/**
    *
    * 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.FileNotFoundException;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.NavigableMap;
  import java.util.TreeMap;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.catalog.MetaReader;
  import org.apache.hadoop.hbase.client.HTable;
  import org.apache.hadoop.hbase.exceptions.InvalidFamilyOperationException;
  import org.apache.hadoop.hbase.exceptions.TableExistsException;
  import org.apache.hadoop.hbase.exceptions.TableNotDisabledException;
  import org.apache.hadoop.hbase.executor.EventHandler;
  import org.apache.hadoop.hbase.executor.EventType;
  import org.apache.hadoop.hbase.master.BulkReOpen;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.zookeeper.KeeperException;
  
  import com.google.common.collect.Lists;
  import com.google.common.collect.Maps;
  
  /**
   * Base class for performing operations against tables.
   * Checks on whether the process can go forward are done in constructor rather
   * than later on in {@link #process()}.  The idea is to fail fast rather than
   * later down in an async invocation of {@link #process()} (which currently has
   * no means of reporting back issues once started).
   */
  @InterfaceAudience.Private
  public abstract class TableEventHandler extends EventHandler {
    private static final Log LOG = LogFactory.getLog(TableEventHandler.class);
    protected final MasterServices masterServices;
    protected final byte [] tableName;
    protected final String tableNameStr;
    protected TableLock tableLock;
    private boolean isPrepareCalled = false;
  
    public TableEventHandler(EventType eventType, byte [] tableName, Server server,
        MasterServices masterServices) {
      super(server, eventType);
      this.masterServices = masterServices;
      this.tableName = tableName;
      this.tableNameStr = Bytes.toString(this.tableName);
    }
  
    public TableEventHandler prepare() throws IOException {
      //acquire the table write lock, blocking
      this.tableLock = masterServices.getTableLockManager()
          .writeLock(tableName, eventType.toString());
      this.tableLock.acquire();
      boolean success = false;
      try {
        try {
          this.masterServices.checkTableModifiable(tableName);
        } catch (TableNotDisabledException ex)  {
          if (isOnlineSchemaChangeAllowed()
              && eventType.isOnlineSchemaChangeSupported()) {
            LOG.debug("Ignoring table not disabled exception " +
                "for supporting online schema changes.");
          } else {
            throw ex;
          }
        }
        prepareWithTableLock();
        success = true;
      } finally {
        if (!success ) {
          releaseTableLock();
        }
     }
     this.isPrepareCalled = true;
     return this;
   }
 
   /** Called from prepare() while holding the table lock. Subclasses
    * can do extra initialization, and not worry about the releasing
    * the table lock. */
   protected void prepareWithTableLock() throws IOException {
   }
 
   private boolean isOnlineSchemaChangeAllowed() {
     return this.server.getConfiguration().getBoolean(
       "hbase.online.schema.update.enable", false);
   }
 
   @Override
   public void process() {
     if (!isPrepareCalled) {
       //For proper table locking semantics, the implementor should ensure to call
       //TableEventHandler.prepare() before calling process()
       throw new RuntimeException("Implementation should have called prepare() first");
     }
     try {
       LOG.info("Handling table operation " + eventType + " on table " +
           Bytes.toString(tableName));
 
       List<HRegionInfo> hris =
         MetaReader.getTableRegions(this.server.getCatalogTracker(),
           tableName);
       handleTableOperation(hris);
       if (eventType.isOnlineSchemaChangeSupported() && this.masterServices.
           getAssignmentManager().getZKTable().
           isEnabledTable(Bytes.toString(tableName))) {
         if (reOpenAllRegions(hris)) {
           LOG.info("Completed table operation " + eventType + " on table " +
               Bytes.toString(tableName));
         } else {
           LOG.warn("Error on reopening the regions");
         }
       }
       completed(null);
     } catch (IOException e) {
       LOG.error("Error manipulating table " + Bytes.toString(tableName), e);
       completed(e);
     } catch (KeeperException e) {
       LOG.error("Error manipulating table " + Bytes.toString(tableName), e);
       completed(e);
     } finally {
       releaseTableLock();
     }
   }
 
   protected void releaseTableLock() {
     if (this.tableLock != null) {
       try {
         this.tableLock.release();
       } catch (IOException ex) {
         LOG.warn("Could not release the table lock", ex);
       }
     }
   }
 
   /**
    * Called after that process() is completed.
    * @param exception null if process() is successful or not null if something has failed.
    */
   protected void completed(final Throwable exception) {
   }
 
   public boolean reOpenAllRegions(List<HRegionInfo> regions) throws IOException {
     boolean done = false;
     LOG.info("Bucketing regions by region server...");
     HTable table = new HTable(masterServices.getConfiguration(), tableName);
     TreeMap<ServerName, List<HRegionInfo>> serverToRegions = Maps
         .newTreeMap();
     NavigableMap<HRegionInfo, ServerName> hriHserverMapping = table.getRegionLocations();
     List<HRegionInfo> reRegions = new ArrayList<HRegionInfo>();
     for (HRegionInfo hri : regions) {
       ServerName rsLocation = hriHserverMapping.get(hri);
 
       // Skip the offlined split parent region
       // See HBASE-4578 for more information.
       if (null == rsLocation) {
         LOG.info("Skip " + hri);
         continue;
       }
       if (!serverToRegions.containsKey(rsLocation)) {
         LinkedList<HRegionInfo> hriList = Lists.newLinkedList();
         serverToRegions.put(rsLocation, hriList);
       }
       reRegions.add(hri);
       serverToRegions.get(rsLocation).add(hri);
     }
 
     LOG.info("Reopening " + reRegions.size() + " regions on "
         + serverToRegions.size() + " region servers.");
     this.masterServices.getAssignmentManager().setRegionsToReopen(reRegions);
     BulkReOpen bulkReopen = new BulkReOpen(this.server, serverToRegions,
         this.masterServices.getAssignmentManager());
     while (true) {
       try {
         if (bulkReopen.bulkReOpen()) {
           done = true;
           break;
         } else {
           LOG.warn("Timeout before reopening all regions");
         }
       } catch (InterruptedException e) {
         LOG.warn("Reopen was interrupted");
         // Preserve the interrupt.
         Thread.currentThread().interrupt();
         break;
       }
     }
     return done;
   }
 
 
   /**
    * Gets a TableDescriptor from the masterServices.  Can Throw exceptions.
    *
    * @return Table descriptor for this table
    * @throws TableExistsException
    * @throws FileNotFoundException
    * @throws IOException
    */
   public HTableDescriptor getTableDescriptor()
   throws FileNotFoundException, IOException {
     final String name = Bytes.toString(tableName);
     HTableDescriptor htd =
       this.masterServices.getTableDescriptors().get(name);
     if (htd == null) {
       throw new IOException("HTableDescriptor missing for " + name);
     }
     return htd;
   }
 
   byte [] hasColumnFamily(final HTableDescriptor htd, final byte [] cf)
   throws InvalidFamilyOperationException {
     if (!htd.hasFamily(cf)) {
       throw new InvalidFamilyOperationException("Column family '" +
         Bytes.toString(cf) + "' does not exist");
     }
     return cf;
   }
 
   protected abstract void handleTableOperation(List<HRegionInfo> regions)
   throws IOException, KeeperException;
 }