/**
    *
    * 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.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.exceptions.NotAllMetaRegionsOnlineException;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.exceptions.TableExistsException;
  import org.apache.hadoop.hbase.catalog.CatalogTracker;
  import org.apache.hadoop.hbase.catalog.MetaEditor;
  import org.apache.hadoop.hbase.catalog.MetaReader;
  import org.apache.hadoop.hbase.executor.EventHandler;
  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.TableLockManager;
  import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
  import org.apache.hadoop.hbase.util.FSTableDescriptors;
  import org.apache.hadoop.hbase.util.ModifyRegionUtils;
  import org.apache.zookeeper.KeeperException;
  
  /**
   * Handler to create a table.
   */
  @InterfaceAudience.Private
  public class CreateTableHandler extends EventHandler {
    private static final Log LOG = LogFactory.getLog(CreateTableHandler.class);
    protected final MasterFileSystem fileSystemManager;
    protected final HTableDescriptor hTableDescriptor;
    protected final Configuration conf;
    private final AssignmentManager assignmentManager;
    private final CatalogTracker catalogTracker;
    private final TableLockManager tableLockManager;
    private final HRegionInfo [] newRegions;
    private final TableLock tableLock;
  
    public CreateTableHandler(Server server, MasterFileSystem fileSystemManager,
        HTableDescriptor hTableDescriptor, Configuration conf, HRegionInfo [] newRegions,
        MasterServices masterServices) {
      super(server, EventType.C_M_CREATE_TABLE);
  
      this.fileSystemManager = fileSystemManager;
      this.hTableDescriptor = hTableDescriptor;
      this.conf = conf;
      this.newRegions = newRegions;
      this.catalogTracker = masterServices.getCatalogTracker();
      this.assignmentManager = masterServices.getAssignmentManager();
      this.tableLockManager = masterServices.getTableLockManager();
  
      this.tableLock = this.tableLockManager.writeLock(this.hTableDescriptor.getName()
          , EventType.C_M_CREATE_TABLE.toString());
    }
  
    public CreateTableHandler prepare()
        throws NotAllMetaRegionsOnlineException, TableExistsException, IOException {
      int timeout = conf.getInt("hbase.client.catalog.timeout", 10000);
      // Need META availability to create a table
      try {
        if(catalogTracker.waitForMeta(timeout) == null) {
          throw new NotAllMetaRegionsOnlineException();
        }
      } catch (InterruptedException e) {
        LOG.warn("Interrupted waiting for meta availability", e);
        InterruptedIOException ie = new InterruptedIOException(e.getMessage());
        ie.initCause(e);
        throw ie;
      }
  
      //acquire the table write lock, blocking. Make sure that it is released.
     this.tableLock.acquire();
     boolean success = false;
     try {
       String tableName = this.hTableDescriptor.getNameAsString();
       if (MetaReader.tableExists(catalogTracker, tableName)) {
         throw new TableExistsException(tableName);
       }
 
       // If we have multiple client threads trying to create the table at the
       // same time, given the async nature of the operation, the table
       // could be in a state where .META. table hasn't been updated yet in
       // the process() function.
       // Use enabling state to tell if there is already a request for the same
       // table in progress. This will introduce a new zookeeper call. Given
       // createTable isn't a frequent operation, that should be ok.
       //TODO: now that we have table locks, re-evaluate above
       try {
         if (!this.assignmentManager.getZKTable().checkAndSetEnablingTable(tableName)) {
           throw new TableExistsException(tableName);
         }
       } catch (KeeperException e) {
         throw new IOException("Unable to ensure that the table will be" +
           " enabling because of a ZooKeeper issue", e);
       }
       success = true;
     } finally {
       if (!success) {
         releaseTableLock();
       }
     }
     return this;
   }
 
   @Override
   public String toString() {
     String name = "UnknownServerName";
     if(server != null && server.getServerName() != null) {
       name = server.getServerName().toString();
     }
     return getClass().getSimpleName() + "-" + name + "-" + getSeqid() + "-" +
       this.hTableDescriptor.getNameAsString();
   }
 
   @Override
   public void process() {
     String tableName = this.hTableDescriptor.getNameAsString();
     LOG.info("Attempting to create the table " + tableName);
 
     try {
       MasterCoprocessorHost cpHost = ((HMaster) this.server).getCoprocessorHost();
       if (cpHost != null) {
         cpHost.preCreateTableHandler(this.hTableDescriptor, this.newRegions);
       }
       handleCreateTable(tableName);
       completed(null);
       if (cpHost != null) {
         cpHost.postCreateTableHandler(this.hTableDescriptor, this.newRegions);
       }
     } catch (Throwable e) {
       LOG.error("Error trying to create the table " + tableName, e);
       completed(e);
     }
   }
 
   /**
    * 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) {
     releaseTableLock();
     if (exception != null) {
       // Try deleting the enabling node in case of error
       // If this does not happen then if the client tries to create the table
       // again with the same Active master
       // It will block the creation saying TableAlreadyExists.
       try {
         this.assignmentManager.getZKTable().removeEnablingTable(
             this.hTableDescriptor.getNameAsString(), false);
       } catch (KeeperException e) {
         // Keeper exception should not happen here
         LOG.error("Got a keeper exception while removing the ENABLING table znode "
             + this.hTableDescriptor.getNameAsString(), e);
       }
     }
   }
 
   /**
    * Responsible of table creation (on-disk and META) and assignment.
    * - Create the table directory and descriptor (temp folder)
    * - Create the on-disk regions (temp folder)
    *   [If something fails here: we've just some trash in temp]
    * - Move the table from temp to the root directory
    *   [If something fails here: we've the table in place but some of the rows required
    *    present in META. (hbck needed)]
    * - Add regions to META
    *   [If something fails here: we don't have regions assigned: table disabled]
    * - Assign regions to Region Servers
    *   [If something fails here: we still have the table in disabled state]
    * - Update ZooKeeper with the enabled state
    */
   private void handleCreateTable(String tableName) throws IOException, KeeperException {
     Path tempdir = fileSystemManager.getTempDir();
     FileSystem fs = fileSystemManager.getFileSystem();
 
     // 1. Create Table Descriptor
     FSTableDescriptors.createTableDescriptor(fs, tempdir, this.hTableDescriptor);
     Path tempTableDir = new Path(tempdir, tableName);
     Path tableDir = new Path(fileSystemManager.getRootDir(), tableName);
 
     // 2. Create Regions
     List<HRegionInfo> regionInfos = handleCreateHdfsRegions(tempdir, tableName);
 
     // 3. Move Table temp directory to the hbase root location
     if (!fs.rename(tempTableDir, tableDir)) {
       throw new IOException("Unable to move table from temp=" + tempTableDir +
         " to hbase root=" + tableDir);
     }
 
     if (regionInfos != null && regionInfos.size() > 0) {
       // 4. Add regions to META
       MetaEditor.addRegionsToMeta(this.catalogTracker, regionInfos);
 
       // 5. Trigger immediate assignment of the regions in round-robin fashion
       try {
         assignmentManager.getRegionStates().createRegionStates(regionInfos);
         assignmentManager.assign(regionInfos);
       } catch (InterruptedException e) {
         LOG.error("Caught " + e + " during round-robin assignment");
         InterruptedIOException ie = new InterruptedIOException(e.getMessage());
         ie.initCause(e);
         throw ie;
       }
     }
 
     // 6. Set table enabled flag up in zk.
     try {
       assignmentManager.getZKTable().setEnabledTable(tableName);
     } catch (KeeperException e) {
       throw new IOException("Unable to ensure that " + tableName + " will be" +
         " enabled because of a ZooKeeper issue", e);
     }
   }
 
   private void releaseTableLock() {
     if (this.tableLock != null) {
       try {
         this.tableLock.release();
       } catch (IOException ex) {
         LOG.warn("Could not release the table lock", ex);
       }
     }
   }
 
   /**
    * Create the on-disk structure for the table, and returns the regions info.
    * @param tableRootDir directory where the table is being created
    * @param tableName name of the table under construction
    * @return the list of regions created
    */
   protected List<HRegionInfo> handleCreateHdfsRegions(final Path tableRootDir,
     final String tableName)
       throws IOException {
     return ModifyRegionUtils.createRegions(conf, tableRootDir,
         hTableDescriptor, newRegions, null);
   }
 }