ruby_constant_lookup_cache_benchmark.rb

const_lookup.rb

# ruby caches the const lookup like method lookup
# due to this no need to explicitly memonize in code
# although, i think eval will break this cache
# TODO: what will clear the const/method cache
# http://yehudakatz.com/2010/02/25/rubys-implementation-does-not-define-its-semantics/

require 'benchmark'

LOGGER = 10

module Foo
  module Bar
    Benchmark.bm { |x|
      x.report("access_once") { LOGGER }
      x.report("access_once_more") { LOGGER }
      x.report("access_again_1") { LOGGER }
      x.report("access_again_2") { LOGGER }
      x.report("access_again_3") { LOGGER }
      x.report("access_else") { 10.times { LOGGER } }
      x.report("access_last") { LOGGER }
    }
    module Again1
      module Again2
        module Again3
          module Again4
            module Again5
              module Again6
                Benchmark.bm { |x|
                  # is the same as 'access_once_more', uses the cached value 
                  x.report("access_inside_once") { LOGGER }
                  x.report("access_inside_once_more") { LOGGER }
                  x.report("access_inside_again_1") { LOGGER }
                  x.report("access_inside_again_2") { LOGGER }
                  x.report("access_inside_again_3") { LOGGER }
                }
              end
            end
          end
        end
      end
    end
  end
end

module Foo
  remove_const :Bar
end

module Foo
  module Bar
    Logger = 20
    Benchmark.bm { |x|
      x.report("access_once") { LOGGER }
      # puts LOGGER
      x.report("access_once_more") { LOGGER }
      x.report("access_again_1") { LOGGER }
      x.report("access_again_2") { LOGGER }
      x.report("access_again_3") { LOGGER }
      x.report("access_else") { 10.times { LOGGER } }
      x.report("access_last") { LOGGER }
    }
    module Again1
      module Again2
        module Again3
          module Again4
            module Again5
              module Again6
                LOGGER = 30
                Benchmark.bm { |x|
                  # time-taken is less than 'access_once' as the const is nearer in the lookup chain
                  # thereafter it is cached
                  x.report("access_inside_once") { LOGGER }
                  # puts LOGGER
                  x.report("access_inside_once_more") { LOGGER }
                  x.report("access_inside_again_1") { LOGGER }
                  x.report("access_inside_again_2") { LOGGER }
                  x.report("access_inside_again_3") { LOGGER }
                }
              end
            end
          end
        end
      end
    end
  end
end

__END__

task "resque:setup" => :environment do
  require 'stdout_logger'
  logger = StdoutLogger.new_logger
  Kernel.const_set(:RESQUE_LOGGER, logger)
  ActiveRecord::Base.logger = logger
  Kernel.const_set(:RAILS_DEFAULT_LOGGER, logger)
end

class ResqueTask
  def logger
    RESQUE_LOGGER
  end
  
  def self.logger
    RESQUE_LOGGER
  end
end