/*
    * 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.chaos.actions;
  
  import java.util.List;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper;
  import org.apache.hadoop.hbase.zookeeper.ZKUtil;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import org.apache.hadoop.hdfs.DFSUtil;
  import org.apache.hadoop.hdfs.HAUtil;
  import org.apache.hadoop.hdfs.server.namenode.ha.proto.HAZKInfoProtos.ActiveNodeInfo;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Action that tries to restart the active namenode.
   */
  public class RestartActiveNameNodeAction extends RestartActionBaseAction {
    private static final Logger LOG =
        LoggerFactory.getLogger(RestartActiveNameNodeAction.class);
  
    // Value taken from org.apache.hadoop.ha.ActiveStandbyElector.java, variable :- LOCK_FILENAME
    private static final String ACTIVE_NN_LOCK_NAME = "ActiveStandbyElectorLock";
  
    // Value taken from org.apache.hadoop.ha.ZKFailoverController.java
    // variable :- ZK_PARENT_ZNODE_DEFAULT and ZK_PARENT_ZNODE_KEY
    private static final String ZK_PARENT_ZNODE_DEFAULT = "/hadoop-ha";
    private static final String ZK_PARENT_ZNODE_KEY = "ha.zookeeper.parent-znode";
  
    public RestartActiveNameNodeAction(long sleepTime) {
      super(sleepTime);
    }
  
    @Override protected Logger getLogger() {
      return LOG;
    }
  
    @Override
    public void perform() throws Exception {
      getLogger().info("Performing action: Restart active namenode");
      Configuration conf = FSUtils.getRootDir(getConf()).getFileSystem(getConf()).getConf();
      String nameServiceID = DFSUtil.getNamenodeNameServiceId(conf);
      if (!HAUtil.isHAEnabled(conf, nameServiceID)) {
        throw new Exception("HA for namenode is not enabled");
      }
      ZooKeeperWatcher zkw = null;
      RecoverableZooKeeper rzk = null;
      String activeNamenode = null;
      String hadoopHAZkNode = conf.get(ZK_PARENT_ZNODE_KEY, ZK_PARENT_ZNODE_DEFAULT);
      try {
        zkw = new ZooKeeperWatcher(conf, "get-active-namenode", null);
        rzk = zkw.getRecoverableZooKeeper();
        String hadoopHAZkNodePath = ZKUtil.joinZNode(hadoopHAZkNode, nameServiceID);
        List<String> subChildern = ZKUtil.listChildrenNoWatch(zkw, hadoopHAZkNodePath);
        for (String eachEntry : subChildern) {
          if (eachEntry.contains(ACTIVE_NN_LOCK_NAME)) {
            byte[] data =
                rzk.getData(ZKUtil.joinZNode(hadoopHAZkNodePath, ACTIVE_NN_LOCK_NAME), false,
                  null);
            ActiveNodeInfo proto = ActiveNodeInfo.parseFrom(data);
            activeNamenode = proto.getHostname();
          }
        }
      } finally {
        if (zkw != null) {
          zkw.close();
        }
      }
      if (activeNamenode == null) {
        throw new Exception("No active Name node found in zookeeper under " + hadoopHAZkNode);
      }
      getLogger().info("Found active namenode host:" + activeNamenode);
      ServerName activeNNHost = ServerName.valueOf(activeNamenode, -1, -1);
      getLogger().info("Restarting Active NameNode :" + activeNamenode);
      restartNameNode(activeNNHost, sleepTime);
    }
  }