Cacher is the code snippet organizer for pro developers

option_accessor :client_ttl

def call!(env)
  @trace = []
  @env = options.merge(env)
  @request = Request.new(@env.dup.freeze)

  response =
    if @request.get? || @request.head?
      if !@env['HTTP_EXPECT']
        lookup
      else
        pass
      end
    else
      invalidate
    end

  # log trace and set X-Rack-Cache tracing header
  trace = @trace.join(', ')
  response.headers['X-Rack-Cache'] = trace

  # write log message to rack.errors
  if verbose?
    message = "cache: [%s %s] %s\n" %
      [@request.request_method, @request.fullpath, trace]
    @env['rack.errors'].write(message)
  end

  # tidy up response a bit
  response.not_modified! if not_modified?(response)
  response.client_ttl = self.client_ttl
  response.body = [] if @request.head?
  response.to_a
end