My little script to download Ruby source files in parallel with Async

fetch.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'async'
require 'async/barrier'
require 'async/http/client'
require 'async/http/endpoint'
require 'async/logger'
require 'optionparser'

options = ARGV.options do |command|
  command.banner = "Usage: #{command.program_name} ruby_version"
  command.version = '0.0.1'
  command
end
options.freeze.permute!

ruby_version = ARGV.shift
raise ArgumentError, "missing argument: ruby_version\n#{options.banner}" unless ruby_version

host = 'https://cache.ruby-lang.org'
major, minor, *_rest = ruby_version.split('.')
dir = File.join('pub', 'ruby', "#{major}.#{minor}")
basename = "ruby-#{ruby_version}"
extensions = %w[tar.gz tar.xz zip].freeze

Async do
  endpoint = Async::HTTP::Endpoint.parse(host)
  client = Async::HTTP::Client.new(endpoint)
  barrier = Async::Barrier.new

  extensions.each do |extension|
    file = "#{basename}.#{extension}"
    path = File.join(dir, file)
    url = File.join(host, path)

    barrier.async do |task|
      Async.logger.info "Requesting #{url} ..."
      response = client.get(path)

      if response.success?
        bytes = response.body.length.digits.each_slice(3).map(&:join).join(',').reverse
        Async.logger.info "Downloading #{file}, #{bytes} bytes ..."
        response.save(file)

        Async.logger.info "Downloaded #{file}, #{bytes} bytes saved ..."
      else
        if response.valid?
          Async.logger.error "Downloading #{file} failed with a #{response.status} error status ..."
        else
          Async.logger.error "Downloading #{file} failed with invalid response ..."
        end

        task.stop
      end
    end
  end

  barrier.wait
ensure
  client&.close
end