org.eclipse.gyrex.cloud.internal.zk.ZooKeeperMonitor.java Source code

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Here is the source code for org.eclipse.gyrex.cloud.internal.zk.ZooKeeperMonitor.java

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/*******************************************************************************
 * Copyright (c) 2010, 2012 AGETO Service GmbH and others.
 * 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:
 *     Gunnar Wagenknecht - initial API and implementation
 *******************************************************************************/
package org.eclipse.gyrex.cloud.internal.zk;

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Base class for Gyrex ZooKeeper event handlers
 */
public class ZooKeeperMonitor implements Watcher {

    private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperMonitor.class);

    /**
     * A child has been created or removed for the specified path.
     * 
     * @param path
     */
    protected void childrenChanged(final String path) {
        // empty
    }

    /**
     * The path has been created (it may now exist)
     * 
     * @param path
     */
    protected void pathCreated(final String path) {
        // empty
    }

    /**
     * The path has been deleted (it may now no longer exist)
     * 
     * @param path
     */
    protected void pathDeleted(final String path) {
        // empty
    }

    @Override
    public void process(final WatchedEvent event) {
        switch (event.getType()) {
        case NodeChildrenChanged:
            childrenChanged(event.getPath());
            break;
        case NodeCreated:
            pathCreated(event.getPath());
            break;
        case NodeDeleted:
            pathDeleted(event.getPath());
            break;
        case NodeDataChanged:
            recordChanged(event.getPath());
            break;
        case None:
            // state of the connection changed
            // TODO: how to handle/consume this event here?
            // our prefered way of working with ZK connect/disconnect/expired events
            // is using the ZKGate which has it's own connect listener (integrated into ZKBasedService)
            //         switch (event.getState()) {
            //            case SyncConnected:
            //               // connection established, nothing to do because watches
            //               // will be automatically re-registered and delivered by ZooKeeper
            //               connected();
            //               break;
            //            case Disconnected:
            //               // session disconnected, the gate will recover
            //               disconnected();
            //               break;
            //            case Expired:
            //               // session expired, the gate will close
            //               expired();
            //               break;
            //         }
            break;
        default:
            LOG.warn("Unhandled event ({}) in ({})", new Object[] { event, this });
            break;
        }
    }

    /**
     * Data has been updated.
     * 
     * @param path
     */
    protected void recordChanged(final String path) {
        // empty
    }

}