cache database connection in module space about monk HOT 3 OPEN

var monk = require('monk');

function MongoConnector() {
  this.collections = {};
  this._queue = [];
  this.on('open', function (db) {
    this._queue.forEach(function (cb) {
      cb(db);
    });
  });
}

MongoConnector.prototype = Object.create(monk.prototype);
MongoConnector.prototype.executeWhenOpened = function() {
  switch (this._state) {
    case 'open':
      return Promise.resolve(this._db);
    case 'opening':
    case 'closed':
    default:
      return new Promise(resolve => {
        this._queue.push(resolve);
      });
  }
};

var connector = module.exports = new MongoConnector;

module.exports.connect = (uri, opts) => {
  return new Promise(resolve => {
    connector.open(uri, opts, resolve);
  });
};

module.exports.disconnect = (force) => {
  return new Promise(resolve => {
    connector.close(force, resolve);
  });
};

var connector = require('./path/to/connector/');
connector.connect('mongodb://localhost/mydb');

var connector = require('./path/to/connector/');
var collection = connector.get('mycollection');
collection.find({});