README.textile

The Problem

app = Rack::Builder.new do
  use Rack::CommonLogger
  use Rack::Reloader # this is the interesting part
  use Rack::ShowExceptions
  run HelloWorld.new
end

For some reason, the Reloader script’s timestamp keeps getting updated each and every request. WTF? It’s as if the Reloader class kept getting reinitialized every single request.

The Solution

It was.

app = Rack::Builder.new do
  use Rack::CommonLogger
  use Rack::Reloader # this is the interesting part
  use Rack::ShowExceptions
  run HelloWorld.new
end.to_app

The call to to_app call wraps it up and prevents the classes from being reinitialized over and over.

Hmmm.

hellotest.rb

require 'reloader'
require 'helloworld'

app = Rack::Builder.new do
  use Rack::CommonLogger
  use Rack::Reloader
  use Rack::ShowExceptions
  run HelloWorld.new
end.to_app

Rack::Handler::Thin.run app, :Port => 4000

hellotest.ru

require 'reloader'
require 'helloworld'

use Rack::CommonLogger
use Rack::Reloader
use Rack::ShowExceptions
run HelloWorld.new

helloworld.rb

%w(rubygems rack thin).each{|dep| require dep }

class HelloWorld
  def call(env)
    [200, {"Content-Type" => "text/html"}, "Hello World\n"]
  end
end

reloader.rb

require 'thread'

module Rack
  # Rack::Reloader checks on every request, but at most every +secs+
  # seconds, if a file loaded changed, and reloads it, logging to
  # rack.errors.
  #
  # It is recommended you use ShowExceptions to catch SyntaxErrors etc.
  
  class Reloader
    def initialize(app, secs=10)
      puts "Initializing Reloader"
      @app = app
      @secs = secs              # reload every @secs seconds max
      @last = Time.now
    end
    
    def call(env)
      # puts "TIMING: #{Time.now} > #{@last + @secs} => #{Time.now > @last + @secs}"
      # puts "ERRORS #{(env["rack.errors"].read rescue nil).inspect}"
      
      if Time.now > @last + @secs
        Thread.exclusive {
          reload!(env['rack.errors'])
          @last = Time.now
        }
      end
      
      @app.call(env)
    end
    
    def reload!(stderr=STDERR)
      puts "reloading #{stderr}"
      need_reload = $LOADED_FEATURES.find_all { |loaded|
        begin
          if loaded =~ /\A[.\/]/  # absolute filename or 1.9
            abs = loaded
          else
            abs = $LOAD_PATH.map { |path| ::File.join(path, loaded) }.
                             find { |file| ::File.exist? file }
          end
          
          if abs
            ::File.mtime(abs) > @last - @secs  rescue false
          else
            false
          end
        end
      }
      
      need_reload.each { |l|
        $LOADED_FEATURES.delete l
      }
      
      need_reload.each { |to_load|
        begin
          if require to_load
            stderr.puts "#{self.class}: reloaded `#{to_load}'"
          end
        rescue LoadError, SyntaxError => e
          raise e                 # Possibly ShowExceptions
        end
      }
      
      stderr.flush
      need_reload
    end
  end
end