TimelyRep: Timing deterministic replay for Android web applications.

With the constantly growing and changing requirements of app users, web techniques are used in mobile application development for better cross-platform compatibility and online update. As the embedded web contents gain complexity, debugging web apps become a critical demand. Web replay tools can record program inputs and reproduce the same execution for debugging and performance tuning. However, traditional replay approaches are largely intended for apps with desktop interaction methods (keyboard, mouse) and require modification to the browser, which limits their applicability in mobile platforms. In this paper, we develop TimelyRep, which provides deterministic record-and-replay as a software library, running on commodity Android. TimelyRep can be used for app development with unmodified Android devices and for production to collect faulty execution from users. Also, we propose an efficient replay timing control mechanism and achieve higher timing precision as facing higher event rate on touchscreen devices. TimelyRep also supports cross-device replay and can replay logged event traces on different devices, which is useful for developers to reproduce user inputs on their own devices. We evaluate TimelyRep with real-world web applications. The results show that TimelyRep is useful for recreating program bugs and maintaining low delays for touch-intensive web games.