@Override
  public SettableFuture<ConfigTaskResult> dropSubscription(
      final DropSubscriptionStatement dropSubscriptionStatement) {
    final SettableFuture<ConfigTaskResult> future = SettableFuture.create();
    try (ConfigNodeClient configNodeClient =
        CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.CONFIG_REGION_ID)) {
      final TSStatus tsStatus =
          configNodeClient.dropSubscriptionById(
              new TDropSubscriptionReq()
                  .setSubsciptionId(dropSubscriptionStatement.getSubscriptionId())
                  .setIfExistsCondition(dropSubscriptionStatement.hasIfExistsCondition())
                  .setIsTableModel(dropSubscriptionStatement.isTableModel()));
      if (TSStatusCode.SUCCESS_STATUS.getStatusCode() != tsStatus.getCode()) {
        future.setException(new IoTDBException(tsStatus.message, tsStatus.code));
      } else {
        future.set(new ConfigTaskResult(TSStatusCode.SUCCESS_STATUS));
      }
    } catch (Exception e) {
      future.setException(e);
    }
    return future;
  }
FIXME Consolidate this clientManager with the upper one.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/executor/ClusterConfigTaskExecutor.java