Redis + Node PubSub vs. Task Publisher / Task Runner

pub.js

// PubSub example, check pub.js and sub.js
// This is the publising of messages
// Messages will only be seen by subscribers that are already listening
// Credits: https://thisdavej.com/guides/redis-node/node/pubsub.html

const Redis = require('ioredis')
const pub = new Redis()
const channel = 'mychannel:123'

console.log('Started publisher...')
let i = 0

setInterval(() => {
  i++
  pub.publish(channel, JSON.stringify({ iterator: i, message: 'Hi' }))
}, 1000)

sub.js

// PubSub example, check pub.js and sub.js
// This is the subscribing to messages
// Credits: https://thisdavej.com/guides/redis-node/node/pubsub.html

const Redis = require('ioredis')
const redis = new Redis()
const channel = 'garage:*'

// Use on('message'), (channel, message) for exact channel match,
// use on('pmessage'), (sub, channel, message) for wildcard channel match
redis.on('pmessage', (sub, channel, message) => {
  console.log(`Received the following message from ${sub}, ${channel}`, message);
})

const handler = (error, count) => {
  if (error) throw new Error(error)
  console.log(`Subscribed to ${count} channel. Listening for updates on the ${channel} channel.`)
}

// Use subscribe for a exact channel match subscription
// Use psubscribe for a wildcard subscription
redis.psubscribe(channel, handler)

// You can unsubscribe with:
//   redis.unsubscribe(channel)
// Or in case of a wildcard subscription:
//   redis.punsubscribe(channel)

task-pub.js

const Redis = require('ioredis')
const pub = new Redis()

let i = 0
setInterval(() => {
  i++
  pub.rpush('somequeue', 'jobdetails_' + i)
}, 1000)

// Get queue length: pub.llen('somequeue').then(...)
// Get queue item value: pub.lindex('somequeue', index || 0).then(...)

task-run.js

const Redis = require('ioredis')
const tasks = new Redis()

const getSomethingToDo = () => {
  // blplop = 'Blocking plop', so it will wait until
  // a message comes in. Don't setInterval this,
  // invoking one after processing the last job
  // is enough: it will trigger automatically
  // when a new job comes in.

  tasks.blpop('somequeue', 0).then(d => {
    console.log('somequeue item:', d)
    // Wait for the next message
    getSomethingToDo()
  })
}

getSomethingToDo()