/**
    *
    * 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 org.apache.hadoop.hbase.zookeeper;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.regionserver.HRegionServer;
  import org.apache.hadoop.hbase.regionserver.handler.FinishRegionRecoveringHandler;
  import org.apache.zookeeper.KeeperException;
  
  /**
   * Watcher used to be notified of the recovering region coming out of recovering state
   */
  @InterfaceAudience.Private
  public class RecoveringRegionWatcher extends ZooKeeperListener {
    private static final Log LOG = LogFactory.getLog(RecoveringRegionWatcher.class);
  
    private HRegionServer server;
  
    /**
     * Construct a ZooKeeper event listener.
     */
    public RecoveringRegionWatcher(ZooKeeperWatcher watcher, HRegionServer server) {
      super(watcher);
      watcher.registerListener(this);
      this.server = server;
    }
  
    /**
     * Called when a node has been deleted
     * @param path full path of the deleted node
     */
    @Override
    public void nodeDeleted(String path) {
      if (this.server.isStopped() || this.server.isStopping()) {
        return;
      }
  
      String parentPath = path.substring(0, path.lastIndexOf('/'));
      if (!this.watcher.recoveringRegionsZNode.equalsIgnoreCase(parentPath)) {
        return;
      }
  
      String regionName = path.substring(parentPath.length() + 1);
  
      server.getExecutorService().submit(new FinishRegionRecoveringHandler(server, regionName, path));
    }
  
    @Override
    public void nodeDataChanged(String path) {
      registerWatcher(path);
    }
  
    @Override
    public void nodeChildrenChanged(String path) {
      registerWatcher(path);
    }
  
    /**
     * Reinstall watcher because watcher only fire once though we're only interested in nodeDeleted
     * event we need to register the watcher in case other event happens
     */
    private void registerWatcher(String path) {
      String parentPath = path.substring(0, path.lastIndexOf('/'));
      if (!this.watcher.recoveringRegionsZNode.equalsIgnoreCase(parentPath)) {
        return;
      }
  
      try {
        ZKUtil.getDataAndWatch(watcher, path);
      } catch (KeeperException e) {
        LOG.warn("Can't register watcher on znode " + path, e);
      }
    }
  }