/**
    *
    * 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.util;
  
  import java.io.IOException;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  import java.util.Random;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.MetaTableAccessor;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.ZooKeeperConnectionException;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.Admin;
  import org.apache.hadoop.hbase.client.ClusterConnection;
  import org.apache.hadoop.hbase.client.Connection;
  import org.apache.hadoop.hbase.client.ConnectionFactory;
  import org.apache.hadoop.hbase.client.HConnection;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.master.RegionState;
  import org.apache.hadoop.hbase.master.ServerManager;
  import org.apache.hadoop.hbase.regionserver.HRegion;
  import org.apache.zookeeper.KeeperException;
  
  import java.io.IOException;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  import java.util.Random;
  
  /**
   * This class contains helper methods that repair parts of hbase's filesystem
   * contents.
   */
  @InterfaceAudience.Private
  public class HBaseFsckRepair {
    private static final Log LOG = LogFactory.getLog(HBaseFsckRepair.class);
  
    /**
     * Fix multiple assignment by doing silent closes on each RS hosting the region
     * and then force ZK unassigned node to OFFLINE to trigger assignment by
     * master.
     *
     * @param connection HBase connection to the cluster
     * @param region Region to undeploy
     * @param servers list of Servers to undeploy from
     */
    public static void fixMultiAssignment(HConnection connection, HRegionInfo region,
        List<ServerName> servers)
    throws IOException, KeeperException, InterruptedException {
      HRegionInfo actualRegion = new HRegionInfo(region);
  
      // Close region on the servers silently
      for(ServerName server : servers) {
        closeRegionSilentlyAndWait(connection, server, actualRegion);
      }
  
      // Force ZK node to OFFLINE so master assigns
      forceOfflineInZK(connection.getAdmin(), actualRegion);
    }
  
    /**
     * Fix unassigned by creating/transition the unassigned ZK node for this
     * region to OFFLINE state with a special flag to tell the master that this is
     * a forced operation by HBCK.
     *
     * This assumes that info is in META.
     *
     * @param admin
     * @param region
     * @throws IOException
     * @throws KeeperException
     */
    public static void fixUnassigned(Admin admin, HRegionInfo region)
       throws IOException, KeeperException, InterruptedException {
     HRegionInfo actualRegion = new HRegionInfo(region);
 
     // Force ZK node to OFFLINE so master assigns
     forceOfflineInZK(admin, actualRegion);
   }
 
   /**
    * In 0.90, this forces an HRI offline by setting the RegionTransitionData
    * in ZK to have HBCK_CODE_NAME as the server.  This is a special case in
    * the AssignmentManager that attempts an assign call by the master.
    *
    * @see org.apache.hadoop.hbase.master.AssignementManager#handleHBCK
    *
    * This doesn't seem to work properly in the updated version of 0.92+'s hbck
    * so we use assign to force the region into transition.  This has the
    * side-effect of requiring a HRegionInfo that considers regionId (timestamp)
    * in comparators that is addressed by HBASE-5563.
    */
   private static void forceOfflineInZK(Admin admin, final HRegionInfo region)
   throws ZooKeeperConnectionException, KeeperException, IOException, InterruptedException {
     admin.assign(region.getRegionName());
   }
 
   /*
    * Should we check all assignments or just not in RIT?
    */
   public static void waitUntilAssigned(Admin admin,
       HRegionInfo region) throws IOException, InterruptedException {
     long timeout = admin.getConfiguration().getLong("hbase.hbck.assign.timeout", 120000);
     long expiration = timeout + EnvironmentEdgeManager.currentTime();
     while (EnvironmentEdgeManager.currentTime() < expiration) {
       try {
         boolean inTransition = false;
         for (RegionState rs: admin.getClusterStatus().getRegionsInTransition()) {
           if (rs.getRegion().equals(region)) {
             inTransition = true;
             break;
           }
         }
         if (!inTransition) {
           // yay! no longer RIT
           return;
         }
         // still in rit
         LOG.info("Region still in transition, waiting for "
             + "it to become assigned: " + region);
       } catch (IOException e) {
         LOG.warn("Exception when waiting for region to become assigned,"
             + " retrying", e);
       }
       Thread.sleep(1000);
     }
     throw new IOException("Region " + region + " failed to move out of " +
         "transition within timeout " + timeout + "ms");
   }
 
   /**
    * Contacts a region server and waits up to hbase.hbck.close.timeout ms
    * (default 120s) to close the region.  This bypasses the active hmaster.
    */
   @SuppressWarnings("deprecation")
   public static void closeRegionSilentlyAndWait(HConnection connection,
       ServerName server, HRegionInfo region) throws IOException, InterruptedException {
     long timeout = connection.getConfiguration()
       .getLong("hbase.hbck.close.timeout", 120000);
     ServerManager.closeRegionSilentlyAndWait((ClusterConnection)connection, server,
         region, timeout);
   }
 
   /**
    * Puts the specified HRegionInfo into META with replica related columns
    */
   public static void fixMetaHoleOnlineAndAddReplicas(Configuration conf,
       HRegionInfo hri, Collection<ServerName> servers, int numReplicas) throws IOException {
     Connection conn = ConnectionFactory.createConnection(conf);
     Table meta = conn.getTable(TableName.META_TABLE_NAME);
     Put put = MetaTableAccessor.makePutFromRegionInfo(hri);
     if (numReplicas > 1) {
       Random r = new Random();
       ServerName[] serversArr = servers.toArray(new ServerName[servers.size()]);
       for (int i = 1; i < numReplicas; i++) {
         ServerName sn = serversArr[r.nextInt(serversArr.length)];
         // the column added here is just to make sure the master is able to
         // see the additional replicas when it is asked to assign. The
         // final value of these columns will be different and will be updated
         // by the actual regionservers that start hosting the respective replicas
         MetaTableAccessor.addLocation(put, sn, sn.getStartcode(), -1, i);
       }
     }
     meta.put(put);
     meta.close();
     conn.close();
   }
 
   /**
    * Creates, flushes, and closes a new region.
    */
   public static HRegion createHDFSRegionDir(Configuration conf,
       HRegionInfo hri, HTableDescriptor htd) throws IOException {
     // Create HRegion
     Path root = FSUtils.getRootDir(conf);
     HRegion region = HRegion.createHRegion(hri, root, conf, htd, null);
 
     // Close the new region to flush to disk. Close log file too.
     HRegion.closeHRegion(region);
     return region;
   }
 
   /*
    * Remove parent
    */
   public static void removeParentInMeta(Configuration conf, HRegionInfo hri) throws IOException {
     Connection conn = ConnectionFactory.createConnection(conf);
     MetaTableAccessor.deleteRegion(conn, hri);
   }
 }