Function setLocalDc

lib/policies/load-balancing.js:843–870

* Validates and sets the local data center to be used. * @param {LoadBalancingPolicy} lbp * @param {Client} client * @param {HostMap} hosts * @private

(lbp, client, hosts)

 * @private
 */
function setLocalDc(lbp, client, hosts) {
  if (!(lbp instanceof LoadBalancingPolicy)) {
    throw new errors.DriverInternalError('LoadBalancingPolicy instance was not provided');
  }

  if (client && client.options) {
    if (lbp.localDc && !client.options.localDataCenter) {
      client.log('info', `Local data center '${lbp.localDc}' was provided as an argument to the load-balancing` +
        ` policy. It is preferable to specify the local data center using 'localDataCenter' in Client` +
        ` options instead when your application is targeting a single data center.`);
    }

    // If localDc is unset, use value set in client options.
    lbp.localDc = lbp.localDc || client.options.localDataCenter;
  }

  const dcs = getDataCenters(hosts);

  if (!lbp.localDc) {
    throw new errors.ArgumentError(
      `'localDataCenter' is not defined in Client options and also was not specified in constructor.` +
      ` At least one is required. Available DCs are: [${Array.from(dcs)}]`);
  }

  if (!dcs.has(lbp.localDc)) {
    throw new errors.ArgumentError(`Datacenter ${lbp.localDc} was not found. Available DCs are: [${Array.from(dcs)}]`);
  }
}

function getDataCenters(hosts) {
  return new Set(hosts.values().map(h => h.datacenter));