private void refreshEndpointMap() {
   String keyspace = ConfigHelper.getOutputKeyspace(conf);
   try (Session session =
       CqlConfigHelper.getOutputCluster(ConfigHelper.getOutputInitialAddress(conf), conf)
           .connect(keyspace)) {
     rangeMap = new HashMap<>();
     metadata = session.getCluster().getMetadata();
     Set<TokenRange> ranges = metadata.getTokenRanges();
     for (TokenRange range : ranges) {
       rangeMap.put(range, metadata.getReplicas(keyspace, range));
     }
   }
 }
  CqlRecordWriter(Configuration conf) {
    this.conf = conf;
    this.queueSize =
        conf.getInt(ColumnFamilyOutputFormat.QUEUE_SIZE, 32 * FBUtilities.getAvailableProcessors());
    batchThreshold = conf.getLong(ColumnFamilyOutputFormat.BATCH_THRESHOLD, 32);
    this.clients = new HashMap<>();

    try {
      String keyspace = ConfigHelper.getOutputKeyspace(conf);
      try (Session client =
          CqlConfigHelper.getOutputCluster(ConfigHelper.getOutputInitialAddress(conf), conf)
              .connect(keyspace)) {
        ringCache = new NativeRingCache(conf);
        if (client != null) {
          TableMetadata tableMetadata =
              client
                  .getCluster()
                  .getMetadata()
                  .getKeyspace(client.getLoggedKeyspace())
                  .getTable(ConfigHelper.getOutputColumnFamily(conf));
          clusterColumns = tableMetadata.getClusteringColumns();
          partitionKeyColumns = tableMetadata.getPartitionKey();

          String cqlQuery = CqlConfigHelper.getOutputCql(conf).trim();
          if (cqlQuery.toLowerCase().startsWith("insert"))
            throw new UnsupportedOperationException(
                "INSERT with CqlRecordWriter is not supported, please use UPDATE/DELETE statement");
          cql = appendKeyWhereClauses(cqlQuery);
        } else {
          throw new IllegalArgumentException("Invalid configuration specified " + conf);
        }
      }
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
    /** Loops collecting cql binded variable values from the queue and sending to Cassandra */
    public void run() {
      outer:
      while (run || !queue.isEmpty()) {
        List<ByteBuffer> bindVariables;
        try {
          bindVariables = queue.take();
        } catch (InterruptedException e) {
          // re-check loop condition after interrupt
          continue;
        }

        ListIterator<InetAddress> iter = endpoints.listIterator();
        while (true) {
          // send the mutation to the last-used endpoint.  first time through, this will NPE
          // harmlessly.
          try {
            int i = 0;
            PreparedStatement statement = preparedStatement(client);
            while (bindVariables != null) {
              BoundStatement boundStatement = new BoundStatement(statement);
              for (int columnPosition = 0;
                  columnPosition < bindVariables.size();
                  columnPosition++) {
                boundStatement.setBytesUnsafe(columnPosition, bindVariables.get(columnPosition));
              }
              client.execute(boundStatement);
              i++;

              if (i >= batchThreshold) break;
              bindVariables = queue.poll();
            }
            break;
          } catch (Exception e) {
            closeInternal();
            if (!iter.hasNext()) {
              lastException = new IOException(e);
              break outer;
            }
          }

          // attempt to connect to a different endpoint
          try {
            InetAddress address = iter.next();
            String host = address.getHostName();
            client = CqlConfigHelper.getOutputCluster(host, conf).connect();
          } catch (Exception e) {
            // If connection died due to Interrupt, just try connecting to the endpoint again.
            // There are too many ways for the Thread.interrupted() state to be cleared, so
            // we can't rely on that here. Until the java driver gives us a better way of knowing
            // that this exception came from an InterruptedException, this is the best solution.
            if (canRetryDriverConnection(e)) {
              iter.previous();
            }
            closeInternal();

            // Most exceptions mean something unexpected went wrong to that endpoint, so
            // we should try again to another.  Other exceptions (auth or invalid request) are
            // fatal.
            if ((e instanceof AuthenticationException || e instanceof InvalidQueryException)
                || !iter.hasNext()) {
              lastException = new IOException(e);
              break outer;
            }
          }
        }
      }
      // close all our connections once we are done.
      closeInternal();
    }