content: /**
   * 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 com.alibaba.wasp.client;
  
  import com.alibaba.wasp.ServerName;
  import com.alibaba.wasp.zookeeper.FServerTracker;
  import com.alibaba.wasp.zookeeper.ZKUtil;
  import com.alibaba.wasp.zookeeper.ZooKeeperWatcher;
  import org.apache.zookeeper.KeeperException;
  
  import java.io.IOException;
  import java.util.List;
  
  public class FClientFServerTracker extends FServerTracker {
  
    /**
     * Hacked from FServerTracker.
     * 
     * @param watcher
     */
    public FClientFServerTracker(ZooKeeperWatcher watcher) {
      super(watcher, null, null);
    }
  
    @Override
    public void nodeDeleted(String path) {
      if (path.startsWith(watcher.fsZNode)) {
        String serverName = ZKUtil.getNodeName(path);
        LOG.info("FServer ephemeral node deleted, processing expiration ["
            + serverName + "]");
        ServerName sn = ServerName.parseServerName(serverName);
        remove(sn);
      }
    }
  
    @Override
    public void nodeChildrenChanged(String path) {
      if (path.equals(watcher.fsZNode)) {
        try {
          List<String> servers = ZKUtil.listChildrenAndWatchThem(watcher,
              watcher.fsZNode);
          add(servers);
        } catch (IOException e) {
          LOG.warn("Unexpected zk exception getting RS nodes", e);
        } catch (KeeperException e) {
          LOG.warn("Unexpected zk exception getting RS nodes", e);
        }
      }
    }
  }
  