/**
    *
    * 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.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.CoordinatedStateException;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.MetaTableAccessor;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.TableNotDisabledException;
  import org.apache.hadoop.hbase.TableNotFoundException;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  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.BulkAssigner;
  import org.apache.hadoop.hbase.master.GeneralBulkAssigner;
  import org.apache.hadoop.hbase.master.HMaster;
  import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
  import org.apache.hadoop.hbase.master.MasterServices;
  import org.apache.hadoop.hbase.master.RegionStates;
  import org.apache.hadoop.hbase.master.ServerManager;
  import org.apache.hadoop.hbase.master.TableLockManager;
  import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.zookeeper.MetaTableLocator;
  
  /**
   * Handler to run enable of a table.
   */
  @InterfaceAudience.Private
  public class EnableTableHandler extends EventHandler {
    private static final Log LOG = LogFactory.getLog(EnableTableHandler.class);
    private final TableName tableName;
    private final AssignmentManager assignmentManager;
    private final TableLockManager tableLockManager;
    private boolean skipTableStateCheck = false;
    private TableLock tableLock;
    private MasterServices services;
  
    public EnableTableHandler(Server server, TableName tableName,
        AssignmentManager assignmentManager, TableLockManager tableLockManager,
        boolean skipTableStateCheck) {
      super(server, EventType.C_M_ENABLE_TABLE);
      this.tableName = tableName;
      this.assignmentManager = assignmentManager;
      this.tableLockManager = tableLockManager;
      this.skipTableStateCheck = skipTableStateCheck;
    }
  
    public EnableTableHandler(MasterServices services, TableName tableName,
        AssignmentManager assignmentManager,
        TableLockManager tableLockManager, boolean skipTableStateCheck) {
      this((Server)services, tableName, assignmentManager, tableLockManager,
          skipTableStateCheck);
      this.services = services;
    }
  
    public EnableTableHandler prepare()
        throws TableNotFoundException, TableNotDisabledException, IOException {
      //acquire the table write lock, blocking
      this.tableLock = this.tableLockManager.writeLock(tableName,
          EventType.C_M_ENABLE_TABLE.toString());
      this.tableLock.acquire();
  
      boolean success = false;
      try {
        // Check if table exists
        if (!MetaTableAccessor.tableExists(this.server.getConnection(), tableName)) {
          // retainAssignment is true only during recovery.  In normal case it is false
          if (!this.skipTableStateCheck) {
            throw new TableNotFoundException(tableName);
          }
         try {
           this.assignmentManager.getTableStateManager().checkAndRemoveTableState(tableName,
             ZooKeeperProtos.Table.State.ENABLING, true);
           throw new TableNotFoundException(tableName);
         } catch (CoordinatedStateException e) {
           // TODO : Use HBCK to clear such nodes
           LOG.warn("Failed to delete the ENABLING node for the table " + tableName
               + ".  The table will remain unusable. Run HBCK to manually fix the problem.");
         }
       }
 
       // There could be multiple client requests trying to disable or enable
       // the table at the same time. Ensure only the first request is honored
       // After that, no other requests can be accepted until the table reaches
       // DISABLED or ENABLED.
       if (!skipTableStateCheck) {
         try {
           if (!this.assignmentManager.getTableStateManager().setTableStateIfInStates(
               this.tableName, ZooKeeperProtos.Table.State.ENABLING,
               ZooKeeperProtos.Table.State.DISABLED)) {
             LOG.info("Table " + tableName + " isn't disabled; skipping enable");
             throw new TableNotDisabledException(this.tableName);
           }
         } catch (CoordinatedStateException e) {
           throw new IOException("Unable to ensure that the table will be" +
             " enabling because of a coordination engine 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() + "-" +
         tableName;
   }
 
   @Override
   public void process() {
     try {
       LOG.info("Attempting to enable the table " + this.tableName);
       MasterCoprocessorHost cpHost = ((HMaster) this.server)
           .getMasterCoprocessorHost();
       // this executes within assignment manager, so not overriding user
       if (cpHost != null) {
         cpHost.preEnableTableHandler(this.tableName, null);
       }
       handleEnableTable();
       if (cpHost != null) {
         cpHost.postEnableTableHandler(this.tableName, null);
       }
     } catch (IOException e) {
       LOG.error("Error trying to enable the table " + this.tableName, e);
     } catch (CoordinatedStateException e) {
       LOG.error("Error trying to enable the table " + this.tableName, e);
     } catch (InterruptedException e) {
       LOG.error("Error trying to enable the table " + this.tableName, e);
     } finally {
       releaseTableLock();
     }
   }
 
   private void releaseTableLock() {
     if (this.tableLock != null) {
       try {
         this.tableLock.release();
       } catch (IOException ex) {
         LOG.warn("Could not release the table lock", ex);
       }
     }
   }
 
   private void handleEnableTable() throws IOException, CoordinatedStateException,
       InterruptedException {
     // I could check table is disabling and if so, not enable but require
     // that user first finish disabling but that might be obnoxious.
 
     // Set table enabling flag up in zk.
     this.assignmentManager.getTableStateManager().setTableState(this.tableName,
       ZooKeeperProtos.Table.State.ENABLING);
     boolean done = false;
     ServerManager serverManager = ((HMaster)this.server).getServerManager();
     // Get the regions of this table. We're done when all listed
     // tables are onlined.
     List<Pair<HRegionInfo, ServerName>> tableRegionsAndLocations;
     if (TableName.META_TABLE_NAME.equals(tableName)) {
       tableRegionsAndLocations = new MetaTableLocator().getMetaRegionsAndLocations(
         server.getZooKeeper());
     } else {
       tableRegionsAndLocations = MetaTableAccessor.getTableRegionsAndLocations(
         server.getZooKeeper(), server.getConnection(), tableName, true);
     }
 
     int countOfRegionsInTable = tableRegionsAndLocations.size();
     Map<HRegionInfo, ServerName> regionsToAssign =
         regionsToAssignWithServerName(tableRegionsAndLocations);
     if (services != null) {
       // need to potentially create some regions for the replicas
       List<HRegionInfo> unrecordedReplicas = AssignmentManager.replicaRegionsNotRecordedInMeta(
           new HashSet<HRegionInfo>(regionsToAssign.keySet()), services);
       Map<ServerName, List<HRegionInfo>> srvToUnassignedRegs =
             this.assignmentManager.getBalancer().roundRobinAssignment(unrecordedReplicas,
                 serverManager.getOnlineServersList());
       if (srvToUnassignedRegs != null) {
         for (Map.Entry<ServerName, List<HRegionInfo>> entry : srvToUnassignedRegs.entrySet()) {
           for (HRegionInfo h : entry.getValue()) {
             regionsToAssign.put(h, entry.getKey());
           }
         }
       }
     }
     int regionsCount = regionsToAssign.size();
     if (regionsCount == 0) {
       done = true;
     }
     LOG.info("Table '" + this.tableName + "' has " + countOfRegionsInTable
       + " regions, of which " + regionsCount + " are offline.");
     List<ServerName> onlineServers = serverManager.createDestinationServersList();
     Map<ServerName, List<HRegionInfo>> bulkPlan =
         this.assignmentManager.getBalancer().retainAssignment(regionsToAssign, onlineServers);
     if (bulkPlan != null) {
       LOG.info("Bulk assigning " + regionsCount + " region(s) across " + bulkPlan.size()
           + " server(s), retainAssignment=true");
 
       BulkAssigner ba =
           new GeneralBulkAssigner(this.server, bulkPlan, this.assignmentManager, true);
       try {
         if (ba.bulkAssign()) {
           done = true;
         }
       } catch (InterruptedException e) {
         LOG.warn("Enable operation was interrupted when enabling table '"
             + this.tableName + "'");
         // Preserve the interrupt.
         Thread.currentThread().interrupt();
       }
     } else {
       done = true;
       LOG.info("Balancer was unable to find suitable servers for table " + tableName
           + ", leaving unassigned");
     }
     if (done) {
       // Flip the table to enabled.
       this.assignmentManager.getTableStateManager().setTableState(
         this.tableName, ZooKeeperProtos.Table.State.ENABLED);
       LOG.info("Table '" + this.tableName
       + "' was successfully enabled. Status: done=" + done);
     } else {
       LOG.warn("Table '" + this.tableName
       + "' wasn't successfully enabled. Status: done=" + done);
     }
   }
 
   /**
    * @param regionsInMeta
    * @return List of regions neither in transition nor assigned.
    * @throws IOException
    */
   private Map<HRegionInfo, ServerName> regionsToAssignWithServerName(
       final List<Pair<HRegionInfo, ServerName>> regionsInMeta) throws IOException {
     Map<HRegionInfo, ServerName> regionsToAssign =
         new HashMap<HRegionInfo, ServerName>(regionsInMeta.size());
     RegionStates regionStates = this.assignmentManager.getRegionStates();
     for (Pair<HRegionInfo, ServerName> regionLocation : regionsInMeta) {
       HRegionInfo hri = regionLocation.getFirst();
       ServerName sn = regionLocation.getSecond();
       if (regionStates.isRegionOffline(hri)) {
         regionsToAssign.put(hri, sn);
       } else {
         if (LOG.isDebugEnabled()) {
           LOG.debug("Skipping assign for the region " + hri + " during enable table "
               + hri.getTable() + " because its already in tranition or assigned.");
         }
       }
     }
     return regionsToAssign;
   }
 }