/**
    *
    * 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.master.handler;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.CoordinatedStateException;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.MetaTableAccessor;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.backup.HFileArchiver;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.Delete;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.ResultScanner;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.executor.EventType;
  import org.apache.hadoop.hbase.master.AssignmentManager;
  import org.apache.hadoop.hbase.master.HMaster;
  import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
  import org.apache.hadoop.hbase.master.MasterFileSystem;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.master.RegionState.State;
  import org.apache.hadoop.hbase.master.RegionStates;
  import org.apache.hadoop.hbase.regionserver.HRegion;
  
  @InterfaceAudience.Private
  public class DeleteTableHandler extends TableEventHandler {
    private static final Log LOG = LogFactory.getLog(DeleteTableHandler.class);
  
    protected HTableDescriptor hTableDescriptor = null;
  
    public DeleteTableHandler(TableName tableName, Server server,
        final MasterServices masterServices) {
      super(EventType.C_M_DELETE_TABLE, tableName, server, masterServices);
    }
  
    @Override
    protected void prepareWithTableLock() throws IOException {
      // The next call fails if no such table.
      hTableDescriptor = getTableDescriptor();
    }
  
    protected void waitRegionInTransition(final List<HRegionInfo> regions)
        throws IOException, CoordinatedStateException {
      AssignmentManager am = this.masterServices.getAssignmentManager();
      RegionStates states = am.getRegionStates();
      long waitTime = server.getConfiguration().
        getLong("hbase.master.wait.on.region", 5 * 60 * 1000);
      for (HRegionInfo region : regions) {
        long done = System.currentTimeMillis() + waitTime;
        while (System.currentTimeMillis() < done) {
          if (states.isRegionInState(region, State.FAILED_OPEN)) {
            am.regionOffline(region);
          }
          if (!states.isRegionInTransition(region)) break;
          try {
            Thread.sleep(waitingTimeForEvents);
          } catch (InterruptedException e) {
            LOG.warn("Interrupted while sleeping");
            throw (InterruptedIOException)new InterruptedIOException().initCause(e);
          }
          LOG.debug("Waiting on region to clear regions in transition; "
            + am.getRegionStates().getRegionTransitionState(region));
        }
        if (states.isRegionInTransition(region)) {
          throw new IOException("Waited hbase.master.wait.on.region (" +
            waitTime + "ms) for region to leave region " +
            region.getRegionNameAsString() + " in transitions");
        }
      }
    }
  
   @Override
   protected void handleTableOperation(List<HRegionInfo> regions)
       throws IOException, CoordinatedStateException {
     MasterCoprocessorHost cpHost = ((HMaster) this.server).getMasterCoprocessorHost();
     if (cpHost != null) {
       cpHost.preDeleteTableHandler(this.tableName);
     }
 
     // 1. Wait because of region in transition
     waitRegionInTransition(regions);
 
     try {
       // 2. Remove table from hbase:meta and HDFS
       removeTableData(regions);
     } finally {
       // 3. Update table descriptor cache
       LOG.debug("Removing '" + tableName + "' descriptor.");
       this.masterServices.getTableDescriptors().remove(tableName);
 
       AssignmentManager am = this.masterServices.getAssignmentManager();
 
       // 4. Clean up regions of the table in RegionStates.
       LOG.debug("Removing '" + tableName + "' from region states.");
       am.getRegionStates().tableDeleted(tableName);
 
       // 5. If entry for this table in zk, and up in AssignmentManager, remove it.
       LOG.debug("Marking '" + tableName + "' as deleted.");
       am.getTableStateManager().setDeletedTable(tableName);
 
       // 6.Clean any remaining rows for this table.
       cleanAnyRemainingRows();
     }
 
     if (cpHost != null) {
       cpHost.postDeleteTableHandler(this.tableName);
     }
     ((HMaster) this.server).getMasterQuotaManager().removeTableFromNamespaceQuota(tableName);
   }
 
   /**
    * There may be items for this table still up in hbase:meta in the case where the
    * info:regioninfo column was empty because of some write error. Remove ALL rows from hbase:meta
    * that have to do with this table. See HBASE-12980.
    * @throws IOException
    */
   private void cleanAnyRemainingRows() throws IOException {
     Scan tableScan = MetaTableAccessor.getScanForTableName(tableName);
     try (Table metaTable =
         this.masterServices.getConnection().getTable(TableName.META_TABLE_NAME)) {
       List<Delete> deletes = new ArrayList<Delete>();
       try (ResultScanner resScanner = metaTable.getScanner(tableScan)) {
         for (Result result : resScanner) {
           deletes.add(new Delete(result.getRow()));
         }
       }
       if (!deletes.isEmpty()) {
         LOG.warn("Deleting some vestigal " + deletes.size() + " rows of " + this.tableName +
           " from " + TableName.META_TABLE_NAME);
         if (LOG.isDebugEnabled()) {
           for (Delete d: deletes) LOG.debug("Purging " + d);
         }
         metaTable.delete(deletes);
       }
     }
   }
 
   /**
    * Removes the table from hbase:meta and archives the HDFS files.
    */
   protected void removeTableData(final List<HRegionInfo> regions)
   throws IOException, CoordinatedStateException {
     // 1. Remove regions from META
     LOG.debug("Deleting regions from META");
     MetaTableAccessor.deleteRegions(this.server.getConnection(), regions);
 
     // -----------------------------------------------------------------------
     // NOTE: At this point we still have data on disk, but nothing in hbase:meta
     //       if the rename below fails, hbck will report an inconsistency.
     // -----------------------------------------------------------------------
 
     // 2. Move the table in /hbase/.tmp
     MasterFileSystem mfs = this.masterServices.getMasterFileSystem();
     Path tempTableDir = mfs.moveTableToTemp(tableName);
 
     // 3. Archive regions from FS (temp directory)
     FileSystem fs = mfs.getFileSystem();
     for (HRegionInfo hri : regions) {
       LOG.debug("Archiving region " + hri.getRegionNameAsString() + " from FS");
       HFileArchiver.archiveRegion(fs, mfs.getRootDir(),
           tempTableDir, HRegion.getRegionDir(tempTableDir, hri.getEncodedName()));
     }
 
     // 4. Delete table directory from FS (temp directory)
     if (!fs.delete(tempTableDir, true)) {
       LOG.error("Couldn't delete " + tempTableDir);
     }
 
     LOG.debug("Table '" + tableName + "' archived!");
   }
 
   @Override
   protected void releaseTableLock() {
     super.releaseTableLock();
     try {
       masterServices.getTableLockManager().tableDeleted(tableName);
     } catch (IOException ex) {
       LOG.warn("Received exception from TableLockManager.tableDeleted:", ex); //not critical
     }
   }
 
   @Override
   public String toString() {
     String name = "UnknownServerName";
     if(server != null && server.getServerName() != null) {
       name = server.getServerName().toString();
     }
     return getClass().getSimpleName() + "-" + name + "-" + getSeqid() + "-" + tableName;
   }
 }