Prediction and ranking of co-change candidates for clones

Abstract

Code clones are identical or similar code fragments scattered in a code-base. A group of code fragments that are similar to one another form a clone group. Clones in a particular group often need to be changed together (i.e., co-changed) consistently. However, all clones in a group might not require consistent changes, because some clone fragments might evolve independently. Thus, while changing a particular clone fragment, it is important for a programmer to know which other clone fragments in the same group should be consistently cochanged with that particular clone fragment.In this research work, we empirically investigate whether we can automatically predict and rank these other clone fragments (i.e., the co-change candidates) from a clone group while making changes to a particular clone fragment in this group. For prediction and ranking we automatically retrieve and infer evolutionary coupling among clones by mining the past clone evolution history. Our experimental result on six subject systems written in two different programming languages (C, and Java) considering both exact and near-miss clones implies that we can automatically predict and rank co-change candidates for clones by analyzing evolutionary coupling. Our ranking mechanism can help programmers pinpoint the likely co-change candidates while changing a particular clone fragment and thus, can help us to better manage software clones.

Evaluating Performance of Clone Detection Tools in Detecting Cloned Cochange Candidates

“…This scenario shows that a good clone detector can perform poorly in detecting cloned co-change candidates if it does not detect enough clone fragments and does not cover enough unique lines by those clone fragments in the source file. Though, earlier study [5] suggests that NiCad is an excellent clone detector in both of these cases, it falls at the bottom of the list. Even though NiCad performs very well in detecting clone fragments, it provides a lower number of clone fragments and also the lower number of line coverage by those clone fragments in the software systems.…”

“…We also consider the availability of substantial revisions and diversity in size and application domain as an essential factor for subject systems to produce a generalizable investigation result for this study. Besides these, we also reviewed some related studies [6,3,4,5] and the programming language used in these subject systems. Considering all of these factors, we have selected the subject systems used in this study.…”

Evaluating the Performance of Clone Detection Tools in Detecting Cloned Co-change Candidates

“…Our point of interest is to detect cloned co-change candidates during the software commit operations. Mondal et al [5] used the detected clone results of Nicad to predict and rank both the cloned and dissimilar co-change candidates (CCC and DCC) by analyzing evolutionary coupling from previously made change history. However, no other clone detection tool is included in their study to compare the performance of different clone detection tools in their prediction and ranking technique.…”

“…A single commit operation may contain both related and independent changes. Related changes are known as co-change candidates in the literature [5], which represents a group of changes. Suppose any code fragment of a co-change group is experiencing any update.…”