/**
   * PoolSelector
   */
  var PoolSelector = module.exports = {};
  
  PoolSelector.RR = function PoolSelectorRoundRobin() {
    var index = 0;
  
    return function(clusterIds) {
      if (index >= clusterIds.length) {
        index = 0;
      }
  
      var clusterId = clusterIds[index++];
  
      return clusterId;
    };
  };
  
  PoolSelector.RANDOM = function PoolSelectorRandom() {
    return function(clusterIds) {
      return clusterIds[Math.floor(Math.random() * clusterIds.length)];
    };
  };
  
  PoolSelector.ORDER = function PoolSelectorOrder() {
    return function(clusterIds) {
      return clusterIds[0];
    };
  };