gabegorelick / yarnl Goto Github PK

var AWS = require('aws-sdk');
var redis = require('redis');
var bluebird = require('bluebird');
var s3 = new AWS.S3();
var Lock = require('yarnl');
var request = require('request');

bluebird.promisifyAll(redis.RedisClient.prototype);
bluebird.promisifyAll(redis.Multi.prototype);

var client = redis.createClient({
  host: "localhost",
  port: 6379
});

module.exports = {
  getFromRedis: function(req, res) {
    client.getAsync('hash').then(function(data) {
      if(data) {
        console.log('fetch from cache');
        return res.send(data);
      } else {
        new Lock('url').lock(function (err, unlock) {
          if (err){
            throw err
          }

          if (!unlock) {
            console.log('first lock');
            return res.send('first lock');
          } else {
            console.log('fetch crawl');
            request('/fetch_data_from_db', function (err, response, body) {
              client.set('hash', body);
              unlock(function (err) {
                if(err) {
                  throw err
                }

                console.log('releasing lock');
                return res.send(body);
              });
            });
          }
        });
      }
    });
  }
}

fetch crawl
releasing lock
fetch from cache
fetch from cache
fetch from cache
fetch from cache
fetch crawl
releasing lock
fetch crawl
releasing lock
fetch crawl
releasing lock
...