org.prot.frontend.zookeeper.jobs.WatchMaster.java Source code

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Here is the source code for org.prot.frontend.zookeeper.jobs.WatchMaster.java

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/*******************************************************************************
 * Copyright (c) 2010 Andreas Wolke.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Andreas Wolke - initial API and implementation and initial documentation
 *******************************************************************************/
package org.prot.frontend.zookeeper.jobs;

import java.io.IOException;

import org.apache.log4j.Logger;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
import org.prot.frontend.config.Configuration;
import org.prot.util.zookeeper.Job;
import org.prot.util.zookeeper.JobState;
import org.prot.util.zookeeper.ZNodes;
import org.prot.util.zookeeper.ZooHelper;

public class WatchMaster implements Watcher, Job {
    private static final Logger logger = Logger.getLogger(WatchMaster.class);

    private ZooHelper zooHelper;

    @Override
    public void process(WatchedEvent event) {
        logger.info("Processing Watcher: " + event.getPath());
        zooHelper.getQueue().insert(this);
    }

    @Override
    public JobState execute(ZooHelper zooHelper) throws KeeperException, InterruptedException, IOException {
        ZooKeeper zk = zooHelper.getZooKeeper();

        Stat statMaster = zk.exists(ZNodes.ZNODE_MASTER, false);
        if (statMaster == null) {
            logger.info("Could not find " + ZNodes.ZNODE_MASTER + " in the ZooKeeper. Waiting for the ZNode");

            // Update the configuration
            Configuration.getConfiguration().setManagerAddress(null);
        } else {
            logger.info("Updating configuration with the Manager");

            // Update the configuration
            byte[] data = zk.getData(ZNodes.ZNODE_MASTER, this, statMaster);
            Configuration.getConfiguration().setManagerAddress(new String(data));
        }

        // Install a watcher
        zk.exists(ZNodes.ZNODE_MASTER, this);

        return JobState.OK;
    }

    @Override
    public boolean isRetryable() {
        return true;
    }

    @Override
    public void init(ZooHelper zooHelper) {
        this.zooHelper = zooHelper;
    }
}