[Ruby] roughly split & save the downloaded file.

chunked_download.rb

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

# roughly split & save the downloaded file.

class Main
  require 'uri'
  require 'net/http'
  require 'fileutils'
  require 'thwait'

  FILE_URI = 'http://archive.apache.org/dist/httpd/httpd-2.4.43.tar.bz2'

  def initialize
    @dir = './chunked_data'

    FileUtils.rm_rf   @dir
    FileUtils.mkdir_p @dir

    @size_limit = 2 * 1024 ** 2

    @uri = URI.parse(FILE_URI)
  end

  def run
    http = Net::HTTP.new(@uri.host)
    http.read_timeout = 5

    pos = 1
    chunk = ''

    threads = []
    http.request_get(@uri.path) do |response|
      response.read_body do |data|
        chunk += data

        # split & save content (async)
        if chunk.size > @size_limit
          threads << Thread.new(pos, chunk) do |p, c|
            save_content p, c
          end

          chunk = ''
          pos += 1
        end
      end
    end

    # save the remnant (sync)
    if chunk.size.positive?
      save_content pos, chunk
    else
      pos -= 1
    end

    # wait all threads done
    ThreadsWait.new(*threads)

    puts '=> total %d files saved' % pos
  end

  private

  def save_content(pos, chunk)
    sleep 2

    File.open file(pos), 'wb' do |f|
      f.write chunk
    end

    puts 'file %d saved (%d)' % [pos, chunk.size]
  end

  def file(pos)
    File.join(@dir, '%02d.bin' % pos)
  end
end

Main.new.run