Temporary workaround for Rails globbing performance issue https://github.com/rails/rails/issues/30502

path_resolver_dir_glob_cache.rb

# frozen_string_literal: true

# config/initializers/path_resolver_dir_glob_cache.rb
#
# Work around glob performance woes for JS requests in development, c.f
# https://github.com/rails/rails/issues/30502, by
# prepending ActionView::PathResolver#find_template_paths to use a
# result cache.  Cache invalidation via fs listeners.
# Use at your own peril.

hacks = Module.new do
  module_function
  def dir_name_from_query(query)
    File.dirname(query.gsub(/(?<!\\){.*/, ''))
  end

  GLOB_CACHE = Concurrent::Hash.new
  GLOB_CACHE_LISTENERS = Concurrent::Hash.new do |hash, dir|
    hash[dir] = Listen.to(dir) do
      GLOB_CACHE.delete_if do |cached_query, _|
        dir == dir_name_from_query(cached_query)
      end
    end
  end

  def find_template_paths(query)
    dirname = dir_name_from_query(query)
    return [] unless Dir.exist?(dirname)

    if GLOB_CACHE.has_key?(query)
      GLOB_CACHE[query]
    else
      GLOB_CACHE_LISTENERS[dirname].start
      GLOB_CACHE[query] = super
    end
  end
end

ActionView::PathResolver.prepend(hacks) if Rails.env.development?