Reload is not worked with roda. about zeitwerk

[zw963]

This is the best auto reload solution among the nearly ten solutions I tried, thank you!

To make it easier for other people to read or copy it, following is this awesome solution.

# config.ru
require 'roda'
require 'zeitwerk'

loader = Zeitwerk::Loader.new
# loader.logger = method(:puts)
loader.push_dir(__dir__)
loader.setup

if ENV['RACK_ENV'] == 'production'
  Zeitwerk::Loader.eager_load_all
  run App
else
  run ->(env) {
    loader.reload
    App.call(env)
  }
end

[fxn]

Followup (still on my phone). If you want to reload on each request, the reload call would go at the beginning of the request, something like (untested)

# config.ru
loader = Zeitwerk::Loader.new
loader.push_dir(__dir__)
loader.setup

run ->(env) {
  loader.reload
  App.call(env)
}

You have to remove then loader calls in the routes.

[fxn]

Probably negligible, but this alternative would be 👌 (untested):

if ENV['RACK_ENV'] == 'production'
  Zeitwerk::Loader.eager_load_all
  run App
else
  run ->(env) {
    loader.reload
    App.call(env)
  }
end

See? Since you know at boot which is the environment, you can fine tune exactly which application you want to run, the lambda wrapper, or App. Also, this gives you a natural place for eager loading.

[zw963]

Hi, the above idea was extract into a ruby gem since one years ago, with extra bonus: autoload automatically if some file was changed. Please check: https://github.com/zw963/hot_reloader.

A dead simple ruby code hot reloader wrap around zeitwerk and listen.

hope can help someone develop with Roda more easiler, anyway, we don't want missing autoload feature from rails anymore!

[fxn]

On my phone.

You don’t see the changes because Rack evaluated App in config.ru at boot and therefore it is using always the same class object.

For it to work, you need to add an indirection: It could be as easy as running a lambda run ->(env) { App.call(env) } (untested, off the top of my head).

Please let me know if that helps.

[zw963]

It worked now like a charm! Thanks.

[zw963]

Still have a question about performance.

for roda, we don't need hot reloader in production,
if we don't need eager_load too, for this case,
just comment loader.reload as this:

# config.ru
require 'roda'
require 'zeitwerk'

loader = Zeitwerk::Loader.new
loader.logger = method(:puts)
loader.push_dir(__dir__)
loader.setup

run ->(env) {
  loader.reload unless ENV['RACK_ENV'] == 'production'
  App.call(env)
}

is there have any performance penalty?

Thanks

[will]

Thanks, I also ran into this problem, and this issue helped me.

[will]

Actually, I ran into a problem where Zeitwerk was saying that a file didn't define a constant, even though it did, while using this as my config.ru with puma and Roda.

# frozen_string_literal: true

require_relative "config/environment" # not a rails app, but using the same conventions

if Config.allow_code_reloading?
  run ->(env) do
    RELOAD.call # this is defined in a zeitwerk initializer
    Web.call(env)
  end
else
  run Web.freeze.app
end

in the initializer

# ...
if Config.allow_code_reloading?
  loader.enable_reloading

  RELOAD = -> { loader.reload }
end

Using puma with a max of one thread -t 1:1 fixed the problem, and also wrapping the reload and call in a mutex also fixed it.

if Config.allow_code_reloading?
  mutex = Mutex.new
  run ->(env) do
    mutex.synchronize do
      RELOAD.call
      Web.call(env)
    end
  end
else
  run Web.freeze.app
end

which was confusing to me, because I was under the impression that Zeitwerk was thread safe. Maybe not on reloading?

[fxn]

Exactly:

Zeitwerk is also able to reload code, which may be handy while developing web applications. Coordination is needed to reload in a thread-safe manner. The documentation below explains how to do this.

See also https://github.com/fxn/zeitwerk#reloading.

[will]

Thanks! I swear I read through the readme a few times while putting this into my project, but must have had that part slip out of my memory :)

[fxn]

No prob, and great to know you're using the lib with Roda :).