/**
    *
    * 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.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.concurrent.Callable;
  import java.util.concurrent.CompletionService;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorCompletionService;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  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.regionserver.HRegion;
  import org.apache.hadoop.hbase.master.AssignmentManager;
  
  /**
   * Utility methods for interacting with the regions.
   */
  @InterfaceAudience.Private
  public abstract class ModifyRegionUtils {
    private static final Log LOG = LogFactory.getLog(ModifyRegionUtils.class);
  
    private ModifyRegionUtils() {
    }
  
    public interface RegionFillTask {
      void fillRegion(final HRegion region) throws IOException;
    }
  
    public interface RegionEditTask {
      void editRegion(final HRegionInfo region) throws IOException;
    }
  
    public static HRegionInfo[] createHRegionInfos(HTableDescriptor hTableDescriptor,
        byte[][] splitKeys) {
      long regionId = System.currentTimeMillis();
      HRegionInfo[] hRegionInfos = null;
      if (splitKeys == null || splitKeys.length == 0) {
        hRegionInfos = new HRegionInfo[]{
          new HRegionInfo(hTableDescriptor.getTableName(), null, null, false, regionId)
        };
      } else {
        int numRegions = splitKeys.length + 1;
        hRegionInfos = new HRegionInfo[numRegions];
        byte[] startKey = null;
        byte[] endKey = null;
        for (int i = 0; i < numRegions; i++) {
          endKey = (i == splitKeys.length) ? null : splitKeys[i];
          hRegionInfos[i] =
               new HRegionInfo(hTableDescriptor.getTableName(), startKey, endKey,
                   false, regionId);
          startKey = endKey;
        }
      }
      return hRegionInfos;
    }
  
    /**
     * Create new set of regions on the specified file-system.
     * NOTE: that you should add the regions to hbase:meta after this operation.
     *
     * @param conf {@link Configuration}
     * @param rootDir Root directory for HBase instance
     * @param hTableDescriptor description of the table
     * @param newRegions {@link HRegionInfo} that describes the regions to create
     * @throws IOException
     */
    public static List<HRegionInfo> createRegions(final Configuration conf, final Path rootDir,
        final HTableDescriptor hTableDescriptor, final HRegionInfo[] newRegions) throws IOException {
      return createRegions(conf, rootDir, hTableDescriptor, newRegions, null);
   }
 
   /**
    * Create new set of regions on the specified file-system.
    * NOTE: that you should add the regions to hbase:meta after this operation.
    *
    * @param conf {@link Configuration}
    * @param rootDir Root directory for HBase instance
    * @param hTableDescriptor description of the table
    * @param newRegions {@link HRegionInfo} that describes the regions to create
    * @param task {@link RegionFillTask} custom code to populate region after creation
    * @throws IOException
    */
   public static List<HRegionInfo> createRegions(final Configuration conf, final Path rootDir,
       final HTableDescriptor hTableDescriptor, final HRegionInfo[] newRegions,
       final RegionFillTask task) throws IOException {
 
       Path tableDir = FSUtils.getTableDir(rootDir, hTableDescriptor.getTableName());
       return createRegions(conf, rootDir, tableDir, hTableDescriptor, newRegions, task);
   }
 
   /**
    * Create new set of regions on the specified file-system.
    * NOTE: that you should add the regions to hbase:meta after this operation.
    *
    * @param conf {@link Configuration}
    * @param rootDir Root directory for HBase instance
    * @param tableDir table directory
    * @param hTableDescriptor description of the table
    * @param newRegions {@link HRegionInfo} that describes the regions to create
    * @param task {@link RegionFillTask} custom code to populate region after creation
    * @throws IOException
    */
   public static List<HRegionInfo> createRegions(final Configuration conf, final Path rootDir,
       final Path tableDir, final HTableDescriptor hTableDescriptor, final HRegionInfo[] newRegions,
       final RegionFillTask task) throws IOException {
     if (newRegions == null) return null;
     int regionNumber = newRegions.length;
     ThreadPoolExecutor exec = getRegionOpenAndInitThreadPool(conf,
         "RegionOpenAndInitThread-" + hTableDescriptor.getTableName(), regionNumber);
     try {
       return createRegions(exec, conf, rootDir, tableDir, hTableDescriptor, newRegions, task);
     } finally {
       exec.shutdownNow();
     }
   }
 
   /**
    * Create new set of regions on the specified file-system.
    * NOTE: that you should add the regions to hbase:meta after this operation.
    *
    * @param exec Thread Pool Executor
    * @param conf {@link Configuration}
    * @param rootDir Root directory for HBase instance
    * @param tableDir table directory
    * @param hTableDescriptor description of the table
    * @param newRegions {@link HRegionInfo} that describes the regions to create
    * @param task {@link RegionFillTask} custom code to populate region after creation
    * @throws IOException
    */
   public static List<HRegionInfo> createRegions(final ThreadPoolExecutor exec,
       final Configuration conf, final Path rootDir, final Path tableDir,
       final HTableDescriptor hTableDescriptor, final HRegionInfo[] newRegions,
       final RegionFillTask task) throws IOException {
     if (newRegions == null) return null;
     int regionNumber = newRegions.length;
     CompletionService<HRegionInfo> completionService =
       new ExecutorCompletionService<HRegionInfo>(exec);
     List<HRegionInfo> regionInfos = new ArrayList<HRegionInfo>();
     for (final HRegionInfo newRegion : newRegions) {
       completionService.submit(new Callable<HRegionInfo>() {
         @Override
         public HRegionInfo call() throws IOException {
           return createRegion(conf, rootDir, tableDir, hTableDescriptor, newRegion, task);
         }
       });
     }
     try {
       // wait for all regions to finish creation
       for (int i = 0; i < regionNumber; i++) {
         regionInfos.add(completionService.take().get());
       }
     } catch (InterruptedException e) {
       LOG.error("Caught " + e + " during region creation");
       throw new InterruptedIOException(e.getMessage());
     } catch (ExecutionException e) {
       throw new IOException(e);
     }
     return regionInfos;
   }
 
   /**
    * Create new set of regions on the specified file-system.
    * @param conf {@link Configuration}
    * @param rootDir Root directory for HBase instance
    * @param tableDir table directory
    * @param hTableDescriptor description of the table
    * @param newRegion {@link HRegionInfo} that describes the region to create
    * @param task {@link RegionFillTask} custom code to populate region after creation
    * @throws IOException
    */
   public static HRegionInfo createRegion(final Configuration conf, final Path rootDir,
       final Path tableDir, final HTableDescriptor hTableDescriptor, final HRegionInfo newRegion,
       final RegionFillTask task) throws IOException {
     // 1. Create HRegion
     HRegion region = HRegion.createHRegion(newRegion,
       rootDir, tableDir, conf, hTableDescriptor, null,
       false, true);
     try {
       // 2. Custom user code to interact with the created region
       if (task != null) {
         task.fillRegion(region);
       }
     } finally {
       // 3. Close the new region to flush to disk. Close log file too.
       region.close();
     }
     return region.getRegionInfo();
   }
 
   /**
    * Execute the task on the specified set of regions.
    *
    * @param exec Thread Pool Executor
    * @param regions {@link HRegionInfo} that describes the regions to edit
    * @param task {@link RegionFillTask} custom code to edit the region
    * @throws IOException
    */
   public static void editRegions(final ThreadPoolExecutor exec,
       final Collection<HRegionInfo> regions, final RegionEditTask task) throws IOException {
     final ExecutorCompletionService<Void> completionService =
       new ExecutorCompletionService<Void>(exec);
     for (final HRegionInfo hri: regions) {
       completionService.submit(new Callable<Void>() {
         @Override
         public Void call() throws IOException {
           task.editRegion(hri);
           return null;
         }
       });
     }
 
     try {
       for (HRegionInfo hri: regions) {
         completionService.take().get();
       }
     } catch (InterruptedException e) {
       throw new InterruptedIOException(e.getMessage());
     } catch (ExecutionException e) {
       IOException ex = new IOException();
       ex.initCause(e.getCause());
       throw ex;
     }
   }
 
   /*
    * used by createRegions() to get the thread pool executor based on the
    * "hbase.hregion.open.and.init.threads.max" property.
    */
   static ThreadPoolExecutor getRegionOpenAndInitThreadPool(final Configuration conf,
       final String threadNamePrefix, int regionNumber) {
     int maxThreads = Math.min(regionNumber, conf.getInt(
         "hbase.hregion.open.and.init.threads.max", 10));
     ThreadPoolExecutor regionOpenAndInitThreadPool = Threads
     .getBoundedCachedThreadPool(maxThreads, 30L, TimeUnit.SECONDS,
         new ThreadFactory() {
           private int count = 1;
 
           @Override
           public Thread newThread(Runnable r) {
             return new Thread(r, threadNamePrefix + "-" + count++);
           }
         });
     return regionOpenAndInitThreadPool;
   }
 
   /**
    * Triggers a bulk assignment of the specified regions
    *
    * @param assignmentManager the Assignment Manger
    * @param regionInfos the list of regions to assign
    * @throws IOException if an error occurred during the assignment
    */
   public static void assignRegions(final AssignmentManager assignmentManager,
       final List<HRegionInfo> regionInfos) throws IOException {
     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;
     }
   }
 }