Thread safe autoload test

autoload_test.rb

require 'thread'
require 'fileutils'

# Disregard the Latch/Barrier classes, they are unimportant
class Latch
  def initialize(count = 1)
    @count = count
    @mutex = Mutex.new
    @cond  = ConditionVariable.new
  end

  def release
    @mutex.synchronize do
      @count -= 1 if @count > 0
      @cond.broadcast if @count.zero?
    end
  end

  def await
    @mutex.synchronize do
      @cond.wait @mutex if @count > 0
    end
  end
end

class Barrier < Latch
  def await
    @mutex.synchronize do
      if @count.zero? # fall through
      elsif @count > 0
        @count -= 1
        @count.zero? ? @cond.broadcast : @cond.wait(@mutex)
      end
    end
  end
end

AUTOLOAD_DIR = '____autoload_test_dir'
COUNT        = 10
THREAD_COUNT = 100

$LOAD_PATH << '.' unless $LOAD_PATH.include?('.')

def setup_autoload_modules
  FileUtils.mkdir_p(AUTOLOAD_DIR)
  mod_names = []
  
  COUNT.times do |i|
    mod_name  = :"Mod#{i}"
    file_name = "#{AUTOLOAD_DIR}/mod_#{i}.rb"
    File.open(file_name, 'w') do |f|
      f << <<-RUBY_EVAL
        module #{mod_name}
          sleep(0.3)
          def self.foo
          end
        end
      RUBY_EVAL
    end
    autoload mod_name, file_name.sub(/\.rb\Z/, '')
    mod_names << mod_name
  end
  
  mod_names
end

begin
  mod_names = setup_autoload_modules
  
  barrier = Barrier.new(THREAD_COUNT)
  
  (0..THREAD_COUNT).map do
    Thread.new do
      barrier.await
      mod_names.each do |mod_name|
        Object.const_get(mod_name).foo
      end
    end
  end.map(&:join)
ensure
  FileUtils.rm_r(AUTOLOAD_DIR) if File.directory?(AUTOLOAD_DIR)
end