ruby_callback.rb

class Mutex

  def self.busy?
    @busy ||= false
  end

  def self.engage
    @busy = true
  end

  def self.free
    @busy = false
  end

end

# some worker with concurrency 1
def upload_to_s3(filename, &callback)
  t1 = Time.now
  # simulate sidekiq's perform_async
  Thread.new do
    puts "Double execution alert!!!!" if Mutex.busy?
    Mutex.engage
    puts "Uploading #{filename} to s3"
    sleep rand(1..3)
    callback.call filename, (Time.now - t1)
    Mutex.free
  end
end

upload_to_s3("song.mp3") do |filename, elapsed|
  puts "Uploading #{filename} to s3 took #{elapsed} seconds"
end

upload_to_s3("transcript.txt") do |filename, elapsed|
  puts "Uploading #{filename} to s3 took #{elapsed} seconds"
end

# worker with concurrency 1
class S3Uploader
  # include Sidekiq::Worker

  def self.perform(filename, bucket_name, &block)
    puts "Connecting to #{bucket_name} bucket"
    puts "Uploading #{filename} to #{bucket_name}"
    block.call filename, bucket_name
  end
end

S3Uploader.perform("song1.mp3", "songs") do |filename, bucket_name|
  puts "Done uploading #{filename} to #{bucket_name}"
end

# called from somewhere else
S3Uploader.perform("transcript123.srt", "transcripts") do |filename, bucket_name|
  puts "Done uploading #{filename} to #{bucket_name}"
end