# File lib/rack/runtime.rb, line 15 15: def call(env) 16: start_time = Time.now 17: status, headers, body = @app.call(env) 18: request_time = Time.now - start_time 19: 20: if !headers.has_key?(@header_name) 21: headers[@header_name] = "%0.6f" % request_time 22: end 23: 24: [status, headers, body] 25: end