk = ZKConnectionManager.connectToZookeeper(sourceZk);
    }

    /**
     * Triggers the recursive fetch of all the zk data for a given path
     *
     * @return znode Zookeeper Data Node that stores all zookeeper path data
     * @throws Exception
     */
    public ZkDataNode traverse() throws Exception {
        try {
            populate(znode);
        } catch (KeeperException e) {
            throw new ZkDataTraversalException(ExceptionUtils.getStackTrace(e));
        } catch (InterruptedException e) {
            throw new ZkDataTraversalException(ExceptionUtils.getStackTrace(e));
        }
        return znode;
    }

    /**
     * Recursively populates the ZkDataNode by reading all zk nodes
     * and its children.
     *
     * @param zkDataNode Zookeeper Data Node that stores all zookeeper path data
     * @throws Exception
     */
    public void populate(ZkDataNode zkDataNode) throws Exception {
        Stat stat = null;
        String path = zkDataNode.getFQPath();
        logger.info("Reading node " + path);
        byte[] data = zk.getData(path, false, stat);
        zkDataNode.setNodeData(data);

        List<String> subFolders = zk.getChildren(path, false);
        for (String folder : subFolders) {
            ZkDataNode childNode = new ZkDataNode(zkDataNode, folder);
            zkDataNode.addChild(childNode);
            populate(childNode);
        }
        return;
    }
}