optimistic lock implementation in mongodb

demo.js

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');

var ThingSchema = new mongoose.Schema({
  count: Number,
  version: Number,
});
var Thing = mongoose.model('Thing', ThingSchema);

var doAdd = function(id, retryTimes){
  if (retryTimes == undefined) retryTimes = 1;
  Thing.findById(id, function(err, thing){ 

    thing.count++;

    Thing.findOneAndUpdate({"_id": id, "version": thing.version}, 
      {$set: {count: thing.count}, $inc: {"version": 1}}, 
      function(err, data){
        if (!data) {
          console.log("retry times " + retryTimes);
          if (retryTimes == 1000) {console.log("exceed retry times, failed!"); return -1;}
          doAdd(id, ++retryTimes);
        }
      }
    );
  });
};

//test
var id = "53e890fbb9f46000001d8056";
doAdd(id);
doAdd(id);
doAdd(id);

:)