Impact of Methodological Choices on the Analysis of Code Metrics and Maintenance

The repo-data folder contains 53 .json files, each corresponding to one of the 53 Java open-source projects. Each file contains various metrics for methods in the project.

 {
        "hawtio-3976.json": {
            "Age": 794,
            "sloc": [11,11,11],
            "slocAsItIs": [11,14,14],
            "slocNoCommentPretty": [11,11,11],
            "diffSizes": [0,7,0 ],
            "bodychanges": [0,1,0], 
            "newAdditions": [0,5,0],
            "isGetter": [false,false,false],
            "isSetter": [false,false,false],
            "changeDates": [0,3,794],
            "isEssentialChange": [false,true,false],
            "isBuggy": [false,false,false],
            "changeTypes": ["Yintroduced","Ybodychange","Yfilerename"],
            "filename": "hawtio-3976.json",
            "authors": ["X","Y","Z"],
            "editDistance": [0, 68, 0],
            "repo": "hawtio"
        },
        "method_id": {...},
        "method_id": {...}
    }

The above method with id hawtio-3976.json has total 3 revisions which is why the array of values for a particular metric (e.g., sloc: [11,11,11]) are of length 3. Index 0 of the array represents the introduction value of a particular metric for the above method.

• Age: Age of the method in days
• sloc: Source line of code of a method without comment and blank lines
• slocAsItIs: Source line of code of a method with comment and blank lines
• slocNoCommentPretty: Source line of code pretty printed without comment and blank lines
• diffSizes: Total number of lines added + removed in git diff
• bodychanges: Contains value 0 or 1; where 1 implies occurrence of body change
• newAdditions: Total number of lines added in git diff
• isGetter: Contains true or false; where true indicates it is a get method
• isSetter: Contains true or false; where true indicates it is a set method
• changeDates: Contains the date difference in days from when the method was introduced. Index 0 is always 0 which indicates the introduction date
• isEssentialChange: Contains true or false; where true indicates it is an essential change. Essential change includes: Ybodychange, Ymodifierchange, Yexceptionschange, Yrename, Yparameterchange, Yreturntypechange and Yparametermetachange detected by CodeShovel
• isBuggy: Contains true or false; where true indicates the method bug was fixed at a particular revision
• changeTypes: All transformations applied to the method at each revision. The full list of transformation that is detected by CodeShovel are: Ybodychange, Ymodifierchange, Yexceptionschange, Yrename, Yparameterchange, Yreturntypechange, Yparametermetachange, Yannotationchange, Ydocchange, Yformatchange, Yfilerename and Ymovefromfile
• filename: It is the method id


  bugData folder contains 53 .json files with bug information, each belonging to one of the 53 Java open-source projects. The sample JSON schema of a file is given below:

  {
      "hawtio-3976.json":{
          "exactBug0Match": [false, false, false],
          "exactBug1Match": [false, false, false],
          "exactBug2Match": [false, false, false],
          "exactBug3Match": [false, false, false],
          "regExBug0": [false, false, false],
          "regExBug1": [false, false, false],
          "regExBug2": [false, false, false],
          "regExBug3": [false, false, false]
      },
      "method_id": {...},
      "method_id": {...},
  }

  The above method can be mapped to its metrics dataset using the method_id. For e.g., the above method with id hawtio-3976.json in bugData/hawtio.jsonthat has 3 revision can be found in the metric dataset using the same id hawtio-3976.json in the file repo-data/hawtio.json.
  Description of bug dataset

  Each key in the above example contains value true or false indicating if a method was buggy or not at each revision. The "hawtio-3976.json method has 3 revisions (including method's introduction) which is why the array length is 3. The keys in the above json output represent bug-fix classification based on buggy keywords adopted from prior work.

  We identified bug-fix commit using two approaches:

      Exact case insensitive match of buggy keywords from the commit message (keys prefix wih exact represent this)
      Partial case insensitive substring match (using regular expression) excluding words that ends with fix or bug. (keys prefix with regEx represent this)

      Bug0: This is the approach that we have used for classifying bug-fix commit. Buggy keyword list: ["error", "bug", "fixes", "fixing", "fix", "fixed", "mistake", "incorrect", "fault", "defect", "flaw"]
      Bug1: Same keyword list as exactBug0Match with the addition of keyword issues
      Bug2: Buggy keyword list from prior work: ["bug", "fix", "error", "issue", "crash", "problem", "fail", "defect", "patch"]
      Bug3: Buggy keyword list from prior work: ["error", "bug", "fix", "issue", "mistake", "incorrect", "fault", "defect", "flaw", "type"]