/*
 * 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;

import java.io.Closeable;
import java.io.IOException;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.ThreadLocalRandom;
import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.AsyncClusterConnection;
import org.apache.hadoop.hbase.client.AsyncRegionServerAdmin;
import org.apache.hadoop.hbase.client.ClusterConnectionFactory;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.favored.FavoredNodeAssignmentHelper;
import org.apache.hadoop.hbase.favored.FavoredNodesPlan;
import org.apache.hadoop.hbase.security.User;
import org.apache.hadoop.hbase.util.FSUtils;
import org.apache.hadoop.hbase.util.FutureUtils;
import org.apache.hadoop.hbase.util.MunkresAssignment;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.hbase.thirdparty.com.google.common.io.Closeables;
import org.apache.hbase.thirdparty.org.apache.commons.cli.CommandLine;
import org.apache.hbase.thirdparty.org.apache.commons.cli.GnuParser;
import org.apache.hbase.thirdparty.org.apache.commons.cli.HelpFormatter;
import org.apache.hbase.thirdparty.org.apache.commons.cli.Options;
import org.apache.hbase.thirdparty.org.apache.commons.cli.ParseException;

import org.apache.hadoop.hbase.shaded.protobuf.RequestConverter;
import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.UpdateFavoredNodesRequest;
import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.UpdateFavoredNodesResponse;

/**
 * A tool that is used for manipulating and viewing favored nodes information for regions. Run with
 * -h to get a list of the options
 */
@InterfaceAudience.Private
// TODO: Remove? Unused. Partially implemented only.
public class RegionPlacementMaintainer implements Closeable {
  private static final Logger LOG =
    LoggerFactory.getLogger(RegionPlacementMaintainer.class.getName());
  // The cost of a placement that should never be assigned.
  private static final float MAX_COST = Float.POSITIVE_INFINITY;

  // The cost of a placement that is undesirable but acceptable.
  private static final float AVOID_COST = 100000f;

  // The amount by which the cost of a placement is increased if it is the
  // last slot of the server. This is done to more evenly distribute the slop
  // amongst servers.
  private static final float LAST_SLOT_COST_PENALTY = 0.5f;

  // The amount by which the cost of a primary placement is penalized if it is
  // not the host currently serving the region. This is done to minimize moves.
  private static final float NOT_CURRENT_HOST_PENALTY = 0.1f;

  private static boolean USE_MUNKRES_FOR_PLACING_SECONDARY_AND_TERTIARY = false;

  private Configuration conf;
  private final boolean enforceLocality;
  private final boolean enforceMinAssignmentMove;
  private RackManager rackManager;
  private Set<TableName> targetTableSet;
  private AsyncClusterConnection connection;

  public RegionPlacementMaintainer(Configuration conf) throws IOException {
    this(conf, true, true);
  }

  public RegionPlacementMaintainer(Configuration conf, boolean enforceLocality,
    boolean enforceMinAssignmentMove) {
    this.conf = conf;
    this.enforceLocality = enforceLocality;
    this.enforceMinAssignmentMove = enforceMinAssignmentMove;
    this.targetTableSet = new HashSet<>();
    this.rackManager = new RackManager(conf);
  }

  private static void printHelp(Options opt) {
    new HelpFormatter().printHelp(
      "RegionPlacement < -w | -u | -n | -v | -t | -h | -overwrite -r regionName -f favoredNodes "
        + "-diff>" + " [-l false] [-m false] [-d] [-tables t1,t2,...tn] [-zk zk1,zk2,zk3]"
        + " [-fs hdfs://a.b.c.d:9000] [-hbase_root /HBASE]",
      opt);
  }

  private AsyncClusterConnection getConnection() throws IOException {
    if (connection == null) {
      connection =
        ClusterConnectionFactory.createAsyncClusterConnection(this.conf, null, User.getCurrent());
    }
    return connection;
  }

  public void setTargetTableName(String[] tableNames) {
    if (tableNames != null) {
      for (String table : tableNames)
        this.targetTableSet.add(TableName.valueOf(table));
    }
  }

  /** Returns the new RegionAssignmentSnapshot */
  public SnapshotOfRegionAssignmentFromMeta getRegionAssignmentSnapshot() throws IOException {
    SnapshotOfRegionAssignmentFromMeta currentAssignmentShapshot =
      new SnapshotOfRegionAssignmentFromMeta(ConnectionFactory.createConnection(conf));
    currentAssignmentShapshot.initialize();
    return currentAssignmentShapshot;
  }

  /**
   * Verify the region placement is consistent with the assignment plan
   */
  public List<AssignmentVerificationReport> verifyRegionPlacement(boolean isDetailMode)
    throws IOException {
    System.out
      .println("Start to verify the region assignment and " + "generate the verification report");
    // Get the region assignment snapshot
    SnapshotOfRegionAssignmentFromMeta snapshot = this.getRegionAssignmentSnapshot();

    // Get all the tables
    Set<TableName> tables = snapshot.getTableSet();

    // Get the region locality map
    Map<String, Map<String, Float>> regionLocalityMap = null;
    if (this.enforceLocality == true) {
      regionLocalityMap = FSUtils.getRegionDegreeLocalityMappingFromFS(conf);
    }
    List<AssignmentVerificationReport> reports = new ArrayList<>();
    // Iterate all the tables to fill up the verification report
    for (TableName table : tables) {
      if (!this.targetTableSet.isEmpty() && !this.targetTableSet.contains(table)) {
        continue;
      }
      AssignmentVerificationReport report = new AssignmentVerificationReport();
      report.fillUp(table, snapshot, regionLocalityMap);
      report.print(isDetailMode);
      reports.add(report);
    }
    return reports;
  }

  /**
   * Generate the assignment plan for the existing table
   * @param munkresForSecondaryAndTertiary if set on true the assignment plan for the tertiary and
   *                                       secondary will be generated with Munkres algorithm,
   *                                       otherwise will be generated using
   *                                       placeSecondaryAndTertiaryRS
   */
  private void genAssignmentPlan(TableName tableName,
    SnapshotOfRegionAssignmentFromMeta assignmentSnapshot,
    Map<String, Map<String, Float>> regionLocalityMap, FavoredNodesPlan plan,
    boolean munkresForSecondaryAndTertiary) throws IOException {
    // Get the all the regions for the current table
    List<RegionInfo> regions = assignmentSnapshot.getTableToRegionMap().get(tableName);
    int numRegions = regions.size();

    // Get the current assignment map
    Map<RegionInfo, ServerName> currentAssignmentMap =
      assignmentSnapshot.getRegionToRegionServerMap();

    // Get the all the region servers
    List<ServerName> servers = new ArrayList<>();
    servers.addAll(FutureUtils.get(getConnection().getAdmin().getRegionServers()));

    LOG.info("Start to generate assignment plan for " + numRegions + " regions from table "
      + tableName + " with " + servers.size() + " region servers");

    int slotsPerServer = (int) Math.ceil((float) numRegions / servers.size());
    int regionSlots = slotsPerServer * servers.size();

    // Compute the primary, secondary and tertiary costs for each region/server
    // pair. These costs are based only on node locality and rack locality, and
    // will be modified later.
    float[][] primaryCost = new float[numRegions][regionSlots];
    float[][] secondaryCost = new float[numRegions][regionSlots];
    float[][] tertiaryCost = new float[numRegions][regionSlots];

    if (this.enforceLocality && regionLocalityMap != null) {
      // Transform the locality mapping into a 2D array, assuming that any
      // unspecified locality value is 0.
      float[][] localityPerServer = new float[numRegions][regionSlots];
      for (int i = 0; i < numRegions; i++) {
        Map<String, Float> serverLocalityMap =
          regionLocalityMap.get(regions.get(i).getEncodedName());
        if (serverLocalityMap == null) {
          continue;
        }
        for (int j = 0; j < servers.size(); j++) {
          String serverName = servers.get(j).getHostname();
          if (serverName == null) {
            continue;
          }
          Float locality = serverLocalityMap.get(serverName);
          if (locality == null) {
            continue;
          }
          for (int k = 0; k < slotsPerServer; k++) {
            // If we can't find the locality of a region to a server, which occurs
            // because locality is only reported for servers which have some
            // blocks of a region local, then the locality for that pair is 0.
            localityPerServer[i][j * slotsPerServer + k] = locality.floatValue();
          }
        }
      }

      // Compute the total rack locality for each region in each rack. The total
      // rack locality is the sum of the localities of a region on all servers in
      // a rack.
      Map<String, Map<RegionInfo, Float>> rackRegionLocality = new HashMap<>();
      for (int i = 0; i < numRegions; i++) {
        RegionInfo region = regions.get(i);
        for (int j = 0; j < regionSlots; j += slotsPerServer) {
          String rack = rackManager.getRack(servers.get(j / slotsPerServer));
          Map<RegionInfo, Float> rackLocality = rackRegionLocality.get(rack);
          if (rackLocality == null) {
            rackLocality = new HashMap<>();
            rackRegionLocality.put(rack, rackLocality);
          }
          Float localityObj = rackLocality.get(region);
          float locality = localityObj == null ? 0 : localityObj.floatValue();
          locality += localityPerServer[i][j];
          rackLocality.put(region, locality);
        }
      }
      for (int i = 0; i < numRegions; i++) {
        for (int j = 0; j < regionSlots; j++) {
          String rack = rackManager.getRack(servers.get(j / slotsPerServer));
          Float totalRackLocalityObj = rackRegionLocality.get(rack).get(regions.get(i));
          float totalRackLocality =
            totalRackLocalityObj == null ? 0 : totalRackLocalityObj.floatValue();

          // Primary cost aims to favor servers with high node locality and low
          // rack locality, so that secondaries and tertiaries can be chosen for
          // nodes with high rack locality. This might give primaries with
          // slightly less locality at first compared to a cost which only
          // considers the node locality, but should be better in the long run.
          primaryCost[i][j] = 1 - (2 * localityPerServer[i][j] - totalRackLocality);

          // Secondary cost aims to favor servers with high node locality and high
          // rack locality since the tertiary will be chosen from the same rack as
          // the secondary. This could be negative, but that is okay.
          secondaryCost[i][j] = 2 - (localityPerServer[i][j] + totalRackLocality);

          // Tertiary cost is only concerned with the node locality. It will later
          // be restricted to only hosts on the same rack as the secondary.
          tertiaryCost[i][j] = 1 - localityPerServer[i][j];
        }
      }
    }

    if (this.enforceMinAssignmentMove && currentAssignmentMap != null) {
      // We want to minimize the number of regions which move as the result of a
      // new assignment. Therefore, slightly penalize any placement which is for
      // a host that is not currently serving the region.
      for (int i = 0; i < numRegions; i++) {
        for (int j = 0; j < servers.size(); j++) {
          ServerName currentAddress = currentAssignmentMap.get(regions.get(i));
          if (currentAddress != null && !currentAddress.equals(servers.get(j))) {
            for (int k = 0; k < slotsPerServer; k++) {
              primaryCost[i][j * slotsPerServer + k] += NOT_CURRENT_HOST_PENALTY;
            }
          }
        }
      }
    }

    // Artificially increase cost of last slot of each server to evenly
    // distribute the slop, otherwise there will be a few servers with too few
    // regions and many servers with the max number of regions.
    for (int i = 0; i < numRegions; i++) {
      for (int j = 0; j < regionSlots; j += slotsPerServer) {
        primaryCost[i][j] += LAST_SLOT_COST_PENALTY;
        secondaryCost[i][j] += LAST_SLOT_COST_PENALTY;
        tertiaryCost[i][j] += LAST_SLOT_COST_PENALTY;
      }
    }

    RandomizedMatrix randomizedMatrix = new RandomizedMatrix(numRegions, regionSlots);
    primaryCost = randomizedMatrix.transform(primaryCost);
    int[] primaryAssignment = new MunkresAssignment(primaryCost).solve();
    primaryAssignment = randomizedMatrix.invertIndices(primaryAssignment);

    // Modify the secondary and tertiary costs for each region/server pair to
    // prevent a region from being assigned to the same rack for both primary
    // and either one of secondary or tertiary.
    for (int i = 0; i < numRegions; i++) {
      int slot = primaryAssignment[i];
      String rack = rackManager.getRack(servers.get(slot / slotsPerServer));
      for (int k = 0; k < servers.size(); k++) {
        if (!rackManager.getRack(servers.get(k)).equals(rack)) {
          continue;
        }
        if (k == slot / slotsPerServer) {
          // Same node, do not place secondary or tertiary here ever.
          for (int m = 0; m < slotsPerServer; m++) {
            secondaryCost[i][k * slotsPerServer + m] = MAX_COST;
            tertiaryCost[i][k * slotsPerServer + m] = MAX_COST;
          }
        } else {
          // Same rack, do not place secondary or tertiary here if possible.
          for (int m = 0; m < slotsPerServer; m++) {
            secondaryCost[i][k * slotsPerServer + m] = AVOID_COST;
            tertiaryCost[i][k * slotsPerServer + m] = AVOID_COST;
          }
        }
      }
    }
    if (munkresForSecondaryAndTertiary) {
      randomizedMatrix = new RandomizedMatrix(numRegions, regionSlots);
      secondaryCost = randomizedMatrix.transform(secondaryCost);
      int[] secondaryAssignment = new MunkresAssignment(secondaryCost).solve();
      secondaryAssignment = randomizedMatrix.invertIndices(secondaryAssignment);

      // Modify the tertiary costs for each region/server pair to ensure that a
      // region is assigned to a tertiary server on the same rack as its secondary
      // server, but not the same server in that rack.
      for (int i = 0; i < numRegions; i++) {
        int slot = secondaryAssignment[i];
        String rack = rackManager.getRack(servers.get(slot / slotsPerServer));
        for (int k = 0; k < servers.size(); k++) {
          if (k == slot / slotsPerServer) {
            // Same node, do not place tertiary here ever.
            for (int m = 0; m < slotsPerServer; m++) {
              tertiaryCost[i][k * slotsPerServer + m] = MAX_COST;
            }
          } else {
            if (rackManager.getRack(servers.get(k)).equals(rack)) {
              continue;
            }
            // Different rack, do not place tertiary here if possible.
            for (int m = 0; m < slotsPerServer; m++) {
              tertiaryCost[i][k * slotsPerServer + m] = AVOID_COST;
            }
          }
        }
      }

      randomizedMatrix = new RandomizedMatrix(numRegions, regionSlots);
      tertiaryCost = randomizedMatrix.transform(tertiaryCost);
      int[] tertiaryAssignment = new MunkresAssignment(tertiaryCost).solve();
      tertiaryAssignment = randomizedMatrix.invertIndices(tertiaryAssignment);

      for (int i = 0; i < numRegions; i++) {
        List<ServerName> favoredServers =
          new ArrayList<>(FavoredNodeAssignmentHelper.FAVORED_NODES_NUM);
        ServerName s = servers.get(primaryAssignment[i] / slotsPerServer);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        s = servers.get(secondaryAssignment[i] / slotsPerServer);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        s = servers.get(tertiaryAssignment[i] / slotsPerServer);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));
        // Update the assignment plan
        plan.updateFavoredNodesMap(regions.get(i), favoredServers);
      }
      LOG.info("Generated the assignment plan for " + numRegions + " regions from table "
        + tableName + " with " + servers.size() + " region servers");
      LOG.info("Assignment plan for secondary and tertiary generated " + "using MunkresAssignment");
    } else {
      Map<RegionInfo, ServerName> primaryRSMap = new HashMap<>();
      for (int i = 0; i < numRegions; i++) {
        primaryRSMap.put(regions.get(i), servers.get(primaryAssignment[i] / slotsPerServer));
      }
      FavoredNodeAssignmentHelper favoredNodeHelper =
        new FavoredNodeAssignmentHelper(servers, conf);
      favoredNodeHelper.initialize();
      Map<RegionInfo, ServerName[]> secondaryAndTertiaryMap =
        favoredNodeHelper.placeSecondaryAndTertiaryWithRestrictions(primaryRSMap);
      for (int i = 0; i < numRegions; i++) {
        List<ServerName> favoredServers =
          new ArrayList<>(FavoredNodeAssignmentHelper.FAVORED_NODES_NUM);
        RegionInfo currentRegion = regions.get(i);
        ServerName s = primaryRSMap.get(currentRegion);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        ServerName[] secondaryAndTertiary = secondaryAndTertiaryMap.get(currentRegion);
        s = secondaryAndTertiary[0];
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        s = secondaryAndTertiary[1];
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));
        // Update the assignment plan
        plan.updateFavoredNodesMap(regions.get(i), favoredServers);
      }
      LOG.info("Generated the assignment plan for " + numRegions + " regions from table "
        + tableName + " with " + servers.size() + " region servers");
      LOG.info("Assignment plan for secondary and tertiary generated "
        + "using placeSecondaryAndTertiaryWithRestrictions method");
    }
  }

  public FavoredNodesPlan getNewAssignmentPlan() throws IOException {
    // Get the current region assignment snapshot by scanning from the META
    SnapshotOfRegionAssignmentFromMeta assignmentSnapshot = this.getRegionAssignmentSnapshot();

    // Get the region locality map
    Map<String, Map<String, Float>> regionLocalityMap = null;
    if (this.enforceLocality) {
      regionLocalityMap = FSUtils.getRegionDegreeLocalityMappingFromFS(conf);
    }
    // Initialize the assignment plan
    FavoredNodesPlan plan = new FavoredNodesPlan();

    // Get the table to region mapping
    Map<TableName, List<RegionInfo>> tableToRegionMap = assignmentSnapshot.getTableToRegionMap();
    LOG.info("Start to generate the new assignment plan for the "
      + +tableToRegionMap.keySet().size() + " tables");
    for (TableName table : tableToRegionMap.keySet()) {
      try {
        if (!this.targetTableSet.isEmpty() && !this.targetTableSet.contains(table)) {
          continue;
        }
        // TODO: maybe run the placement in parallel for each table
        genAssignmentPlan(table, assignmentSnapshot, regionLocalityMap, plan,
          USE_MUNKRES_FOR_PLACING_SECONDARY_AND_TERTIARY);
      } catch (Exception e) {
        LOG.error("Get some exceptions for placing primary region server" + "for table " + table
          + " because " + e);
      }
    }
    LOG.info("Finish to generate the new assignment plan for the "
      + +tableToRegionMap.keySet().size() + " tables");
    return plan;
  }

  @Override
  public void close() throws IOException {
    Closeables.close(connection, true);
  }

  /**
   * Some algorithms for solving the assignment problem may traverse workers or jobs in linear order
   * which may result in skewing the assignments of the first jobs in the matrix toward the last
   * workers in the matrix if the costs are uniform. To avoid this kind of clumping, we can
   * randomize the rows and columns of the cost matrix in a reversible way, such that the solution
   * to the assignment problem can be interpreted in terms of the original untransformed cost
   * matrix. Rows and columns are transformed independently such that the elements contained in any
   * row of the input matrix are the same as the elements in the corresponding output matrix, and
   * each row has its elements transformed in the same way. Similarly for columns.
   */
  protected static class RandomizedMatrix {
    private final int rows;
    private final int cols;
    private final int[] rowTransform;
    private final int[] rowInverse;
    private final int[] colTransform;
    private final int[] colInverse;

    /**
     * Create a randomization scheme for a matrix of a given size.
     * @param rows the number of rows in the matrix
     * @param cols the number of columns in the matrix
     */
    public RandomizedMatrix(int rows, int cols) {
      this.rows = rows;
      this.cols = cols;
      Random random = ThreadLocalRandom.current();
      rowTransform = new int[rows];
      rowInverse = new int[rows];
      for (int i = 0; i < rows; i++) {
        rowTransform[i] = i;
      }
      // Shuffle the row indices.
      for (int i = rows - 1; i >= 0; i--) {
        int r = random.nextInt(i + 1);
        int temp = rowTransform[r];
        rowTransform[r] = rowTransform[i];
        rowTransform[i] = temp;
      }
      // Generate the inverse row indices.
      for (int i = 0; i < rows; i++) {
        rowInverse[rowTransform[i]] = i;
      }

      colTransform = new int[cols];
      colInverse = new int[cols];
      for (int i = 0; i < cols; i++) {
        colTransform[i] = i;
      }
      // Shuffle the column indices.
      for (int i = cols - 1; i >= 0; i--) {
        int r = random.nextInt(i + 1);
        int temp = colTransform[r];
        colTransform[r] = colTransform[i];
        colTransform[i] = temp;
      }
      // Generate the inverse column indices.
      for (int i = 0; i < cols; i++) {
        colInverse[colTransform[i]] = i;
      }
    }

    /**
     * Copy a given matrix into a new matrix, transforming each row index and each column index
     * according to the randomization scheme that was created at construction time.
     * @param matrix the cost matrix to transform
     * @return a new matrix with row and column indices transformed
     */
    public float[][] transform(float[][] matrix) {
      float[][] result = new float[rows][cols];
      for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
          result[rowTransform[i]][colTransform[j]] = matrix[i][j];
        }
      }
      return result;
    }

    /**
     * Copy a given matrix into a new matrix, transforming each row index and each column index
     * according to the inverse of the randomization scheme that was created at construction time.
     * @param matrix the cost matrix to be inverted
     * @return a new matrix with row and column indices inverted
     */
    public float[][] invert(float[][] matrix) {
      float[][] result = new float[rows][cols];
      for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
          result[rowInverse[i]][colInverse[j]] = matrix[i][j];
        }
      }
      return result;
    }

    /**
     * Given an array where each element {@code indices[i]} represents the randomized column index
     * corresponding to randomized row index {@code i}, create a new array with the corresponding
     * inverted indices.
     * @param indices an array of transformed indices to be inverted
     * @return an array of inverted indices
     */
    public int[] invertIndices(int[] indices) {
      int[] result = new int[indices.length];
      for (int i = 0; i < indices.length; i++) {
        result[rowInverse[i]] = colInverse[indices[i]];
      }
      return result;
    }
  }

  /**
   * Print the assignment plan to the system output stream
   */
  public static void printAssignmentPlan(FavoredNodesPlan plan) {
    if (plan == null) return;
    LOG.info("========== Start to print the assignment plan ================");
    // sort the map based on region info
    Map<String, List<ServerName>> assignmentMap = new TreeMap<>(plan.getAssignmentMap());

    for (Map.Entry<String, List<ServerName>> entry : assignmentMap.entrySet()) {

      String serverList = FavoredNodeAssignmentHelper.getFavoredNodesAsString(entry.getValue());
      String regionName = entry.getKey();
      LOG.info("Region: " + regionName);
      LOG.info("Its favored nodes: " + serverList);
    }
    LOG.info("========== Finish to print the assignment plan ================");
  }

  /**
   * Update the assignment plan into hbase:meta
   * @param plan the assignments plan to be updated into hbase:meta
   * @throws IOException if cannot update assignment plan in hbase:meta
   */
  public void updateAssignmentPlanToMeta(FavoredNodesPlan plan) throws IOException {
    try {
      LOG.info("Start to update the hbase:meta with the new assignment plan");
      Map<String, List<ServerName>> assignmentMap = plan.getAssignmentMap();
      Map<RegionInfo, List<ServerName>> planToUpdate = new HashMap<>(assignmentMap.size());
      Map<String, RegionInfo> regionToRegionInfoMap =
        getRegionAssignmentSnapshot().getRegionNameToRegionInfoMap();
      for (Map.Entry<String, List<ServerName>> entry : assignmentMap.entrySet()) {
        planToUpdate.put(regionToRegionInfoMap.get(entry.getKey()), entry.getValue());
      }

      FavoredNodeAssignmentHelper.updateMetaWithFavoredNodesInfo(planToUpdate, conf);
      LOG.info("Updated the hbase:meta with the new assignment plan");
    } catch (Exception e) {
      LOG.error(
        "Failed to update hbase:meta with the new assignment" + "plan because " + e.getMessage());
    }
  }

  /**
   * Update the assignment plan to all the region servers
   */
  private void updateAssignmentPlanToRegionServers(FavoredNodesPlan plan) throws IOException {
    LOG.info("Start to update the region servers with the new assignment plan");
    // Get the region to region server map
    Map<ServerName, List<RegionInfo>> currentAssignment =
      this.getRegionAssignmentSnapshot().getRegionServerToRegionMap();

    // track of the failed and succeeded updates
    int succeededNum = 0;
    Map<ServerName, Exception> failedUpdateMap = new HashMap<>();

    for (Map.Entry<ServerName, List<RegionInfo>> entry : currentAssignment.entrySet()) {
      List<Pair<RegionInfo, List<ServerName>>> regionUpdateInfos = new ArrayList<>();
      try {
        // Keep track of the favored updates for the current region server
        FavoredNodesPlan singleServerPlan = null;
        // Find out all the updates for the current region server
        for (RegionInfo region : entry.getValue()) {
          List<ServerName> favoredServerList = plan.getFavoredNodes(region);
          if (
            favoredServerList != null
              && favoredServerList.size() == FavoredNodeAssignmentHelper.FAVORED_NODES_NUM
          ) {
            // Create the single server plan if necessary
            if (singleServerPlan == null) {
              singleServerPlan = new FavoredNodesPlan();
            }
            // Update the single server update
            singleServerPlan.updateFavoredNodesMap(region, favoredServerList);
            regionUpdateInfos.add(new Pair<>(region, favoredServerList));
          }
        }
        if (singleServerPlan != null) {
          // Update the current region server with its updated favored nodes
          AsyncRegionServerAdmin rsAdmin = getConnection().getRegionServerAdmin(entry.getKey());
          UpdateFavoredNodesRequest request =
            RequestConverter.buildUpdateFavoredNodesRequest(regionUpdateInfos);
          UpdateFavoredNodesResponse updateFavoredNodesResponse =
            FutureUtils.get(rsAdmin.updateFavoredNodes(request));
          LOG.info("Region server "
            + FutureUtils.get(rsAdmin.getServerInfo(RequestConverter.buildGetServerInfoRequest()))
              .getServerInfo()
            + " has updated " + updateFavoredNodesResponse.getResponse() + " / "
            + singleServerPlan.size() + " regions with the assignment plan");
          succeededNum++;
        }
      } catch (Exception e) {
        failedUpdateMap.put(entry.getKey(), e);
      }
    }
    // log the succeeded updates
    LOG.info("Updated " + succeededNum + " region servers with " + "the new assignment plan");

    // log the failed updates
    int failedNum = failedUpdateMap.size();
    if (failedNum != 0) {
      LOG.error("Failed to update the following + " + failedNum
        + " region servers with its corresponding favored nodes");
      for (Map.Entry<ServerName, Exception> entry : failedUpdateMap.entrySet()) {
        LOG.error("Failed to update " + entry.getKey().getAddress() + " because of "
          + entry.getValue().getMessage());
      }
    }
  }

  public void updateAssignmentPlan(FavoredNodesPlan plan) throws IOException {
    LOG.info("Start to update the new assignment plan for the hbase:meta table and"
      + " the region servers");
    // Update the new assignment plan to META
    updateAssignmentPlanToMeta(plan);
    // Update the new assignment plan to Region Servers
    updateAssignmentPlanToRegionServers(plan);
    LOG.info("Finish to update the new assignment plan for the hbase:meta table and"
      + " the region servers");
  }

  /**
   * Return how many regions will move per table since their primary RS will change
   * @param newPlan - new AssignmentPlan
   * @return how many primaries will move per table
   */
  public Map<TableName, Integer> getRegionsMovement(FavoredNodesPlan newPlan) throws IOException {
    Map<TableName, Integer> movesPerTable = new HashMap<>();
    SnapshotOfRegionAssignmentFromMeta snapshot = this.getRegionAssignmentSnapshot();
    Map<TableName, List<RegionInfo>> tableToRegions = snapshot.getTableToRegionMap();
    FavoredNodesPlan oldPlan = snapshot.getExistingAssignmentPlan();
    Set<TableName> tables = snapshot.getTableSet();
    for (TableName table : tables) {
      int movedPrimaries = 0;
      if (!this.targetTableSet.isEmpty() && !this.targetTableSet.contains(table)) {
        continue;
      }
      List<RegionInfo> regions = tableToRegions.get(table);
      for (RegionInfo region : regions) {
        List<ServerName> oldServers = oldPlan.getFavoredNodes(region);
        List<ServerName> newServers = newPlan.getFavoredNodes(region);
        if (oldServers != null && newServers != null) {
          ServerName oldPrimary = oldServers.get(0);
          ServerName newPrimary = newServers.get(0);
          if (oldPrimary.compareTo(newPrimary) != 0) {
            movedPrimaries++;
          }
        }
      }
      movesPerTable.put(table, movedPrimaries);
    }
    return movesPerTable;
  }

  /**
   * Compares two plans and check whether the locality dropped or increased (prints the information
   * as a string) also prints the baseline locality
   * @param movesPerTable     - how many primary regions will move per table
   * @param regionLocalityMap - locality map from FS
   * @param newPlan           - new assignment plan
   */
  public void checkDifferencesWithOldPlan(Map<TableName, Integer> movesPerTable,
    Map<String, Map<String, Float>> regionLocalityMap, FavoredNodesPlan newPlan)
    throws IOException {
    // localities for primary, secondary and tertiary
    SnapshotOfRegionAssignmentFromMeta snapshot = this.getRegionAssignmentSnapshot();
    FavoredNodesPlan oldPlan = snapshot.getExistingAssignmentPlan();
    Set<TableName> tables = snapshot.getTableSet();
    Map<TableName, List<RegionInfo>> tableToRegionsMap = snapshot.getTableToRegionMap();
    for (TableName table : tables) {
      float[] deltaLocality = new float[3];
      float[] locality = new float[3];
      if (!this.targetTableSet.isEmpty() && !this.targetTableSet.contains(table)) {
        continue;
      }
      List<RegionInfo> regions = tableToRegionsMap.get(table);
      System.out.println("==================================================");
      System.out.println("Assignment Plan Projection Report For Table: " + table);
      System.out.println("\t Total regions: " + regions.size());
      System.out.println(
        "\t" + movesPerTable.get(table) + " primaries will move due to their primary has changed");
      for (RegionInfo currentRegion : regions) {
        Map<String, Float> regionLocality = regionLocalityMap.get(currentRegion.getEncodedName());
        if (regionLocality == null) {
          continue;
        }
        List<ServerName> oldServers = oldPlan.getFavoredNodes(currentRegion);
        List<ServerName> newServers = newPlan.getFavoredNodes(currentRegion);
        if (newServers != null && oldServers != null) {
          int i = 0;
          for (FavoredNodesPlan.Position p : FavoredNodesPlan.Position.values()) {
            ServerName newServer = newServers.get(p.ordinal());
            ServerName oldServer = oldServers.get(p.ordinal());
            Float oldLocality = 0f;
            if (oldServers != null) {
              oldLocality = regionLocality.get(oldServer.getHostname());
              if (oldLocality == null) {
                oldLocality = 0f;
              }
              locality[i] += oldLocality;
            }
            Float newLocality = regionLocality.get(newServer.getHostname());
            if (newLocality == null) {
              newLocality = 0f;
            }
            deltaLocality[i] += newLocality - oldLocality;
            i++;
          }
        }
      }
      DecimalFormat df = new java.text.DecimalFormat("#.##");
      for (int i = 0; i < deltaLocality.length; i++) {
        System.out.print("\t\t Baseline locality for ");
        if (i == 0) {
          System.out.print("primary ");
        } else if (i == 1) {
          System.out.print("secondary ");
        } else if (i == 2) {
          System.out.print("tertiary ");
        }
        System.out.println(df.format(100 * locality[i] / regions.size()) + "%");
        System.out.print("\t\t Locality will change with the new plan: ");
        System.out.println(df.format(100 * deltaLocality[i] / regions.size()) + "%");
      }
      System.out.println("\t Baseline dispersion");
      printDispersionScores(table, snapshot, regions.size(), null, true);
      System.out.println("\t Projected dispersion");
      printDispersionScores(table, snapshot, regions.size(), newPlan, true);
    }
  }

  public void printDispersionScores(TableName table, SnapshotOfRegionAssignmentFromMeta snapshot,
    int numRegions, FavoredNodesPlan newPlan, boolean simplePrint) {
    if (!this.targetTableSet.isEmpty() && !this.targetTableSet.contains(table)) {
      return;
    }
    AssignmentVerificationReport report = new AssignmentVerificationReport();
    report.fillUpDispersion(table, snapshot, newPlan);
    List<Float> dispersion = report.getDispersionInformation();
    if (simplePrint) {
      DecimalFormat df = new java.text.DecimalFormat("#.##");
      System.out.println("\tAvg dispersion score: " + df.format(dispersion.get(0))
        + " hosts;\tMax dispersion score: " + df.format(dispersion.get(1))
        + " hosts;\tMin dispersion score: " + df.format(dispersion.get(2)) + " hosts;");
    } else {
      LOG.info("For Table: " + table + " ; #Total Regions: " + numRegions
        + " ; The average dispersion score is " + dispersion.get(0));
    }
  }

  public void printLocalityAndDispersionForCurrentPlan(
    Map<String, Map<String, Float>> regionLocalityMap) throws IOException {
    SnapshotOfRegionAssignmentFromMeta snapshot = this.getRegionAssignmentSnapshot();
    FavoredNodesPlan assignmentPlan = snapshot.getExistingAssignmentPlan();
    Set<TableName> tables = snapshot.getTableSet();
    Map<TableName, List<RegionInfo>> tableToRegionsMap = snapshot.getTableToRegionMap();
    for (TableName table : tables) {
      float[] locality = new float[3];
      if (!this.targetTableSet.isEmpty() && !this.targetTableSet.contains(table)) {
        continue;
      }
      List<RegionInfo> regions = tableToRegionsMap.get(table);
      for (RegionInfo currentRegion : regions) {
        Map<String, Float> regionLocality = regionLocalityMap.get(currentRegion.getEncodedName());
        if (regionLocality == null) {
          continue;
        }
        List<ServerName> servers = assignmentPlan.getFavoredNodes(currentRegion);
        if (servers != null) {
          int i = 0;
          for (FavoredNodesPlan.Position p : FavoredNodesPlan.Position.values()) {
            ServerName server = servers.get(p.ordinal());
            Float currentLocality = 0f;
            if (servers != null) {
              currentLocality = regionLocality.get(server.getHostname());
              if (currentLocality == null) {
                currentLocality = 0f;
              }
              locality[i] += currentLocality;
            }
            i++;
          }
        }
      }
      for (int i = 0; i < locality.length; i++) {
        String copy = null;
        if (i == 0) {
          copy = "primary";
        } else if (i == 1) {
          copy = "secondary";
        } else if (i == 2) {
          copy = "tertiary";
        }
        float avgLocality = 100 * locality[i] / regions.size();
        LOG.info("For Table: " + table + " ; #Total Regions: " + regions.size()
          + " ; The average locality for " + copy + " is " + avgLocality + " %");
      }
      printDispersionScores(table, snapshot, regions.size(), null, false);
    }
  }

  /**
   * @param favoredNodesStr The String of favored nodes
   * @return the list of ServerName for the byte array of favored nodes.
   */
  public static List<ServerName> getFavoredNodeList(String favoredNodesStr) {
    String[] favoredNodesArray = StringUtils.split(favoredNodesStr, ",");
    if (favoredNodesArray == null) return null;

    List<ServerName> serverList = new ArrayList<>();
    for (String hostNameAndPort : favoredNodesArray) {
      serverList.add(ServerName.valueOf(hostNameAndPort, ServerName.NON_STARTCODE));
    }
    return serverList;
  }

  public static void main(String args[]) throws IOException {
    Options opt = new Options();
    opt.addOption("w", "write", false, "write the assignments to hbase:meta only");
    opt.addOption("u", "update", false,
      "update the assignments to hbase:meta and RegionServers together");
    opt.addOption("n", "dry-run", false, "do not write assignments to META");
    opt.addOption("v", "verify", false, "verify current assignments against META");
    opt.addOption("p", "print", false, "print the current assignment plan in META");
    opt.addOption("h", "help", false, "print usage");
    opt.addOption("d", "verification-details", false, "print the details of verification report");

    opt.addOption("zk", true, "to set the zookeeper quorum");
    opt.addOption("fs", true, "to set HDFS");
    opt.addOption("hbase_root", true, "to set hbase_root directory");

    opt.addOption("overwrite", false, "overwrite the favored nodes for a single region,"
      + "for example: -update -r regionName -f server1:port,server2:port,server3:port");
    opt.addOption("r", true, "The region name that needs to be updated");
    opt.addOption("f", true, "The new favored nodes");

    opt.addOption("tables", true,
      "The list of table names splitted by ',' ;" + "For example: -tables: t1,t2,...,tn");
    opt.addOption("l", "locality", true, "enforce the maximum locality");
    opt.addOption("m", "min-move", true, "enforce minimum assignment move");
    opt.addOption("diff", false, "calculate difference between assignment plans");
    opt.addOption("munkres", false, "use munkres to place secondaries and tertiaries");
    opt.addOption("ld", "locality-dispersion", false,
      "print locality and dispersion " + "information for current plan");
    try {
      CommandLine cmd = new GnuParser().parse(opt, args);
      Configuration conf = HBaseConfiguration.create();

      boolean enforceMinAssignmentMove = true;
      boolean enforceLocality = true;
      boolean verificationDetails = false;

      // Read all the options
      if (
        (cmd.hasOption("l") && cmd.getOptionValue("l").equalsIgnoreCase("false"))
          || (cmd.hasOption("locality") && cmd.getOptionValue("locality").equalsIgnoreCase("false"))
      ) {
        enforceLocality = false;
      }

      if (
        (cmd.hasOption("m") && cmd.getOptionValue("m").equalsIgnoreCase("false"))
          || (cmd.hasOption("min-move") && cmd.getOptionValue("min-move").equalsIgnoreCase("false"))
      ) {
        enforceMinAssignmentMove = false;
      }

      if (cmd.hasOption("zk")) {
        conf.set(HConstants.ZOOKEEPER_QUORUM, cmd.getOptionValue("zk"));
        LOG.info("Setting the zk quorum: " + conf.get(HConstants.ZOOKEEPER_QUORUM));
      }

      if (cmd.hasOption("fs")) {
        conf.set(FileSystem.FS_DEFAULT_NAME_KEY, cmd.getOptionValue("fs"));
        LOG.info("Setting the HDFS: " + conf.get(FileSystem.FS_DEFAULT_NAME_KEY));
      }

      if (cmd.hasOption("hbase_root")) {
        conf.set(HConstants.HBASE_DIR, cmd.getOptionValue("hbase_root"));
        LOG.info("Setting the hbase root directory: " + conf.get(HConstants.HBASE_DIR));
      }

      // Create the region placement obj
      try (RegionPlacementMaintainer rp =
        new RegionPlacementMaintainer(conf, enforceLocality, enforceMinAssignmentMove)) {

        if (cmd.hasOption("d") || cmd.hasOption("verification-details")) {
          verificationDetails = true;
        }

        if (cmd.hasOption("tables")) {
          String tableNameListStr = cmd.getOptionValue("tables");
          String[] tableNames = StringUtils.split(tableNameListStr, ",");
          rp.setTargetTableName(tableNames);
        }

        if (cmd.hasOption("munkres")) {
          USE_MUNKRES_FOR_PLACING_SECONDARY_AND_TERTIARY = true;
        }

        // Read all the modes
        if (cmd.hasOption("v") || cmd.hasOption("verify")) {
          // Verify the region placement.
          rp.verifyRegionPlacement(verificationDetails);
        } else if (cmd.hasOption("n") || cmd.hasOption("dry-run")) {
          // Generate the assignment plan only without updating the hbase:meta and RS
          FavoredNodesPlan plan = rp.getNewAssignmentPlan();
          printAssignmentPlan(plan);
        } else if (cmd.hasOption("w") || cmd.hasOption("write")) {
          // Generate the new assignment plan
          FavoredNodesPlan plan = rp.getNewAssignmentPlan();
          // Print the new assignment plan
          printAssignmentPlan(plan);
          // Write the new assignment plan to META
          rp.updateAssignmentPlanToMeta(plan);
        } else if (cmd.hasOption("u") || cmd.hasOption("update")) {
          // Generate the new assignment plan
          FavoredNodesPlan plan = rp.getNewAssignmentPlan();
          // Print the new assignment plan
          printAssignmentPlan(plan);
          // Update the assignment to hbase:meta and Region Servers
          rp.updateAssignmentPlan(plan);
        } else if (cmd.hasOption("diff")) {
          FavoredNodesPlan newPlan = rp.getNewAssignmentPlan();
          Map<String, Map<String, Float>> locality =
            FSUtils.getRegionDegreeLocalityMappingFromFS(conf);
          Map<TableName, Integer> movesPerTable = rp.getRegionsMovement(newPlan);
          rp.checkDifferencesWithOldPlan(movesPerTable, locality, newPlan);
          System.out.println("Do you want to update the assignment plan? [y/n]");
          Scanner s = new Scanner(System.in);
          String input = s.nextLine().trim();
          if (input.equals("y")) {
            System.out.println("Updating assignment plan...");
            rp.updateAssignmentPlan(newPlan);
          }
          s.close();
        } else if (cmd.hasOption("ld")) {
          Map<String, Map<String, Float>> locality =
            FSUtils.getRegionDegreeLocalityMappingFromFS(conf);
          rp.printLocalityAndDispersionForCurrentPlan(locality);
        } else if (cmd.hasOption("p") || cmd.hasOption("print")) {
          FavoredNodesPlan plan = rp.getRegionAssignmentSnapshot().getExistingAssignmentPlan();
          printAssignmentPlan(plan);
        } else if (cmd.hasOption("overwrite")) {
          if (!cmd.hasOption("f") || !cmd.hasOption("r")) {
            throw new IllegalArgumentException("Please specify: "
              + " -update -r regionName -f server1:port,server2:port,server3:port");
          }

          String regionName = cmd.getOptionValue("r");
          String favoredNodesStr = cmd.getOptionValue("f");
          LOG.info("Going to update the region " + regionName + " with the new favored nodes "
            + favoredNodesStr);
          List<ServerName> favoredNodes = null;
          RegionInfo regionInfo =
            rp.getRegionAssignmentSnapshot().getRegionNameToRegionInfoMap().get(regionName);
          if (regionInfo == null) {
            LOG.error("Cannot find the region " + regionName + " from the META");
          } else {
            try {
              favoredNodes = getFavoredNodeList(favoredNodesStr);
            } catch (IllegalArgumentException e) {
              LOG.error("Cannot parse the invalid favored nodes because " + e);
            }
            FavoredNodesPlan newPlan = new FavoredNodesPlan();
            newPlan.updateFavoredNodesMap(regionInfo, favoredNodes);
            rp.updateAssignmentPlan(newPlan);
          }
        } else {
          printHelp(opt);
        }
      }
    } catch (ParseException e) {
      printHelp(opt);
    }
  }
}