ractor_rack.rb

require 'webrick'
# How much of this is solved by frozen string literal?
Ractor.make_shareable(WEBrick::Config::HTTP)
Ractor.make_shareable(WEBrick::LF)
Ractor.make_shareable(WEBrick::CRLF)
Ractor.make_shareable(WEBrick::HTTPRequest::BODY_CONTAINABLE_METHODS)
Ractor.make_shareable(WEBrick::HTTPStatus::StatusMessage)

# To pick up changes from https://github.com/ruby/ruby/pull/4007
Object.send(:remove_const, :URI)
require '/Users/kir/src/github.com/ruby/ruby/lib/uri.rb'

require 'rack'
# Make it frozen
Ractor.make_shareable(Rack::VERSION)

# https://github.com/ruby/ruby/pull/4008
Ractor.make_shareable(Time::RFC2822_DAY_NAME)
Ractor.make_shareable(Time::RFC2822_MONTH_NAME)

require 'uri'
Ractor.make_shareable(URI::RFC3986_PARSER)
Ractor.make_shareable(URI::DEFAULT_PARSER)

require 'stringio'

pipe = Ractor.new do
  loop do
    Ractor.yield(Ractor.recv, move: true)
  end
end

# has to be explicitly required from the main thread:
# https://bugs.ruby-lang.org/issues/17477
require 'pp'

def env_from_request(req)
  env = req.meta_vars
  env.delete_if { |k, v| v.nil? }

  rack_input = StringIO.new(req.body.to_s)
  rack_input.set_encoding(Encoding::BINARY)

  env.update(
    Rack::RACK_VERSION      => Rack::VERSION,
    Rack::RACK_INPUT        => rack_input,
    Rack::RACK_ERRORS       => $stderr,
    Rack::RACK_MULTITHREAD  => true,
    Rack::RACK_MULTIPROCESS => false,
    Rack::RACK_RUNONCE      => false,
    Rack::RACK_URL_SCHEME   => ["yes", "on", "1"].include?(env[Rack::HTTPS]) ? "https" : "http"
  )

  env[Rack::QUERY_STRING] ||= ""
  unless env[Rack::PATH_INFO] == ""
    path, n = req.request_uri.path, env[Rack::SCRIPT_NAME].length
    env[Rack::PATH_INFO] = path[n, path.length - n]
  end
  env[Rack::REQUEST_PATH] ||= [env[Rack::SCRIPT_NAME], env[Rack::PATH_INFO]].join
  env
end

CPU_COUNT = 4
workers = CPU_COUNT.times.map do
  Ractor.new(pipe) do |pipe|
    app = lambda do |e|
      [200, {'Content-Type' => 'text/html'}, ['hello world']]
    end

    loop do
      s = pipe.take

      req = WEBrick::HTTPRequest.new(WEBrick::Config::HTTP.merge(RequestTimeout: nil))
      req.parse(s)

      env = env_from_request(req)

      status, headers, body = app.call(env)

      resp = WEBrick::HTTPResponse.new(WEBrick::Config::HTTP)

      begin
        resp.status = status.to_i
        io_lambda = nil
        headers.each { |k, vs|
          if k.downcase == "set-cookie"
            resp.cookies.concat vs.split("\n")
          else
            # Since WEBrick won't accept repeated headers,
            # merge the values per RFC 1945 section 4.2.
            resp[k] = vs.split("\n").join(", ")
          end
        }

        body.each { |part|
          resp.body << part
        }
      ensure
        body.close  if body.respond_to? :close
      end

      pp env

      resp.send_response(s)
    end
  end
end

listener = Ractor.new(pipe) do |pipe|
  server = TCPServer.new(8080)
  loop do
    conn, _ = server.accept
    pipe.send(conn, move: true)
  end
end

loop do
  Ractor.select(listener, *workers)
  # if the line above returned, one of the workers or the listener has crashed
end