класс Rails::Rack::Logger

# File railties/lib/rails/rack/logger.rb, line 15
def initialize(app, taggers = nil)
  @app          = app
  @taggers      = taggers || []
end

# File railties/lib/rails/rack/logger.rb, line 20
def call(env)
  request = ActionDispatch::Request.new(env)

  env["rails.rack_logger_tag_count"] = if logger.respond_to?(:push_tags)
    logger.push_tags(*compute_tags(request)).size
  else
    0
  end

  call_app(request, env)
end

# File railties/lib/rails/rack/logger.rb, line 33
def call_app(request, env) # :doc:
  logger_tag_pop_count = env["rails.rack_logger_tag_count"]

  instrumenter = ActiveSupport::Notifications.instrumenter
  handle = instrumenter.build_handle("request.action_dispatch", { request: request })
  handle.start

  logger.info { started_request_message(request) }
  status, headers, body = response = @app.call(env)
  body = ::Rack::BodyProxy.new(body) { finish_request_instrumentation(handle, logger_tag_pop_count) }

  if response.frozen?
    [status, headers, body]
  else
    response[2] = body
    response
  end
rescue Exception
  finish_request_instrumentation(handle, logger_tag_pop_count)
  raise
end

# File railties/lib/rails/rack/logger.rb, line 64
def compute_tags(request) # :doc:
  @taggers.collect do |tag|
    case tag
    when Proc
      tag.call(request)
    when Symbol
      request.send(tag)
    else
      tag
    end
  end
end

# File railties/lib/rails/rack/logger.rb, line 56
def started_request_message(request) # :doc:
  sprintf('Started %s "%s" for %s at %s',
    request.raw_request_method,
    request.filtered_path,
    request.remote_ip,
    Time.now)
end