Where does this code come from and where does it go? — Integrated code history tracker for open source systems

When we reuse a code fragment in an open source system, it is very important to know the history of the code, such as the code origin and evolution. In this paper, we propose an integrated approach to code history tracking for open source repositories. This approach takes a query code fragment as its input, and returns the code fragments containing the code clones with the query code. It utilizes publicly available code search engines as external resources. Based on this model, we have designed and implemented a prototype system named Ichi Tracker. Using Ichi Tracker, we have conducted three case studies. These case studies show the ancestors and descendents of the code, and we can recognize their evolution history.