code: function RedisStore (options) {
    options = options || {};
    this._host = options.host || '127.0.0.1';
    this._port = options.port || 6379;
    this._db = options.db || 0;
    this._prefix = options.prefix || '';
    this._pool = options.pool = (options.pool > 1 ? options.pool : 1);
  
    debug('create: host=%s, port=%s, db=%s, prefix=%s', this._host, this._port, this._db, this._prefix);
  
    // 兼容旧的redis模块配置
    options.password = options.password || options.auth_pass;
  
    this._clients = [];
    this._clientIndex = -1;
    for (var i = 0; i < options.pool; i++) {
      this._clients.push(new Redis(options));
    }
  
    return this;
  }
docs: RedisStore
  
  @param {Object} options
  - {String} host
  - {String} port
  - {String} prefix
  - {Number} db
  - {String} password
  - {Number} pool