trunk/clients/csharp/src/Kafka/Kafka.Client/ZooKeeperIntegration/Listeners/ZKSessionExpireListener.cs

/**
 * 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.
 */

namespace Kafka.Client.ZooKeeperIntegration.Listeners
{
    using System;
    using System.Globalization;
    using System.Reflection;
    using Kafka.Client.Consumers;
    using Kafka.Client.Utils;
    using Kafka.Client.ZooKeeperIntegration.Events;
    using log4net;
    using ZooKeeperNet;

    internal class ZKSessionExpireListener : IZooKeeperStateListener
    {
        private static readonly ILog Logger = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        private readonly string consumerIdString;

        private readonly ZKRebalancerListener loadBalancerListener;

        private readonly ZookeeperConsumerConnector zkConsumerConnector;

        private readonly ZKGroupDirs dirs;

        private readonly TopicCount topicCount;

        public ZKSessionExpireListener(ZKGroupDirs dirs, string consumerIdString, TopicCount topicCount, ZKRebalancerListener loadBalancerListener, ZookeeperConsumerConnector zkConsumerConnector)
        {
            this.consumerIdString = consumerIdString;
            this.loadBalancerListener = loadBalancerListener;
            this.zkConsumerConnector = zkConsumerConnector;
            this.dirs = dirs;
            this.topicCount = topicCount;
        }

        /// <summary>
        /// Called when the ZooKeeper connection state has changed.
        /// </summary>
        /// <param name="args">The <see cref="Kafka.Client.ZooKeeperIntegration.Events.ZooKeeperStateChangedEventArgs"/> instance containing the event data.</param>
        /// <remarks>
        /// Do nothing, since zkclient will do reconnect for us.
        /// </remarks>
        public void HandleStateChanged(ZooKeeperStateChangedEventArgs args)
        {
            Guard.NotNull(args, "args");
            Guard.Assert<ArgumentException>(() => args.State != KeeperState.Unknown);
        }

        /// <summary>
        /// Called after the ZooKeeper session has expired and a new session has been created.
        /// </summary>
        /// <param name="args">The <see cref="Kafka.Client.ZooKeeperIntegration.Events.ZooKeeperSessionCreatedEventArgs"/> instance containing the event data.</param>
        /// <remarks>
        /// You would have to re-create any ephemeral nodes here.
        /// Explicitly trigger load balancing for this consumer.
        /// </remarks>
        public void HandleSessionCreated(ZooKeeperSessionCreatedEventArgs args)
        {
            Guard.NotNull(args, "args");

            Logger.InfoFormat(
                CultureInfo.CurrentCulture,
                "ZK expired; release old broker partition ownership; re-register consumer {0}",
                this.consumerIdString);
            this.loadBalancerListener.ResetState();
            this.zkConsumerConnector.RegisterConsumerInZk(this.dirs, this.consumerIdString, this.topicCount);
            this.loadBalancerListener.SyncedRebalance();
        }
    }
}