“...I've been working since 2008 with Ruby / Ruby on Rails, love a bit of Elixir / Phoenix and learning Rust. I also poke through other people's code and make PRs for OpenSource Ruby projects that sometimes make it. Currently working for InPay...”

Rob Lacey
Senior Software Engineer, UK

Bunny Consumer

No, not something that eats bunnies. I wanted to know if I could easily run a RabbitMQ consumer that just sat there listening. It seems incorrect to have a loop sat there just doing nothing all the time but I guess it the connection is open then it should just sit there, if not it can stop and have forty winks.

Gemfile

source 'https://rubygems.org'

gem 'bunny'
gem 'pry'
gem 'pry-coolline'

gimmick.rb

require 'rubygems'
# ENV['BUNDLE_GEMFILE'] ||= File.expand_path('Gemfile', __dir__)
require 'bundler/setup'
Bundler.require(:default)

conn = Bunny.new
conn.start
# open a channel
ch = conn.create_channel

# declare a queue
q = ch.queue('test1')

q.subscribe do |_, _, payload|
  Thread.new do
    puts "payload #{payload}"
    sleep(5)
    puts "finished sleeping"
  end
end

while conn.status == :open do
  # nothing is happening here
end

As expected, when an event occurs the subscribe block is called and the payload is send to STDOUT. Wait five seconds and finish. Had I not added Thread.new consumer would have waited 5 seconds and order is not quaranteed.

Robs-iMac:consumer roblacey$ ruby gimmick.rb 
payload 2
payload 1
payload 4
payload 3
payload 5
finished sleeping
finished sleeping
finished sleeping
finished sleeping
finished sleeping

Interesting to note that when using manual_ack. Events are not automatically re-read from the queue until a new connection is made if the job is not ack’ed.

q.subscribe(manual_ack: true) do |delivery_info, _, payload|
  Thread.new do
    puts "payload #{payload} - Redelivered #{delivery_info.redelivered?}\n"
    sleep(5)
    puts "finished sleeping #{payload}\n"
    puts payload.class
    ch.acknowledge(delivery_info.delivery_tag, false) unless payload == '1' && !delivery_info.redelivered?
  end
end

while conn.status == :open do
  # nothing is happening here
end
GPK of the Day Mean GENE