private void addRegion(RegionInfo regionInfo) {
    // Process the region name to region info map
    regionNameToRegionInfoMap.put(regionInfo.getRegionNameAsString(), regionInfo);

    // Process the table to region map
    TableName tableName = regionInfo.getTable();
    List<RegionInfo> regionList = tableToRegionMap.get(tableName);
    if (regionList == null) {
      regionList = new ArrayList<>();
    }
    // Add the current region info into the tableToRegionMap
    regionList.add(regionInfo);
    tableToRegionMap.put(tableName, regionList);
  }
Initialize the region assignment snapshot by scanning the hbase:meta table
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/SnapshotOfRegionAssignmentFromMeta.java